Dipyridamoie Decreases Platelet-Derived Growth Factor Levels in Human Serum

Mitogenic activities on confluent f ibroblasts by sera from patients with scleroderma and normal controls were studied. In experiments using eight different fibroblast strains (one human fetal lung fibroblast, one foreskin fibroblast, three adult skin fibroblast, and three scleroderma fibroblast), pooled scleroderma serum showed low-er mitogenic activity by 3H-thymidine incorporation assay than pooled normal serum. Individual serum investigations revealed that 11 of 33 patients (33%) showed low mitogenic activities; all 11 patients were receiving dipyridamoie. Of 15 patients, 11 (73%) receiving dipyridamoie showed low mitogenic activities; none of 18 patients not receiving dipyridamoie showed low mitogenic activities. Approximately 70 % of this serum activity was inhibited by the addition of antl-platelet-derived growth factor (PDGF) antibody indicating that most of this serum activity seemed to be derived from PDGF. Western blot analysis of extracts of normal sera before and after administration of dipyridamoie with antihuman PDGF antibody showed a large decrease in the amount of immunoreactive PDGF present. These data indicate that dipyridamoie is an effective drug to lower release of PDGF during blood clotting