Is dipyridamole an angiogenic agent?

Dipyridamole, a potent inhibitor of the nucleoside transport into cells, has recently been reported to stimulate the proliferation of capillary endothelial cells in the heart and skeletal muscle of rats following long-term treatment. We tested this drug on cultured calf aortic endothelial cells and obtained no evidence that dipyridamole is able to stimulate directly the proliferation and migration of these cells. By using the chorioallantoic membrane model we observed that the pharmaceutical preparation Curantyl induces vascular responses almost regularly. This effect, however, was found to be dependent on the high concentration of hydrogen ions in this preparation and could be prevented by increasing the pH value. A direct angiogenic effect of dipyridamole could not be demonstrated on the CAM.