Involvement of extracellular-matrix-degrading metalloproteinases in rabbit aortic smooth-muscle cell proliferation.

We investigated the influence of two structurally unrelated inhibitors of matrix-degrading metalloproteinases, Ro 31-4724 and Ro 31-7467, on the primary proliferation of smooth-muscle cells from rabbit aortic explants. Both agents inhibited proliferation in a concentration-dependent manner, but did not affect cell viability. Smooth-muscle cells grown out from explants secreted 95 kDa and 72 kDa gelatinase enzymes that were also inhibited in a concentration-dependent manner by Ro 31-4724 and Ro 31-7467. Interstitial collagenase and stromelysin were not detected. We conclude that metalloproteinases are likely to be involved in the initiation of smooth-muscle proliferation.