Cowpea-like bi-lineage nanofiber mat for repairing chronic rotator cuff tear and inhibiting fatty infiltration

The repair of chronic rotator cuff injury primarily depends on surgery to biomechanically strengthen the connection between the tendon and bone. There are numerous studies on tendon-to-bone healing to promote bone regeneration or collagen reconstruction in tendons. However, chronic rotator cuff injuries are often associated with fat infiltration, and few studies have taken this aspect into account, let alone overcome the two challenges of bone healing and fat infiltration at the same time. Here, inspired by the structure of cowpea (Vigna unguiculata), we have developed lithium-containing mesoporous silica combined with electrospun PEUU nanofibers (Li+@MSNs/PEUU), which can slowly release lithium ions, inhibiting rotator cuff fat infiltration, and promoting bone regeneration to enhance tendon-to-bone healing on the basis of surgical repair. Using in vitro experiments we studied the mechanism of lithium ions playing a two-way role, which was found to be closely related to the Wnt pathway. In vivo, the system showed significant success in the treatment of chronic rotator cuff injury model in rats. Both histological and micro-CT results confirmed that the healing condition of the Li+@MSNs/PEUU nanofibrous mat group was better than that of the other control groups after 8 weeks. Overall, this work shows that lithium-containing mesoporous silica-bound electrospun nanofibrous mat have a long-term effect on promoting postoperative healing of rotator cuff injury with fat infiltration, and the regulation of the two lineages is achieved using only a single medium, leading to good potential for application.