VARIATION IN RESPONSE TO GROWTH-FACTOR STIMULI IN SATELLITE CELL-POPULATIONS

Variation in response to growth factor stimuli in myogenic satellite c ell populations was investigated using a clonal-derived satellite cell culture system. Satellite cell crones were established from one muscl e from one individual animal. One clone (''Early'') which reached conf luence on day 19 and one clone (''Late''), which reached confluence on day 29, were chosen for further examination. In previous studies, the se two clones were found to differ in their growth rates in serum-cont aining medium. In the present study, the influence of growth factors o n the proliferation oi the two clones was compared in serum-free defin ed medium. Although basic fibroblast growth factor (bFGF), insulin-lik e growth factor-I (IGF-I), insulin, and platelet-derived growth factor -BE (PDGF BB) stimulated proliferation of both clones, the Early clone was more responsive to arl growth factors tested than the Late clone (P less than or equal to 0.05). The Early clone was also more responsi ve to the proliferative and differentiative depressing effects of admi nistered transforming growth factor-beta (p less than or equal to 0.05 ). Examination of properties of the PDGF, FGF, and IGF-I receptors on these two clones revealed no differences in either dissociation consta nts or receptor numbers (P greater than or equal to 0.05). The results suggest that there is heterogeneity in satellite cell response to gro wth factors. (C) 1997 Elsevier Science Inc.