Development of an injectable thiolated icariin functionalized collagen/hyaluronic hydrogel to promote cartilage formation in vitro and in vivo.

Development of an in situ injectable hydrogel with controlled-release of bioactive molecules is an effective strategy to maintain chondrocyte phenotype and promote cartilage formation for clinical applications. In this study, we developed an injectable thiolated icariin functionalized hyaluronic acid/collagen hydrogel (HIC) under physiological conditions. In order to covalently introduce icariin (Ica) into an injectable hydrogel and increase its loading, thiolated icariin (Ica-SH) was successfully synthesized. Ica-SH could not only decrease the cytotoxicity of Ica, but also increase the Ica loading in hydrogels. Compared to hyaluronic acid/collagen hydrogels, HICs facilitated chondrocyte proliferation, maintained chondrocyte phenotype and promoted the secretion of the cartilage extracellular matrix. Overall, this study suggests that HIC has great potential to be developed as an effective and less invasive candidate for clinical application in articular cartilage repair.