Metabolic and cellular physiological differences between embryonic breast and leg muscle satellite cells in chickens

This study aimed to compare the anatomical characteristics of embryonic chicken muscle satellite cells (CMSCs) derived from breast and leg muscles of 18-day-old embryos. We analyzed the cellular behaviors related to proliferation, metabolism, and differentiation capacity. Breast-derived CMSCs exhibited significantly higher proliferation rates and accelerated cell cycle progression, as evidenced by a higher S phase distribution and lower G2/M phase distribution compared to leg-derived CMSCs. In addition, immunofluorescence staining for myogenic regulatory factors revealed that breast-derived CMSCs exhibited higher expression levels of paired box protein 7 (PAX7), consistent with elevated PAX7 and myogenic differentiation 1 (MYOD) mRNA expression compared with leg-derived CMSCs. In contrast, leg-derived CMSCs showed significantly higher expression of myogenin (MYOG). Moreover, leg-derived CMSCs exhibited significantly higher mitochondrial respiratory activity indices, including oxygen consumption rate and basal respiration. In differentiation capacity analysis, the leg-derived CMSCs formed structurally more developed myotubes, and the expression of muscle-specific genes (MYOD, MYOG, MYH1E, MYH7, TNNI1, TNNI2) was also significantly higher. These findings suggest that breast-derived CMSCs exhibit superior proliferative capacity, while leg-derived CMSCs possess enhanced myogenic differentiation potential, as supported by their increased oxidative phosphorylation activity and elevated expression of differentiation-related markers. In conclusion, the anatomical origin of CMSCs significantly influences their proliferative and differentiation capacities as well as their metabolic properties, providing a valuable basis for selecting optimal cell sources for cultured meat production and meat quality improvement.