Abstract 266: Distinct Satellite Cell Trajectories Characterize Regenerative And Non-regenerative Responses In The Ischemic Limb

Introduction: Skeletal muscle regeneration is a critical determinant of outcomes in the ischemic limb. The precise mechanisms of skeletal muscle recovery in the ischemic limb remain unknown. A major hindrance to fully understanding the regenerative process in limb ischemia is determining the heterogeneity and cell fate decisions of muscle satellite cells (MuSCs). Methods: We analyzed muscle regeneration in C57BL/6 (regenerative phenotype) and BALB/c (non-regenerative phenotype) mice undergoing limb ischemia using single-cell RNA sequencing spanning 4 distinct time points (no injury, days 1, 3, and 7). We also performed trajectory inference to observe stage-specific regulatory programs during this dynamic process. Results: We identified 9 distinct MuSC populations in both strains (Figure A). Pseudotime analysis presented an organized regeneration trajectory of cells from quiescent to proliferative to differentiated MuSCs (Figures B-C). Further analysis demonstrated disparate MuSC fate decisions between C57BL/6 and BALB/c mice (Figure D-E). C57BL/6 mice displayed an organized progression of cells from a quiescent sate to proliferating and committed myoblast. In contrast, BALB/c mice demonstrated aberrant MuSC regeneration, highlighted by precocious differentiation (Figure E). Furthermore, gene set enrichment analysis (GSEA) confirmed impaired MuSC proliferation in BALB/c mice (Figure F). Conclusions: These findings advance our understanding of MuSC fate decisions in the ischemic limb and provide a potential mechanism for myopathy observed in PAD patients.