Effects of collagen matrix on proliferation and differentiation of vascular smooth muscle cells in vitro.

In an attempt to better define the relationship between collagen matrices and vascular smooth muscle cells in vitro, proliferation of smooth muscle cells was observed in the early stages of culture. Cells spread on collagen gels had a longer doubling time and less incorporation of [3H]thymidine into DNA on the first day of culture than did cells grown on a plastic substrate. Cells on collagen gels were more elongated than were those on the plastic substrate and showed a "hills and valleys" arrangement from the first day in culture on the collagen type III gel. All cells were identified as smooth muscle having definite microfilaments, dense bodies, and pinocytotic vesicles. They had a distinct actin filament running from end to end when labeled with nitrobenzoxadiazole-phallacidin. Cells on the collagen gels had a larger number of actin filaments traveling parallel to the direction of the major axis of their cytoplasm than did those on the glass substrate. Therefore, cultured smooth muscle cells in the more physiological environment for cells in vitro, i.e., on collagen gels, show a suppression of cellular proliferation and an enhancement of differentiation in the early stages of culture. The effects of collagens on the differentiation of cells vary with the collagen phenotype.