Effect Of Surface Topography Of Polyurethane On Cell Differentiation Behaviours

The surface properties of biomaterials are essential for biocompatibility.Complexity of surface composition and structure of the biomaterial makes it difficult to pinpoint how chemical properties and structures of the surface of the material controls the biological response between the surfaces and proteins or cells.The surface morphology of the material,as one of the important biological properties of biomaterials,has a great impact on cell behaviors.Polyurethanes are well-known biocompatible materials.Their controllable chemical structures make them controllable degradability and mechanical properties so they are widely used as cardiovascular scaffolds,orthopedic materials,heart valves and tissue engineering scaffold materials.The excellent mechanical properties and adjustable degradation properties make them become the ideal choices of articular cartilage scaffold materials.In this study,hydroxyapatite?HAP?and zirconia?Zr O₂?with different particle sizes?48 to100 mesh,100 to 160 mesh,160 to 300 mesh?and different particle contents with the same size?100 to 160 mesh?were mixed with polyurethane to prepare series of convex films:HA-x group;HA-Dx group;Zx group and Z-Dx group.Concave films?N-1,N-2,N-3?with different pole sizes were prepared by using sodium chloride as pore agent.The analysis results showed that the polyurethane films with controlled surface roughness can be obtained by regulating relevant process.Mouse mesenchymal stem cells?mBMSCs?,ATDC5 cells and human chondrocytes?HC?were chosen to simulate different stages of cell differentiation during the development of cartilage.The aim was to explore surface morphology features of substrate surfaces required for different stages of cell growth by studying cell proliferation,spread and differentiation behaviors of different cell types on virous surface of polyurethane films.Cell proliferation experiments showed steady proliferation trend on each group of materials,and live&dead staining showed that dead cells on all material surfaces were little,inferring good cell compatibility of polyurethane.At the same time,there was no significant difference in cytoskeleton between each series of groups,indicating that changing roughness by irregular morphological changes had no significant effect on cell morphology.The results of RT-PCR and sGAG showed that the more little roughness Ra=0.59?m in PU/ZrO₂?Z-x?series was the most suitable surface for chondrogenic differentiation of ATDC5 and mBMSCs.The medium roughness Ra=26.8?m in PU/HAP?H-x?series was optimal for differentiation of chondrogenic phenotype maintenance of HC and osteogenic differentiation of mBMSCs.ATDC5,HC and mBMSCs showed the same trend for chondrogenic differentiation on concave films,that is,N-2 group was more suitable for chondrogenic differentiation and chondrogenic maintenance.The results of this study informed that cells in different differentiation stages during tissue growth and development have different dependency on morphology of extracellular matrix.Above all,it provides relevant design ideas for future design on polyurethane materials.