Response of human chondrocytes on polymer surfaces with different micropore sizes for tissue-engineered cartilage

Response of chondrocytes on polymer surfaces is important for applications of tissue-engineered cartilage, and tissue engineering contains the interaction of cells on material surfaces. We examined the behavior of human chondrocytes cultured on polycarbonate (PC) membranes with different micropore sizes (0.2-8.0 μm in diameter). The adhesion and proliferation of chondrocytes were evaluated by measuring the number of attached cells after 1, 2, and 4 days of culture and morphological observations. It seems that the cell adhesion and proliferation were progressively inhibited, as the PC membranes had micropores with increasing size, probably due to surface discontinuities produced by track-etched pores. On the PC membrane with smaller micropore sizes, the cells seemed to override these surface discontinuities. Phenotype of chondrocyte was assessed by Safranin-O staining for anionic sulfated proteoglycans. Chondrocytes on the 8.0 μm-diameter membrane surface proliferated, on 8 days, formed morphology of round shape, and expressed proteoglycans, because of limitation of spreading by the track-etched micropores. They maintained their phenotype under conditions that support a round cell shape on the large pore diameter substrate, whereas chondrocyte phenotypes lost on the small pore diameter membranes. In conclusion, this study demonstrated that micropore sizes as well as pore-to-pore distance play an important role for adhesion, proliferation, and phenotype of human articular chondrocytes.