Type 2 diabetes mellitus impairs the maturation of endothelial progenitor cells and increases the number of circulating endothelial cells in peripheral blood

Type 2 diabetes mellitus (T2DM) is associated with endothelial dysfunction, which leads to vascular complications. Endothelial progenitor cells (EPCs) are thought to be a subset of cells derived from the bone marrow that play a crucial role in the neovascularization of ischemic tissue and in the maintenance of endothelial cell integrity. In contrast, circulating endothelial cells (CECs) are of endothelial origin and become detached from the intima of blood vessels in response to pathological stimuli. The study investigated the effects of T2DM on subpopulations of EPCs and CECs in peripheral blood, as compared with the effects on unacylated (UAG) and acylated (AG) ghrelin levels, which have been shown recently to play an important role in endothelial dysfunction associated with diabetes. Using the high-performance flow cytometer FACSCanto, and UAG/AG ghrelin enzyme immunoassay kits, we analyzed whole peripheral blood samples from: (i) diabetic patients with a history of disease of less than 1 year and no clinical evidence of angiopathy, (ii) diabetic patients with long-standing disease with vascular complications, and (iii) healthy donors. We found that T2DM did not affect bone-marrow mobilization, but it altered the UAG/AG profile and decreased the number of highly differentiated EPCs (late EPCs) greatly. In addition, T2DM increased the number of CECs, together with the number of activated CECs. Our results suggest that: (i) the endothelial damage could be due mainly to altered maturation/commitment of EPCs, rather than a simple decrease in their production in the bone marrow; and (ii) EPC subpopulations and ghrelin levels could be useful markers to assess endothelial damage in diabetes.