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Title: Synthesis and characterization of Collagen-terpolymer fibers for applications in tissue engineering
Keywords: cell encapsulation, collagen, fibers, stem cells, polypyrrole, electrical stimulation
Issue Date: 7-Jan-2009
Source: YOW SOH ZEOM (2009-01-07). Synthesis and characterization of Collagen-terpolymer fibers for applications in tissue engineering. ScholarBank@NUS Repository.
Abstract: Living tissues consist of groups of cells organized in a controlled manner to perform a specific function. Spatial distribution and organization 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 (methacrylic acid, hydroxyethyl methacrylate and methyl methacrylate). Both natural and synthetic polymers were chosen with the intention of synergising the merits of both polymer types to produce fibers with the desired complementary properties. The collagen component was found to be well distributed in the polyelectrolyte complex (PEC) fibers, which had a mean ultimate tensile strength of 244.6 B1 43.0 MPa. The ambient operating conditions of this IPC technique permit the encapsulation of human mesenchymal stem cells (hMSCs) within the PEC fibers and they have remained viable. 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, PPARN32, nestin, GFAP, collagen I, osteopontin and osteonectin genes. Beyond that, seeded hMSCs started to express neuronal-specific genes such as aggrecan and MAP2. Polypyrrole polymer was incorporated into the PEC fibers to produce a collagen-based electroactive fiber system. hMSCs and mouse skeletal cells C2C12 were cultured on these fibers under an electrical stimulation. Both cell lines showed increased proliferation over a period of 5 days. Immunofluorescent staining of hMSCs showed an upregulation of synaptophysin, indicating the establishment of synapse and electrical communication between cells. Upregulation of connexin 43 and myosin heavy chain proteins and Troponin I and F-actin striations were observed in C2C12 cells. The studies suggest that the electroactive PEC fibers could support the neuronal and skeletal differentiation of hMSC and C2C12 respectively.In conclusion, the study demonstrates the appeal of IPC for scaffold design in general and the promise of collagen-based and electroactive 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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