Dissertations / Theses on the topic 'Regeneration'

The United Kingdom’s seaside resorts are in decline. This has been addressed by various regeneration strategies. The Gambling Act 2005 threw a potential lifeline to some seaside resorts that wished to utilise casinos as cultural regeneration tools. However, this is a unique example of a regeneration lever that generates new policy processes. This thesis explores the development and passage of the casino regeneration strategy in three seaside resorts: Great Yarmouth, Scarborough and Torbay. All of these resorts had differing cultural and socio-economic contexts. Linking the perceptions of this type of cultural development demanded a specific methodology. Casinos are cultural objects and social spaces. The intersection of the cultural, economic and social demanded an overarching theoretical guide within which these perceptions could be explored. Of particular value was the work of Lefebvre in his core work on ‘The Production of Space’ (1991) and du Gay et al. ‘Circuit of Culture’ (1997). How policymakers, business and community representatives conceived casino spaces was explored through the regulatory environment at the national, regional and local levels of governance. The perception of how casino spaces should be produced to arrive at culturally compatible representations and identities for consumption followed. It was found that the regulatory environment was experimental and confusing to some. However, most interviewees wanted to see large casino complexes developed in their towns. Potential moral, social and cultural hazards were perceived but not to have been fully considered in the government’s strategy, however the economic advantages outweighed these. This study argues that further research is required into this contested cultural activity, and the spaces that house that activity once they are built and operating.

Liver injury stimulates hepatocyte proliferation, regenerating the liver through self-replication. In cases where there is severe, repetitive, parenchymal damage, as seen in human chronic liver disease, hepatocyte mediated regeneration becomes impaired. In this setting it is currently unclear whether endogenous biliary epithelial cells can repopulate the hepatocyte compartment. This thesis therefore aimed to address this point by lineage tracing the main two liver epithelia populations on a background of impaired hepatocyte regeneration. To impair regeneration, an Itgb1 transgene was specifically deleted, conditionally, from the hepatocyte epithelium. Long-term loss of β1-Integrin alone or with additional injury caused an epithelial ductular reaction of biliary origin. Alongside β1-Integrin ablation, the hepatocyte epithelium was also labelled with a heritable ROSA26LSLtdTomato reporter. Impaired hepatocyte regeneration mediated by β1- integrin ablation resulted in 25% of hepatocytes becoming tdTomato negative (non-hepatocyte derived). To verify that the non-hepatocyte mediated regeneration was originating from the biliary epithelium, anti-Itgb1 RNAi was administrated to K19CreERT LSLtdTomato mice. Resulting in tdTomato positive hepatocytes that had differentiated from the labelled tdTomato positive biliary epithelial cells. In summary, this thesis demonstrates that hepatocyte β1-Integrin ablation combined with toxic damage causes marked ductular reactions and results in a substantial regeneration of functional hepatocytes from the biliary epithelium.

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária
Em Medicina Dentária a taxa de incidência de patologia pulpar é elevada. Atualmente o tratamento realizado nestes casos passa pelo tratamento endodôntico não cirúrgico e obturação do sistema tridimensional de canais do dente permanente e maturo necrosado. Quando o tecido pulpar sofre necrose o prognóstico do dente está comprometido. Até então a abordagem terapêutica nestes casos passa por tratamento dos canais radiculares no caso de dentes com ápices maduros, apexificação em dentes com ápice imaturo ou extração. Apesar de estas modalidades terapêuticas apresentarem elevadas taxas de sucesso, a presença de uma polpa vital é fundamental para manter a homeostase e longevidade da peça dentária. Uma forma de terapia ideal pode consistir em abordagens regenerativas que consistem na remoção e substituição da polpa danificada ou necrosada por tecido pulpar saudável de forma a revitalizar o dente. Para atingir este objetivo os investigadores têm estudado diversas técnicas: revascularização por coágulo sanguíneo, terapia com células estaminais, implantação pulpar, implantação de scaffold, impressão tridimensional celular, scaffold injetável e terapia genética. Este tipo de tratamentos envolve combinação de desinfeção, desbridamento do canal afetado, utilização de células estaminais adultas, scaffolds e fatores de crescimento. Pode ser necessário também o alargamento apical para permitir a revascularização. Com esta revisão pretende-se compreender melhor o procedimento de revascularização pulpar no geral, vantagens e desvantagens, sua aplicabilidade na prática clinica diária e aferir sobre os resultados obtidos na literatura. Apesar de os desafios para a introdução das técnicas regenerativas como tratamento alternativo de dentes necrosados serem substancias, estas podem ser benéficas pois apresentam a possibilidade de restabelecer a funcionalidade pulpar, tornando a polpa vital capaz de promover a correta maturação apical. A inexistência de um protocolo fiável de atuação que permita a criação das condições necessárias para que ocorra a revitalização do tecido torna este tratamento pouco utilizado como tratamento alternativo na prática clinica. Assim, mais estudos são necessários para que futuramente seja possível elaborar um protocolo que possibilite a introdução das técnicas de revascularização pulpar na prática clinica diária. Dentistry in the incidence rate of pulpal pathology is high. Currently the treatment performed in these cases through the nonsurgical endodontic treatment and obturation of the three-dimensional system of permanent tooth and necrosed mature channels. When the pulp tissue undergoes necrosis prognosis of the tooth is compromised. Until then the therapeutic approach in these cases involves treatment of root canals in the case of teeth with mature apices, apexificação in teeth with immature apex or extraction. Despite these therapeutic modalities have high success rates, the presence of a vital pulp is essential to maintain homeostasis and longevity of tooth number. An ideal form of therapy might consist of regenerative approaches involving the removal and replacement of damaged or necrotic pulp by healthy pulp tissue to revitalize the tooth. To achieve this goal researchers have studied various techniques: revascularization by a blood clot, stem cell therapy, pulp, implantation of scaffold, cell dimensional printing, injectable scaffold and gene therapy. This type of treatment involves combination of disinfection, debridement of the affected channel, use of adult stem cells, scaffolds and growth factors. You may also need the apical enlargement to allow revascularization. With this revision is intended to better understand the procedure of pulp revascularization in general, advantages and disadvantages, its applicability in daily clinical practice and benchmark the results obtained in the literature. Although the challenges for the introduction of regenerative techniques as an alternative treatment of necrotic teeth are substances, these can be beneficial since they have the ability to restore functionality pulp making the vital pulp capable of promoting correct apical maturation. The absence of a reliable protocol operation that allows the creation of conditions necessary for the revitalization of the fabric makes this treatment occurs rarely used as an alternative treatment in clinical practice. Thus, further studies are needed, in future be possible to develop a protocol which would include the pulp revascularization in endodontics.

In a world of excess, people rarely stop to realize their impact on their environments. Our built environment is especially feeling the effect of our irresponsibility, and the solution is only a matter of re-wiring our perceptions of energy usage. Many technologies make it possible to have the impossible, but nobody stops to question whether or not these advances are beneficial. A presumably sustainable system turned out to be one of the most energy wasteful ones in existence. In the complex process of getting food from the field to your house, the best solution is to simplify. Nature will do most of the work; we need to learn to work with it. Current building practices can benefit greatly from this concept, to rethink the existing process by simply cutting out the unneeded steps and using the free energy available to us every day. Our values need to change. Because the corporation controls so much of our daily lives, they are the ones that will bring about the change in consciousness we desperately need. By re-designing Sysco headquarters to do everything that the company claims to do (and currently doesn't), and interact with the public in a new and radical way, not only can we make changes to how we think about the built environment, but we can also start to show that a change in awareness is entirely possible. If we can change the values of those that make the biggest differences in our world, then we've effectively changed an entire populations' way of thinking.

AURAL REGENERATION by MYRNA LEE PRONCHUK Under the Direction of Craig Dongoski ABSTRACT The aim of this thesis is to survey the abstraction of the human experience obscuring the confines between form and expression, sound and visual, experience and imitation. In establishing multiple levels of communication, I began with gathering discarded found objects, which I repurposed through building hybrid musical sculptures. The act of mark making mapped out systems and direction, and escalated into a form of hybrid musical notation. Both forms of hybrids informed each other in its development process. When the hybrid instruments and notation were placed in an environment together with the elements of Digital Signal Processing (DSP), it created a natural progression for performance. The objects required interaction: to be hit, tapped, bowed and plucked, with their sounds processed through DSP, and projected back into the audience, who participated in creating interactivity. In producing mechanical musical instruments, along with mark making, installation and experimental sound recordings, a platform is established allowing for a dialogue between audio and visual elements, and human experience.

Skeletal muscle regeneration is dependent upon the influences of intrinsic and extrinsic factors that stimulate satellite cells. Regenerating proteins are upregulated at the onset of trauma or inflammation in the pancreas, gastrointestinal tract, liver, neural cells and other tissues. Studies have shown that Reg proteins have a mitogenic, anti-apoptotic and anti-inflammatory function in damaged tissues and is necessary for normal progression of regeneration. As skeletal muscle is also able to regenerate itself at a rapid rate, it seems highly likely that Reg proteins function to promote myogenesis in skeletal muscle regeneration. Therefore, the goal of our research was to characterize the expression of the Reg proteins and receptor in regenerating skeletal muscle and satellite cells, investigate the effect of exogenous Reg protein on myogenesis, and to examine direct Reg protein effect on satellite cell activity. To determine whether Reg proteins participate in skeletal muscle regeneration, mice were injected with marcaine in their tibialis anterior muscles to induce skeletal muscle damage. The gene expression analysis of undamaged and marcaine-damaged tibialis anterior muscles and mice satellite cells showed that Reg I, II, IIIα, IIIγ, IV and EXTL3 genes are present during skeletal muscle regeneration and satellite cells significantly express Reg I, IIIα, IIIγ and EXTL3. As Reg I and IIIα are most prevalent in vivo and in vitro respectively, we advocate these isoforms as the predominant candidates in skeletal muscle regeneration. To determine the effect of exogenous Reg protein on myogenesis, we performed gene expression and muscle morphometry analysis of Reg IIIα or PBS injected tibialis anterior muscles. Interestingly, our results indicate that the addition of Reg IIIα to damaged muscles inhibited myogenesis. To determine the direct effect of Reg protein on myogenic stem cell activity, Reg proteins were added to mice satellite cells and C2C12 cells. Results from these studies were inconclusive due to the failure of known positive and negative controls. Overall, our studies suggest that Reg proteins contribute to skeletal muscle regeneration; however, as an overabundance of Reg IIIα in regenerating tissues may have inhibited myogenesis, it is imperative that other isoforms or lower concentrations be investigated.

This dissertation investigates the latent potential of the mining belt in Johannesburg through a regenerative theory, by placing a catalytic intervention which respects the heritage of the mining belt, with a focus on the ecology and the socio-economic value of the land has, thereby turning a liability into an asset. This intervention is seen as the first point of acupuncture in a long rehabilitation process and focuses on using this space to deal with context specific issues. The proposed intervention will investigate the potential of architecture to activate a harmed dormant space in the realm of a decentralized city node. It recognizes the potential of the currently fragmented mining belt to become a gateway to the South of Johannesburg, and embraces an opportunity to restitch the urban fabric.
Mini Dissertation MArch(Prof)--University of Pretoria, 2018.
Architecture
MArch(Prof)
Unrestricted

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1987.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Bibliography: leaves 126-134.
by Carl P. Tausczik.
Ph.D.

The esophagus is critical for passage of oral bolus into the gastrointestinal tract. Diseases of the esophagus, such as malignancy, can necessitate resection of esophageal tissue. To maintain esophageal continuity with the remainder of the gastrointestinal tract, reconstruction is mandatory. Current reconstructive options are morbid and involve autologous conduits such as stomach, small bowel, or colon. An alternative tissue engineered conduit that facilitates esophageal regrowth to reduce the need for these morbid reconstructions would have significant clinical utility. Several critical challenges must be addressed in order to make these conduits a clinical reality. First, scaffolds should be designed to ideally mimic mechanical behavior of the native esophagus. To accomplish this, a non-destructive method to mechanically assess these constructs benchmarked to native esophagi is necessary before and after implantation. Second, scaffolds should be both biocompatible and mechanically stable in vitro; this would allow selection of desirable candidates for subsequent in vivo testing. Finally, in vivo testing of the esophageal conduit requires development of an analogous large animal model to human disease. In vivo large animal model testing is required as proof of concept for esophageal regeneration as a critical step toward future human use.3

Bone defects caused by trauma, tumor resection or disease present a significant clinical problem. Failures in 'high risk' fractures and large bone defects have been reported to be as high as 30-50%. The drawbacks associated with current bone grafting procedures have stimulated the search for improved techniques for bone repair. Tissue engineering/regenerative medicine approaches promote tissue repair by providing a combination of physical and biological cues through structural scaffolds and bioactive agents. Though they have demonstrated significant promise for bone regeneration, very little has been translated to clinical practice. The goal of this thesis was to investigate the potential of electrospun nanofiber mesh scaffolds for bone regeneration. Nanofiber meshes were utilized in a three-pronged approach. First, we validated their ability to robustly support osteogenic cell functions, including proliferation and matrix mineralization. We also demonstrated their efficacy as a cell delivery vehicle. Second, we investigated the effects of modulating nanofiber bioactivity and orientation on stem cell programming. Our results indicate that functionalization of nanofiber meshes with a collagen-mimetic peptide enhanced the migration, proliferation and osteogenic differentiation of cells. Fiber alignment improved cell migration along the direction of fiber orientation. Finally, a nanofiber mesh based hybrid system for growth factor delivery was developed for bone repair and tested in a challenging animal model. The delivery of bone morphogenetic protein (BMP) via this system resulted in the functional restoration of limb function, and in fact proved more efficacious than the current clinical standard for BMP delivery. The studies performed in this thesis have suggested novel techniques for improving the repair of clinically challenging bone defects. They indicate that the delivery of BMP via the hybrid system may reduce the dose and side effects of BMP, thereby broadening the use of BMP based bone augmentation procedures. Therefore, this nanofiber mesh based system has the potential to become the standard of care for clinically challenging bone defects, including large bone defects, open tibial fractures, and nonunions.

Severe extremity trauma often involves significant damage to multiple tissue types, including bones, skeletal muscles, peripheral nerves, and blood vessels. Such injuries present unique challenges for reconstruction, and improving structural and functional outcomes of intervention remains a pressing, unmet clinical need. While tissue engineering/regenerative medicine (TE/RM) therapeutics offer promising potential to overcome the status quo limitations of surgical reconstruction, very few products have transitioned to clinical practice. Improving treatment options will likely require advancing our understanding of the biological interactions occurring in the repair of damaged tissues. Bone tissue is known to be innervated and highly vascularized, and both tissue types are involved in normal bone physiology. However, the degree to which these tissue relationships influence the repair of large, multi-tissue defects remains unknown. Accordingly, the goal of this thesis was to investigate tissue regeneration in two novel composite injury models. First, we characterized interactions in a composite bone and nerve injury model where a segmental bone defect was combined with a peripheral nerve gap. Our results indicated that although tissue regeneration was not impaired, the composite injury group experienced a marked functional deficit in the operated limb compared to single-tissue injury. Second, we developed a model of composite bone and vascular extremity trauma by combining a critically-sized segmental bone defect with surgically-induced hind limb ischemia to evaluate the effects on BMP-2-mediated bone repair. Interestingly, our results demonstrated a stimulatory effect of the recovery response to ischemia on bone regeneration. Finally, we investigated early vascular growth and gene expression as potential mechanisms coupling the response to ischemia with bone defect repair. Although the response to ischemia promoted robust vascular growth in the thigh, it did not directly augment vascularization at the site of bone regeneration. In addition, the stimulatory effects of ischemia on bone regeneration could not be explained by gene expression alone based on the genes and time points investigated. Taken together, this thesis presents pioneering work on a new thrust of TE/RM research – tissue regeneration in models of composite injury. This work has provided new insights on the complexity of composite tissue repair, specifically in regard to the relationship between vascular tissue growth and bone healing. Going forward, successful leverage of models of composite tissue injuries will provide valuable test beds for screening new technologies, advance the understanding of tissue repair biology, and ultimately, may produce new therapeutic interventions for limb salvage and reconstruction that improve outcomes for extremity trauma patients.

Culture-led regeneration policy has become a global trend in many major cities worldwide (UNCHS, 2004; Miles and Paddison, 2005). While overseas governments such as the United Kingdom, Japan and Australia have directed their regeneration policies to encourage the creative class and industries; Hong Kong is again left behind. Some scholars suggest that the culture-led strategy can act as the twenty-first century driver for regeneration, able to better preserve social networks and capital, and hence bring greater benefit to the local residents (Szeto, 2007). However, the methods of promoting culture-led regeneration in the Hong Kong context are rarely discussed. In addition, to what extend urban planning could help to facilitate creative class, and its possible impact on local residents is yet to be studied. This dissertation therefore has a two-way focus; on one hand, it seeks to address the research gap on how culture-led regeneration can be implemented in Hong Kong; on the other hand, it contributes to the academic debate by exploring the mechanism of capitalising culture in a regeneration project in order to maximise the ways at which local residents can truly benefit. It is often assumed that the integration of cultural production, consumption and community art programmes bring about the greatest benefits for the local economy, and hence benefit the locals by ‘trickle down’ effect (Binns, 2005). However, this dissertation argues that the community and its institutions play an important role in distributing the wealth created by culture-led redevelopment. While gentrification as well as the displacement of local residents, is usually observed in culture-led regeneration, progressive community planning and community ownership of the ‘Common’ can help in breaking the monopoly of rent and fixed capitals, to the benefit of local residents. The case of Hoxton – with the success of its local organizations in reducing the pressures of gentrification – is studied alongside with a case of similar background, Noho, Hong Kong, to explore new research and enlighten a possible new policy direction of culture-led regeneration in Hong Kong. Both cases are led by artists and creative industries in the area with the aim of revitalizing poor local economies. In light of this, the two cases are compared to firstly address the research gap on the community role in a sustainable culture-led regeneration, and then to enlighten a possible new policy direction of culture-led regeneration in Hong Kong.
published_or_final_version
Urban Planning and Design
Master
Master of Science in Urban Planning

Ability to regenerate is found in many groups of metazoans but the majority of research is focused on adults from just a few taxa, such as planarians and hydra (Agata and Inoue, 2012; Bely et al., 2014). Increasing the diversity of study organisms and life stages can reveal new and interesting aspects of regeneration mechanisms. This study focuses on regeneration of the nemertean pilidium larva. The planktotrophic pilidium of Maculaura alaskensis provides a unique model in which to observe several components of the regeneration process. Here I have documented a timeline for regeneration and have begun to evaluate the cells responsible for regenerative success. This study has revealed the interplay between regeneration and degeneration, a tradeoff between larval and juvenile structures, as well as the important relationship between global versus local signaling in proliferation and differentiation responses.

This thesis examines a recent trend in contemporary science and speculative fiction to produce new and/or alternative iterations of reproduction that are not limited by biology, gender, or species. Through Donna Haraway’s notion of “cyborg regeneration” and recent critical and theoretical revisionings of this concept, I investigate this trend in three key texts: Jeanette Winterson’s The Stone Gods, Nalo Hopkinson’s Midnight Robber, and Larissa Lai’s long poem “rachel” from her book of poetry Automaton Biographies. Each of these authors offers representations of reproduction that counter gender stereotypes and essentialism and produce new cyborg maternal or explicitly non-maternal figures unbound to patriarchal models of repronormativity and colonialist constructions of the mother. By portraying these nonunitary maternal figures and/or non-reproductive bodies, I argue that these sf texts present new forms of procreation that further feminist conversations about gender, the body, the limits of the human, future populations, and desire.

There is continuing academic and policy interest in the potential for culture-based urban regeneration, including the use of major arts and cultural festivals to attract investment, re-imagine places and create jobs. However, the social regeneration benefits of such events have been questioned especially when cultural events focus mainly on high profile economic development in central areas of a city. Social regeneration needs to be built into cultural event planning. This research seeks to examine how a one-year cultural event can play an influential role in aspects of social regeneration by focusing on the 2015 Culture City of East Asia (CCEA) event in Cheongju, South Korea. The CCEA is a collaboration between South Korea, China and Japan held since 2014, and is aimed at cultural exchange programmes, the development and regeneration of provincial cities through cultural programmes, and building solidarity in the East Asia regions. The research is based on document review, semi-structured interviews and focus groups with residents and community representatives in three areas of deprivation in the city. The key findings from the PhD are that social regeneration impacts are limited with limited engagement with the CCEA. The limited social regeneration impact is traced to the weak integration of social regeneration priorities and provision within the CCEA. It is argued that the CCEA reflects the wider tendency for cultural events to focus on visitors to the area, where main cultural venue is located, and reimaging at the expense of social regeneration. In the Korean context the weak dimension of social regeneration is reinforced by the weak and limited aspect of social regeneration nationally. In the CCEA the potential to engage communities through arts and culture is largely unrealised despite some prospect and pressure to widen the scope of the programme. The PhD contributes a distinctive Korean perspective to the literature on arts and culture- based regeneration. As this study relies on qualitative methods, it enables a deeper analysis of social regeneration, and local residents were placed into a high priority to attempt to produce a realistic consideration of how residents consider a cultural approach for regenerating an area, developing communities and individual environments. The findings of this thesis not only advance theory within the culture-led urban regeneration literature, but also offer an insight into the opinions of actual residents that can be referred to in the further management of cultural events, to improve the social regeneration through cultural approach.

Die Anwendbarkeit von Mikrowellen zur Regeneration von Dieselpartikelfiltern im Pkw-Bereich wird untersucht und im Rahmen dessen ein mikrowellenbasiertes Regenerationsmodul entwickelt. Hierbei wird ein neuer Lösungsansatz verfolgt, der auf der Anwendung einer mikrowellentransparenten Keramik basiert. Statt einer gleichmäßigen Erwärmung des Filters wird eine selektive Erwärmung des Rußes mit einem Weiterwandern des Mikrowellenfeldes nach Rußabbrand angestrebt. Am Anfang stehen temperaturabhängige Mikrowellenabsorptionsuntersuchungen verschiedener marktüblicher und neuer Filterkeramiken. Hierfür wird ein Messverfahren entwickelt. Weiter wird ein Verfahren zur Bestimmung der Dielektrizitätszahl dargestellt. Mit dem Programm FEMLAB werden Modellrechnungen hinsichtlich der Mikrowellen- und Wärmequellenverteilung verschiedener Applikatorformen durchgeführt. Die Bewertung der Eignung erfolgt mittels eines Wärmebilanzmodells, welches die maximale Rußtemperatur entlang eines Filterkanals unter Berücksichtigung von Wärmeverlusten durch die Kanaldurchströmung berechnet. Als Ergebnis werden ein Mehrwegefiltermodul und ein Regenerationsverfahren vorgestellt, welche an einem Motorenversuchsstand getestet werden. Bei dem Test konnten 75 % des Rußes regeneriert werden, wobei noch von weiterem Optimierungspotential ausgegangen werden kann.

Ceric sulfate slurries were regenerated electrochemically from cerous sulfate slurries in 1.6 molar sulfuric acid using a labsize tube and wire electrochemical cell. The cell consisted of a platinised titanium tube as the anode and a tungsten wire as the cathode. The reactor was run in a batchwise fashion. The anode to cathode area ratio was eleven. The dissolved ceric sulfate concentration was varied from 0 to 0.5 molar whereas the total cerium concentration was varied from 0.5 to 0.8 molar. The anode current density was varied between 90 and 250 mAmps/cm² with a corresponding cathode current density of 1000 to 2800 mAmps/cm². All runs were conducted at 50 degrees Celsius and atmospheric, or slightly above atmospheric, pressure. In a separate voltametric study, the technique of linear sweep voltammetry was applied to both anode and cathode. Current interruption was used to correct for the iR-drop at the cathode. However, any theoretical or mechanistic modelling attempts based on the obtained kinetic data were unsuccessful. This is attributed to the presence of a highly unstable system due to the presence of adsorption processes at both cathode and anode. The potential and current readings changed with time as the thickness and nature of the adsorbed layer changed. An empirical model, based on the data from the flow reactor, illustrated that an increase in electrolyte velocity (from 1.1 to 2.8 m/sec), an increase in total cerium concentration, or a decrease in the superficial current density gave an increase in the cell current efficiency for cerium(IV). Some other important qualitative findings were: • The dissolved cerous sulfate concentration was found to be a function of the dissolved ceric sulfate concentration as well as the total cerium concentration. • It was observed that the presence of cerium sulfate solids led to an inhibition of mass transfer at the anode, resulting in a reduced electrode current efficiency for cerium(IV). • Adsorption of cerium sulfate species on the cathode inhibits the cerium reduction reaction.The electrode current efficiency for hydrogen was never observed to be lower than 94 percent.
Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate

This thesis analyses the factors influencing the purchase of vinyl records by the members of generation Y in Sweden. Two interviews with local stores owners as well as a survey were perfomed in this regard.

The design quality in the public realm can have a profound effect on the quality of life experienced within it. An environment in which people can feel safe and which helps to foster a sense of civic pride within communities can have a positive effect in terms of social cohesion and collective wellbeing. The research considers both the hard and soft issues within this context exploring both aspects of the physical built environment as well as the social element of communities. The role of designers and design thinking in the 21'1 century extends far beyond the traditional view of the creation of a manufactured object in terms of its form, function and material. Product Designers now operate in a wider labour market and their skills are utilised in service, interaction and experience design among others in a transdisciplinary mode of design and design thinking. There is an opportunity in regeneration for design thinking to assist in the design of urban environments which positively impact on quality of life and deliver sustainable outcomes for communities. This research investigates the case for design-led responses to regeneration and the issues which it aims to address drawing on primary data collected from a workshop, interviews and project all directed by the Author as well as case studies of UK and European cities. The thesis also deals with the identification of a correlation between quality of life and quality of environment, highlights the visual impact of the environment and considers retrospectively the impact of major events and flagship buildings. From this research thesis offers Design and Implementation Guidelines with regards to regeneration for the benefit of communities and concludes that design and design thinking can have a positive impact in this area by utilising the skill set of designers and the design process as a methodology. It is also suggested that cities must place greater importance on the health and social issues which affect communities with the context of regeneration and that the design process provides a platform from which to achieve the case specific outcomes which are required in order to provide lasting and viable solutions.

Changes in the structural organization of cartilage and synovial tissue, or in the macromolecules produced by their cells, alter the properties of the tissues. Elucidation of the changes under controlled experimental conditions could make a significant contribution to the understanding of the pathogenesis of arthritis. To this end a model system has been developed to study proteoglycan and collagen regeneration in porcine articular cartilage and synovial tissue: partially depleted of matrix by exogenous enzyme(s), the tissues were maintained in organ culture, the medium consisting of Dulbecco's modification of Eagle's medium and 15% rabbit serum, and the responses of the chondrocytes and synoviocytes studied biochemically and histologically. Cleavage of proteoglycan core protein in cartilage explants by trypsin, equivalent to the disruption occurring in joint inflammation, induced glycosaminoglycan synthesis. The chondrocytes, particularly of the mid and hypertrophic zones, acquiring a basophilic territorial matrix and eventually an interterritorial matrix, which replaced the ex vivo material. Further damage to collagen by bacterial collagenase induced collagen synthesis, and enhanced glycosaminoglycan synthesis, but hyaluronic acid disruption proved partially inhibitory to recovery, the interterritorial matrix being less basophilic than comparable trypsinized explants. ³⁵SO₄ uptake by depleted explants showed a similar but sustained rate of glycosaminoglycan synthesis compared with untreated explants. The effects of corticosteroids, currently used for the temporary palliation of joint inflammation, on the regeneration processes were studied. The hydrolytic potential of the cultures and the frequency of medium changes had a profound effect on biologically active cortisol levels when cortisol succinate was present. Lower than physiological levels of cortisol (≤2.76 x 10^-7M) promoted glycosaminoglycan synthesis in all disrupted explants except those with cleaved hyaluronic acid chains. During the later stages of culture, in the presence of cortisol, (≤2.76 x 10-7M), the interterritorial glycosaminoglycan concentration increased. Whether collagen fibres were disrupted or not, collagen synthesis was evident, although with pharmacological concentrations of steroid (≤2.76 x 10^-6 M) all synthetic processes were increasingly inhibited. Exogenous trypsin induced extensive resorption of collagen fibres in minced synovial tissue, probably by activation of synovial collagenase. The destruction was partially reduced with trypsin inhibitor or cortisol. In areas of degradation macrophage-like cells accumulated but with early removal of trypsin, despite loss of collagen, fibroblast-like cells accumulated at the base of the explants with synthesized pericellular collagen evident. Collagen release into the medium was measured by an improved hydroxyproline assay designed to reduce interference from serum proteins. Although physiological doses of cortisol (≤2.76 x 10-7 M) enhanced collagen synthesis by, and the development of, the fibroblastic cells, extensive tissue repair was not observed, merely the formation of a cell population in the Millipore membrane. This model of tissue regeneration, remodelling and repair leads to the conclusion that within the arthritic joint the chondrocyte has the potential to rapidly attempt to repair damaged matrix, the extent of synthesis being proportional to the extent and type of matrix disruption. The chondrocyte responds by synthesizing glycosaminoglycans, that aggregate within the matrix, and collagen, with cortisol, at below physiological concentrations, enhancing this regeneration. Synovial tissue did not recover from disruption although the synoviocytes, on reversion to fibroblast-like cells, accumulated new collagen.

The mechanisms through which tropical trees, and thereby tropical forest areas, regenerate themselves remain little understood.  The area of greatest ignorance in the life cycle of tree species is the early pre-seedling stage and, therefore, a set of experiments to investigate this stage was undertaken.  Firstly, a field experiment to measure the secondary dispersal dynamics of three pioneer tree species in the Barro Colorado Island (BCI) forest of Panamá was carried out.  Seeds were sown out in the forest and later recovered by excavating the surface soil where they were sown.  The results of this project gave an estimate of the displacement and burial percentages to be expected for a small clump of seeds dispersed onto the forest floor.  An assessment was made of the relative importance of abiotic and biotic mechanisms of secondary dispersal.  Secondly, a modelling and field experiment used a soil water and heat transport model to characterise and predict soil drying in forest gaps.  A three scenario modification to the gap-understorey dichotomy was suggested by the field measurements and model results.  Thirdly, a modelling project used s simulation of the ground-level radiation regime of a forest, based on data from BCI, to investigate the relationship between high light areas and the areas delimited as gaps according to four different definitions.  In addition to proposing a new method of surveying large forest areas for gaps, this project produced a well-validated model of forest structure.  Finally, the results and programme produced during these three projects were synthesised into a description of several forest simulation sub-models, and possible directions for further research were outlined that may combine these into a full simulation model for a tropical forest.

Fluidised bed combustion offers potential advantages over conventional power generation systems, particularly with respect to sulphur capture using injected limestone. The stone calcines on entry to the hot bed, forming CaO, and then reacts with SO₂ to produce CaSO₄. Regenerative schemes aim to reduce the sorbent loading by stripping off the sulphur from the spent limestone which is then reused. This subject of this dissertation is an investigation into the fundamentals of the regeneration of sulphated limestone by reductive decomposition. Following a detailed discussion of the thermodynamic limitations on the reaction system, attention is focussed on the kinetics of the reductive decomposition scheme. The results of a study on the reaction of CaSO₄ powder with CO are reported. This made use of two experimental techniques, X-ray powder diffraction and thermogravimetric analysis. These experiments highlighted the major features of the reaction scheme and allowed the study of two special cases, the sulphidation of CaSO₄ to produce CaS only and the solid-solid reaction between CaS and CaSO₄. The major experimental technique used for this work was the batch addition of limestone to a fluidised bed. After a brief discussion of the results of sulphation experiments, typical regeneration experiments are described. By varying the test conditions as well as performing several special experiments, a mechanism for the overall reaction is deduced. The effect of the operating variables on the product split is then explicable. The evidence suggests that the closed pores resulting from the sulphation reaction lead to strong diffusion resistance on regeneration which controls the rate during the early and middle stages. By utilising high CO₂ concentrations the formation of CaS was inhibited; the reaction was then amenable to quantitative analysis which revealed an approximate first order dependence on CO concentration and an activation energy of 110kJ/mol. One method for reducing the quantities of CaS produced is to operate the fluidised bed in a two-zone fashion i.e. with oxidising and reducing regions. An investigation into this reactor configuration is included with particular attention paid to the oxidation of CaS. The results obtained are explicable in terms of the results from the single zone bed and allow the effects of operating variables on the reactor performance to be predicted. Finally, the mathematical modelling of the gas-solid reactions is considered. The changing grain size model is introduced by considering the sulphation of limestone. The final conditions from this model then form the initial conditions for the regeneration model, which considers mildly reducing conditions only. The final model then uses as a basis the mechanism proposed in chapter 5 and is applied to the thermogravimetric analysis results.

The presence of inhibitory molecules is believed to contribute to the failure of axonal regeneration in the adult mammalian CNS. This thesis is focussed on the role of the Nogo-66 receptor (NgR), and its ligands, in preventing axonal regeneration, and the use of genetically modified herpes simplex virus type-1 (HSV-1) for the disruption of these interactions. The expression of ngr, nogo-66 (i.e. pan-nogo), nogo-a and omgp mRNA in the intact and injured adult rodent nervous system has been examined by in situ hybridisation. Nogo-A expression was investigated by immunohistochemistry. The most significant findings were that, although cerebral cortical neurons strongly express ngr, many other neurons do not express ngr mRNA; indeed, ngr transcripts were absent from the corpus striatum and weakly expressed, if at all, by most spinal cord neurons and most primary sensory neurons. In contrast, nogo isoforms were expressed by many types of neuron in the CNS and PNS. Nogo-A protein was found to be prominently expressed in growing and regenerating axons. It is therefore unlikely that NgR/Nogo interactions can explain the general failure of axonal regeneration in the CNS. Several genetically modified HSV-1 vectors were constructed for the disruption of the NgR-ligand interactions. The first of these was constructed for the expression of a tagged-secreted form of the NgR antagonist peptide (NEP1-40); but, this was found to express poorly both in vitro and in vivo. Additionally, a system for the expression of functional shRNA from HSV-1 is reported. As a proof of principle, eGFP expression was successfully targeted in a cell line in vitro. Similarly, NgR was also targeted in primary cultures of cerebellar granule cells in vitro, but with less effect.

[ES] Las lesiones del sistema nervioso que implican la interrupción de haces axonales son devastadoras para el individuo. La regeneración autónoma de los tractos axonales dañados o degenerados es poco frecuente, ya que intervienen una gran cantidad de factores que limitan esta recuperación. Hoy en día, la medicina convencional no cuenta con tratamientos efectivos y exitosos para estas lesiones, y el tratamiento de los síntomas suele ser la mejor solución. Para revertirlo y lograr la reconexión funcional de las neuronas, la ingeniería de tejidos actualmente opta por el uso de soportes tridimensionales biocompatibles, células y moléculas bioactivas. Específicamente, una de las estrategias propuestas han sido los conductos nerviosos guiados, no solo para lesiones de nervios periféricos sino también para tractos del sistema nervioso central. En esta Tesis Doctoral, se propone la combinación de un conducto tubular hueco de ácido hialurónico (HA) relleno con fibras de ácido poli-L-lactida (PLA) en su lumen, y con células de Schwann (SC) pre-cultivadas como células de soporte de la extension axonal para superar los obstáculos que limitan la regeneración de axones in vivo. Se ha demostrado que el conducto de HA y las fibras de PLA mantienen la proliferación de las SC, las cuales forman una estructura cilíndica denominada 'vaina de SC' en la pared interna del lumen del conducto y a su vez crecen de forma direccional en las fibras de PLA. El conjunto unidireccional paralelo formado por las fibras PLA y las SC recapitula las características direccionales de los tractos axonales en el sistema nervioso. Al sembrar un explante de ganglio de la raíz dorsal (DRG) en uno de los extremos del conducto, se ha conseguido el crecimiento de los axones del DRG y se ha estudiado las características de las SC, los axones crecidos y su asociación, comprobando que el biohíbrido es capaz de soportar el crecimiento axonal. Además, se propone un concepto multimodular para superar las limitaciones típicas de la regeneración axonal a larga distancia, con la combinación de haces de fibras de PLA en el lumen de varios conductos o módulos de HA individuales más cortos que se posicionan uno detrás del otro, diseñando conductos nerviosos guiados con la longitud deseada, junto con SC pre-cultivadas. El conducto multimodular demostró ser eficaz para promover el crecimiento dirigido de axones. Además, se ha desarrollado un constructo compuesto por la estructura formada por las fibras de PLA y las SC, denominado 'cordón neural', tras eliminar el conducto de HA, lo que abre la puerta a la generación de una estructura neural in vitro para su trasplante.
[CA] Les lesions de el sistema nerviós que impliquen la interrupció de feixos axonals són devastadores per a l'individu. La regeneració autònoma dels tractes axonals danyats o degenerats és poc freqüent, ja que intervenen una gran quantitat de factors que limiten aquesta recuperació. Avui dia, la medicina convencional no compta amb tractaments efectius i reeixits per aquestes lesions, i el tractament dels símptomes sol ser la millor solució. Per revertir i aconseguir la reconnexió funcional de les neurones, l'enginyeria de teixits actualment opta per l'ús de suports tridimensionals biocompatibles, cèl·lules i molècules bioactives. Específicament, una de les estratègies proposades han estat els conductes nerviosos guiats, no només per lesions de nervis perifèrics sinó també per tractes de sistema nerviós central. En aquesta tesi doctoral, es proposa la combinació d'un conducte tubular buit d'àcid hialurònic (HA) farcit amb fibres d'àcid poli-L-lactida (PLA) en el seu lumen, i amb cèl·lules de Schwann (SC) pre-cultivades com a cèl·lules de suport de l'extension axonal per superar els obstacles que limiten la regeneració d'axons in vivo. S'ha demostrat que el conducte d'HA i les fibres de PLA mantenen la proliferació de les SC, les quals formen una estructura cilíndica anomenada 'beina de SC' a la paret interna de l'lumen de l'conducte i al seu torn creixen de manera direccional en les fibres de PLA. El conjunt unidireccional paral·lel format per les fibres PLA i les SC recapitula les característiques direccionals dels tractes axonals en el sistema nerviós. A l'sembrar un explantament de gangli de l'arrel dorsal (DRG) en un dels extrems de l'conducte, s'ha seguit el creixement dels axons de l'DRG i s'ha estudiat les característiques de les SC, els axons crescuts i la seva associació, comprovant que el biohíbrido és capaç de suportar el creixement axonal. A més, es proposa un concepte multimodular per superar les limitacions típiques de la regeneració axonal a llarga distància, amb la combinació de feixos de fibres de PLA en el lumen de diversos conductes o mòduls de HA individuals més curts que es posicionen un darrere l'l'altre, dissenyant conductes nerviosos guiats amb la longitud desitjada, juntament amb SC pre-cultivades. El conducte multimodular va demostrar ser eficaç per promoure el creixement dirigit d'axons. A més, s'ha desenvolupat un constructe format per l'estructura formada per les fibres de PLA i les SC, denominat 'cordó neural', després d'eliminar el conducte d'HA, el que obre la porta a la generació d'una estructura neural in vitro per al seu trasplantament.
[EN] Injuries to the nervous system that involve the disruption of axonal bundles are devastating to the individual. Autonomous regeneration of damaged or degenerated axonal tracts is infrequent since a large number of factors are involved limiting this recovery. Nowadays, conventional medicine does not have effective and successful treatments for these injuries, and the treatment of symptoms is often the best solution. In order to reverse it and achieve the functional reconnection of neurons, tissue engineering currently opts for the use of biocompatible three-dimensional supports, cells, and bioactive molecules. Specifically, one of the proposed strategies has been nerve guidance conduits, not only for peripheral nerve injuries but also for tracts of the central nervous system. In this Doctoral Thesis, we propose the combination of hyaluronic acid (HA) single-channel tubular conduit filled with poly-L-lactide acid (PLA) fibres in its lumen, with pre-cultured Schwann cells (SC) as cells supportive of axon extension to overcome the obstacles limiting axon regeneration in vivo. We have proved that HA conduit and PLA fibres sustain the proliferation of SC, which form a cylindrical structure named 'SC sheath' on the inner wall of the lumen of the conduit and in turn grow directionally in the PLA fibres. The parallel unidirectional ensemble formed by PLA fibres and SC recapitulates the directional features of axonal pathways in the nervous system. Planting a dorsal root ganglion (DRG) explant on one of the conduit's ends, we have followed axon outgrowth from the DRG and studied the features of SC, the grown axons and their association, checking that the biohybrid is capable of supporting axonal growth. Furthermore, we propose a multimodular concept to overcome the typical limitations of long-distance axonal regeneration, with the combination of PLA fibres bundle in the lumen of several shorter individual HA conduits or modules which positioned themselves one behind the other, designing nerve guided conduits with the desired length, together with pre-cultured SC. The multimodular conduit proved effective in promoting directed axon growth. Moreover, we developed a construct consisting of the structure formed by the PLA fibres and the SC, named 'neural cord', after eliminating the HA conduit, that opens the door to the generation of a neural structure in vitro for transplantation.
La presente tesis doctoral se ha realizado con la financiación del Ministerio de Economía y Competitividad a través de los proyectos MAT2015-66666-C3-1-R, DPI2015-72863-EXP, y AEI RTI2018-095872-B-C21-C22/ERDF. Agradezco también la beca FPU15/04975 al Ministerio de Educación Cultura y Deportes.
Rodríguez Doblado, L. (2021). Biohybrids for Neural Tracts Regeneration [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/165196
TESIS

My PhD project is divided in two parts, focusing on the development of new strategies for orthopedic tissue regeneration. In particular, the first part is about cartilage regeneration using human lipoaspirate as autologous injectable active scaffold for one-step repair of cartilage defects, the second part is about bone regeneration, through an injectable medicated graft substitute active on bone tissue regeneration. I. Cartilage regeneration Research on mesenchymal stem cells from adipose tissue (ASC) shows promising results for cell-based therapy in cartilage lesions: in these studies cells have been isolated, expanded, and differentiated in vitro, before transplantation into the damaged cartilage, or onto materials used as scaffolds to deliver cells to the impaired area. The present study employed in vitro assays to investigate the potential of intra-articular injection of micro-fragmented lipoaspirate, as a one-step repair strategy; it aimed to determine whether adipose tissue can act as a scaffold for cells naturally present at their anatomical site. Cultured clusters of lipoaspirate showed a spontaneous outgrowth of cells with mesenchymal phenotype and with multilineage differentiation potential. Transduction of lipoaspirate clusters by lentiviral vectors expressing GFP underlined the propensity of the outgrown cells to repopulate fragments of damaged cartilage. On the basis of the results, which showed an induction of proliferation and extracellular matrix (ECM) production of human primary chondrocytes, it was hypothesized that lipoaspirate may play a paracrine role. Moreover, the structure of a floating culture of lipoaspirate, treated for three weeks with chondrogenic growth factors, changed: tissue with a high fat component was replaced by a tissue with a lower fat component and connective tissue rich in glycosaminoglycan (GAG) and in collagen type I, increasing the mechanical strength of the tissue. From these promising in vitro results, it may be speculated that an injectable autologous biologically-active scaffold (lipoaspirate), employed intra-articularly, may: 1) become a fibrous tissue that provides mechanical support for the load on the damaged cartilage; 2) induce host chondrocytes to proliferate and produce ECM; 3) provide cells at the site of injury, which could regenerate or repair the damaged or missing cartilage. II. Bone regeneration With the aim to obtain an injectable medicated scaffold, which speeds bone formation in sinus lift augmentation, in bony void and in fracture repair, we have developed a three-dimensional (3D) jelly collagen containing Lysophosphatidic acid (LPA) and 1a,25-Dihydroxyvitamin D3 (1,25D3) using soluble native collagen prepared from rat tail tendons. We have demonstrated with an in vitro 3D culture model of bone fracture an osteoblasts’Rho-kinase mediated contraction of the collagen that causes an approach of human bone trabecular fragments with the formation of new union tissue within 3 weeks of organ culture. The contraction was faster in LPA medicated collagen while 1,25D3 enhanced the mineralization of the new formed tissue that showed also increased tensile strength. LPA was shown to modulate gel contraction rate not only mechanically, working in cytoskeleton reorganization, but also osteoconductively evidencing activity on proliferation, differentiation and migration of human primary osteoblasts (hOB). When LPA was used in combination with 1,25D3 a synergism on hOB’s activity in term of alkaline phosphatase and mineralization was seen. On the basis of these data, collagen can be considered as an injectable natural scaffold that allows the migration of cells from the side of bone defect and its enrichment with LPA and 1,25D3 could be used in vivo to accelerate bone growth and fracture healing.

Nowadays, there are approximately 10 million people worldwide with visual impairment due to corneal diseases. Currently, the main therapeutic solution is the transplant of a donor's cornea. The great majority of transplants is due to some failure in the inner layer of the cornea, which is called the corneal endothelium and this is mainly related with the inability of this layer to regenerate in vivo. However, transplants present several limitations such as the low number of healthy donors or immunological rejection by the patient. In order to overcome these problems, several researchers have focused in culturing corneal endothelial cells (CEC) to subsequently replace non-functional CEC. However, cell therapy is still very recent and still presents a series of drawbacks. For instance, using animal CEC or cells from other patients has shown to lead into immunological rejection. In order to avoid this, it is possible to use stem cells from the same patient, which have the ability to differentiate into many cell types, including the corneal endothelium. Currently, the stem cells used to regenerate CEC are mainly pluripotent stem cells, either embryonic stem cells (ESC) or induced pluripotent stem cells (iPSC), which are derived from adult cells. Despite their great potential for treating diseases, these types of stem cells present major limitations such as the risk of teratoma formation. In addition, they present other disadvantages such as ethical problems associated with the use of ESCs, safety problems related to iPSC since they requires the use of virus for their production hence limiting its clinical application. For this reason, and in order to solve the current problems in the regeneration of corneal endothelium, this thesis project uses dental pulp stem cells (DPSC) for the formation of CEC. DPSC are an accessible source derived from the same patient, avoiding possible future problems of rejection. In addition, the use of DPSC avoids the ethical and security problems associated with ESC and iPSC. Furthermore, DPSC and CEC have the same embryological origin, as they both arise from neural crest stem cells. In fact, DPSC express neural crest stem cells markers, which facilitates their differentiation into neural crest stem cells (NCSC), which is an intermediate step for the formation of CEC. Therefore, this thesis project uses a two-step protocol, where DPSC are differentiated into NCSC and, subsequently, NCSC are derived into CEC. Because the use of cell therapies alone may present limited cell viability once it is injected, the field of tissue engineering is a new discipline that has appeared to overcome this limitation. Tissue engineering combines the use of cells, biomaterials and biological molecules. It has been demonstrated that the use of different topographies in cell culture modulates cell behavior, and may have an effect on their functionality, cell distribution or cell size. Therefore, this thesis project applies tissue engineering as another strategy for the generation of functional CEC with its characteristic phenotype and morphology. For doing this, we have mimicked the natural CEC environment by cultivating the cells on substrates with different curvatures, composition or topographies that are able to mimic those of the human eye. In conclusion, this thesis project proposes the use of bioengineering, by differentiating CEC from stem cells derived from the patient and the use of biomaterials with different topographies and curvatures, for the regeneration of corneal endothelium.

The fin exoskeleton of the zebrafish is comprised of lepidotrichia (or fin rays) and actinotrichia. In uncut fins, the fin rays span the entire length of the fin and the actinotrichia are found at the distal tips of each of the fin rays. Both of these fin exoskeletal components are capable of regenerating following amputation or injury. The regulation of the regeneration of these exoskeletal components is the central topic of this thesis and is explored in two different projects. The first project focuses on zebrafish fin ray regeneration during which bone segments are periodically added at the distal tips of each fin ray, each segment being separated by a joint. Joint formation involves the expression of a unique set of genes: hoxa13a, evx1, and pthlha. The alternation between bone segment formation and joint formation during fin ray regeneration seems to closely correlate with positional outgrowth during regeneration. We investigated whether or not the calcineurin and retinoic acid (RA) signalling pathways, both of which may be potential regulators of positional outgrowth, are involved in regulating joint formation. FK506-induced calcineurin inhibition and RA treatments each resulted in the suppression of joint marker expression. In RA-treated fins, bone deposition occurs in the joints as a result of joint cells being induced to differentiate into osteoblasts. These results suggest that the calcineurin and RA pathways may provide the positional information that regulates joint and bone segment formation. The second project focuses on the regulation of actinotrichia formation during adult fin regeneration. Throughout the early to intermediate stages of fin ray regeneration, actinotrichia fibers are found deep to the regenerating hemirays. As regeneration progresses, these actinotrichia fibers become gradually restricted to the distal domain of the fin regenerate. Actinotrichia contain structural proteins known as actinodin. There are four actinodin genes in zebrafish, actinodin1-4. We studied the comparative activity of the cis-acting regulatory elements of actinodin1 during fin regeneration. We have previously identified tissue-specific cis-acting regulatory elements in a 2kb genomic region upstream of the first exon, termed 2P, that drive reporter expression in the fin fold ectoderm and mesenchyme during embryonic development. Within 2P is a 150bp region, named epi, which contains an ectodermal/epithelial enhancer. Using in silico analysis, we have identified four main clusters of transcription factor binding sites within epi, termed epi1-4. Using a reporter transgenic approach, we have identified epi3 as a site containing an early mesenchymal-specific repressor and an epithelial-specific enhancer. We have also shown that the first exon and intron of actinodin1 contains a general transcriptional enhancer in adulthood and an alternative promoter. Overall, these results suggest that there is a difference between the regulation of actinodin1 during embryonic development and that of adult fin regeneration.

The aim of this study was to determine the trends in protocol, success rates, and consistency in follow up of revascularization procedures in a controlled environment. Patients of the Virginia Commonwealth University School of Dentistry were identified who were offered revascularization therapy as a treatment option on immature permanent teeth from January 1, 2010 to May 31, 2017. A total of 77 patients and 78 teeth were evaluated for revascularization therapy. For patients accepting treatment, records were reviewed for outcome assessment and consistency of follow up. A total of 30 patients (31 teeth) were treated following revascularization protocols, with only 20 patients (21 teeth) returning for follow up. Six of the 21 teeth needed some form of additional therapy due to patients remaining symptomatic, however 15/21 exhibited varying levels of success. Recall rate was 67.7%. With a success rate of 71.4%, revascularization therapy should continue to be considered for all patients with teeth having necrotic pulps and immature root apices. However, changes to recall protocols need to be improved in order to better monitor the status of teeth that undergo revascularization therapy.

In response to high and rising amputation rates, significant advances have been made in the field of prosthetic limb design. Unfortunately, there exists a lag in the neural interfacing technology required to provide an adequate link between the nervous system and this emerging generation of advanced prosthetic devices. Novel approaches to peripheral nerve interfacing are required to establish the stable, high channel count connections necessary to provide natural, thought driven control of an external prosthesis. Here, a tissue engineering-based approach has been used to create a device capable of interfacing with a regenerated portion of amputated nerve. As part of this work, a nerve guidance channel design, in which small amounts of interior scaffolding material could be precisely positioned, was evaluated. Guidance channels containing a single thin-film sheet of aligned scaffolding were shown to support robust functional nerve regeneration across extended injury gaps by minimally supplementing natural repair mechanisms. Significantly, these "thin-film enhanced nerve guidance channels" also provided the capability to guide the course of axons regenerating from a cut nerve. This capability to control axonal growth was next leveraged to create "regenerative scaffold electrodes (RSEs)" able to interface with axons regenerating from an amputated nerve. In the RSE design, low-profile arrays of interfacing electrodes were embedded within layers of aligned scaffolding material, such that regenerating axons were topographically guided by the scaffolding through the device and directly across the embedded electrodes. Chronically implanted RSEs were successfully used to record evoked neural activity from amputated nerves in an animal model. These results demonstrate that the use of topographic cues within a nerve guidance channel might offer the potential to influence the course of nerve regeneration to the advantage of a peripheral nerve interface suitable for limb amputees.

In this thesis project, different existing granular activated carbon regeneration methods/technologies are assessed based on existing literature. The project aims to identify and analyse the method with the highest on-site regeneration potential by using the Himmerfjärdsverket wastewater treatment plant as a reference and performing a cost estimation analysis.  Information is gathered about different methods from the literature study and then sorted into the following parts: working principle, technology readiness and cost, advantages and disadvantages, and references (case studies). The methods are then assessed and compared by a scoring and weightage system, where the factors which are regeneration efficiency, ease of implementation, sustainability, cost, and reliability are weighted and then scored for each method. Furthermore, the highest scoring method is then compared to the proposed regeneration method at Himmerfjärdsverket.  The results from my comparison and assessment show that chemical regeneration is the highest scored method, followed by microwave and wet-oxidation regeneration methods. On applying chemical regeneration at Himmerfjärdsverket, it is found out that it may indeed be cheaper and more sustainable than the proposed off-site regeneration method. However, thermal and biological regeneration are better alternatives at Himmerfjärdsverket than microwave and wet- oxidation.  From the above results, chemical regeneration has the highest potential for on-site regeneration of granular activated carbon in Sweden.
Läkemedel i vatten är ett stort hot mot miljö och hälsa. Kommunalt avloppsvatten består av avloppsvatten från hushåll, privata och offentliga institutioner och dagvattenavrinning. En viktig läkemedelskälla i avloppsvatten är ett läkemedel som kommer in via urin och / eller avföring. Olika tekniker finns för avlägsnande av farmaceutiska rester och andra mikroföroreningar från avloppsvatten. En sådan teknik är adsorptionen av dessa rester med hjälp av Granulärt Aktivtkor (GAC). Aktivtkor (AC) är ett kolhaltigt material med liten pordiameter, stora porvolymer och hög specifik yta rea vid bearbetning. Det anses vara det bästa adsorptionsmedlet för att adsorbera organiska, oorganiska och giftiga metalljoner som finns i avloppsvattnet. Det finns två typer av aktivtkol som används för att avlägsna farmaceutiska rester: Granulärt aktivtkol och pulveriserat aktivt kol.  Denna forskning syftar till att identifiera, jämföra och bedöma befintlig regenereringsteknik för att hitta den teknik som har störst potential och använda den på ett referensavloppsreningsverk. Det finns olika metoder för regenerering av använt aktivt kol (SAC). Dessa är termisk regenerering, kemisk regenerering, biologisk regenerering, elektrokemisk regenerering, mikrovågsregenerering och våt-oxidationsregenerering. Metoderna listas och förklaras med hjälp av deras arbetsprincip, beredskap, kostnad, fördelar, nackdelar och referenser till studier där de har använts.  Flera kriterier / faktorer beaktas för bedömning och jämförelse av olika regenereringsmetoder. Faktorerna poängsätts sedan med hjälp av ett viktat poängsystem. Var och en av de ovannämnda faktorerna görs mellan 0–5 och tilldelas en vikt mellan 1–3. En högre poäng betyder bättre prestanda i den givna faktorn. Medan en högre vikt betyder betydelsen av faktorn.  Från bedömningen visar sig kemisk regenerering vara den mest lämpliga metoden för regenerering av GAC på plats. Den minst lämpliga metoden är biologisk regenerering med en total poäng på 39. De två bästa regenereringsmetoderna på plats är kemisk och mikrovågsregenerering. I procent har kemisk regenerering och mikrovågsregenerering en rating på 93,3% och 90%. För att validera resultatet av bedömningen används Himmerfjärdsverket som referensavloppsverk.  Himmerfjärdsverket bygger om och expanderar till en högteknologisk anläggning. Den nya anläggningen kommer att bestå av modern reningsteknik och hög reningskapacitet. Den planerade nya anläggningen förväntas vara klar 2025, medan byggandet påbörjades i januari 2020.  I en studie genomförd av Syvab i samarbete med Ramboll, IVL och SU anges att det skulle behövas kolförbrukning på 15–20 g / m3 vatten. Den totala kostnaden per behandlat avloppsvatten skulle sannolikt öka med 20–30% till 2027 om läkemedelsreningen genomförs på Himmerfjärdsverket med hjälp av GAC och av regenereringsmetoden utanför anläggningen. Himmerfjärdsverket kommer att konsumera 3,92 ton kol dagligen eller 27,56 ton varje vecka. Detta kommer att kosta 28,7 miljoner SEK / år för 20 000 EBV (i värsta fall) och 11,5 miljoner SEK / år för 50 000 EBV.  Medan kostnaden för kemisk regenerering av GAC med högsta regenereringseffektivitet uppskattas till 27,4 miljoner SEK / år för användning av flytande NaOH-lösning och 17,7 miljoner SEK / år för användning av fast NaOH för 20 000 EBV. För mängden 573 t / år kol kommer NaOH-förbrukningen att vara 2083,5 t / år, vilket kommer att kosta 7,1 och 10,9 miljoner SEK / år för 50 000 EBV.  Eftersom kostnad är en av de viktigaste faktorerna som motverkar tillämpningen av metoder som är lika tillförlitliga som termisk regenerering. Om termisk regenerering implementeras på Himmerfjärdsverket kan installationen användas för att regenerera GAC från andra reningsverk från Stockholm. 2 GAC-bio filter i serieskapare bättre förutsättningar för biologisk regenerering av GAC samt ger låga föroreningskoncentrationer och höga syrekoncentrationer. För att lägga till det producerar Himmerfjärdsverket biogas som kan användas för att uppnå höga temperaturer som krävs enligt denna metod eller generera den erforderliga elen eller båda. I alla tre fall kommer kostnaden att minskas ytterligare.  Avslutningsvis har kemisk regenerering den högsta regenereringspotentialen på plats bland alla andra studerade metoder. Medan termisk regenerering är nära den andra på grund av kolförlusten. En pilotstudie krävs för att validera de regenereringseffektivitet som nämns i litteraturen och bearbetningsförhållandena och typerna av adsorbera vid Himmerfjärdsverket behöver utvärderas liksom behandlingsförhållandena.

The transformation of urban waterfronts is one of the key urban design and planning stories of the late twentieth century. The decline of the waterfront in post-industrial cities meant the deterioration of both a physical and social nature of significant portions of urban fabric. Cities have reacted to this state of affairs with substantial regeneration programs, approaching the decline of waterfront as an opportunity rather than a problem. However, since the success of early regeneration programs in North America, changing urban waterfronts on a global scale has led to a manifestation of globalisation, becoming a synonym of uniformity and monotony of cities. The urban waterfront also has become a battleground for a number of intersecting forces and different interests and desires. This research aims to study the phenomenon of urban waterfront regeneration, specifically analysing how it has operated within the UK context since the late 20th century until the present. It focuses on investigating the process of transformation of the urban waterfront in the city of Liverpool. Liverpool has suffered from a serious urban decline following the degeneration of its seven miles of docks due to a number of internal and external factors. However, since the 1980s, the image of an abandoned waterfront has started to change with massive waterfront regeneration schemes that aim to improve the physical, environmental, social and economic conditions of the area. This research argues that by understanding the process and the context of this regeneration, several lessons can be learned and models of good practice can be identified. The research is based on a series of lengthy interviews with key stakeholders closely linked with the development in the city, a review of documents related to the regeneration of Liverpool waterfront, including urban design policies and guidance, a substantial review of relevant news articles that were written throughout the periods of the recent transformation of the city, and numerous site visits to reflect upon the development carried out recently. The research also identifies and discusses a number of key urban issues such as image and identity, cultural built heritage, place marketing and branding, urban governance. The research identifies three distinctive eras of waterfront regeneration and several key regeneration schemes. Each of these eras reflects the many factors that shaped the urban landscape. The research argues that there are no specific models that can create successful waterfront regeneration, yet, what is important is ensuring the complexity and the inclusiveness of the process of the regeneration. An inclusive and a complex process will result in attaining urban competitiveness besides securing distinctive, genuine and imaginative urban identity. The research also highlighted the central role of urban design as a mediator between the numerous processes and different forces that shape the urban landscape.

Le toluène est un composé organique volatil (COV) toxique présent dans les environnements intérieurs et extérieurs. La dépollution du toluène se fait généralement par adsorption ou oxydation catalytique. Dans ce dernier cas, le toluène est converti en CO2 et H2O, mais des espèces toxiques peuvent s'accumuler sur les catalyseurs, provoquant leur empoisonnement, leur désactivation et leur frittage. Pour surmonter ces inconvénients, nous proposons des procédés hybrides innovants de "stockage-régénération". Il s’agit de procédés séquentiels basés l’adsorption suivie de l'oxydation catalytique activée soit thermiquement (ATC) ou par un plasma (APC). Ces procédés sont divisés en deux étapes : "L'étape de stockage où le toluène gazeux est adsorbé sur la surface du matériau et l'étape d'oxydation où le toluène adsorbé est converti catalytiquement en CO2 et H2O dans un environnement thermique ou plasma. Le processus ATC a été testé sur de l'hopcalite commerciale (CuMnOx), de la Cérine-NR et de l'UiO-66-SO3H. L'hopcalite se distingue des autres par sa grande capacité d'adsorption "utile" et ses propriétés redox, permettant une activité et une sélectivité en CO2 élevées dans l'oxydation du toluène. Dans le procédé APC, la morphologie de la poudre et le manque d'effet de synergie dans la Cérine-NR et l'UiO-66-SO3H ne permettent pas de générer un plasma stable. Ainsi, seule l'Hopcalite a été étudiée de manière approfondie en APC. Il est observé que l'activité d'oxydation du toluène adsorbé est significativement affectée par les variables du procédé. La stabilité du matériau a été étudiée dans les deux cas au moyen de différentes techniques de caractérisation et il a été confirmé que les matériaux Hopcalite sont très stables. L'activité catalytique a été améliorée par l'imprégnation d'une phase active telle que l'argent, ce qui a conduit à une augmentation de la sélectivité et du rendement en CO2 avec une charge d'argent très faible, tant dans l'ATC que dans l'APC. Un examen approfondi du matériau a révélé qu'un bon équilibre entre la capacité d'adsorption et l'activité catalytique (Cu2+,3+ et Mn3+,4+) est nécessaire. De plus, le coût énergétique de l'APC se situe dans une fourchette acceptable (11.6 kWh-m-3), ce qui signifie qu'avec une optimisation supplémentaire des différents paramètres expérimentaux, il peut être facilement mis à l'échelle de manière rentable. L'ATC et l'APC permettent tous deux d'atteindre une efficacité de réduction du toluène et de conversion en CO2 supérieure à 95 % au premier passage et à 75 % pour les matériaux stabilisés. Ces résultats montrent que les deux procédés ATC et APC pourraient être des procédés prometteurs de réduction du toluène, efficaces sur le plan énergétique, et ouvrent la voie à de nouveaux développements et à une mise à l'échelle
Toluene is a toxic volatile organic compound (VOC) present in indoor and outdoor environments. The abatement of toluene is typically done by adsorption or catalytic oxidation. In the latter case, toluene is converted into CO2 and H2O, but toxic species can build up on catalysts, causing poisoning, deactivation, and sintering. To overcome these drawbacks, we propose innovative “storage-regeneration” hybrid processes based on sequential adsorption-thermal catalytic oxidation (ATC) and sequential adsorption-plasma catalysis (APC). These processes are divided into two steps: “storage step” where gaseous toluene adsorbed on the surface of material and “oxidation step” where the adsorbed toluene species is catalytically converted into CO2 and H2O in thermal or plasma environment. ATC process was tested on commercial Hopcalite (CuMnOx), Ceria-NR and UiO-66-SO3H. Hopcalite stands out from others owing to its high “useful” adsorption capacity and redox properties, allowing a high activity and CO2 selectivity in toluene oxidation. In APC process, the powder morphology and lack of synergy effect in Ceria-NR and UiO-66-SO3H does not allow to generate stable plasma. Thus only Hopcalite has been studied in depth in APC. It is observed that the oxidation activity of the adsorbed toluene is significantly affected by the process variables. The stability of material was investigated in both cases, and it was confirmed that Hopcalite materials are very stable as evidenced by various characterization techniques. The catalytic activity was enhanced by impregnating active phase such as silver which led to improvement in the CO2 selectivity and CO2 yield at very low silver loading in both ATC and APC. A thorough examination of the material revealed that a good balance of adsorption capacity and catalytic activity (Cu2+,3+ and Mn3+,4+) is required. Moreover, the energy cost of APC is in the range of acceptable level (11.6 kWh·m−3) as a result with further optimization in different experimental parameters, it can be easily scalable in cost-effective manner. Both ATC and APC allow to reach toluene abatement efficiency and conversion to CO2 above 95 % on first run and 75% on stabilized materials. These results show that both ATC and APC process could be a promising energy-efficient toluene abatement processes and open the path for further development and scale-up

After ischemic damage in kidney, alternatively activated or M2 macrophages are key players in resolving inflammation and participating in kidney repair. Obtaining this particular phenotype is a process controlled by deregulation of a series of genes. Modulation of those genes could result in controlling macrophages phenotype and functions, aiming new approaches in resolving ARF. The first aim of this study was to identify genes that are related to M2 macrophages that are involved in tissue repair. By functional genomics we have identified the expression of 14 genes crucial for the induction of the endogenous reparative capacity of the kidney that are modulated by the presence of macrophages. We also demonstrated that modulation of Ivns1abp gene can modulate renal repair. More concrete we show that over-expression of the Ivns1abp gene can enhance macrophages regenerative capacity and switch their phenotype towards M2, provoking modulation of their inflammatory state and increasing its resistance against inflammation inputs. We also demonstrated that silencing of the Ivns1abp genet to macrophages leads them to acquire a M1 phenotype and decrease their reparative and phagocytosis capacity. As a last step, we define pathways that regulate the transcription of the Ivns1abp gene. We show that Ivns1abp gene expression in macrophages is regulated by the c-myc transcription factor and modulated by the presence of cytokines determining cell fate.
Después de la lesión isquémica en el riñón, los macrófagos activados alternativamente o M2 no solo participan en la reparación del daño sino son factores clave en la resolución de la inflamación. La obtención de este fenotipo particular es un proceso controlado por la desregulación de una serie de genes. Modulando estos genes, se podría controlar el fenotipo y las funciones de los macrófagos, con el objetivo de nuevos enfoques en el tratamiento de FRA. El primer objetivo de este estudio fue identificar los genes que están implicados en la reparación de tejidos y que están relacionados con los macrófagos M2. Por genómica funcional hemos identificado la expresión de 14 genes cruciales para la inducción de la capacidad regeneradora endógena del riñón y modulados por la presencia de macrófagos. A continuación hemos demostrado que la modulación del gen Ivns1abp puede modular la reparación renal. En concreto hemos demostrado que la sobre-expresión del gen Ivns1abp en macrófagos puede mejorar su capacidad regenerativa y cambiar su fenotipo hacia M2, provocando la modulación de su estado inflamatorio y aumento de su resistencia frente la inflamación. Se demostró además que el silenciamiento del gen Ivns1abp en macrófagos disminuye su capacidad reparadora y fagocítica transformando su fenotipo a M1. Como ultimo, hemos definido las vías que regulan la transcripción del gen Ivns1abp. Hemos demostrado que la expresión del gen Ivns1abp en los macrófagos está regulada por el factor del trascripción c-myc y modulada por la presencia de citoquinas, determinando el destino de la célula.

The aim of this PhD thesis was to study experimental approaches for revitalization of necrotic teeth. Revitalization, also known as regenerative endodontic procedures (REPs), is a relatively new treatment for necrotic teeth which tries to regenerate the dentine-pulp complex instead of obturating the root canal with biologically inert materials (root canal treatment). Until very recently, the most reliable option for the treatment of immature necrotic teeth was apexification followed by root canal treatment. However, endodontically treated teeth remain devitalized throughout the patient's lifetime and therefore defenceless to new caries lesions, as the absence of pulp implies the lack of tooth immune mechanisms. On the contrary, the regeneration of the dentine-pulp complex allows further root development and aims to recover the natural immune and secretory system of the pulp, making teeth more resistant to future lesions or traumatisms. The therapy was developed to treat necrotic immature teeth (i.e. those that have not completed their root development). Clinically, the outcomes can be considered successful since there is a resolution of the symptomatology, healing of the apical pathosis and further root development in most cases. However, histological analysis has demonstrated that the tissues formed after the therapy are reparative tissues – such as cementum-like tissue – instead of dentine, as well as an unorganized connective tissue, instead of pulp with its characteristic odontoblast layer. Currently, numerous efforts are being made to shed light on the clinical and biological aspects involved in the regeneration of pulp. Chapter 1: As previously said, evidence shows that no dentine but reparative tissues (cementum-like tissue) are responsible for the root development after regenerative endodontics. As cementum is less hard and less elastic than dentine, the question arises whether a root with apposition of cementum can endure mechanical stress similarly to roots completed by dentine. Thus, one of the objectives of this thesis was to compare the biomechanical performance of cementum- and dentine-reinforced teeth, and therefore to evaluate the biomechanical advantages of dentine regeneration after regenerative endodontics. We developted a finite element model of cementum- and dentinereinformed teeth and studied the stress distribution after the simulation of biting, trauma and orthodontic movement. The results showed that apposition of hard tissue (whether cementum or dentine) after REPs reduces mechanical stress on 17 immature teeth and, more important, that the formation of dentine is advantageous because it, unlike cementum, facilitates an even stress distribution throughout the root. As far as we know, ours was the first study showing the biomechanical advantages of dentine regeneration. Chapter 2: Odontoblasts are post-mitotic cells that secrete dentine. The isolation and culture of odontoblasts may open numerous possibilities to study this cell type under standardized conditions, shedding light on their roles in dentine formation, immune defence and transmission of external stimuli. We evaluated different protocols of enzymatic treatment to isolate primary odontoblasts from human molars. The results showed that, regardless of the enzymatic solution used, odontoblasts in culture did not remain viable after 24 h. Additionally, we identified increased expression of nestin (NE), bone sialoprotein (BSP) and dentine matrix acidic phosphoprotein 1 (DMP1) in the odontoblast layer compared to pulp fibroblasts. Though primary odontoblasts can still not be cultivated after isolation, characteristic genes were identified to differentiate odontoblasts from pulp fibroblasts. Chapter 3: We analysed the effects of autologous platelet concentrates (APCs) in the clinical and histological outcomes of the therapy and the different clinical protocols clinically used through systematic reviews. The results indicated that APCs improve the clinical and radiographic outcomes of regenerative endodontics since the teeth treated with APCs achieved significantly better thickening of the dentine walls and root lengthening. However, true regeneration of pulp was not achieved with the addition of platelet concentrates, which only stimulated tissue repair. Additionally, most of the studies did not follow a standard clinical protocol for regenerative endodontic therapy and used irritant and intracanal medicaments that are cytotoxic and affect the differentiation and adherence of the stem cells. Chapters 4 and 5: As will be mentioned in detail, a small apical foramen acts as a physical barrier that hinders tissue ingrowth into the root canal and therefore reduces the possibility of revitalization of mature teeth. We studied different methods for apical foramen enlargement of mature teeth as a basis to apply it in a further animal study. We analysed manual instrumentation at different working lengths and apicoectomy on extracted human teeth and in situ teeth. We concluded that apicoectomy is not an effective technique for apical foramen enlargement and therefore should not be used for that purpose. Instrumentation 18 0.5mm beyond the apex resulted in the most effective technique. Later, we performed an animal study and evaluated pulp tissue regeneration/repair in mature teeth and the differentiation of the stem cells from the periapical tissues into odontoblast-like cells by adding preameloblast-conditioned medium. Preameloblast-conditioned medium was applied in pulpectomized ferret canines, whose apical foramina were enlarged using the previously developed method. We observed vascularized connective tissue occupying the apical third of the canal space in 50% of the teeth, showing the potential of revascularization of mature teeth. However, no odontoblast-like cells were observed showing that in vivo odontoblast-like differentiation of stem cells is still not possible with the tested technique. Chapter 6: Finally, we present here the preliminary data of characterization and odontoblast-like differentiation of amnion epithelial cells. Human amnion epithelial cells (hAECs) express pluripotent stem cell markers and have been proven to differentiate in cells of the three embryologic layers. However, as far as we know, these are the first experiments that have proved the potential of odontoblast-like differentiation of these cells in vitro. To induce the odontoblast-like differentiation, we seeded hAECs over dentine disks treated with EDTA and evaluated the morphological characteristic of cells. We observed that hAECs present a characteristic odontoblast-like morphology, with cytoplasmic processes located in dentinal tubuli, after 48 h. Further studies will be carried out with known concentrations of dentine matrix proteins and qPCR.
El objetivo de esta tesis doctoral fue estudiar enfoques experimentales para la revitalización de dientes necróticos. La revitalización o endodoncia regenerativa es un tratamiento nuevo para dientes necróticos que busca regenerar el complejo dentino-pulpar, en lugar de obturar el conducto radicular con materiales biológicamente inertes (obturación radicular). Los dientes tratados endodónticamente permanecen desvitalizados durante toda la vida del paciente y, por lo tanto, indefensos ante nuevas lesiones de caries, ya que la ausencia de pulpa implica la falta del mecanismo inmune del diente. Por el contrario, la regeneración del complejo dentino-pulpar permite un mayor desarrollo de la raíz y tiene como objetivo recuperar el sistema inmune y secretor natural de la pulpa, haciendo que los dientes sean más resistentes a futuras lesiones o traumatismos. En esta tesis doctoral se realizó un estudio de elementos finitos que probó por primera vez que la distribución de la tensión mecánica es más desventajosa en dientes inmaduros y maduros con tejido reparativo (como el formado después de la endodoncia regenerativa), que en dientes desarrollados con dentina. Se llevaron a cabo estudios en material cadavérico para analizar métodos de ampliación del foramen apical de dientes maduros y un estudio experimental para evaluar a efectividad de la terapia en dientes maduros de hurón con forámenes ampliados. Los resultados mostraron que es posible la formación de un tejido conectivo vascularizado en el interior del canal de dientes maduros, pero este tejido ocupó solo el tercio apical. Se realizaron revisiones sistemáticas relativas al efecto de concentrados de plaquetas en la terapia, y se concluyó que si bien los dientes tratados con concentrados de plaquetas mostraron mejores resultados clínicos, el tejido neoformado es tejido reparativo, es decir, carente de odontoblastos y dentina. Se llevó a cabo un estudio in vitro para aislar y cultivar odontoblastos y se concluyó que no es posible mantener odontoblastos vitales in vitro, probablemente debido a la disrupción del proceso odontoblástico durante la aislación. Por último, se realizó experimentos in vitro que buscan evaluar la capacidad de diferenciación odontogénica de las células pluripotentes del amnios, investigación que actualmente está en fase de ejecución.

Nerve autografts are widely used clinically to repair nerve grafts. However, nerve grafts have many limitations, such as, availability of donor nerve grafts, and loss of function at donor site. To overcome these problems, we have used a tissue engineering approach to design three-dimensional (3D) agarose scaffolds containing gradients of laminin-1 (LN-1) and nerve growth factor (NGF) to mimic in vivo conditions to promote nerve regeneration in rats. To determine the effect of LN-1 gradients on neurite extension in vitro, dorsal root ganglia (DRG) from chick embryos were cultured in 3D hydrogels. A gradient of LN-1 molecules in agarose gels was made by diffusion technique. LN-1 was then immobilized to the agarose hydrogels using a photo-crosslinker, Sulfo-SANPAH (Sulfosuccinimidyl-6-[4-azido-2-nitrophenylamino] hexanoate). Anisotropic scaffolds with three different slopes of LN-1 gradients were used. Isotropic scaffolds with uniform concentrations of LN-1, at various levels, were used as a positive control. DRG cultured in anisotropic scaffolds with optimal slope of LN-1 gradient extended neurites twice as fast as DRG in optimal concentration in isotropic scaffolds. Also, in the anisotropic scaffolds the faster growing neurites were aligned along the direction of LN-1 gradient. To promote nerve regeneration in vivo, tubular polysulfone guidance channels containing agarose hydrogels with gradients of LN-1 and NGF (anisotropic scaffolds) were used to bridge 20-mm nerve gaps in rats. Nerve autografts were used as positive controls and isotropic scaffolds, with uniform concentration of LN-1 and NGF, were used as negative controls. After 4-months, the rats were sacrificed and nerve histology was done to test for nerve regeneration. Only anisotropic scaffolds and nerve autografts contained evidence of axonal regeneration. Both groups had similar numbers of myelinated axons and similar axonal-diameter distribution. However, nerve graft group performed better in functional outcome as measured by relative gastrocnemius muscle weight (RGMW) and electrophysiology. Optimization of performance of anisotropic scaffolds by varying the LN-1 and NGF concentration gradients might lead to development of scaffolds that can perform as well as nerve auotgrafts for nerve regeneration over long nerve gaps.