Variation in Response to Growth Factor Stimuli in Satellite Cell Populations

Variation in response to growth factor stimuli in myogenic satellite cell populations was investigated using a clonal-derived satellite cell culture system. Satellite cell clones were established from one muscle from one individual animal. One clone ( Early ) which reached confluence on day 19 and one clone ( Late ) which reached confluence on day 29 were chosen for further examination. In previous studies these 2 clones were found to differ in their growth rates in serum-containing medium. In the present study, the influence of growth factors on the proliferation of the 2 clones was compared in serum-free defined medium. Although basic fibroblast growth factor (bFGF), platelet-derived growth factor-BB (PD GF-BB), insulin-like growth factor- I ( I GF- I ) and insulin stimulated proliferation of both clones, the Early clone was more responsive to all growth factors tested than the Late clone (P0.05). The Early clone was also more responsive to the proliferative and differentiative depressing effects of administered transforming growth factor- (P0. 05). Examination of properties of the FGF, PDGF and I GF- I receptors on these 2 clones revealed no difference in either dissociation constants or receptor numbers (P0. 05). The results suggest that there is heterogeneity in satellite cell responses to growth factors