The Role of Insulin in the Proliferation and Differentiation of Bovine Muscle Satellite (Stem) Cells for Cultured Meat Production.

Muscle satellite (stem) cells (MSCs) reside in skeletal muscle and are essential for myogenesis. Thus, MSCs are widely used in cultured meat research. This study aimed to identify substances that promote MSC proliferation and differentiation while maintaining their intrinsic properties, with the long-term goal of replacing fetal bovine serum (FBS) for bovine MSC cultivation. Therefore, this study evaluated the effects of six growth factors (TGF-β, HGF, PDGF, insulin, IGF-1, and EGF) and the cytokine IL-2 on bovine MSCs. Each factor was applied during the proliferation and differentiation of MSCs, and the proliferation rate, differentiation rate, and expression of relevant mRNA and proteins were analyzed. Insulin most effectively promoted MSC proliferation and differentiation. Specifically, insulin increased cell proliferation rates, proliferation markers Ki67 and PCNA expressions, and markers of differentiation, such as myotube formation and creatine kinase activity, alongside the expressions of MYOD, MYOG, and MYH. Furthermore, insulin suppressed low FBS-induced reductions in proliferation and differentiation markers. This study suggests insulin can promote MSC proliferation and differentiation and reduce FBS usage. Thus, this study provides a potential means of cultivating MSCs on a large scale for cultured meat production.