Dissertations / Theses on the topic 'Biomaterials platform'

Homeostasis of hematopoietic stem cells (HSC) in the mammalian bone marrow stem cell niche is regulated by signals of the local microenvironment. Besides juxtacrine, endocrine and metabolic cues, paracrine and autocrine signals are involved in controlling quiescence, proliferation and differentiation of HSC with strong implications on expansion and differentiation ex vivo as well as in vivo transplantation. Towards this aim, a cell culture analysis on a polymer microcavity carrier platform was combined with a partial least square analysis of a mechanistic model of cell proliferation. We could demonstrate the discrimination of specific autocrine and paracrine signals from soluble factors as stimulating and inhibitory effectors in hematopoietic stem and progenitor cell culture. From that we hypothesize autocrine signals to be predominantly involved in maintaining the quiescent state of HSC in single-cell niches and advocate our analysis platform as an unprecedented option for untangling convoluted signaling mechanisms in complex cell systems being it of juxtacrine, paracrine or autocrine origin.

Biopolymers are becoming more attractive as advanced wound dressings because of their naturally derived origin, abundance, low cost and high compatibility with the wound environment. Arabinoxylan (AX) is a class of polysaccharide polymers derived from cereal grains that are primarily used in food products and cosmetic additives. Its application as a wound dressing material has yet to be realized. In this two-pronged project, arabinoxylan ferulate (AXF) was fabricated into electrospun fibers and gel foams to be evaluated as platforms for wound dressing materials. In the first study, AXF was electrospun with varying amounts of gelatin. In the second study, AXF was dissolved in water, enzymatically crosslinked and lyophilized to form gel foams. The morphology, mechanical properties, porosity, drug release kinetics, fibroblast cell response and anti-microbial properties were examined for both platforms. Carbohydrate assay was conducted to validate the presence of arabinoxylan ferulate in the electrospun GEL-AXF fibers. Swelling and endotoxin quantification studies were done to evaluate the absorptive capacity and sterilization agent efficacy respectively in AXF foams. The results indicated successful fabrication of both platforms which validated the porous, absorptive, biocompatibility and drug release properties. The results also exhibited that silver impregnated AXF scaffolds inhibited growth of Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis bacteria species, anti-microbial properties necessary to function as advanced wound dressing materials. Future work will be done to improve the stability of both platforms as well as evaluate its applications in vivo.

Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2008.
Title from electronic title page (viewed Dec. 11, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry." Discipline: Chemistry; Department/School: Chemistry.

Mestrado em Materiais e Dispositivos Biomédicos
The discovery of piezoelectricity in bone by Fukada brought to light the idea of using piezoelectrics to enhance bone growth. Piezoelectric polymers like poly (L-lactic) acid (PLLA), a synthetic semi-crystalline polyester combining adjustable biodegradability and physical properties, stands out and therefore can be used as scaffolds for bone regeneration. In addition, some PLLA products have been approved for implantation in human body by the Food and Drug Administration (FDA). In the present work PLLA films with different crystallinities and thicknesses were produced in order to improve the dielectric properties and cellular adhesion. The maximum crystalline degree obtained was 35%. A complete characterization of PLLA films with different thicknesses and crystallinities was performed. The dielectric analysis included permittivity, dielectric loss and polarization. The highest relative permittivity value was 52.58 for amorphous samples at 120 ºC and 153 kHz. Dielectric loss reached its maximum at 27 ºC for a frequency of 1 MHz, being the value 1.64 on crystalline films. Polarization was studied by the technique Thermal Stimulated Depolarization Currents (TSDC), a method that measures polarization through thermal stimulus. In terms of polarization, the values increase proportionally with crystallinity, being the highest values 180 μC/cm2 on crystalline samples polarized during half an hour. In addition to cell-based assays, exists the metabolomics studies, a powerful tool since it can provide detailed information on the specific metabolic pathways responding and adapting to each of the selected material formulations. The work carried out in this project is the first stage of a wider program including in vitro biological characterization. It is presented the first metabolomics study using human osteoblasts in contact with piezoelectric PLLA, on PLLA standard films with 3% crystallinity, negatively poled.
A descoberta da piezoeletricidade no osso por Fukada levou à ideia de usar materiais piezoeléctricos para melhorar o crescimento ósseo. Polímeros piezoeléctricos como o poli (L-ácido láctico) (PLLA), um poliéster semicristalino sintético que combina biodegradabilidade e propriedades físicas ajustáveis, destacam-se pois podem ser utilizados como estruturas temporárias para a regeneração óssea. Para além disso, alguns produtos feitos à base de PLLA estão já aprovados para implantação no corpo humano pela Food and Drug Administration (FDA).Neste trabalho foram produzidos filmes de PLLA com diferentes cristalinidades e espessuras com o intuito de melhorar as propriedades dielétricas do material e a adesão celular. O grau de cristalinidade máximo obtido foi de aproximadamente 35%. Efectuou-se uma caracterização completa dos filmes com diferentes cristalinidades e espessuras. As medidas dielétricas realizadas abrangeram permitividade relativa, perda dielétrica e polarização. O valor mais alto de permitividade relativa medido foi de 52,58 para o filme amorfo, a 120 ºC e 153 kHz. A perda dielétrica atingiu o seu máximo nos filmes cristalinos aos 27 ºC para uma frequência de 1 MHz, com o valor de 1,64. A polarização foi estudada segundo a técnica TSDC (Thermal Stimulation Depolarization Current), um método que mede a polarização do material através do estímulo térmico. Em termos de polarização os valores aumentaram proporcionalmente com a cristalinidade, sendo o mais elevado 180 μC/cm2 para as amostras cristalinas polarizadas durante meia hora. Para além dos ensaios celulares, existe a metabolómica, hoje em dia uma ferramenta poderosa pois pode fornecer informações detalhadas sobre as vias metabólicas específicas que respondem e permitem a adaptação celular a cada uma das formulações de materiais selecionados. O trabalho realizado neste projecto constitui a primeira etapa de um programa mais amplo de caracterização biológica in vitro. É apresentado o primeiro estudo de metabolómica, utilizando osteoblastos humanos, em contato com o piezoelétrico PLLA, utilizando filmes de PLLA standard, 3% de cristalinidade, polarizados negativamente.

Mestrado em Ciência e Engenharia de Materiais
The development of scaffolds based on biomaterials is a promising strategy for Tissue Engineering and cellular regeneration. This work focuses on Bone Tissue Engineering, the aim is to develop electrically tailored biomaterials with different crystalline and electric features, and study their impacts onto cell biological behavior, so as to predict the materials output in the enhancement of bone tissue regeneration. It is accepted that bone exhibits piezoelectricity, a property that has been proved to be involved in bone growth/repair mechanism regulation. In addition electrical stimulations have been proved to influence bone growth and repair. Piezoelectric materials are therefore widely investigated for a potential use in bone tissue engineering. The main goal is the development of novel strategies to produce and employ piezoelectric biomaterials, with detailed knowledge of mechanisms involved in cell-material interaction. In the current work, poly (L-lactic) acid (PLLA), a synthetic semi-crystalline polymer, exhibiting biodegradibility, biocompatibility and piezoelectricity is studied and proposed as a promoter of enhanced tissue regeneration. PLLA has already been approved for implantation in human body by the Food and Drug Administration (FDA), and at the moment it is being used in several clinical strategies. The present study consists of first preparing films with different degrees of crystallinity and characterizing these PLLA films, in terms of surface and structural properties, and subsequently assessing the behavior of cells in terms of viability, proliferation, morphology and mineralization for each PLLA configuration. PLLA films were prepared using the solvent cast technique and submitted to different thermal treatments in order to obtain different degrees of crystallinity. Those platforms were then electrically poled, positively and negatively, by corona discharge in order to tailor their electrical properties. The cellular assays were conducted by using two different osteoblast cell lines grown directly onto the PLLA films:Human osteoblast Hob, a primary cell culture and Human osteosarcoma MG-63 cell line. This thesis gives also a comprehensive introduction to the area of Bone Tissue Engineering and provides a review of the work done in this field in the past until today, in that same field, including the one related with bone’s piezoelectricity. Then the experimental part deals with the effects of the crystallinity degrees and of the polarization in terms of surface properties and cellular bio assays. Three different degrees of crystallinity, and three different polarization conditions were prepared; which results in 9 different configurations under investigation.
O desenvolvimento de scaffolds baseados em biomateriais é uma estratégia promissora para a engenharia de tecidos e entrega de fármacos. Este trabalho centra-se na engenharia de tecido ósseo, o objectivo é desenvolver biomateriais electricamente modificados, com diferentes valores de cristalinidade e propriedades eléctricas, e estudar o seu impacto no comportamento biológico da célula de modo a prever o efeito desses materiais na regeneração do tecido. É já amplamente conhecido o fato de o osso possuir características piezoeléctricas, e reconhecido que estas contribuem para os mecanismos de regulação do crescimento e reparação do tecido ósseo. Além disso é um facto aceite que a estimulação eléctrica também influencia o crescimento e reparação do osso. Os materiais piezoeléctricos apresentam assim vantagens quanto à sua utilização em engenharia de tecido ósseo, e têm vindo a ser estudados para esse efeito. No presente trabalho foram desenvolvidos filmes de ácido poli-L-láctico (PLLA), um polímero sintético semi-cristalino que é biocompatível, biodegradável, e piezoeléctrico, que se apresenta como promotor da regeneração óssea. O PLLA é um material aceite para implantes em humanos pela “Food and Drug Administration” (FDA), e está já a ser utilizado em várias estratégias e produtos para uso clínico. O presente estudo consiste numa primeira fase de preparação e caracterização de filmes de PLLA em termos de propriedades estruturais e de superfície, e numa segunda fase de avaliação do comportamento celular em termos de viabilidade, proliferação, morfologia e mineralização, para cada uma das configurações de PLLA obtidas. Os filmes foram preparados pelo método de evaporação do solvente com molde, e submetidos a diferentes tratamentos térmicos de forma a obter diferentes valores de cristalinidade. Estas plataformas foram depois electricamente polarizadas, positiva e negativamente, por meio de descarga de corona para modular as suas propriedades eléctricas. Os ensaios celulares foram realizados utilizando duas linhas celulares osteoblásticas, em contacto direto com as superfícies de PLLA: Osteoblastos Humanos - Hob, cultura primária de células, e linha de Osteosarcoma Humano - MG-63. Este trabalho também inclui uma introdução teórica para área da Engenharia de Tecido Ósseo, e resume o trabalho de investigação realizado nesta área até hoje incluindo aquele relacionado com a piezoelectricidade do tecido ósseo. A parte experimental dedica-se aos efeitos do grau de cristalinidade e da polarização nas propriedades de superfície do material e nos ensaios biológicos. Foram estudadas nove configurações, originadas por três valores de cristalinidade: 0, 7 e 35%, e três tipos de polarização: positiva, negativa e neutra (apenas com o tratamento térmico análogo).

El cartílag articular té una capacitat limitada de creixement i regeneració i, els tractaments per restaurar la funció del teixit, després d’una lesió, són limitats i poc entesos per la comunitat mèdica. Existeix, per tant, un gran interès en trobar una solució pràctica i agradable pel pacient que aconsegueixi la reparació del cartílag. La enginyeria de teixits va sorgir per restablir teixits danyats usant noves plataformes terapèutiques basades en cèl·lules i/o biomaterials. Aquestes noves teràpies pretenen crear estructures similars al cartílag que imiten les propietats mecàniques i biològiques que trobem in vivo. En aquest context, l’ús de matrius biomimètiques que reprodueixin estructural i funcionalment el microambient natiu han despertat gran interès en aquest camp. Els pèptids auto-ensamblants representen candidats ideals per crear nínxols cel·lulars, ja que les seves nanofibres i propietats biomecàniques son similars a les de la matriu extracel·lular. En aquesta tesi, s’ha desenvolupat nous biomaterials sintètics amb gran potencial per la reparació de cartílag. Aquests estan basats en el pèptid auto-ensamblant RAD16-I decorat amb motius bioactius, amb l’objectiu de reproduir la matriu del cartílag. Donada la versatilitat del hidrogel RAD16-I, les noves matrius es van formar per simple mescla del pèptid RAD16-I amb molècules d’heparina, condroitin sulfat i decorina. Aquestes matrius bi-composades presenten bona estabilitat química i estructural a pH fisiològic i son capaces d’unir i alliberar, gradualment, factors de creixement. L’avaluació d’aquestes matrius es va dur a terme mitjançant dues estratègies in vitro diferents: la rediferenciació de condròcits articulars humans i la inducció del llinatge condrogènic en cèl·lules mare derivades de teixit adipós. Ambdós tipus cel·lulars son considerats una bona font cel·lular per obtenir constructes que reparin defectes al cartílag. Els resultats presentats en aquest treball mostren diferencies a nivell de comportament cel·lular, patrons d’expressió i propietats mecàniques entre els dos tipus cel·lulars i les diferents condicions de cultiu (matrius i medis). Cal destacar que els dos tipus cel·lulars es diferencien a un llinatge condrogènic en medi d’inducció i que els constructes presenten propietats mecàniques compatibles amb un sistema condrogènic. A més s’ha determinat que la presencia de molècules d’heparina a la matriu promou la supervivència de les cèl·lules mare derivades de teixit adipós. En conjunt, les noves matrius bi-composades representen un material fàcil de preparar i prometedor per promoure la diferenciació condrogènica. Finalment, part d’aquesta tesi s’ha centrat en el desenvolupament d’una nova matriu composta mitjançant la infiltració del pèptid RAD16-I amb cèl·lules en microfibres de policaprolactona (PCL). S’ha demostrat que aquesta nova combinació ofereix una estructura funcional i biomimètica, ja que proporciona suport mecànic per les fibres de PCL i a la vegada, facilita l’adhesió i el creixement cel·lular per l’hidrogel RAD16-I. El cultiu in vitro de condròcits humans desdiferenciats demostra que la nova matriu composada promou la supervivència cel·lular i el restabliment del llinatge condrogènic. En general, les propietats sinèrgiques de la nova matriu composada proporcionen una plataforma terapèutica ideal per ajudar a la reparació del cartílag.
El cartílago articular tiene una capacidad limitada de crecimiento y regeneración y, los tratamientos para restaurar la función del tejido, después de una lesión, son limitados y poco entendidos por la comunidad médica. Existe, por tanto, un gran interés en encontrar una solución práctica y agradable para el paciente que consiga la reparación del cartílago. La ingeniería de tejidos surgió para restaurar tejidos dañados usando nuevas plataformas terapéuticas basadas en células y/o biomateriales. Estas nuevas terapias pretenden crear estructuras similares al cartílago que imiten las propiedades mecánicas y biológicas que se dan in vivo. En este sentido, el uso de matrices biomiméticas que reproduzcan estructural y funcionalmente el microambiente nativo ha generado gran interés en este campo. Los péptidos auto-ensamblantes representan candidatos ideales para crear nichos celulares dado que, sus nanofibras y propiedades biomecánicas son similares a las de la matriz extracelular. En esta tesis, se han desarrollado nuevos biomateriales sintéticos con gran potencial para la reparación de cartílago. Éstos, están basados en el péptido auto-ensamblante RAD16-I decorado con motivos bioactivos, tratando de reproducir la matriz del cartílago. Dada la versatilidad del hidrogel RAD16-I, las nuevas matrices se formaron por simple mezcla del péptido RAD16-I con moléculas de heparina, condroitin sulfato y decorina. Estas matrices bi-compuestas presentan buena estabilidad química y estructural a pH fisiológico y son capaces de unir y liberar, gradualmente, factores de crecimiento. La evaluación de estas matrices se llevó a cabo mediante dos estrategias in vitro diferentes: la rediferenciación de condrocitos articulares humanos y, la inducción del linaje condrogénico en células madre derivadas de tejido adiposo. Ambos tipos celulares son considerados una buena fuente de células para obtener constructos que reparen defectos en el cartílago. Los resultados presentados en este trabajo muestran diferencias a nivel de comportamiento celular, patrones de expresión y propiedades mecánicas entre los dos tipos celulares y las diferentes condiciones de cultivo (matrices y medios). Cabe destacar que, ambos tipos celulares se diferencian a un linaje condrogénico en medio de inducción y que los constructos presentan propiedades mecánicas compatibles con un sistema condrogénico. Además, se ha determinado que la presencia de moléculas de heparina en la matriz promueve la supervivencia de las células madre derivadas de tejido adiposo. En conjunto, las nuevas matrices bi-compuestas representan un material fácil de preparar y prometedor para promover la diferenciación condrogénica. Por último, parte de esta tesis se ha centrado en el desarrollo de una nueva matriz compuesta mediante la infiltración del péptido RAD16-I con células en microfibras de policaprolactona (PCL). Se ha demostrado que esta nueva combinación ofrece una estructura funcional y biomimética, dado que, proporciona soporte mecánico por las fibras PCL y a su vez, facilita la adhesión y el crecimiento celular debido al hidrogel RAD16-I. El cultivo in vitro de condrocitos humanos desdiferenciados demuestra que la nueva matriz compuesta promueve la supervivencia celular y el restablecimiento del linaje condrogénico. En general, las propiedades sinérgicas de la nueva matriz compuesta proporcionan una plataforma terapéutica ideal para ayudar a la reparación del cartílago.
Adult articular cartilage has a limited capacity for growth and regeneration and, after injury, treatments to restore tissue function remain poorly understood by the medical community. Therefore, there is currently great interest in finding practical and patient-friendly strategies for cartilage repair. Tissue engineering has emerged to restore damaged tissue by using new cellular or biomaterial-based therapeutic platforms. These approaches aim to produce cartilage-like structures that reproduce the complex mechanical and biological properties found in vivo. To this end, the use of biomimetic scaffolds that recreate structurally and functionally the native cell microenvironment has become of increasing interest in the field. Self-assembling peptides are attractive candidates to create artificial cellular niches, because their nanoscale network and biomechanical properties are similar to those of the natural extracellular matrix (ECM). In the present thesis, new composite synthetic biomaterials were developed for cartilage tissue engineering (CTE). They were based on the non-instructive self-assembling peptide RAD16-I and decorated with bioactive motifs, aiming to emulate the native cartilage ECM. We employed a simple mixture of the self-assembling peptide RAD16-I with either heparin, chondroitin sulfate or decorin molecules, taking advantage of the versatility of RAD16-I. The bi-component scaffolds presented good structural and chemical stability at a physiological pH and the capacity to bind and gradually release growth factors. Then, these composite scaffolds were characterized using two different in vitro assessments: re-differentiation of human articular chondrocytes (ACs) and induction of human adipose derived stem cells (ADSCs) to a chondrogenic commitment. Both native chondrocytes and adult mesenchymal stem cells (MSCs), either bone marrow or adipose-tissue derived, are considered good cell sources for CTE applications. The results presented in this work revealed differences in cellular behavior, expression patterns and mechanical properties between cell types and culture conditions (scaffolds and media). Remarkably, both cell types underwent into chondrogenic commitment under inductive media conditions and 3D constructs presented mechanical properties compatible to a system undergoing chondrogenesis. Interestingly, as a consequence of the presence of heparin moieties in the scaffold cell survival of ADSCs was enhanced. Altogether, the new bi-component scaffolds represent a promising "easy to prepare" material for promoting chondrogenic differentiation. Finally, part of this thesis was focus on developing a composite scaffold by infiltrating a three-dimensional (3D) woven microfiber poly (ε-caprolactone) (PCL) scaffold with the RAD16-I self-assembling peptide and cells. This new combination resulted into a multi-scale functional and biomimetic tissue-engineered structure providing mechanical support by PCL scaffold and facilitating cell attachment and growth by RAD16-I hydrogel. The in vitro 3D culture of dedifferentiated human ACs evidenced that the new composite supports cell survival and promotes the reestablishment of the chondrogenic lineage commitment. Overall, the synergistic properties of the novel composite scaffold may provide an ideal therapeutic platform to assist cartilage repair.

El potencial curatiu de les immunoteràpies per a estimular o suprimir respostes immunes ha revolucionat el paradigma sota el qual malalties como el càncer o trastorns autoimmunes son tractats; no obstant, una implementació extensa d’aquestes no ha sigut possible degut a la seva toxicitat. Donada la capacitat dels nanomaterials de reconduir fàrmacs immunomoduladors cap a teixits diana, les plataformes per alliberar fàrmacs dissenyades a partir de biomaterials podrien solucionar les necessitats més urgents d’aquest camp com l’alliberació específica a cèl·lules diana, l’alliberament local —en comptes de sistèmic— i l’acumulació a teixits diana per tal d’augmentar la seva eficàcia i seguretat. Aquesta tesi proposa l’ús de poly(β-amino ester)s (PBAEs) per al desenvolupant de vehicles d’alliberament dirigits cap a les pell amb l’objectiu de modular el sistema immune a nivell local en els àmbits de la vacunació amb àcids nucleics, la immunoteràpia contra el càncer y la teràpia adoptiva. S’ha presentat una nova llibreria de PBAEs modificats amb oligopèptids i manosa amb especificitat cel·lular cap a les cèl·lules dendrítiques, les principals presentadores d’antigen a la pell. L’efecte sinèrgic entre els oligopèptids i el lligand ha permès millorar substancialment el rendiment d’aquests vector per a vacunació amb mRNA/DNA. Addicionalment, aquest s’han pogut formular sense necessitar de fer servir solvents ni en forma de nanopartícules, a més de poder-los integrar en dispositius mèdics com microagulles, ja sigui en forma de partícules o films, per tal de transferir gens de manera no invasiva. Com a teràpia contra el càncer, una microagulles innovadores fetes a partir d’hidrogels s’han utilitzat per a alliberar un fàrmac immunomodulador mentre recol·lectaven líquid intersticial simultàniament per tal monitoritzar l’eficiència de la teràpia. Les microagulles carregades amb PBAEs foren capaces de reduir la mida de tumors y modular el microambient tumoral, la composició immunològica del qual correlaciona amb la del líquid intersticial mostrejat. Finalment, les microagulles s’han reciclat com a plataforma per a restablir l’equilibri immunològic en transplantaments de pell. Les microagulles reclutaren cèl·lules T reguladores cap als transplantaments gràcies a l’alliberació de citocines mentre vigilaven in situ la migració d’aquestes. En conclusió, aquesta tesi demostra el potencial de les plataformes transdèrmiques derivades de PBAEs per a induir immunomodulació a nivell local. Prioritzant plataformes sense solvents, locals i no-invasives, en aquesta tesi s’han optimitzat nous sistemes basats en PBAEs i integrats en dispositius mèdics com microagulles per a immunoteràpia.
El potencial curativo de las inmunoterapias para estimular o suprimir el sistema inmune ha revolucionado el paradigma bajo el que enfermedades como el cáncer o trastornos autoinmunes son tratados; no obstante, la implementación de dichas terapias se ha visto restringida por su toxicidad. Dada la capacidad de los nanomateriales para redirigir fármacos inmunomoduladores a tejidos dianas, las plataformas de liberación basadas en biomateriales podrían solventar las mayores necesidades del ámbito incluyendo, liberación específica a células diana, localizada —en vez de sistémica— y acumulación en tejidos diana para así aumentar su potencia y seguridad. Usando los poly(β-amino ester)s (PBAEs) como piedra angular, esta tesis propone desarrollar vectores dirigidos hacía la piel con el fin de modular el sistema inmune a nivel local en ámbitos tales como vacunación con ácidos nucleicos, inmunoterapia contra cáncer y terapia celular adoptiva. Se ha presentado una nueva librería de PBAEs modificados con oligopéptidos y manosa que poseen especificidad celular hacia células dendríticas, las principales instigadoras en la presentación de antígenos en la piel. El efecto sinérgico entre oligopéptidos y ligando ha permitido mejorar sustancialmente estos vehículos de transporte para vacunación. Además, los PBAEs se han podido formular como vectores alternativos a las nanopartículas y que no precisan solventes, así como integrarlos en dispositivos médicos como microagujas, ya sea en forma de partículas o de films, para transferir genes de manera no invasiva. Como terapia contra el cáncer, se han diseñado microagujas de hidrogel que permiten la liberación de un fármaco inmunoestimulante además de colectar líquido intersticial para monitorear la respuesta a la terapia in situ. Las microagujas cargadas con PBAEs pudieron reducir el tamaño de los tumores y modular el microambiente tumoral, la composición del cual correlaciona con la del líquido intersticial colectado con dicha plataforma. Finalmente, las microagujas fueron usadas para restablecer el equilibrio inmunológico en trasplantes de piel. Las microagujas pudieron reclutar células T reguladoras hacia el trasplante mediante la liberación de citoquinas quimioatrayentes además de informar sobre su proceso de migración hacia el trasplante. En conclusión, esta tesis demuestra el potencial de las plataformas transdérmicas basadas en PBAEs para inducir inmunomodulación local. Priorizando plataformas sin solventes, locales, y poco invasivas, se han desarrollado sistemas basados en PBAEs e integrados con microagujas para inmunoterapia.
The curative potential of immunotherapies to augment or suppress immune responses has shifted the paradigm for managing various diseases including cancer and autoimmune disorders, yet broad implementation has been curtailed by detrimental off-target toxicities. Given the ability of nanomaterials to direct immunomodulators to target tissues, nanomedicine-based delivery platforms formulated in carrier biomaterials could surmount the most pressing needs in the field being cell-specific targeting, local —rather than systemic— administration, and tissue accumulation to ultimately enhance the safety and potency of these therapeutic products. Using poly(β-amino ester)s (PBAEs) as foundational nanocarriers, this thesis proposes to engineer PBAE-based delivery platforms to target the immunologically rich milieu of the skin for local immunomodulation in the contexts of nucleic acid vaccination, cancer immunotherapy and adoptive T cell therapy. First, a novel library of oligopeptide- and mannose-modified PBAEs is presented for refined targeting of dendritic cells (DCs) as primary orchestrators of antigen presentation in the skin. The synergistic potential of oligopeptide and ligand decoration to target dermal DC subsets has been demonstrated as a powerful tool to upgrade delivery vectors for gene vaccination. Nanoparticle- and solvent-free delivery of nucleic acids using PBAEs formulated as polyelectrolyte films (PEMs) has also been confirmed. PBAEs can be successfully integrated in transdermal devices such as microneedles, either as PEMs or as polyplexes, to mediate minimally-invasive gene transfer. Moving to cancer immunotherapy, a hydrogel-based MN platform is presented for delivery of an immunostimulatory drug and retrieval of interstitial skin fluid (ISF) for in situ immune surveillance of the response to therapy. It has been proven that PBAE-loaded MNs suppress tumor growth and modulate the immune signature of the tumor microenvironment, which appears to correlate with that from MN-sampled ISF. Finally, hydrogel MNs are proposed for restoring immune homeostasis in transplanted skin allografts. Recruitment of adoptively-transferred regulatory T cells into the allografts has been achieved by delivering chemoattractant chemokines with the MNs while also monitoring the Treg homing process via ISF sampling, confirming the potential of MNs as a mode of tissue surveillance. In conclusion, this thesis demonstrates the potential of transdermal platforms derived from PBAEs for local immunomodulation. Shifting from hypodermic administration to solvent-free, local, and minimally-invasive approaches, PBAE-based systems have been engineered with microneedles for immunotherapy delivery.

Personalized medicine requires the development of new technologies for controlled or targeted drug delivery. Three-dimensional (3D) printing and additive manufacturing techniques can be used to generate customized constructs for bioactive compound delivery. Nanotechnology in the form of nanoparticles, used as a stand-alone construct or for material enhancements, can significantly improve established biomaterials such as PMMA based bone cements or enable new technology to have enhanced capabilities. Combinations of the technologies can be used in such applications as infectious disease treatments, chemotherapeutic targeted drug delivery or targeted delivery of nearly any bioactive compound.

Chemotherapeutic or antibiotic enhanced 3D printing filaments were invented and designed to allow for the fabrication of antibiotic beads, drug eluting catheters, drains, stents, screws or any bioactive construct. Halloysite nanotubes (HNTs) were investigated as a modular platform and solely or in combinations were coated in metals including: iron for magnetic targeted delivery including hyperthermia, gold for laser targeted hyperthermia or barium as a contrast agent for visualization. The particles were test loaded with antibiotics or chemotherapeutics as well as coated in biocompatible coatings containing lipids or layered polyelectrolytes. Nanoparticles were added to 3D printing filaments or bone cements to test increases in strength, contrast or pore size.

3D print filaments and bioactive constructs that eluted gentamicin sulfate were tested using clinical microbiology lab standards and were shown to inhibit bacterial growth. 3D print filaments that eluted methotrexate were shown to inhibit proliferation of osteosarcoma cells and also provided a means for sustained drug release. Halloysite was successfully shown as a modular platform that could be highly customized for patient specific uses. Single coatings or combinations of magnetically susceptible iron coatings, gold coatings, drug loading of multiple bioactive compounds and biocompatible coatings were also developed. Bone cements with barium-coated particles were shown to have enhanced contrast.

The first ever ability to create and use bioactive 3D printing filaments on consumer printers was realized and HNTs were developed as proof of principle for multifunctional and real time customizable nanoparticle platforms. Nanoparticles as additives showed ways to modify established biomaterials or 3D printing filaments with enhanced features and properties.

Over 500 million people worldwide suffer from disease associated with intestinal inflammation, including gastric cancer, inflammatory bowel disease, h. pylori infections, and numerous viral and bacterial infections. Although potentially effective therapeutics exist for many of these pathologies, delivery challenges thwart their clinical viability. The objective of this work was to develop drug delivery platforms that could target toxic immunomodulatory therapeutics to diseased intestinal tissues. To meet this objective, we developed an oral delivery vehicle for siRNA and an NF-κB inhibiting nanoparticle that reduces drug-resistance. Small interfering RNA (siRNA) represents a promising treatment strategy for numerous gastrointestinal (GI) diseases; however, the oral delivery of siRNA to inflamed intestinal tissues remains a major challenge. In this presentation, we describe a delivery vehicle for siRNA, termed thioketal nanoparticles (TKNs), that can orally deliver siRNA to sites of intestinal inflammation, and thus inhibit gene expression in diseased intestinal tissue. Using a murine model of ulcerative colitis, we demonstrate that orally administered TKNs loaded with TNFα-siRNA (TNFα-TKNs) diminish TNFα messenger RNA (mRNA) levels in the colon and protect mice from intestinal inflammation. Activation of nuclear factor-κB (NF-κB) results in the expression of numerous prosurvival genes that block apoptosis, thus mitigating the efficacy of chemotherapeutics. Paradoxically, all conventional therapeutics for cancer activate NF-κB, and in doing so initiate drug resistance. Although adjuvant strategies that block NF-κB activation could potentiate the activity of chemotherapeutics in drug resistant tumors, clinical evidence suggests that current adjuvant strategies also increase apoptosis in non-malignant cells. In this presentation, we present a nanoparticle, formulated from a polymeric NF-κB-inhibiting prodrug, that target the chemotherapeutic irinotecan (CPT-11) to solid tumors, and thus abrogates CPT-11-mediated drug resistance and inhibits tumor growth. In order to maximize the amount of NF-κB inhibitor delivered to tumors, we synthesized a novel polymeric prodrug, termed PCAPE, that releases the NF-κB inhibitor caffeic acid phenethyl ester (CAPE) as its major degradation product. Using a murine model of colitis-associated cancer, we demonstrate that when administered systemically, CPT-11-loaded PCAPE-nanoparticles (CCNPs) are three time more effective than a cocktail of the free drugs at reducing both tumor multiplicity and tumor size.

Polymers have great potential as building blocks to construct biomaterials for applications in biomedicine, pharmaceutics and biotechnology. Their chemical flexibility leads to the synthesis of materials with diverse physical and mechanical properties. Specifically, stimuli-responsive polymers are engineered to undergo chemical or physical transitions in response to specific external triggers. One such response involves the cleavage or degradation of a dynamic covalent bond within the polymer structure. Particularly, the reduction of disulfide bonds has gained significant attention in the development of complex delivery systems for therapeutics. This thesis describes the development of two different reduction-responsive biomaterials. Amphiphilic block copolymers (ABPs) self-assemble in aqueous solutions to form core/shell micelles consisting of a hydrophobic core, capable of carrying a variety of hydrophobic therapeutic agents, and a hydrophilic corona, able to improve circulation time and delay immune responses. This unique property, in addition to enhanced colloidal stability and tunable size with narrow size distribution, makes micelles promising candidates for drug delivery systems. Hence, a polyester-based reduction-responsive degradable ABP with disulfide linkages positioned repeatedly on the main chain at regular intervals is synthesized. These well-defined ABPs were synthesized by a combination of polycondensation and atom transfer radical polymerization (ATRP). These ABPs self-assemble in aqueous solution, resulting in spherical micelles with a monomodal distribution. In the presence of a reducing agent, disulfide bonds are cleaved, leading to a destabilization of the micellar core and thus enhanced release of encapsulated model drugs. Demonstrating the potential drug delivery applications of polymeric micellar systems, functionalization with biotin (vitamin H) leads to bioconjugated micelles capable of potential cell-targeting. Hydrogels are three-dimensional networks of hydrophilic polymers that have shown promise as tissue engineering scaffolds. Thermo-responsive hydrogels expel water above their lower critical solution temperature (LCST), becoming more hydrophobic, and hence lose volume. Hydrogels were synthesized by ATRP using biocompatible oligo(ethylene oxide) as a scaffolding material in the presence of a disulfide-labeled dimethacrylate cross-linker. The amount of cross-linker affects thermo-responsive and mechanical properties. Cleavage of disulfide bonds lead to an increased LCST, enhanced deswelling kinetics and a decrease in mechanical properties caused by the generation of hydrophilic dangling chains, increasing the overall hydrophilicity of hydrogels. Combined with these results, as well as enhanced release of encapsulated hydrophilic model drugs and non-toxicity, these hydrogels show promise for biomedical applications.

Existing methods for pathogen/pollutant detection or wound infection monitoring employ high-cost instruments that could only be operated by trained personnel, and costly device-based detection requires a time-consuming field-to-lab process. This expensive process with multiple prerequisites prolongs the time that patients must wait for a diagnosis. Therefore, improved methods for point-of-care biosensing are necessary. In this study, we aimed to develop a direct, easy-to-use, portable, low cost, highly sensitive and selective sensor platform with the goal of pollutant detection and wound infection/cancer migration monitoring. This study has two main parts, including microfluidic, electrical, and optical sensing platforms. The first part, including chapters 2, 3, and 4, focuses on Bisphenol A (BPA) lateral flow assay (LFA) detection; the second part, including chapter 5 focuses on the electrical sensing platform fabrication for one of the markers of inflammation, matrix metalloproteinases-9 (MMP-9), monitoring/detection. In chapters 2, 3, and 4, we found that the few lateral flow assays (LFAs) established for detecting the endocrine-disrupting chemical BPA have employed citrate-stabilized gold nanoparticles (GNPs), which have inevitable limitations and instability issues. To address these limitations, in chapter 2, a more stable and more sensitive biosensor is developed by designing strategies for modifying the surfaces of GNPs with polyethylene glycol and then testing their effectiveness and sensitivity toward BPA in an LFA. In chapter 3, we describe the development of a new range-extended bisphenol A (BPA) detection method that uses a surface enhanced Raman scattering lateral flow assay (SERS-LFA) binary system. In chapter 4, we examine advanced bisphenol A (BPA) lateral flow assays (LFAs) that use multiple nanosystems. The assays include three nanosystems, namely, gold nanostars, gold nanocubes, and gold nanorods, which are rarely applied in LFAs, compared with general gold nanoparticles. The developed LFAs show different performances in the detection of BPA. In chapter 5, a stable electrical sensing platform is developed for MMP-9 detection.

Tese de doutoramento em Engenharia Biomédica
One of the still unaccomplished struggles in the maintenance of population life quality is related to the current need for effective biomaterials. The optimization of tissue engineering (TE) strategies by combining biomaterials, cells and soluble factors usually relies on time-consuming iterative processes. Rapid and low-cost high-throughput testing is needed to accelerate the discovery of ideal TE systems. The main hypothesis of this thesis was that superhydrophobic surfaces patterned with wettable spots were amenable to be used as platforms for high-throughput complete testing of 3D biomaterials. Indeed, such platforms allowed taking advantage of wettability contrast to pattern biomaterials with precise shape and pre-determined height, by controlling the volume dispensed in each spot. The superhydrophobic chips were first used to pattern ionic alginate-based cell-laden hydrogels in the wettable spots. The chemical composition of each biomaterial was evaluated by FTIR and the cellular response of fibroblast and osteoblast-like cell lines was assessed on-chip by image-based analysis. Image-based non-destructive assessment was validated by comparison with conventional biochemical colorimetric tests. Superhydrophobic chips were later used to produce and study miniaturized porous scaffolds. The size of the spots in the milimetric range allowed having porous biomaterial structures with significant pore size for cell migration and growth. Chitosan/alginate scaffolds were processed by polyelectrolyte complexation and freeze-drying, followed by fibronectin adsorption. Cell number and viability were assessed using two cell lines. DMA and μCT techniques were adapted to be used on-chip, in dry conditions, to characterize the scaffolds mechanically and morphologically. The on-chip DMA method was upgraded to be performed under physiological-like conditions using chitosan/bioactive glass nanoparticles hydrogels. The selective adhesion and proliferation of a pre-osteoblast cell line allowed hit-spotting favorable in vitro biomaterial formulations. After demonstrating their adequacy for in vitro cell-3D biomaterials interactions assessment, superhydrophobic chips containing 36 biomaterials were implanted in single Wistar rats, allowing the high-throughput in vivo study of inflammatory response caused by biomaterials. An important aspect in TE is the dependency of tissue regeneration on prolonged action of bioactive agents. Superhydrophobic chips were imprinted with ring-shaped spots with concentric superhydrophobic regions where polymeric protein-loaded spheres were deposited. The acquisition of sequential images of each spot over time using microscopy methods allowed monitoring protein release. Finally, cell suspension droplets were fixed in the wettable regions of the chips to produce cell spheroids/microtissues for drug screening by the hanging drop methodology in a robot-free automated manner. In conclusion, the superhydrophobic platforms patterned with wettable spots used in this thesis proved to be compatible with a complete study of 3D biomaterials-cells interactions, comprising a wide set of factors as biomaterials characterization, in vitro testing, innovative in vivo assessment and bioactive molecules-related tests.
Um dos desafios correntes para a manutenção da qualidade de vida das populações prende-se com a falta de biomateriais eficazes. A otimização de estratégias em engenharia de tecidos (ET) através da combinação de biomateriais, células e fatores solúveis requer, em geral, processos iterativos. Testes expeditos e de baixo custo são necessários para acelerar a descoberta de sistemas de ET ideiais. A hipótese desta tese consiste na possibilidade do uso de superfícies superhidrofóbicas padronizadas com regiões hidrofílicas como plataformas para a análise expedita e completa de biomateriais 3D. As plataformas permitiram usar o contraste de molhabilidade para depositar biomateriais com forma e altura precisas, controlando o volume colocado em cada região hidrofílica. As plataformas foram usadas para dispensar hidrogéis de alginato com células encapsuladas nas regiões molháveis. A composição química de cada biomaterial foi avaliada por FTIR, e a resposta celular foi testada através de análises de imagem, efetuadas no chip. As análises não destrutivas baseadas em imagem foram validadas por comparação com teses bioquímicos colorimétricos. As plataformas foram depois adaptadas para a produção e caracterização de estruturas porosas miniaturizadas. A dimensão milimétrica das regiões molháveis permitiu processar estruturas com poros de tamanho representativo para migração e crescimento celulares. As estruturas porosas de quitosano/alginato foram preparadas por complexação de polielectrólitos/liofilização, seguidas de adsorção de fibronectina. O número e viabilidade celulares foram estudados. As técnicas de DMA e μCT foram adaptadas para uso nos chips, em condições secas, para caracterização mecânica e morfológica. O método de DMA realizado no chip foi melhorado de forma a permitir uma análise em condições semelhantes às fisiológicas, usando hidrogéis de quitosano/nanopartículas de vidro bioactivo. A adesão selectiva e proliferação de uma linha celular de pré-osteoblastos permitiu selecionar as formulações de biomateriais mais favoráveis. Após demonstrar a sua adequabilidade para testes in vitro, implantaram-se plataformas superhidrofóbicas contendo 36 biomateriais em ratos Wistar, mostrando a sua utilidade para testes expeditos executados in vivo,para estudo da resposta inflamatória causada por biomateriais. Outro aspeto importante em ET é a dependência da regeneração de tecidos na ação prolongada de agentes bioactivos. Regiões molháveis com uma região superhidrofóbica concêntrica foram usadas para depositar esferas poliméricas contendo proteína. A aquisição sequencial de imagens por microscopia permitiu monitorizar a libertação de proteína. Finalmente, fixaram-se gotas de suspensão celular nas regiões hidrofílicas para produzir esferóides celulares para a análise de fármacos pelo método da gota suspensa. Em conclusão, as superficies superhidrofóbicas padronizadas com regiões molháveis usadas nesta tese provaram ser compatíveis com um estudo completo de interações entre células e biomateriais 3D, compreendendo um vasto conjunto de fatores, como caracterização dos biomateriais, testes in vitro e in vivo, e testes relacionados com moléculas bioactivas.
Fundação para a Ciência e a Tecnologia (FCT) for the PhD grant SFRH/BD/71396/2010. FEDER through the Competitive Factors Operation Program – COMPETE and by National funds through FCT in the scope of the project PTDC/CTM-BIO/1814/2012.

Cells sense and interact with their microenvironment to retrieve signals which include cell-matrix and cell-cell contacts. These signals account for the influence of culturing conditions and often control the local cellular phenotype and global functions of tissues. Here, I sought to understand if there is any information processed by cells in guiding cellular phenotype given the control of cell shapes and substrate rigidities. If there is, would these phenotypic changes achieve biomedical purposes? What is the strategy to engineer platforms that can handle the longstanding challenges in those fields? In this dissertation, the first chapter serves as an introduction which involves the origin of motivations, which mainly came from current challenges in biomedical researches of kidney podocytes. I have attempted to understand if it is possible to control podocyte differentiation through cell shape control which mimics their in vivo morphology. On the other hand, I have tried to reveal if it is possible that tissue stiffness can affect podocyte phenotype as a result of stiffness sensing. These two topics were rarely investigated for kidney podocytes, which is the critical component of human filtration barrier to perform renal functions. The effort that addresses the question how shape and substrate rigidity as in- formation repositories affect kidney podocytes phenotype has profound meaning in the understanding of renal physiological system and pathological mechanisms. The second chapter will focus on the methods to achieve successful long-term shape control on cells. Engineered cell-device interface using cross-linking biomaterial SU-8 plays a key role in this study. Compared with other previously used approaches summarized in this chapter, SU-8 provides various advantages both in the fabrication of micro- pattern architecture as well as its sustaining effectiveness in controlling cell shape. This approach has been proved very efficient and economic to facilitate single cell level manipulation. The chapter will describe in details the interface micro-fabrication and encountered technical challenges. The results that kidney podocytes were in good compliance with the micro-pattern proved the successful application of this technique. The third chapter will then transfer from micro-fabrication to biological experiments, which discusses in details how in intro kidney podocytes responded to their shapes by enforcing protein localization which characterizes a phenotype found in vivo. This phenotype among in vitro podocytes was further verified that it may contribute to podocytes differentiation and physiological functions. The information processed by shape was proved independent of tension-related processes and thus shape and tension could be regarded as separate contributors in cellular development. The interpretation of shape’s contribution could be referred to my previous publication in the journal of Cell: ”Decoding Information in Cell Shape”. In this study, the motifs of research were applied to other cell lines (Human vascular smooth muscle cell) as a step to generalize the ubiquity of shape’s contribution to cell differentiation. The study here was to differentiate shape and tension through investigating the difference between two major mechanosensors: β3 and β1 integrin receptors. The difference in cell phenotypes through integrin inhibition experiments demonstrated critical but unique role of integrin-based shape sensing in vitro. This chapter in dissertation covers most of the content in a previously submitted paper to Nature Cell Biology. In the fourth chapter, I further carried out a study that investigated if stiffness sensing can influence kidney podocyte phenotype. The fourth chapter will basically review the techniques in the fabrication of hydrogel-based cell culture platforms. In a similar manner to previous study using biomimetic shape for podocytes and find its phenotype, the target of this analysis was to use hydrogel-based biomimetic substrate with renal physiological stiffness and find if there is a differentiation phenotype. Since numerous materials have been reported in hydrogel studies, I will focus on the introduction to representative ones that have been most widely used. Their characteristics will be compared with the demands of kidney podocyte reasearch. Methodologies were the key to a successful research, and in this chapter I will describe in details what choices I made in choosing experimental methods that improved the efficiency and quality of cell culture platforms. A natural enzyme (microbial transglutaminase) cross-linked gelatin hydrogel was adopted here to provide ideal substrate rigidity control for podocytes. This method has demonstrated high efficiency and stability in making large cell culture surface. Moreover, it provides the hydrogel platform with an ideal range of elastic moduli suitable for renal tissue culture. The results will be discussed in detail in the fifth chapter. I successfully found a differentiation phenotype for podocytes cultured on the hydrogel platforms with a physiological stiffness. Similar phenotype, on the contrary, were not found in podocytes on platforms which were either too soft or too stiff. These resutls have formed one of my submitted paper to Scientific Report. The differentiation phenotype for kidney podocytes was characterized by up-regulation of differentiation markers. These findings were in a similar manner to a series of stem cells differentiation guided by regulated substrate stiffnesses. This phenotype of kidney podocytes was verified by microarray technique which confirmed the stiffness sensing using transcription factors. The enrichment analysis of kinases also showed significant response of Src, Fyn etc, of which the activities have been shown critical for podocytes to preserve their physiological functions. These results have successfully suggested the close relations between stiffness changes of glomeruli basement membrane (GBM) and progressive podocyte dysfunction. In summary, this dissertation covers interdisciplinary researches that decoded the information processed by cells from two separate aspects: shape and stiffness sensing. The details in each chapter cover a broader scope than the content selected for publications. Through this dissertation, readers will get in touch with the technique developed for plat- form and their applications to biomedical researches. I wish this will help people new in the field to get my hands-on experience.

This work describes the use of microfluidic technology and biomaterials in cancer research by mimicking the extracellular matrix (ECM) and development of drug delivery system. Initially, biomaterials such as Gelatin methacryloyl (GelMA) and collagen type I were combined to create a hydrogel composite able to mimic both healthy and cancerous ECM. The impact of the tumor microenvironment was analyzed by using the hydrogel inside of a pressurized microfluidic device and by tracking the movement of gold nanoparticles (GNPs). The GNPs showed a decrease in diffusion coefficient of 77% when analyzed in cancerous conditions. This investigation was further explored by analyzing the diffusion of charged GNPs in the same system, while also tracking cellular uptake. An inverse correlation between diffusion and cellular uptake was obtained for charged GNPs in breast cancer cells. Due to the tunable properties and biocompatibility of GelMA, this hydrogel was also employed in the development of pH-responsive drug delivery systems. Since GelMA contains a gelatin backbone, two responsive polymers (Polymers A and B) were synthesized. Microspheres of ~40 μm were fabricated in flow focusing microfluidic devices. Polymer A microspheres displayed a swelling increase of 167% in pH 6.0, while polymer B spheres showed a 296% swelling in pH 10. Considering the unique properties of the tumor microenvironment such as leaky vasculature and acid pH environment, polymer A was selected to be used in the production of nanocarriers. The behavior of this polymer in acidic environment illustrated its potential applicability as drug delivery systems to the tumor area. Polymer A nanogels displayed a uniform size of 74 ± 7 nm. Lastly, GNPs were added to the solution of polymer A, leading to the fabrication of GNPsloaded nanogels, presenting a homogenous distribution of gold particles inside nanogels.
Graduate
2021-07-20

Metatissue® is a spin-off business on the making, dedicated to the development of innovative, chemically modified, human protein-based biomaterials for cell culture . Nowadays, mammalian cell culture is a fundamental aspect in most biomedical research and in the drug discovery/development process. The standard two-dimensional culturing format, extensively used for validating mechanisms of action is outdated, due to being unable to accurately mimic the natural in vivo microenvironment. Advances in biotechnology and materials science led to the development of numerous three-dimensional (3D) cell culture models, proven to simulate more accurately the natural tissue microenvironment, by mimicking the native extracellular matrix in its bio functionality and structural properties. Hydrogels composed from differently sourced materials are the leading platform in the market for cell culture and tissue engineering applications. However, it is yet to be found a perfect solution to be an alternative to current “gold standard” platforms. Metatissue’s human-derived platelet lysate product presents a xeno-free, customizable, versatile, and multifunctional solution, with tuneable mechanical properties, being easy-to-use and cost-effective. Legal framing is also considered, and an ISO 9001 certification is being implemented to guarantee the quality and consistency of the product. With a clear business strategy and value proposition, Metatissue® aims to be a leader in the 3D cell culture market.
A Metatissue® é uma empresa spin-off em ascensão, dedicada ao desenvolvimento de biomateriais inovadores para cultura celular, à base de proteínas humanas, quimicamente modificadas. Atualmente, a cultura de células de mamífero é um aspeto fundamental na maioria da investigação biomédica e no processo de descoberta/desenvolvimento de fármacos. O formato padrão bidimensional de cultura, extensivamente utilizado para validar mecanismos de ação, está desatualizado, devido a ser incapaz de imitar precisamente o microambiente natural in vivo. Os avanços na biotecnologia e engenharia de materiais levaram ao desenvolvimento de inúmeros modelos tridimensionais (3D) de cultura de células, comprovados em simular melhor o microambiente dos tecidos naturais, ao imitar a matriz extracelular nativa na sua bio funcionalidade e propriedades estruturais. Hidrogéis compostos por materiais com diferentes origens são a plataforma que lidera o mercado em aplicações de cultura celular e engenharia de tecidos. Porém, ainda se está por descobrir uma solução perfeita para ser alternativa às plataformas padrão ideais atuais. O produto de lisado de plaquetas de origem humana da Metatissue® representa uma solução sem componentes de espécies estranhas, personalizável, versátil e multifuncional, com propriedades mecânicas adaptáveis, sendo fácil de usar e de favorável custo-benefício. O enquadramento legal é também considerado e um certificado ISO 9001 está a ser implementado, de forma a garantir a qualidade e consistência do produto. Com uma clara estratégia de negócio e proposta de valor, a Metatissue® pretende ser um líder no mercado da cultura de células 3D.
Mestrado em Biotecnologia