HIGH-DOSE TRAPIDIL (TRIAZOLOPYRIMIDINE), A PLATELET-DERIVED GROWTH-FACTOR ANTAGONIST, INHIBITS PROLIFERATIVE ACTIVITY OF HUMAN CORONARY PLAQUE CELLS IN-VITRO

Migration and proliferation of smooth muscle cells (SMC) from the medi a into the subendothelial space are key events in the pathogenesis of restenosis, The inhibition of these cellular activities is of clinical interest, Primary and restenosing plaque tissue was extracted from co ronary arteries of 50 patients with a Simpson atherectomy device, SMC were isolated by enzymatic disaggregation with collagenase/elastase. B y positive reaction with antibodies against smooth muscle a-actin isol ated cells were identified as SMC in more than 90%, Confluent cultures of SMC were trypsinized and seeded into 6-well plates, One day after seeding the medium was exchanged and the platelet-derived growth facto r antagonist trapidil (triazolopyrimidine) was added in 10 concentrati ons ranging from 0.005-500 mu g/mL. After 5 days in culture cell numbe r and cell size distribution was examined in a cell analyser system, F or indirect immunofluorescence studies SMC were fixed in methanol at - 20 degrees C, The following primary antibodies were used: 1) monoclona l anti-smooth muscle alpha-actin, 2) monoclonal antivimentin, 3) monoc lonal anti-tubulin, TRITC-labeled antibodies were used as second antib odies, After 5 days in culture trapidil caused a significant inhibitio n of SMC proliferation (p < 0.001), Peak concentrations of trapidil se verely damaged the cytoskeletal structures of SMC, In conclusion, high dose trapidil inhibited significantly proliferative activities of cor onary primary stenosing and restenosing SMC, In further experimental s tudies with local drug delivery systems the effect of high dose trapid il on restenosis should be elucidated.