Muscle-type-dependent differences in satellite cell proliferation and differentiation in chick breast and leg muscles

In chickens, studies focusing exclusively on intrinsic muscle type-dependent differences in proliferation and differentiation of satellite cells (SCs) are scanty. In this study, we compared the proliferation and differentiation characteristics of SCs derived from chick breast and leg muscles. In addition, the amino acid composition of each muscle tissue was analyzed to evaluate muscle- type-dependent differences. Breast and leg SCs were isolated and cultured, and their proliferative capacity was assessed by measuring cell number, population doubling time (PDT), and paired box 7 (Pax7) expression. Differentiation potential was evaluated using myogenin expression and myotube formation. Leg SCs maintained relatively stable cell numbers, PDT, and Pax7 expression between P2 and P7. In contrast, breast SCs showed a marked decline in cell number (from P3 to P8) and Pax7 expression between P2 and P7. However, breast SC exhibited relatively highly pronounced myogenin expression, robust myotube formation, and a significantly higher fusion index during early differentiation. Amino acid analysis revealed differences in the relative composition between breast and leg muscles, glutamic acid and glycine were abundant in both tissues. Collectively, these findings demonstrate muscle-type-dependent differences in SC proliferation and differentiation, accompanied by distinct tissue-level compositional profiles. By elucidating the intrinsic muscle type-dependent characteristics of SC proliferation and differentiation, this study provides foundational data for future research on muscle-specific meat quality improvement and cell culture strategies.