Repair of critical size cartilage defects in rat xiphoid using adipose-derived stem cells and silk fibroin 3D porous scaffolds

Previous in vitro studies have shown that silk fibroin 3D porous scaffolds can support chondrogenesis of adipose tissue derived stem cells (ASCs). The present study explored the potential of in vivo cartilage repair using rat ASCs and silk fibroin scaffolds in a rat critical size xiphoid chondral defect model. ASCs were cultured with growth medium or chondrogenic medium for 28 days under static or rotation conditions. No significant cell death was observed during culture. Cell constructs cultured in growth medium under rotation had the highest cell proliferation rate, while those cultured in chondrogenic medium under static conditions expressed the highest chondrogenic markers including col2, acan and comp. Cells produced significantly higher levels of sulfated glycosaminoglycan when cultured in chondrogenic medium compared to growth medium. Growth in chondrogenic medium under static conditions resulted in more intense immunofluorescence for collagen II and aggrecan as well as the highest Young’s modulus. Cell/scaffold constructs were implanted after 28 days of culture in 3 mm diameter cartilage defects in xiphoids of athymic rats. l CTand histological analyses of tissues harvested 8 weeks later confirmed larger amounts of neo-cartilage in defect sites with cell constructs grown in chondrogenic medium under static culture compared to rotation culture. In conclusion, ASCs/silk constructs can be used to repair in vivo cartilage defect when an appropriate pre-culture is applied.