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Kam W Leong - One of the best experts on this subject based on the ideXlab platform.
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a 3d electroactive polypyrrole collagen Fibrous Scaffold for tissue engineering
Polymers, 2011Co-Authors: Sohzeom Yow, Evelyn K F Yim, Chwee Teck Lim, Tze Han Lim, Kam W LeongAbstract:Fibers that can provide topographical, biochemical and electrical cues would be attractive for directing the differentiation of stem cells into electro-responsive cells such as neuronal or muscular cells. Here we report on the fabrication of polypyrrole-incorporated collagen-based fibers via interfacial polyelectrolyte complexation (IPC). The mean ultimate tensile strength of the fibers is 304.0 ± 61.0 MPa and the Young’s Modulus is 10.4 ± 4.3 GPa. Human bone marrow-derived mesenchymal stem cells (hMSCs) are cultured on the fibers in a proliferating medium and stimulated with an external electrical pulse generator for 5 and 10 days. The effects of polypyrrole in the fiber system can be observed, with hMSCs adopting a neuronal-like morphology at day 10, and through the upregulation of neural markers, such as noggin, MAP2, neurofilament, β tubulin III and nestin. This study demonstrates the potential of this fiber system as an attractive 3D Scaffold for tissue engineering, where collagen is present on the fiber surface for cellular adhesion, and polypyrrole is encapsulated within the fiber for enhanced electrical communication in cell-substrate and cell-cell interactions.
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a biofunctional Fibrous Scaffold for the encapsulation of human mesenchymal stem cells and its effects on stem cell differentiation
2009Co-Authors: C H Quek, Kam W LeongAbstract:We report a collagen based Fibrous Scaffold for the encapsulation and seeding of human mesenchymal stem cells. The Scaffold was fabricated through interfacial polyelectrolyte complexation (IPC) of an anionic synthetic terpolymer and a cationic methylated collagen in aqueous conditions. The collagen in the fibers was labeled with quantum dots and was found to be evenly distributed in each fiber strand. Encapsulating human mesenchymal stem cells (hMSCs) into these collagen based fibers and maintaining the viability are steps towards the creation of a biofunctionalised Scaffold and the existing problems of the lack of cell infiltration in Scaffolds and effective nutrient/waste exchange can be overcome. This cell encapsulation in Scaffolds technique is simple and least toxic compared to existing fabrication techniques. hMSCs were seeded onto the Fibrous Scaffold and compared with hMSCs encapsulated within the Scaffold. The cytoskeletal organization of seeded hMSCs and encapsulated hMSCs were different and the results were correlated to the gene expressions of both samples.
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Collagen-based Fibrous Scaffold for spatial organization of encapsulated and seeded human mesenchymal stem cells
Biomaterials, 2008Co-Authors: S. Z. Yow, Evelyn K F Yim, C H Quek, Chwee Teck Lim, Kam W LeongAbstract:Living tissues consist of groups of cells organized in a controlled manner to perform a specific function. Spatial distribution of cells within a three-dimensional matrix is critical for the success of any tissue-engineering construct. Fibers endowed with cell-encapsulation capability would facilitate the achievement of this objective. Here we report the synthesis of a cell-encapsulated Fibrous Scaffold by interfacial polyelectrolyte complexation (IPC) of methylated collagen and a synthetic terpolymer. The collagen component was well distributed in the fiber, which had a mean ultimate tensile strength of 244.6 ± 43.0 MPa. Cultured in proliferating medium, human mesenchymal stem cells (hMSCs) encapsulated in the fibers showed higher proliferation rate than those seeded on the Scaffold. Gene expression analysis revealed the maintenance of multipotency for both encapsulated and seeded samples up to 7 days as evidenced by Sox 9, CBFA-1, AFP, PPARγ2, nestin, GFAP, collagen I, osteopontin and osteonectin genes. Beyond that, seeded hMSCs started to express neuronal-specific genes such as aggrecan and MAP2. The study demonstrates the appeal of IPC for Scaffold design in general and the promise of collagen-based hybrid fibers for tissue engineering in particular. It lays the foundation for building Fibrous Scaffold that permits 3D spatial cellular organization and multi-cellular tissue development.
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a dual functional Fibrous Scaffold enhances p450 activity of cultured primary rat hepatocytes
Acta Biomaterialia, 2007Co-Authors: Kianngiap Chua, C H Quek, Kam W Leong, Seeram Ramakrishna, Yenni Tang, Haiquan MaoAbstract:Abstract We have designed a novel dual-functional electrospun Fibrous Scaffold comprising two fiber mesh layers that were modified differently to induce two separate biological responses from hepatocytes. The first fiber layer was galactosylated on the surface to mediate hepatocyte attachment, while the second layer was loaded with 3-methylcholanthrene (3-Mc) to enhance cytochrome P450 activity of hepatocytes. Primary rat hepatocytes cultured on the galactosylated Fibrous Scaffolds loaded with different concentrations of 3-Mc were compared for their cell attachment efficiency, albumin secretion activity and cytochrome P450-dependent 7-ethoxycoumarin O-deethylase activity. This hybrid Fibrous Scaffold mediated hepatocyte attachment with slightly lower efficiency (76 ± 2.3%) than a single-layer galactosylated Fibrous Scaffold (84 ± 3.5%). More importantly, the cytochrome P450 activity of the hepatocytes cultured on the hybrid Scaffold correlated well with the 3-Mc loading level. The results also showed that transfer of 3-Mc to hepatocytes through direct cell–fiber contact was the dominant transport route, with the induced cytochrome P450 activity being 1.9- to 4.8-fold higher than that of transfer of 3-Mc to hepatocytes via dissolution from fibers to medium. This study demonstrates the feasibility of creating multi-functional Fibrous Scaffolds that serve both as an adhesive substrate and as a delivery vehicle for bioactive molecules.
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Tissue Compatibility of Interfacial Polyelectrolyte Complexation Fibrous Scaffold: Evaluation of Blood Compatibility and Biocompatibility
Tissue engineering, 2007Co-Authors: Evelyn K F Yim, I-chien Liao, Kam W LeongAbstract:Interfacial polyelectrolyte complexation (PEC) fiber has been proposed as a biostructural unit and biological construct for tissue engineering applications, with its ability to incorporate proteins, drug molecules, DNA nanoparticles, and cells. In this study, we evaluated the biocompatibility and blood compatibility of PEC fiber in order to assess its potential for in vivo applications in tissue engineering. Although chitosan-alginate PEC Fibrous Scaffold was found to be thrombogenic, the blood compatibility of the Scaffold could be significantly improved by incorporating a small amount of heparin in the polyelectrolyte solution during fiber formation. The platelet microparticle production and platelet adhesion on the chitosan-alginate-heparin Fibrous Scaffold were comparable to those on the resting control. In vitro cytotoxicity test showed that the Scaffold was not toxic to human mesenchymal stem cells (hMSCs). In the in vivo biocompatibility test in rats, no acute inflammation was observed in the subcutaneously or intramuscularly implanted specimens. Good cell infiltration and vascularization were observed after 2 months of implantations. Enhanced extracellular matrix (ECM) deposition was observed when hMSCs were cultured in the transforming growth factor-beta3 (TGF-beta3)-encapsulated PEC Fibrous Scaffold in vitro, or when the TGF-beta3-encapsulated PEC was implanted intramuscularly in vivo. The results showed that this versatile PEC Fibrous Scaffold could be used in various tissue engineering applications for its good biocompatible and blood compatible properties.
Nuno M Neves - One of the best experts on this subject based on the ideXlab platform.
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hierarchical starch based Fibrous Scaffold for bone tissue engineering applications
Journal of Tissue Engineering and Regenerative Medicine, 2009Co-Authors: Albino Martins, Sangwon Chung, A J Pedro, R A Sousa, Alexandra P Marques, Rui L Reis, Nuno M NevesAbstract:This work was partially supported by the European Integrated Project GENOSTEM (Grant No. LSH-STREP-CT-2003-503161) and the European Network of Excellence EXPERTISSUES (Grant No. NMP3-CT-2004-500283). We also acknowledge the Portuguese Foundation for Science and Technology for the project Naturally Nano (Grant No. POCI/EME/58982/2004) and a PhD grant to A. Martins (Grant No. SFRH/BD/24382/2005).
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hierarchical starch based Fibrous Scaffold for bone tissue engineering applications
Journal of Tissue Engineering and Regenerative Medicine, 2009Co-Authors: Albino Martins, Sangwon Chung, A J Pedro, R A Sousa, Alexandra P Marques, Rui L Reis, Nuno M NevesAbstract:Fibrous structures mimicking the morphology of the natural extracellular matrix are considered promising Scaffolds for tissue engineering. This work aims to develop a novel hierarchical starch-based Scaffold. Such Scaffolds were obtained by a combination of starch-polycaprolactone micro- and polycaprolactone nano-motifs, respectively produced by rapid prototyping (RP) and electrospinning techniques. Scanning electron microscopy (SEM) and micro-computed tomography analysis showed the successful fabrication of a multilayer Scaffold composed of parallel aligned microfibres in a grid-like arrangement, intercalated by a mesh-like structure with randomly distributed nanofibres (NFM). Human osteoblast-like cells were dynamically seeded on the Scaffolds, using spinner flasks, and cultured for 7 days under static conditions. SEM analysis showed predominant cell attachment and spreading on the nanofibre meshes, which enhanced cell retention at the bulk of the composed/hierarchical Scaffolds. A significant increment in cell proliferation and osteoblastic activity, assessed by alkaline phosphatase quantification, was observed on the hierarchical Fibrous Scaffolds. These results support our hypothesis that the integration of nanoscale fibres into 3D rapid prototype Scaffolds substantially improves their biological performance in bone tissue-engineering strategies.
Evelyn K F Yim - One of the best experts on this subject based on the ideXlab platform.
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a 3d electroactive polypyrrole collagen Fibrous Scaffold for tissue engineering
Polymers, 2011Co-Authors: Sohzeom Yow, Evelyn K F Yim, Chwee Teck Lim, Tze Han Lim, Kam W LeongAbstract:Fibers that can provide topographical, biochemical and electrical cues would be attractive for directing the differentiation of stem cells into electro-responsive cells such as neuronal or muscular cells. Here we report on the fabrication of polypyrrole-incorporated collagen-based fibers via interfacial polyelectrolyte complexation (IPC). The mean ultimate tensile strength of the fibers is 304.0 ± 61.0 MPa and the Young’s Modulus is 10.4 ± 4.3 GPa. Human bone marrow-derived mesenchymal stem cells (hMSCs) are cultured on the fibers in a proliferating medium and stimulated with an external electrical pulse generator for 5 and 10 days. The effects of polypyrrole in the fiber system can be observed, with hMSCs adopting a neuronal-like morphology at day 10, and through the upregulation of neural markers, such as noggin, MAP2, neurofilament, β tubulin III and nestin. This study demonstrates the potential of this fiber system as an attractive 3D Scaffold for tissue engineering, where collagen is present on the fiber surface for cellular adhesion, and polypyrrole is encapsulated within the fiber for enhanced electrical communication in cell-substrate and cell-cell interactions.
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Collagen-based Fibrous Scaffold for spatial organization of encapsulated and seeded human mesenchymal stem cells
Biomaterials, 2008Co-Authors: S. Z. Yow, Evelyn K F Yim, C H Quek, Chwee Teck Lim, Kam W LeongAbstract:Living tissues consist of groups of cells organized in a controlled manner to perform a specific function. Spatial distribution of cells within a three-dimensional matrix is critical for the success of any tissue-engineering construct. Fibers endowed with cell-encapsulation capability would facilitate the achievement of this objective. Here we report the synthesis of a cell-encapsulated Fibrous Scaffold by interfacial polyelectrolyte complexation (IPC) of methylated collagen and a synthetic terpolymer. The collagen component was well distributed in the fiber, which had a mean ultimate tensile strength of 244.6 ± 43.0 MPa. Cultured in proliferating medium, human mesenchymal stem cells (hMSCs) encapsulated in the fibers showed higher proliferation rate than those seeded on the Scaffold. Gene expression analysis revealed the maintenance of multipotency for both encapsulated and seeded samples up to 7 days as evidenced by Sox 9, CBFA-1, AFP, PPARγ2, nestin, GFAP, collagen I, osteopontin and osteonectin genes. Beyond that, seeded hMSCs started to express neuronal-specific genes such as aggrecan and MAP2. The study demonstrates the appeal of IPC for Scaffold design in general and the promise of collagen-based hybrid fibers for tissue engineering in particular. It lays the foundation for building Fibrous Scaffold that permits 3D spatial cellular organization and multi-cellular tissue development.
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Tissue Compatibility of Interfacial Polyelectrolyte Complexation Fibrous Scaffold: Evaluation of Blood Compatibility and Biocompatibility
Tissue engineering, 2007Co-Authors: Evelyn K F Yim, I-chien Liao, Kam W LeongAbstract:Interfacial polyelectrolyte complexation (PEC) fiber has been proposed as a biostructural unit and biological construct for tissue engineering applications, with its ability to incorporate proteins, drug molecules, DNA nanoparticles, and cells. In this study, we evaluated the biocompatibility and blood compatibility of PEC fiber in order to assess its potential for in vivo applications in tissue engineering. Although chitosan-alginate PEC Fibrous Scaffold was found to be thrombogenic, the blood compatibility of the Scaffold could be significantly improved by incorporating a small amount of heparin in the polyelectrolyte solution during fiber formation. The platelet microparticle production and platelet adhesion on the chitosan-alginate-heparin Fibrous Scaffold were comparable to those on the resting control. In vitro cytotoxicity test showed that the Scaffold was not toxic to human mesenchymal stem cells (hMSCs). In the in vivo biocompatibility test in rats, no acute inflammation was observed in the subcutaneously or intramuscularly implanted specimens. Good cell infiltration and vascularization were observed after 2 months of implantations. Enhanced extracellular matrix (ECM) deposition was observed when hMSCs were cultured in the transforming growth factor-beta3 (TGF-beta3)-encapsulated PEC Fibrous Scaffold in vitro, or when the TGF-beta3-encapsulated PEC was implanted intramuscularly in vivo. The results showed that this versatile PEC Fibrous Scaffold could be used in various tissue engineering applications for its good biocompatible and blood compatible properties.
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proliferation and differentiation of human mesenchymal stem cell encapsulated in polyelectrolyte complexation Fibrous Scaffold
Biomaterials, 2006Co-Authors: Evelyn K F Yim, I-chien Liao, Andrew C A Wan, Catherine Le Visage, Kam W LeongAbstract:A biofunctional Scaffold was constructed with human mesenchymal stem cells (hMSCs) encapsulated in polyelectrolyte complexation (PEC) fibers. Human MSCs were either encapsulated in PEC fibers and constructed into a Fibrous Scaffold or seeded on PEC Fibrous Scaffolds. The proliferation, chondrogenic and osteogenic differentiation of the encapsulated and seeded hMSCs were compared for a culture period of 5.5 weeks. Gene expression and extracellular matrix production showed evidences of chondrogenesis and osteogenesis in the cell-encapsulated Scaffolds and cell-seeded Scaffolds when the samples were cultured in the chondrogenic and osteogenic differentiation media, respectively. However, better cell proliferation and differentiation were observed on the hMSC-encapsulated Scaffolds compared to the hMSC-seeded Scaffolds. The study demonstrated that the cell-encapsulated PEC fibers could support proliferation and chondrogenic and osteogenic differentiation of the encapsulated-hMSCs. Together with our previous works, which demonstrated the feasibility of PEC fiber in controlled release of drug, protein and gene delivery, the reported PEC Fibrous Scaffold system will have the potential in composing a multi-component system for various tissue-engineering applications.
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Proliferation and differentiation of human embryonic germ cell derivatives in bioactive polymeric Fibrous Scaffold
Journal of biomaterials science. Polymer edition, 2005Co-Authors: Evelyn K F Yim, Kam W LeongAbstract:Human embryonic germ cell derivatives, a heterogeneous population of uncommitted embryoid body derived (EBD) cells, were studied in a bioactive three-dimensional (3D) Fibrous culture. Their proliferation, morphology, gene expression and differentiation were investigated to gain insights on development of 3D bioactive Scaffold for pluripotent stem cells. The expansion of the EBD cells in 3D environment was significantly higher than their two-dimensional controls after 21 days. No apparent differentiation of the EBD cells cultured in the 3D environment, as indicated by histology and gene expression profile analysis, was evident. Extracellular matrix production was weak in the long-term 3D culture, and the EBD cells maintained their multilineage gene expressions for the period studied. When nerve growth factor (NGF) was surface-immobilized on the Fibrous Scaffold via chemically-modified Pluronic, the EBD cells cultured in this Scaffold showed evidence of entering the neural pathway. An upregulation of tyrosine hydroxylase mRNA expression was observed when EBD cells were cultured in the NGF-immobilized Fibrous Scaffold, as demonstrated by real-time PCR and immunofluorescence staining. The study suggests the value of such Fibrous 3D culture in manipulating stem cell proliferation/differentiation and as a model for developing a bioactive Scaffold.
Albino Martins - One of the best experts on this subject based on the ideXlab platform.
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hierarchical starch based Fibrous Scaffold for bone tissue engineering applications
Journal of Tissue Engineering and Regenerative Medicine, 2009Co-Authors: Albino Martins, Sangwon Chung, A J Pedro, R A Sousa, Alexandra P Marques, Rui L Reis, Nuno M NevesAbstract:This work was partially supported by the European Integrated Project GENOSTEM (Grant No. LSH-STREP-CT-2003-503161) and the European Network of Excellence EXPERTISSUES (Grant No. NMP3-CT-2004-500283). We also acknowledge the Portuguese Foundation for Science and Technology for the project Naturally Nano (Grant No. POCI/EME/58982/2004) and a PhD grant to A. Martins (Grant No. SFRH/BD/24382/2005).
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hierarchical starch based Fibrous Scaffold for bone tissue engineering applications
Journal of Tissue Engineering and Regenerative Medicine, 2009Co-Authors: Albino Martins, Sangwon Chung, A J Pedro, R A Sousa, Alexandra P Marques, Rui L Reis, Nuno M NevesAbstract:Fibrous structures mimicking the morphology of the natural extracellular matrix are considered promising Scaffolds for tissue engineering. This work aims to develop a novel hierarchical starch-based Scaffold. Such Scaffolds were obtained by a combination of starch-polycaprolactone micro- and polycaprolactone nano-motifs, respectively produced by rapid prototyping (RP) and electrospinning techniques. Scanning electron microscopy (SEM) and micro-computed tomography analysis showed the successful fabrication of a multilayer Scaffold composed of parallel aligned microfibres in a grid-like arrangement, intercalated by a mesh-like structure with randomly distributed nanofibres (NFM). Human osteoblast-like cells were dynamically seeded on the Scaffolds, using spinner flasks, and cultured for 7 days under static conditions. SEM analysis showed predominant cell attachment and spreading on the nanofibre meshes, which enhanced cell retention at the bulk of the composed/hierarchical Scaffolds. A significant increment in cell proliferation and osteoblastic activity, assessed by alkaline phosphatase quantification, was observed on the hierarchical Fibrous Scaffolds. These results support our hypothesis that the integration of nanoscale fibres into 3D rapid prototype Scaffolds substantially improves their biological performance in bone tissue-engineering strategies.
Ghasem Barati - One of the best experts on this subject based on the ideXlab platform.
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core shell Fibrous Scaffold as a vehicle for sustained release of retinal pigmented epithelium derived factor pedf for photoreceptor differentiation of conjunctiva mesenchymal stem cells
Journal of Biomedical Materials Research Part A, 2017Co-Authors: Fatemeh Nasehi, Samad Nadri, Ghasem Barati, Mohsen Karshenas, Ahdiye SalimAbstract:Coaxial electrospinning technique was introduced as a flexible and promising technique for the fabrication of core-shell Fibrous Scaffold from poly ethylene glycol/poly caprolactone (PEG/PCL), where retinal pigmented epithelium-derived factor (PEDF) was encapsulated in the core, for photoreceptor differentiation of conjunctiva mesenchymal stem cells (CJMSCs) seed on Scaffolds. The morphology and structure of fibers were characterized using SEM and TEM and photoreceptor differentiation was examined by quantitative real time PCR (qPCR). Release study showed that, a sustained release of PEDF from PEG/PCL Scaffold was observed over 14 days. qPCR analysis demonstrated that rhodopsin (as a main photoreceptor gene) was significantly expressed in CJMSCs cultured on Scaffold loaded with PEDF. According to the result, the core-shell Scaffold loaded with PEDF (PEG + PEDF)/PCL) has superior control over factor release profile and has a potential for guiding photoreceptor differentiation of mesenchymal stem cells and promoting retinal regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3514-3519, 2017.
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effect of parameters on the quality of core shell Fibrous Scaffold for retinal differentiation of conjunctiva mesenchymal stem cells
Journal of Biomedical Materials Research Part A, 2017Co-Authors: Samad Nadri, Fatemeh Nasehi, Ghasem BaratiAbstract:This article describes the coaxial electrospinning to generate core-shell fibers from polycaprolactone (PCL) and polyethylene glycol (PEG) for differentiation of conjunctiva mesenchymal stem cells (CJMSCs) into photoreceptor-like cells by delivery of taurine. Also, the effects of many parameters such as polymer concentration, nozzle collector distance, applied voltage, and outer solution flow rate on creation of the core-shell structure were examined. The morphology and structure of fibers were characterized using scanning, transmission electron microscopy, and fourier transform infrared spectroscopy and then retinal differentiation was examined by quantitative real time PCR (qPCR). Significant variations between 25% and 35% PEG concentration groups for fiber diameter were documented. As faster flowing rates from the outer nozzle (PCL fluid) were applied, the creation possibility of Fibrous Scaffold was increased. The lowest diameter and the best quality alignment of core-shell Fibrous Scaffold were achieved in 22 Kv and 24 Kv. As rising distancing were applied, the Fibrous diameter increased and spraying was observed. qPCR analysis demonstrated the differentiation of CJMSCs to photoreceptor like cells on PEG/PCL Scaffolds. According to the result, we have proved successful in the creation of core/shell Fibrous Scaffold of PEG/PCL by coaxial electrospinning for retinal tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 189-197, 2017.