Polyamines enhance satellite cell activation and expression of myogenic regulatory factors

Satellite cells (SCs) exist amongst other cell types in a unique microenvironment within skeletal muscle. The interactions between SCs and non‐myogenic cells within this niche are poorly characterized. However, most cells behave differently in co‐culture (CC) compared to mono‐culture (MC). Our results indicate that SCs co‐cultured with preadipocytes express less myogenic differentiation factor ( MyoD ) at 24 ( p=0.04 ) and 48 ( p=0.02 ) hours as well as more sprouty1 ( Spry1 ) at 24 ( p=0.04 ) hours post‐differentiation. Thus, SCs induced to differentiate in a CC with preadipocytes exhibit depressed myogenesis when compared with SCs in MC. Polyamines (putrescine, spermidine and spermine) are potent modulators of cell growth. However, no studies have analyzed effects of these compounds on SCs. Administration of polyamines to SCs in MC and CC systems demonstrates that polyamines increase ( p ≤ 0.05 ) expression of MyoD , myogenin ( Myf4 ), myogenic factor 5 ( Myf5 ) and decrease ( p ≤0.05) expression of paired box transcripton factor 7 ( Pax7 ) and Spry1 . Compared with MC, our CC system better reflects the complexity of the SC niche. Furthermore, our observation of a pro‐myogenic effect of polyamines using CC may indicate a potential natural means of enhancing myogenesis in vivo . We gratefully acknowledge the University of Idaho's Student Grant Program, the USDA NC1184 Hatch Grant and the Idaho Beef Council FY 2013 for funding.