Differential proliferation of fibroblasts cultured from normal and fibrotic human lungs.

We studied the behavior of the cell cycle of cultured, early-passage human diploid pulmonary fibroblastlike cells (HDPFC) when grown in the presence of several growth factors. The rates of growth and growth fractions were studied in cultures from different origins. As much as 85 +/- 5% (SE) of HDPFC cultured from specimens with early fibrosis were cycling when the cells were grown in basal media supplemented with 10% serum or growth factors. In contrast, 55% +/- 8% (SE) of HDPFC from normal lung and only 31% +/- 5% (SE) of HDPFC cultured from specimens with dense fibrosis were cycling in those culture conditions. Results obtained by removal of any of the five growth factors from the defined medium indicated that the altered growth patterns were not related to any single growth factor tested. These studies are consistent with the hypothesis that HDPFC cultured from specimens with early fibrosis have a greater proliferative potential than HDPFC from late fibrosis.