Strontium‑based metal‑organic framework/alendronate‑silk fibroin hydrogels promote tendon‑bone interface healing

Rotator cuff tears (RCTs) represent a common orthopedic injury. Poor healing of the tendon‑bone interface (TBI) represents a notable challenge for the surgical repair of RCTs. In the present study, silk fibroin (SF)‑based hydrogels were prepared for use in RCT repair, which were combined with strontium (Sr)‑based metal organic frameworks (Sr/MOFs) that were loaded with or without alendronate sodium (Aln). The efficacy of SF‑based hydrogels was evaluated using in vitro and in vivo experiments. The results of the present study showed that Sr/MOFs exhibited regular rod‑like morphology, uniform element distribution and high Aln‑loading efficiency. SF + Sr/MOF and SF + Sr/MOF‑Aln hydrogels exhibited notable biocompatibility and antioxidant activity, and enhanced the osteogenic differentiation of bone marrow mesenchymal stem cells. In vivo, compared with the SF and control groups, the SF + Sr/MOF‑Aln group significantly enhanced the maximum load and stiffness of repaired tissues, improved bone microstructure, and promoted the formation of more organized collagen fibers and fibrocartilage at the TBI. Osteogenic stimulation at the TBI using Sr/MOFs and Aln represents a clinically relevant strategy for improving rotator cuff repair outcomes. The findings of the present study provide a novel and clinically promising biomaterial‑based therapeutic strategy for enhancing TBI regeneration and improving surgical outcomes following rotator cuff repair.