Multi-omics analysis reveals sex-specific etiology of human muscle weakness following musculoskeletal injury

Background: Musculoskeletal injuries comprise a growing source of disability worldwide, and the recovery of muscle strength following injury is a critical determinant of patient reported outcomes. Females experience exacerbated muscle atrophy, poorer outcomes, and higher re-injury rates, necessitating a comprehensive interrogation of sex-specific skeletal muscle differences. Our purpose in the current study was to perform an unbiased transcriptomic profiling of muscle samples to identify putative sex-specific molecular targets to enhance recovery in patients who underwent anterior cruciate ligament reconstruction (ACLR). Methods: We performed cellular phenotyping, bulk and single nucleus RNA-sequencing on muscle biopsy samples obtained from thirty-six participants (18M, 18F). Muscle samples were obtained from the ACLR and contralateral limb with follow-up tissue collection of the injured limb also occurring at seven days and four months post-ACLR. Transcriptomic analyses illuminated putative molecular mechanisms through which sex influences muscle recovery following acute injury. Results: Females exhibited greater muscle atrophy relative to males at 4 months post-ACLR compared to the uninjured limb. Bulk and single nucleus paired-limb transcriptomic analyses revealed the emergence of sex-specific myonuclear signaling cascades that demonstrate impaired reactive oxygen species scavenging in females. Females exhibited attenuated SOD2 expression that was associated with increased indices of oxidative stress and protein damage. Within females, angiogenesis signaling was also impaired and associated with capillary rarefaction after reconstructive surgery. Conclusions: These findings reveal inherent sex-based differences in muscle pathology that likely necessitate unique clinical treatments following musculoskeletal injury.