RGDS sequences genetically induced in the fibroin light-chain protein operate positively for cartilage tissue synthesis

Introduction: In vitro generation of articular cartilage tissues requires a large number of cells maintaining the chondrogenic phenotype during in vitro culture. Our previous studies showed that chondrocytes cultured in/on a silk fibroin sponge could proliferate with maintaining their phenotype [1] and exhibited a maximum value of the adhesive stress, which could not seen when using a glass substrate, during initial cell adhesion [2]. In addition, chondrocytes cultured in/on an L_RGDSx2 fibroin sponge, which includes the RGDSRGDS sequence interfused in the light-chain (L-chain) protein of the silk fibroin, synthesized thicker cartilagespecific matrices than those in/on a wild type fibroin sponge (Fig. 1) [3]. In this study, initial adhesion of chondrocytes grown on the L_RGDSx2 fibroin substrate was investigated to clarify effects of the RGDS amino acids in the L-chain protein of the silk fibroin, comparing to effects of fibronectin coated on glass, which is well accepted as a cell-adhesive protein.