Aliskiren directly improves endothelial progenitor cell function from Type II diabetic patients

Background Endothelial progenitor cell (EPC) functions are impaired in the presence of diabetes mellitus. Aliskiren is a direct renin inhibitor, which is expected to modify proangiogenic cells. This study aimed to investigate whether and how aliskiren could improve the function of EPCs from patients with type II diabetes (T2DM). Materials and methods Endothelial progenitor cells fibronectin adhesion assay, chamber assay and in vitro tube formation assay were used to estimate the degree of EPC adhesion, migration and tube formation abilities. EPC protein and mRNA expressions were evaluated by Western blot and quantitative RT-PCR, respectively. EPC vascular endothelial growth factor (VEGF) and (pro)renin receptor ((P)RR) expression was knocked down by VEGF and (P)RR siRNA. Results Aliskiren (0.1 or 10 mu M) dose-dependently improved functions and increased both VEGF and stromal cell-derived factor-1 alpha (SDF-1 alpha) expression of EPCs from patients with T2DM or EPCs from healthy volunteers and treated with high glucose. Transfection with VEGF siRNA significantly reduced the aliskiren-induced SDF-1 alpha expression. Furthermore, (P)RR siRNA transfection impaired the aliskiren-induced VEGF and SDF-1 expression. Conclusions The results show that aliskiren improved EPC function from patients with T2DM in a dose-dependent manner probably via the (P)RR and VEGF/SDF-1 alpha-related mechanisms.