Synthesis of photo-reactive poly (vinyl alcohol) and construction of scaffold-free cartilage like pellets in vitro.

Photo-reactive poly(vinyl alcohol) (PRPVA) was synthesized by introduction of phenyl azido groups into poly(vinyl alcohol) (PVA) and applied for surface modification. PRPVA was grafted onto cell culture plate surface homogeneously or in a micropattern. Human mesenchymal stem cells (hMSCs) cultured on cell culture plate surface and PVA-modified surface showed different behaviors. Cells adhered and spread well on cell culture plate surface, while they did not adhere on PVA-grafted surface at all. When hMSCs were cultured on PVA-micropatterned surface, they formed a cell micropattern. Cells formed pellets after cultured on PVA homogeneously modified surface in chondrogenic induction medium for 2 weeks. The pellets were positively stained by hematoxylin/eosin, safranin-O/fast green and toluidin blue, and they were also stained brown by Type II collagen and proteoglycan immunohistological staining. Real-time PCR analysis was conducted to investigate the expression of colI, colII, colX, aggrecan and sox9 mRNA. Results of gene expression were in agreement with those of histological and immunohistological observations. These results indicated that hMSCs cultured on PVA-modified surface performed chondrogenic differentiation, and it was possible to construct scaffold-free cartilage like pellets with PVA-modified surface in vitro.