Impairment in the number and function of CD34+/KDR+ circulating cells in diabetes and obesity with functional improvement after thymosin &bgr;4 treatment

BackgroundDiabetes and obesity are associated with endothelial dysfunction and atherosclerosis. As mature endothelial cells do not regenerate, CD34+/kinase insert domain receptor (KDR+) circulating cells may be an important source of vascular repair. Thymosin &bgr;4 (T&bgr;4) has been shown to have angiogenic properties. We aim to examine the number and function of CD34+/KDR+ circulating cells from Zucker diabetic fatty (ZDF) rats and investigate the effect of T&bgr;4 on these cells compared with Zucker lean (ZL) rats. MethodsBlood was collected from ZDF (n=20) and ZL (n=21) rats. Peripheral blood mononuclear cells were isolated using Ficoll density gradient centrifugation and grown on fibronectin-coated plates. Enumeration of CD34+ and KDR+ cells was performed with flow cytometry. Colony-forming, migration, and tubule formation assays were performed to determine functionality. Cells were treated with T&bgr;4 (10 ng/ml) for 3 days. ResultsThe number and function of CD34+/KDR+ circulating cells in ZDF rats were significantly reduced compared with ZL (CD34+/KDR+: 0.025±0.002 vs. 0.034±0.003%; colony-forming unit: 1.5±0.5 vs. 3.2±0.8; migrated cell: 7.5±1.0 vs. 11.0±2.1; tubule length: 4.3±0.5 vs. 5.8±1.1 mm2; P<0.05). T&bgr;4 significantly improved the migratory and tubule formation of T&bgr;4-treated CD34+/KDR+ circulating cells from ZDF rats to levels similar to cells from ZL rats (P>0.05). ConclusionA significant impairment in the number and function of CD34+/KDR+ circulating cells in ZDF rats was observed. The use of T&bgr;4 as a potential novel therapeutic target in improving migratory and angiogenic activities may prove to be important in diabetes and obesity.