In vitro collagen synthesis by liver connective tissue cells isolated from schistosomal granulomas

Hepatic injury elicits an excessive deposition of extracellular matrix probably due to a loss of control mechanisms in mesenchymal cells in fibrotic lesions, or a local activity of growth factors. To study collagen synthesis in an in vitro model of fibrotic lesions, we isolated liver connective tissue cells (LCTC) from murine schistosomal granulomas in C3H/HeN mice. Collagen was quantified in culture supernatants using a sirius red dye assay. LCTC and skin fibroblasts (SF) secreted similar amounts of collagen per cell and secretion was inversely proportional to the cell density. Cells cultured at low density (10,000 cells/cm2) secreted two- to three-times more collagen per cell when compared to cells grown in high-density cultures (60,000 cells/cm2). Collagen secretion was stimulated by transforming growth factor-beta (TGF-beta) in both cell lines, but the response of LCTC was detected from 1 ng/ml on, while SF responded only to higher concentrations (2.5 and 5 ng/ml). These data do not support the hypothesis that cells from fibrotic livers have lost the normal control mechanisms and suggest that their control is disturbed locally by the presence of peptide growth factors during the development of fibrosis.