Effects of insulin on proliferation, seneª²scence and NO secretion of endothelial progenitor cells

    ZHAO Li, WANG Haiª²Chang, YIN Tao, CHENG Kang, GAO Feng

    1Department of Cardiology, Xijing Hospital

    2Department of Phyª²siology, School of Basic Medicine, Fourth Military Medical University, Xi¬ðan 710033, China

    ¡¾Abstract¡¿ AIM: To investigate the effects of insulin on endothelial progenitor cell (EPC) proliferation, senescence and nitric oxide (NO) secretion. METHODS: Mononuclear cells were collected from rat bone marrow by density gradient centrifugation, cultured with Medium 199, and were identified to be EPC on day 7 by flkª²1 and AC133 double staining. EPC were harvested and incubated with vehicle or insulin (0.1, 1, 10 nmol/L). After 24 h of incubation, NO secretion of EPC was assessed by Griess reaction. After 7 d of incubation, proliferative capacity was meaª²sured by MTT assay, and senescent level was measured through senescence associated ¦Âª²galactosidase (SAª²¦Âª²Gal) staining. RESULTS: Compared with control group, 0.1 and 1 nmol/L insulin group showed higher EPC proliferative capacity (absorbance: 0.262¡À0.015, 0.290¡À0.021 vs control 0.232¡À0.021, P<0.01), lower EPC senescence [(17.1¡À1.6)%, (11.7¡À1.8)% vs control (27.9¡À13.5)%, P<0.05] after 7 d of incubation, and higher NO production [¦Ìmol/L, (42.4¡À1.4), (54.4¡À5.8) vs control (35.7¡À1.3), P<0.05] after 24 h incubation, while 10 nmol/L insulin group showed no or only minor difference as compared with control group. CONCLUSION: Lowª²level insulin can stimulate EPC proliferation, inhibit its senescence, and enhance its NO secretion capacity. ......