Photo-crosslinkable, injectable sericin hydrogel as 3D biomimetic extracellular matrix for minimally invasive repairing cartilage.

Millions of patients worldwide suffer from cartilage injury and age/disease-related cartilage degeneration. However, cartilage, such as articular cartilage, is poor at self-regeneration. Current treatments are often invasive with limited efficacy. Developing minimal invasive strategies for effective cartilage repair is highly desired. Here, we report an injectable, photo-crosslinkable sericin hydrogel as a biomimetic extracellular matrix for minimal invasively repairing cartilage. Sericin was functionalized to be sericin methacryloyl (SerMA), which formed an in situ hydrogel upon UV light irradiation via photo-crosslinking. Possessing excellent biocompatibility, SerMA hydrogels were adhesive to chondrocytes, and promoted the proliferation of attached chondrocytes even in a nutrition-lacking condition. SerMA hydrogels exhibited photoluminescent property allowing real-time monitoring hydrogels' status. The mechanical properties and degradation rates (73% for SMH-1, 47% for SMH-2 and 37% for SMH-3 after 45 days) of SerMA hydrogels were readily tunable by varying methacryloyl modification degrees to meet various repair requirements. Notably, the in vivo implantation of chondrocyte-laden SerMA hydrogels effectively formed artificial cartilages after 8 weeks. Most importantly, the artificial cartilages molecularly resembled native cartilage as evidenced by high accumulation of cartilage-specific ECM components and upregulated expression of cartilage-critical genes. Together, this sericin hydrogel is a promising tissue engineering scaffold for generating artificial cartilage in vivo towards effective, minimal invasive cartilage repair.