Construction of strontium-loaded injectable lubricating hydrogel and its role in promoting repair of cartilage defects.

Injuries such as articular cartilage defects are prevalent factors in the development and progression of joint diseases. The discontinuity of the articular surface due to cartilage defects significantly accelerates the onset of arthritis. Cartilage tissue-engineered scaffolds are essential for restoring the continuity of the articular surface. This study presents a dual-network hydrogel, GelMA-FT/Sr2+, which demonstrates excellent lubrication properties and accelerates the healing of cartilage defects. The hydrogel is composed of a methacrylated gelatin (GelMA) network, an N-fluorenylmethoxycarbonyl-L-tryptophan (FT) network, and strontium ions (Sr2+). The results indicate that the hydrogel exhibits lubricating properties, and the incorporation of Sr2+ extends the degradation time of the hydrogel. Additionally, the hydrogel shows biocompatibility and enhances chondrogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) into cartilage. In vivo studies further confirm the hydrogel's efficacy in promoting the repair of cartilage defects in a rat model of cartilage injury. In conclusion, the GelMA-FT/Sr2+ hydrogel is a promising scaffold for cartilage tissue engineering, notable for its excellent lubrication properties, ability to recruit stem cells, and effectiveness in facilitating cartilage defect repair.