Comparative effects of human platelet growth factor on the growth and morphology of human fetal and adult diploid fibroblasts

Human platelet growth factor (HPGF) caused marked growth and morphological responses in two lines of fetal and two lines of adult human diploid skin fibroblasts. Dose-response studies demonstrated differences between these two cell types. Adult cells required ten times more HPGF than fetal cells for optimal growth. In the presence of HPGF both cell lines decreased three- to four-fold in size, and their morphology in stationary culture changed to an extremely long, thin fibroblastic shape; reduction in size was accompanied by a corresponding decrease in total protein and fatty acid-containing lipid. These decreases were directly related to the concentration of HPGF in the growth medium. The results suggest that human cells in different stages of cellular development have different requirements for growth-promoting agents (HPGF) and that the use of HPGF on human diploid fibroblasts provides an excellent model system to study growth-associated changes in intermediary metabolism.