The decrement in circulating endothelial progenitor cells (EPCs) in type 2 diabetes is independent of the severity of the hypoadiponectemia

Abstract

Type 2 diabetes mellitus (DM) is associated with a decreased level of circulating endothelial progenitor cells (EPCs) and adiponectin. Experimental studies suggest a potential link between hypoadiponectinaemia and the depletion of the EPC level. This study investigated the relationships between adiponectin level and EPC in patients with type 2 DM. A total of 95 type 2 DM patients (58.5 ± 8.8 years, 42 men) and 95 age- and sex-matched healthy controls were recruited. Circulating EPC levels were determined by flow cytometry using CD133(+), CD34(+), CD133(+) /KDR(+) and CD34(+) /KDR(+) as surface markers. Plasma adiponectin levels were measured by enzyme-linked immunosorbent assay. EPC function was studied by in vitro tube formation and migration assay. The levels of CD133(+) (p < 0.001) and CD133(+) /KDR(+) (p < 0.001) EPCs were independently associated with the presence of type 2 DM. The levels of CD34(+) (p = 0.004) and CD34(+) /KDR(+) (p = 0.013) EPCs were independently associated with haemoglobin A(1c). Nevertheless, there was no relationship between the number of EPCs and adiponectin level. Tube formation assay showed impaired pro-angiogenic function of EPC in DM patients compared with controls (p = 0.007). Interestingly, adiponectin supplementation (5 µg/mL) increased tube formation by 17.6% in EPCs from DM patients (p = 0.002). It also significantly enhanced cell migration by 35.9% in EPCs from DM patients (p = 0.01). We detected no relationship between the reduction in the level of EPC and in the level of total adiponectin in blood from patients with type 2 diabetes. EPC from patients with diabetes were stimulated when exposed to adiponectin in the test tube, findings that warrant further study.