Studies on autocrine system for migration factor for smooth muscle cells

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Following results were obtained using cultured rabbit and rat aortic smooth muscle cells :1. Conditioned media from cultured rabbit and rat aortic smooth muscle cells showed high migration activity for smooth muscle cells. The activity was several times as high as that of purified platelet derived growth factor (PDGF). We named this factor smooth muscle cell derived growth factor (SDGF).2. SDGF was chemotactic but not chemokinetic. It was stable at the treatments such as acidification, alkalization, freezing and thawing, and reduction but was unstable at the treatments such as heating and tripsinization. It was not dializable against the membrane with cutoff pore size 3500. The activity was not neutralized by the antibodies against PDGF or fibronectin. These results suggested that SDMF was a new factor different from known migration factors for smooth muscle cells.3. Secretion of SDMF was 2-3 fold higher in the smooth muscle cells from atherosclerotic intima than that in the smooth muscle cells from normal media.4. Preincubation with transforming growth factor- beta reduced secretion of SDMF from smooth muscle cells.5. Purification : SDMF was adsorbed to heparin-column and eluted by 1M NaC1. The peak of SDMF was collected, dialized, reophilized, and then subjected to a high performance liquid chromatography (HPLC superose 6). Two peaks were obtained at molecular size 400KD and 40KD. The latter peak was again sudjected to HPLC superose 12 with eluate containing SDS. Two peaks were obtained at molecular size 25KD and less than 500D. This purification is now in progress.