Evidence of the heterogeneity of the proliferative capacity and for the selection of vascular smooth muscle cells with high proliferative activity in experimental diabetes.

The proliferative activity of cultivated aortic and venous smooth muscle cells (ASMC and VSMC) was estimated by 3H-thymidine autoradiography according to an exact time schedule in primary explant cultures and in the second subcultures of control and streptozotocin diabetic rats. The proliferative activity in both the primary and the subcultures was significantly higher in diabetes than in the control. The proliferative activity of VSMC was significantly lower than that of ASMC and it was not influenced by diabetes. The proliferative activity of subcultures was found--in general--to be lower than that of the primary cultures. "Diabetic" ASMC, however, exhibited exalted proliferative activity. This is considered as evidence for the preexisting heterogeneity of the proliferative capacity and for the selection of ASMC with high proliferative activity as a key mechanism of vascular disease induced by diabetes. The selective advantage of these cells is readily detectable in low density subcultures.