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Artykuły w czasopismach na temat "Tissue engineering polymer cell culture scaffold hydrophobic"
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Yong, Hsin Nam Ernest, Kim Yeow Tshai i Siew Shee Lim. "Aqueous Stability of Cross-Linked Thermal Responsive Tissue Engineering Scaffold Produced by Electrospinning Technique". Key Engineering Materials 897 (17.08.2021): 39–44. http://dx.doi.org/10.4028/www.scientific.net/kem.897.39.
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Poly (N-isopropylacrylamide) (PNIPAm) has been one of the most widely studied thermal responsive polymer in tissue engineering owing to its reversible hydrophilic-hydrophobic phase transition across its lower critical solution temperature (~32°C) that is close to human physiological temperatures. Among tissue engineering constructs, nanofibrous scaffolds offer an added advantage in mimicking the morphology of the native extracellular matrix (ECM). Electrospinning has been reported as one of the most facile method to produce PNIPAm nanofibres and neat electrospun nanofibres scaffold is known to possess poor aqueous stability, limiting its use in tissue engineering applications. In contrast, numerous studies on PNIPAm hydrogels have shown relatively good aqueous stability owing to the hydrophilic 3D crosslinked structure of the hydrogel which resist instant dissolution but rather swell to a greater or lesser extent. However, the presence of crosslinkages in PNIPAm hydrogels causes it to be hardly electrospinnable into nanofibres. In the present work, crosslinker free PNIPAm was radical polymerized to a high molecular weight of 385 kDa. To produce nanofibers, electrospinning was carried out on a dedicated %wt of PNIPAm solution containing octaglycidyl polyhedral oligomeric silsesquioxane (OpePOSS) and 2-ethyl-4-methylimidazole (EMI). Resulting PNIPAm nanofibrous network was found to strongly resemble the ECM morphology with fiber diameter of 436.35 ± 187.04 nm, pore size 1.24 ± 1.27 μm and 63.6% total porosity. Aqueous stability was studied in cell culture media over the course of 28 days. The current result shows significant improvement with a gradual mass loss up to a maximum of 35% instead of the near immediate dissolution observed in the case of electrospun neat PNIPAm scaffold without crosslinks.
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Jeznach, Oliwia, Dorota Kołbuk, Tobias Reich i Paweł Sajkiewicz. "Immobilization of Gelatin on Fibers for Tissue Engineering Applications: A Comparative Study of Three Aliphatic Polyesters". Polymers 14, nr 19 (4.10.2022): 4154. http://dx.doi.org/10.3390/polym14194154.
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Immobilization of cell adhesive proteins on the scaffold surface has become a widely reported method that can improve the interaction between scaffold and cells. In this study, three nanofibrous scaffolds obtained by electrospinning of poly(caprolactone) (PCL), poly(L-lactide-co-caprolactone) (PLCL) 70:30, or poly(L-lactide) (PLLA) were subjected to chemical immobilization of gelatin based on aminolysis and glutaraldehyde cross-linking, as well as physisorption of gelatin. Two sets of aminolysis conditions were applied to evaluate the impact of amine group content. Based on the results of the colorimetric bicinchoninic acid (BCA) assay, it was shown that the concentration of gelatin on the surface is higher for the chemical modification and increases with the concentration of free NH2 groups. XPS (X-ray photoelectron spectroscopy) analysis confirmed this outcome. On the basis of XPS results, the thickness of the gelatin layer was estimated to be less than 10 nm. Initially, hydrophobic scaffolds are completely wettable after coating with gelatin, and the time of waterdrop absorption was correlated with the surface concentration of gelatin. In the case of all physically and mildly chemically modified samples, the decrease in stress and strain at break was relatively low, contrary to strongly aminolyzed PLCL and PLLA samples. Incubation testing performed on the PCL samples showed that a chemically immobilized gelatin layer is more stable than a physisorbed one; however, even after 90 days, more than 60% of the initial gelatin concentration was still present on the surface of physically modified samples. Mouse fibroblast L929 cell culture on modified samples indicates a positive effect of both physical and chemical modification on cell morphology. In the case of PCL and PLCL, the best morphology, characterized by stretched filopodia, was observed after stronger chemical modification, while for PLLA, there was no significant difference between modified samples. Results of metabolic activity indicate the better effect of chemical immobilization than of physisorption of gelatin.
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Phuegyod, Seubsakul, Sasivimon Pramual, Nungnit Wattanavichean, Supasuda Assawajaruwan, Taweechai Amornsakchai, Panithi Sukho, Jisnuson Svasti, Rudee Surarit i Nuttawee Niamsiri. "Microbial Poly(hydroxybutyrate-co-hydroxyvalerate) Scaffold for Periodontal Tissue Engineering". Polymers 15, nr 4 (9.02.2023): 855. http://dx.doi.org/10.3390/polym15040855.
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In this study, we fabricated three dimensional (3D) porous scaffolds of poly(hydroxybutyrate-co-hydroxyvalerate) with 50% HV content. P(HB-50HV) was biosynthesized from bacteria Cupriavidus necator H16 and the in vitro proliferation of dental cells for tissue engineering application was evaluated. Comparisons were made with scaffolds prepared by poly(hydroxybutyrate) (PHB), poly(hydroxybutyrate-co-12%hydroxyvalerate) (P(HB-12HV)), and polycaprolactone (PCL). The water contact angle results indicated a hydrophobic character for all polymeric films. All fabricated scaffolds exhibited a high porosity of 90% with a sponge-like appearance. The P(HB-50HV) scaffolds were distinctively different in compressive modulus and was the material with the lowest stiffness among all scaffolds tested between the dry and wet conditions. The human gingival fibroblasts (HGFs) and periodontal ligament stem cells (PDLSCs) cultured onto the P(HB-50HV) scaffold adhered to the scaffold and exhibited the highest proliferation with a healthy morphology, demonstrating excellent cell compatibility with P(HB-50HV) scaffolds. These results indicate that the P(HB-50HV) scaffold could be applied as a biomaterial for periodontal tissue engineering and stem cell applications.
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Lis-Bartos, Anna, Agnieszka Smieszek, Kinga Frańczyk i Krzysztof Marycz. "Fabrication, Characterization, and Cytotoxicity of Thermoplastic Polyurethane/Poly(lactic acid) Material Using Human Adipose Derived Mesenchymal Stromal Stem Cells (hASCs)". Polymers 10, nr 10 (28.09.2018): 1073. http://dx.doi.org/10.3390/polym10101073.
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Thermoplastic polyurethane (TPU) and poly(lactic acid) are types of biocompatible and degradable synthetic polymers required for biomedical applications. Physically blended (TPU+PLA) tissue engineering matrices were produced via solvent casting technique. The following types of polymer blend were prepared: (TPU+PLA) 7:3, (TPU+PLA) 6:4, (TPU+PLA) 4:6, and (TPU+PLA) 3:7. Various methods were employed to characterize the properties of these polymers: surface properties such as morphology (scanning electron microscopy), wettability (goniometry), and roughness (profilometric analysis). Analyses of hydrophilic and hydrophobic properties, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) of the obtained polymer blends were conducted. Tensile tests demonstrated that the blends exhibited a wide range of mechanical properties. Cytotoxicity of polymers was tested using human multipotent stromal cells derived from adipose tissue (hASC). In vitro assays revealed that (TPU+PLA) 3:7 matrices were the most cytocompatible biomaterials. Cells cultured on (TPU+PLA) 3:7 had proper morphology, growth pattern, and were distinguished by increased proliferative and metabolic activity. Additionally, it appeared that (TPU+PLA) 3:7 biomaterials showed antiapoptotic properties. hASC cultured on these matrices had reduced expression of Bax-α and increased expression of Bcl-2. This study demonstrated the feasibility of producing a biocompatible scaffold form based on (TPU+PLA) blends that have potential to be applied in tissue engineering.
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Chee, Tan Yong, Abdull Rahim Mohd Yusoff i Nik Ahmad Nizam Nik Malek. "Characterisation of poly(vinyl alcohol)- polycaprolactone hybridized scaffold for potential skin tissue regeneration". Malaysian Journal of Fundamental and Applied Sciences 16, nr 1 (2.02.2020): 6–9. http://dx.doi.org/10.11113/mjfas.v16n1.1469.
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The fabrication of a hybridized scaffold constituting hydrophobic and hydrophilic polymers for tissue engineering has received an increasing attention recently. Due to the high compatibility with water, a hydrophilic polymer, though is able to enhance cell affinity and proliferation, has a very high biodegradable rate and low stability in aqueous medium that eventually puncture its biomedical applications. Thereby, the addition of a hydrophobic polymer in the hydrophilic polymer scaffold is recommended to increase the hydrophobic property of the scaffold in order to reduce the limitation. Nonetheless, the fabrication of the hybridized scaffold is extremely challenging because the hydrophilic and the hydrophobic polymer tends to dissolve in different types of solvents, i.e. water and organic solvent, respectively, that subsequently restricts their blending process. In this work, a poly(vinyl alcohol) (PVA) scaffold, a polycaprolactone (PCL) scaffold, and their hybridized scaffold were produced through casting method for potential skin tissue regeneration. We found that the glacial acetic acid was an appropriate solvent used to prepare hydrophobic PCL solution with low molecular weight (16 kDa) for PCL-PVA blend, with mass ratio 1:1, without using any surfactant. The solvent was also used for the preparation of PCL scaffold with high molecular weight (80 kDa). The fabricated polymer scaffolds were then evaluated using FTIR-ATR, contact angle measurement, and tensile strength analysis. FESEM images of the PVA-PCL hybridized scaffold showed that the PCL was well dispersed in the PVA scaffold. FTIR-ATR spectra showed that the hybridized scaffold exhibited the crucial functional group of PVA and PCL at 3310.97, 1720.10, 1557.80, 1241.69, 1172.90, 1044.95, and 719.44 cm-1. The contact angle of the PVA, PCL, and PVA-PCL hybridized scaffold were 61.3o, 82.7o, and 75.9o, respectively, with tensile strength 16.5747, 2.4038, and 7.417 MPa, respectively.
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Cho, Kwang Joon, Dae Keun Song, Se Heang Oh, Young Joo Koh, Sahng Hoon Lee, Myung Chul Lee i Jin Ho Lee. "Fabrication and Characterization of Hydrophilized Polydioxanone Scaffolds for Tissue Engineering Applications". Key Engineering Materials 342-343 (lipiec 2007): 289–92. http://dx.doi.org/10.4028/www.scientific.net/kem.342-343.289.
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Porous polydioxanone (PDO)/polyvinyl alcohol (PVA) scaffolds were fabricated by blending PDO with a small amount of PVA to improve the hydrophilicity and cell/tissue compatibility of the scaffolds for tissue engineering applications. PDO/PVA scaffolds with different PVA compositions up to 10 wt% were fabricated by a melt-molding particulate-leaching method (non-solvent method). The prepared scaffolds exhibited highly porous, uniform open-cellular pore structures. The PDO/PVA scaffolds with PVA compositions more than 5 % were easily wetted in cell culture medium. The hydrophilized PDO/PVA (5 wt%) scaffold showed better cell adhesion and growth than the control hydrophobic PDO scaffold. The PDO/PVA (5 wt%) scaffold also showed faster tissue infiltration into the scaffold than the PDO scaffold. It seems that 5 wt% addition of PVA to PDO to fabricate PDO/PVA scaffolds is enough for improving the hydrophilicity and cell/tissue compatibility of the scaffolds.
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Lim, Mim Mim, Tao Sun i Naznin Sultana. "In VitroBiological Evaluation of Electrospun Polycaprolactone/Gelatine Nanofibrous Scaffold for Tissue Engineering". Journal of Nanomaterials 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/303426.
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The fabrication of biocompatible and biodegradable scaffolds which mimic the native extracellular matrix of tissues to promote cell adhesion and growth is emphasized recently. Many polymers have been utilized in scaffold fabrication, but there is still a need to fabricate hydrophilic nanosized fibrous scaffolds with an appropriate degradation rate for skin tissue engineering applications. In this study, nanofibrous scaffolds of a biodegradable synthetic polymer, polycaprolactone (PCL), and blends of PCL with a natural polymer, gelatine (Ge), in three different compositions: 85 : 15, 70 : 30, and 50 : 50 were fabricated via an electrospinning technique. The nanofibrous scaffold prepared from 14% w/v PCL/Ge (70 : 30) exhibited more balanced properties of homogeneous nanofibres with an average fibre diameter of 155.60 ± 41.13 nm, 83% porosity, and surface roughness of 176.27 ± 2.53 nm.In vitrocell culture study using human skin fibroblasts (HSF) demonstrated improved cell attachment with a flattened morphology on the PCL/Ge (70 : 30) nanofibrous scaffold and accelerated proliferation on day 3 compared to the PCL nanofibrous scaffold. These results show that the PCL/Ge (70 : 30) nanofibrous scaffold was more favourable and has the potential to be a promising scaffold for skin tissue engineering applications.
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Ghaedamini, Sho'leh, Saeed Karbasi, Batool Hashemibeni, Ali Honarvar i Abbasali Rabiei. "PCL/Agarose 3D-printed scaffold for tissue engineering applications: fabrication, characterization, and cellular activities". Research in Pharmaceutical Sciences 18, nr 5 (2023): 566–79. http://dx.doi.org/10.4103/1735-5362.383711.
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Background and purpose: Biomaterials, scaffold manufacturing, and design strategies with acceptable mechanical properties are the most critical challenges facing tissue engineering. Experimental approach: In this study, polycaprolactone (PCL) scaffolds were fabricated through a novel three-dimensional (3D) printing method. The PCL scaffolds were then coated with 2% agarose (Ag) hydrogel. The 3D-printed PCL and PCL/Ag scaffolds were characterized for their mechanical properties, porosity, hydrophilicity, and water absorption. The construction and morphology of the printed scaffolds were evaluated via Fourier-Transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The attachment and proliferation of L929 cells cultured on the scaffolds were investigated through MTT assay on the cell culture study upon the 1st, 3rd, and 7th days. Findings/Results: The incorporation of Ag hydrogel with PCL insignificantly decreased the mechanical strength of the scaffold. The presence of Ag enhanced the hydrophilicity and water absorption of the scaffolds, which could positively influence their cell behavior compared to the PCL scaffolds. Regarding cell morphology, the cells on the PCL scaffolds had a more rounded shape and less cell spreading, representing poor cell attachment and cell-scaffold interaction due to the hydrophobic nature of PCL. Conversely, the cells on the PCL/Ag scaffolds were elongated with a spindle-shaped morphology indicating a positive cell-scaffold interaction. Conclusion and implications: PCL/Ag scaffolds can be considered appropriate for tissue-engineering applications.
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Yang, Joseph, Masayuki Yamato i Teruo Okano. "Cell-Sheet Engineering Using Intelligent Surfaces". MRS Bulletin 30, nr 3 (marzec 2005): 189–93. http://dx.doi.org/10.1557/mrs2005.51.
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AbstractThe possibility of recreating various tissues and organs for the purpose of regenerative medicine has received much interest. However, the field of tissue engineering has been restricted by the limitations of conventional approaches. A method to circumvent the need for traditional scaffold-based technologies is cell-sheet engineering, which uses temperature-responsive culture dishes. These surfaces, which are created by grafting the temperature-responsive polymer poly(N-isopropylacrylamide) onto ordinary culture dishes, enable the non-invasive harvesting of cells as intact sheets by simple temperature reduction. This article reviews current research on the applications of cell-sheet engineering for the reconstruction of various tissues, as well as the intelligent surfaces used by this novel technology.
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Pacilio, Serafina, Roberta Costa, Valentina Papa, Maria Teresa Rodia, Carlo Gotti, Giorgia Pagnotta, Giovanna Cenacchi i Maria Letizia Focarete. "Electrospun Poly(L-lactide-co-ε-caprolactone) Scaffold Potentiates C2C12 Myoblast Bioactivity and Acts as a Stimulus for Cell Commitment in Skeletal Muscle Myogenesis". Bioengineering 10, nr 2 (11.02.2023): 239. http://dx.doi.org/10.3390/bioengineering10020239.
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Tissue engineering combines a scaffold, cells and regulatory signals, reproducing a biomimetic extracellular matrix capable of supporting cell attachment and proliferation. We examined the role of an electrospun scaffold made of a biocompatible polymer during the myogenesis of skeletal muscle (SKM) as an alternative approach to tissue regeneration. The engineered nanostructure was obtained by electrospinning poly(L-lactide-co-ε-caprolactone) (PLCL) in the form of a 3D porous nanofibrous scaffold further coated with collagen. C2C12 were cultured on the PLCL scaffold, and cell morphology and differentiation pathways were thoroughly investigated. The functionalized PLCL scaffold recreated the SKM nanostructure and performed its biological functions, guiding myoblast morphogenesis and promoting cell differentiation until tissue formation. The scaffold enabled cell–cell interactions through the development of cellular adhesions that were fundamental during myoblast fusion and myotube formation. Expression of myogenic regulatory markers and muscle-specific proteins at different stages of myogenesis suggested that the PLCL scaffold enhanced myoblast differentiation within a shorter time frame. The functionalized PLCL scaffold impacts myoblast bioactivity and acts as a stimulus for cell commitment, surpassing traditional 2D cell culture techniques. We developed a screening model for tissue development and a device for tissue restoration.
Rozprawy doktorskie na temat "Tissue engineering polymer cell culture scaffold hydrophobic"
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Leung, Leo. "An economical, adaptable and user-friendly drip-perfusion bioreactor system designed for in vitro three dimensional cell culturing". Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/92639/1/Leo_Leung_Thesis.pdf.
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This research project investigated a bioreactor system capable of high density cell growth intended for use in regenerative medicine and protein production. The bioreactor was based on a drip-perfusion concept and constructed with minimal costs, readily available components, and straightforward processes for usage. This study involved the design, construction, and testing of the bioreactor where the results showed promising three dimensional cell growth within a polymer structure. The accessibility of this equipment and the capability of high density, three dimensional cell growth would be suitable for future research in pharmaceutical drug manufacturing, and human organ and tissue regeneration.
Części książek na temat "Tissue engineering polymer cell culture scaffold hydrophobic"
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Borah, Rajiv, i Ashok Kumar. "Enhanced Cellular Activity on Conducting Polymer". W Polymer Nanocomposites for Advanced Engineering and Military Applications, 150–89. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7838-3.ch006.
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This chapter includes detailed review of the research undertaken with conducting polymer (CP) based composites with chitosan (Ch) for tissue engineering till date. The beneficial role of electrically conductive biomaterials has been discussed with the possible strategies to overcome the shortcomings of CP alone through blending with Ch due to its excellent biocompatibility, biodegradability, and bioactivity. Additionally, this embodiment deals with the optimization and characterization of electrically conductive, biocompatible and biodegradable Polyaniline: Chitosan (PAni:Ch) nanocomposites as cell culture substrates for MDA-MB-231 and NIH 3T3 fibroblast in order to examine the combined effect of nanofiber structure and surface modification on cell-biomaterial interactions. The nanocomposites were further checked as a conductive scaffold for electrical stimulation of a neuronal model PC12 cell line in order to explore the potential of the materials in neural tissue engineering.
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Borah, Rajiv, i Ashok Kumar. "Enhanced Cellular Activity on Conducting Polymer". W Research Anthology on Emerging Technologies and Ethical Implications in Human Enhancement, 734–73. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-8050-9.ch038.
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This chapter includes detailed review of the research undertaken with conducting polymer (CP) based composites with chitosan (Ch) for tissue engineering till date. The beneficial role of electrically conductive biomaterials has been discussed with the possible strategies to overcome the shortcomings of CP alone through blending with Ch due to its excellent biocompatibility, biodegradability, and bioactivity. Additionally, this embodiment deals with the optimization and characterization of electrically conductive, biocompatible and biodegradable Polyaniline: Chitosan (PAni:Ch) nanocomposites as cell culture substrates for MDA-MB-231 and NIH 3T3 fibroblast in order to examine the combined effect of nanofiber structure and surface modification on cell-biomaterial interactions. The nanocomposites were further checked as a conductive scaffold for electrical stimulation of a neuronal model PC12 cell line in order to explore the potential of the materials in neural tissue engineering.
Streszczenia konferencji na temat "Tissue engineering polymer cell culture scaffold hydrophobic"
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Ma, Liang, Lei Gao, Yichen Luo, Huayong Yang, Bin Zhang, Changchun Zhou, JinGyu Ock i Wei Li. "Flow Analysis of a Porous Polymer-Based Three-Dimensional Cell Culture Device for Drug Screening". W ASME 2018 13th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/msec2018-6313.
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A porous polymer-based three-dimensional (3D) cell culture device has been developed as an in vitro tissue model system for the cytotoxicity of anticancer drug test. The device had two chambers connected in tandem, each loaded with a 3D scaffold made of highly biocompatible poly (lactic acid) (PLA). Hepatoma cells (HepG2) and glioblastoma multiforme (GBM) cancer cells were cultured in the two separate porous scaffolds. A peristaltic pump was adopted to realize a perfusion cell culture. In this study, we focus on cell viability inside the 3D porous scaffolds under flow-induced shear stress effects. A flow simulation was conducted to predict the shear stress based on a realistic representation of the porous structure. The simulation results were correlated to the cell variability measurements at different flow rates. It is shown that the modeling approach presented in this paper can be useful for shear stress predication inside porous scaffolds and the computational fluid dynamics model can be an effective way to optimize the operation parameters of perfused 3D cell culture devices.
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Wang, Hai, i Wei Li. "Selective HIFU Foaming to Fabricate Porous Polymer for Tissue Engineering Scaffolds". W ASME 2006 International Manufacturing Science and Engineering Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/msec2006-21043.
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A novel technique is presented in this paper for the fabrication of tissue engineering scaffolds using the High Intensity Focused Ultrasound (HIFU). This acoustic method is a solvent-free, highly efficient and low cost process that has the potential in scaffold-based tissue engineering. HIFU fabrication technique is capable of creating hierarchically-structured porous polymeric materials, which have various topographical features at different length scales. This will in turn affect the cellular response and behavior of certain type of cells, such as the integration and growth of smooth muscle cells (SMCs). In this study, the effect of HIFU porous polymer fabrication was investigated. Scanning-mode HIFU insonation was performed in the HIFU polymer foaming experiments. The acoustic power and the scanning speed were chosen as the parameters and varied in different groups of experiments. The created microstructures were characterized using the scanning electron microscopy (SEM). The fabricated samples were used for cell culture studies with human aortic SMCs (Passage 4). It was found that the selective HIFU foaming process could be used to create hierarchical structures by choosing appropriate ultrasound parameters. The SMCs were viable on the HIFU-created porous PMMA specimens, and the topographical nature of a HIFU-created porous structure affected the cellular response of SMCs.
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White, Allison, Amanda DeVos, Amr Elamin Elhussein, Jack Blank i Kalyani Nair. "Quantifying Mechanical Properties of PCL-Based Nanofiber Mats Using Atomic Force Microscopy". W ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11944.
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Abstract Polymeric scaffolds aid in creating an environment for cell proliferation and differentiation in tissue engineering applications by acting as temporary artificial extracellular matrices (ECMs) for cells to form functional tissue. Many studies have reported that cell behavior can be significantly affected by the physical and chemical properties of a given scaffold. Therefore, the mechanical and structural properties of these scaffolds must be characterized. Polymeric solutions, such as polycaprolactone (PCL), have been electrospun into nanofiber mats to be used as cell scaffolds. Polycaprolactone (PCL) is a biocompatible polymer and is commonly used in tissue engineering applications; however, PCL is hydrophobic, which makes it difficult for cells to adhere to the mat. Coating the PCL-based mats with collagen, a naturally occurring protein with hydrophilic properties, may improve cell adhesion to the scaffold. The collagen coating may also alter the mechanical properties of the nanofiber mats. In this study, the effect of collagen coating on cell adhesion and proliferation are investigated using alamarBlue tests. Additionally, the mechanical and surface properties of PCL-based nanofiber mats are investigated using a Nanosurf C3000 atomic force microscope (AFM). One batch of PCL mats were coated with collagen, while the uncoated mats were used as controls. The cell behavior and material property values obtained from the uncoated PCL and collagen-coated PCL mats were analyzed and compared. The results of this study suggest that collagen does significantly influence the cell proliferation and material properties of PCL-based mats and that further studies should be conducted to better understand the effects of the nanoscale properties of the PCL-based mats on cell adhesion.
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Xia, Chunguang, i Nicholas Fang. "Enhanced Mass Transport Through Permeable Polymer Microcirculatory Networks". W ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15408.
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One of the obstacles of culturing functioning vital tissues in vitro is to obtain a substantial biomass at a physiological cell density (>108cells/cm3). At this high density, the diffusion length of metabolites is limited to ~100um. As a matter of fact, in real tissue, almost all the cells are located within 100um distance from the capillaries [1]. Studies [2, 3] also confirmed that the cells in the artificial tissue cannot be properly cultured when they are further than 400um from the external nutrient source. Therefore, to culture three dimensional artificial tissue with substantial biomass, vascularization is necessary to enhance the metabolites transport. The short diffusion length of the metabolites requires high capillary density (>100/mm2) in vascularization. To meet this need, we have developed a novel high resolution and high speed 3D microfabrication technique, the projection microstereolithography[4] to explore microcirculatory networks with high density (>150/mm2). Using this technology we designed and fabricated the microreactors as shown in Figure 1. In our samples, 800um PEG microcapillaries with 20um inner radius and 40um outer radius with pitch of 96um are fabricated. Two rings as inlet and outlet are connected to external supply of culture medium. We designed the parameters of the vascularized microbioreactor based on the simulations of oxygen and carbon dioxide transport and metabolism in hepatocytes. As shown in Figure 2, the capillaries are arranged in a hexagonal way. According to the geometric symmetry, the final simulation domain is divided into 2 regions, the polymer capillary wall and the tissue. We assumed that a culture media with dissolved oxygen is pumped through the capillaries at 1.5mm/s rate and diffuses through the capillary wall, into the hepatocytes. The consumption of oxygen follows Michaelis-Menten kinetics [5, 6] and the metabolic rate of carbon dioxide is assumed to be proportional to that of oxygen by a fixed quotient (-0.81) which is addressed and studied by other groups [7]. The carbon dioxide diffuses into the capillaries and can be carried away through the flow of the culture medium. Our simulation indicates that the bottleneck of effective oxygen transport is the permeability of the polymer materials. The oxygen concentration drops off about 90% after diffusing through the capillary wall. It is predicted that the diffusion length at the inlet is 74um and 48um at the outlet; the rapid drop of carbon dioxide concentration also happens across the capillary wall. The predicted carbon dioxide concentration in the tissue is ~80nmol/cm3; this value is much smaller than the toxic value (100mmHg or 3umol/cm3) reported by David Gray and coworkers [8]. In Figure 2, we present the effect of the permeability of the capillary polymer materials on the diffusion length of oxygen and the concentration of carbon dioxide in the tissue. Our study indicates the existence of an optimal permeability for the capillary network, at which the overall diffusion length of oxygen is maximized. Interestingly, we also found a maximum concentration of carbon dioxide in the cultured tissue as the permeability of the polymer material changes. We attribute it to the competition between the tissue thickness and the permeability. Higher permeability increases the cultured tissue thickness, and also increases the ability of capillary to empty carbon dioxide. Not only is this model applicable for oxygen and carbon dioxide, but also for the transport of other metabolites. As an ongoing experimental effort, our fluorescent microscopy measurement validated the diffusion transport of fluorescent species from the capillary (Figure 3). Experiments are also in progress on the oxygen diffusion from the capillaries will cell cultures of high density on the PEG scaffold by introducing proper indicators. In summary, we have established a method to design and manufacture vascularized microcirculatory network to enhance the mass transport during the tissue culture. To ensure the effective nutrient delivery and wastes removal, our numerical simulation also confirms that it is essential to embed high density microcapillaries with optimal permeability.
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Kennedy, James P., i Robert W. Hitchcock. "Mechanically Enhanced Precipitation of Phase-Inversion Sprayed Polyurethane Scaffold May Be Used to Match Tissue Specific Anisotropy". W ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206632.
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Methods of creating a scaffold for tissue engineering that allow for modification of properties such as pore size, porosity, and anisotropy are essential for tissue engineering applications. For example the pore size and material anisotropy have been shown to affect cardiomyocyte elongation and alignment [1]. Phase-inversion spray polymerization (PISP) is a method for rapidly precipitating polymers onto a surface by depositing the polymer solution simultaneously with a nonsolvent, and may be used to create biocompatible scaffolds of engineered morphological and mechanical properties by varying the solubility of the polymer in the nonsolvent [2]. We report here on the fabrication of scaffolds using different nonsolvents and methods of in-process elongation that allow for control of stiffness, anisotropy ratio, porosity, and in vitro cell culture.
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Katti, Kalpana S., Dinesh R. Katti i Avinash H. Ambre. "Unnatural Amino Acids Modified Clays for Design of Scaffolds for Bone Tissue Engineering". W ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASMEDC, 2010. http://dx.doi.org/10.1115/nemb2010-13242.
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Here, we incorporate the results of our new “altered phase theory” (Sikdar et al. 2008a) into design of new polymer clay nanocomposites (PCNs) for bone biomaterials applications. Montmorillonite (MMT) clay was modified using unnatural amino acids as potentially new biocompatible modifiers. The longer carbon chain structures of the unnatural amino acids are expected to enhance non bonded interactions with clay as well as maintaining the usefulness of functional groups of natural amino acids. The specific choice of amino acids is based on both the antibacterial activity reported in literature and also our previous studies on role of chain length, functional groups etc of modifiers in influencing mechanical behavior in PCNs. Biocompatibility studies using cell culture experiments as well as mechanical behavior is evaluated for the PCNs. FTIR spectroscopy is used to compare changes to molecular structure. The increase in d001 spacing of modified clay compared to pure clay obtained from XRD experiments confirms successful intercalation of modifier. The osteoblast cells were found to grow and proliferate over the substrates. The major contribution of this work is the design of novel amino acid biopolymer-clay nanocomposites for biomaterials applications. Porous scaffold structures were also designed and fabricated.
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Jayasuriya, A. Champa, Chiragkumar Shah, Vijay Goel i Nabil A. Ebraheim. "Characterization of Biomimetic Mineral Coated 3D PLGA Scaffolds". W ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14877.
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The bone-like carbonate apatite (BLCA) coatings can be coated biomimetically in the polymer surfaces by soaking in the simulated body fluid (SBF). This SBF contains similar ionic constituents to human blood plasma. Micro-porous 3D poly(lactic-co-glycolic acid) PLGA scaffolds were fabricated by the solvent casting/salt leaching technique using chloroform to dissolve the polymer. We accelerated the deposition of mineral on scaffolds for 1-2 days, modifying the mineralization process using surface treatments and 5x SBF. These scaffolds were analyzed by Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FTIR) and X-ray Diffraction (XRD). The scaffolds coated with BLCA layer were placed in the 24 well plates containing 2 ml of media, such as Tris Buffered Saline-pH 7.4, cell culture media containing αMEM supplemented with 10% FBS, and 1% penicillin-streptomycin and incubated at 37°C for 21 days. The BLCA layer on surfaces of scaffold was stable even after 21 days immersed in Tris Buffered Saline and cell culture media. This study suggests that BLCA were stable for at least 3 weeks in the both media, and therefore, mineral has a potential to use as a carrier for biological molecules for localized release applications as well as bone tissue engineering applications.
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Miller, Kristin S., Brooks V. Udelsman, Yong-Ung Lee, Yuji Naito, Christopher K. Breuer i Jay D. Humphrey. "Computational Growth and Remodeling Model for Evolving Tissue Engineered Vascular Grafts in the Venous Circulation". W ASME 2013 Conference on Frontiers in Medical Devices: Applications of Computer Modeling and Simulation. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fmd2013-16168.
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The field of vascular tissue engineering continues to advance rapidly, yet there is a pressing need to understand better the time course of polymer degradation and the sequence of cell-mediated matrix deposition and organization. Mounting evidence suggests that cells respond to mechanical perturbations through a process of growth and remodeling (G&R) to establish, maintain, and restore a preferred state of homeostatic stress. Previous computational models utilizing G&R approaches have captured arterial responses to diverse changes in mechanical loading [1, 8, 9]. Recently, a G&R framework was also introduced to account for the kinetics of polymer degradation as well as synthesis and degradation of neotissue constituents [5]. Niklason et al. demonstrated that models of G&R can predict both evolving tissue composition and mechanical behavior after extended periods of in vitro culture of polymer-based tissue-engineered vascular grafts (TEVGs), thus providing insights into the timecourse of neotissue formation and polymer removal. Moreover, they suggest that models of G&R can be powerful tools for the future refinement and optimization of scaffold designs. Nevertheless, such computational models have not yet been developed for examining the formation of neotissue following the implantation of a polymeric TEVG in vivo.
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Reza, Anna T., i Steven B. Nicoll. "Dynamic Hydrostatic Pressurization Differentially Regulates Extracellular Matrix Elaboration by Bovine Inner and Outer Annulus Fibrosus Cells Seeded on 3-D Polymer Scaffolds". W ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176539.
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Current surgical treatments for intervertebral disc (IVD) degeneration result in decreased mobility of the spine [1]. A tissue engineering approach may provide an alternative that restores both IVD structure and function. The IVD is comprised of three distinct regions: the outer annulus fibrosus (OA), inner annulus fibrosus (IA), and the nucleus pulposus (NP). Each of the cell populations within these regions possess unique phenotypic properties that are greatly influenced by environmental factors, such as the surrounding 3-D extracellular matrix (ECM) and mechanical loading (i.e., hydrostatic pressurization) [2]. As such, both the 3-D scaffold and in vitro culture conditions may have marked effects on the development of tissue-engineered IVD constructs. Although the influence of mechanical loading on IVD cells and explants has been investigated, no prior studies have examined the impact of hydrostatic pressurization on OA and IA cells in 3-D culture. Therefore, the objective of this study was to determine the effects of dynamic hydrostatic pressurization on OA and IA cells seeded on 3-D fibrous poly(glycolic acid)-poly(L-lactic acid) (PGA-PLLA) scaffolds. We hypothesized that the application of hydrostatic pressure would promote increased production of type II collagen and chondroitin sulfate proteoglycan in both OA- and IA-seeded constructs.
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Baker, Brendon M., Roshan P. Shah i Robert L. Mauck. "Dynamic Tensile Loading Improves the Mechanical Properties of MSC-Laden Aligned Nanofibrous Scaffolds". W ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19447.
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Fibrocartilaginous tissues such as the meniscus and annulus fibrosus serve critical load-bearing roles, relying on arrays of highly organized collagen fibers to resist tensile loads experienced with normal physiologic activities [1]. As these specialized structures are often injured, there exists great demand for engineered tissues for repair or replacement. Towards recreating the structural and mechanical features of these anisotropic tissues in vitro, we fabricate scaffolds composed of co-aligned, ultra-fine biodegradable polymer fibers. These 3D micro-patterns direct mesenchymal stem cell (MSC) orientation and the subsequent formation of organized extracellular matrix (ECM) [2]. As this cell-produced matrix continually develops with time in culture, the mechanical properties of the construct gradually increase. In previous studies aimed at engineering human meniscus tissue, constructs achieved moduli of ∼40MPa after 10 weeks of culture, representing a two-fold increase in the starting properties of the scaffold [3]. Despite this demonstrable increase, this value remains well below that of the native tissue. As mechanical forces are essential to the maintenance of musculoskeletal tissues, this work examined the effect of cyclic tensile loading on MSC-laden nanofibrous constructs to enhance their in vitro maturation. We hypothesized that this loading modality would modulate the transcriptional behavior of seeded MSCs, spur the deposition of collagen-rich matrix, and lead to additional improvements in construct mechanical properties.