Metformin improves the angiogenic functions of endothelial progenitor cells via activating AMPK/eNOS pathway in diabetic mice.
BACKGROUND
Endothelial dysfunction has been suggested as a possible causal link between hyperglycemia and microvascular complications in diabetes mellitus. The effect of metformin on endothelial progenitor cells (EPCs) is still unclear. This study was designed to test the hypothesis that metformin could accelerate wound healing by improving the impaired EPC functions in streptozotocin-induced diabetic mice.


METHODS
Streptozotocin (STZ, 60 mg/kg/d × 5 d, i.p.) was injected to induce type 1 diabetes in male C57BL/6 mice. Mice were treated with metformin (250 mg/kg/d, i.g.) for consecutive 14 days. Wound closure was evaluated by wound area and number of CD31 stained capillaries. Functions of bone marrow-endothelial progenitor cells (BM-EPCs) were assessed by tube formation and migration assays, and expression of AMP-activated protein kinase (AMPK) and endothelial nitric oxide synthase (eNOS) was determined by western blot analysis.


RESULTS
Metformin accelerated wound closure and stimulated angiogenesis in diabetic mice. The number of circulating EPCs was increased significantly in metformin treated diabetic mice. Abilities of tube formation and migration of BM-EPCs were impaired in diabetic mice, which were improved by metformin. Expression of both phosphorylated-AMPK and phosphorylated-eNOS was significantly increased, and nitric oxide (NO) production was enhanced by metformin in BM-EPCs of diabetic mice. In vitro, metformin improved impaired BM-EPC functions, and increased phosphorylated-eNOS expression and NO production in cultured BM-EPCs caused by high glucose, which was prevented by the AMPK inhibitor compound C.


CONCLUSIONS
Our results suggest that metformin could improve BM-EPC functions in STZ-induced diabetic mice, which was possibly dependent on the AMPK/eNOS pathway.
Department of Pharmacy, Zhejiang Xiaoshan Hospital, Hangzhou, 311202, Zhejiang, China.
Jia-Wen
JW
Yu
Department of Pharmacy, Zhejiang Xiaoshan Hospital, Hangzhou, 311202, Zhejiang, China.
Ya-Ping
YP
Deng
Department of Pharmacy, Zhejiang Xiaoshan Hospital, Hangzhou, 311202, Zhejiang, China.
Xue
X
Han
Department of Pharmacy, Zhejiang Xiaoshan Hospital, Hangzhou, 311202, Zhejiang, China.
Guo-Fei
GF
Ren
Department of Pharmacy, Zhejiang Xiaoshan Hospital, Hangzhou, 311202, Zhejiang, China.
Jian
J
Cai
Department of Pharmacy, Zhejiang Xiaoshan Hospital, Hangzhou, 311202, Zhejiang, China. jguojun999@163.com.
Guo-Jun
GJ
Jiang
D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000818:Animals; D002465:Cell Movement / Q000187:drug effects*; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy*; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy* / Q000378:metabolism; D004195:Disease Models, Animal; D066026:Endothelial Progenitor Cells / Q000187:drug effects* / Q000378:metabolism; D006943:Hyperglycemia / Q000188:drug therapy* / Q000378:metabolism; D008297:Male; D008687:Metformin / Q000494:pharmacology*; D008810:Mice, Inbred C57BL; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
D008687:Metformin; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D055372:AMP-Activated Protein Kinases
Angiogenesis; Diabetes mellitus; Endothelial progenitor cells (EPCs); Metformin