Platelet-Derived Mitochondria Attenuate Muscle Atrophy Following Rotator Cuff Tears in a Rat Model.

Background: Rotator cuff tears (RCTs) often result in muscle atrophy, compromising surgical outcomes and recovery. Mitochondrial dysfunction is implicated in this process, suggesting potential for mitochondria-based therapies. This study aimed to investigate the effects of platelet mitochondria (Plt-Mito) administration into the supraspinatus muscle (SSP) following RCTs.

Methods: Seventy-two male Sprague-Dawley rats were allocated into three distinct groups: (1) a sham surgery group, (2) a group with RCTs treated with Plt-Mito, and (3) a group with RCTs treated with PBS. Treatments were administered every two weeks. After 12 weeks, the supraspinatus muscles were analyzed for wet muscle weight ratio, muscle fiber cross-sectional area (CSA), fibrosis, antioxidant activity, mitochondrial markers, capillary density and mitochondrial structure.

Results: Plt-Mito successfully incorporated into SSP, maintaining functional integrity. Compared to the PBS group, Plt-Mito treatment significantly preserved wet muscle weight, increased mean muscle fiber CSA, promoted muscle regeneration, reduced fibrosis, enhanced antioxidant activity (increased superoxide dismutase activity and decreased malondialdehyde activity), improved muscle vascularity (increased CD31 and α-SMA), increased expression of mitochondrial markers (COX IV and UCP-1) and maintained mitochondrial density and structure.

Conclusions: Our findings demonstrated Plt-Mito administration effectively halted muscle atrophy and fibrosis, while attenuating mitochondrial damage and dysfunction following RCTs.