The effects of transforming growth factor-beta 1 on protein production by mouse embryonic palate mesenchymal cells in the presence or absence of serum.

Mouse embryonic palatal mesenchyme cells were cultured on a variety of substrata (plastic, on a collagen gel or within a collagen gel). On each substratum TGF-beta 1 (1 ng/ml) inhibited cell proliferation. Cells cultured within a collagen gel had the lowest rate of proliferation, but were metabolically the most active in terms of incorporation of [3H]-proline into both collagenous and non-collagenous proteins. TGF-beta 1, in the presence of 2.5% donor calf serum stimulated the production of fibronectin and the major collagen types I, III and V. However, in serum-free medium, TGF-beta 1 induced a large reduction in total collagen production, mainly due to an effect on type I collagen, whilst stimulating production of some non-collagenous proteins. Experiments involving combinations of TGF-beta 1 with other growth factors suggested that the different effects of TGF-beta 1 on collagen production, in the presence and absence of serum, may be due to an interaction with platelet-derived growth factor.