Species-specific functions of CSRP3 in satellite cell-driven muscle regeneration and relevance to porcine stem cell therapy

Abstract

Skeletal muscle function deteriorates with injury, disease, or aging. While stem cell therapies offer therapeutic potential, concerns remain regarding the safety and efficacy of transplanted cells. Satellite cells (SCs), the primary endogenous stem cells responsible for muscle repair, demonstrate safe transplantation but limited clinical effectiveness. A deeper understanding of the mechanisms regulating SC activation and differentiation is critical for improving muscle regeneration strategies. We examined the role of CSRP3 in SC-mediated muscle repair using injury models and myoblast differentiation assays. We compared its function in pigs and mice, employing genetic approaches, CSRP3 knockdown ( CSRP3 KD ), Csrp3-/- and overexpression ( CSRP3 OE ), to assess its impact on muscle regeneration. Additionally, we investigated the AKT-SERCA2 signaling axis and its downstream effects on calcium homeostasis, mitochondrial function, and myogenic differentiation. CSRP3 was essential for muscle regeneration and SC differentiation in pigs but not in mice. Genetic ablation of CSRP3 ( CSRP3 KD ) impaired porcine SC differentiation and reduced regenerative capacity, while CSRP3 overexpression ( CSRP3 OE ) enhanced these processes. Mechanistically, CSRP3 deficiency disrupted AKT-SERCA2 signaling, leading to elevated intracellular Ca 2 ⁺, mitochondrial dysfunction, and MYOG protein degradation. Pharmacological AKT activation rescued differentiation defects in CSRP3-deficient cells. Notably, Csrp3-/- mice showed normal SC differentiation and AKT-SERCA2 activity, highlighting a species-specific regulatory role for CSRP3. Our findings identify CSRP3 as a critical regulator of porcine muscle regeneration, with minimal impact in mice. These results suggest that strategically engineered porcine SCs, through CSRP3 modulation, could improve the effectiveness of xenotransplantation-based therapies for muscle repair.