Effects of high glucose plus high insulin on proliferation and apoptosis of mouse endothelial progenitor cells

Objective:  To study the effects of high glucose plus high insulin (GI) on proliferation, apoptosis, morphology and differentiation of endothelial progenitor cells (EPC). Methods:  EPC were isolated and identified by magnetic cell sorting and flow cytometry. EPC proliferation and apoptosis were measured by MTT assay and Annexin-V/PI double labeling, respectively. Cell proliferation- and apoptosis-related factors were examined by Western blotting. Results:  Seven days after GI treatment, EPC were arrested at the G₀/G₁ phase. Treatment with high glucose alone (HG) or GI but not HI (high insulin alone) decreased EPC proliferation and their expression of cyclin E, cdk2 and PCNA compared to control. The inhibitory effects of HG on EPC proliferation and growth-related proteins were more significant than those of GI. HG, GI and HI promoted EPC apoptosis along with caspase-3 overexpression. Conclusion:  The result indicated that GI-induced apoptosis and growth inhibition might be one of mechanisms of EPC reduction and dysfunction in diabetes. Received 17 June 2008; accepted by I. Ahnfeld-R?nne 10 July 2008 W. Zhang, X. Wang: These authors contributed equally.