GLP-1 promotes angiogenesis in human endothelial cells in a dose-dependent manner, through the Akt, Src and PKC pathways

Abstract

Introduction

Novel anti-diabetic medications that mimic or augment the physiological actions of GLP-1 improve cardiovascular risk factors in diabetics and GLP-1 has been proposed to have a beneficial role in the cardiovascular system. GLP-1 may have a direct cardioprotective role by decreasing infarct size and protecting from ischemia–reperfusion injury while prolonging survival in rodent models. The mechanisms underlying these observations remain largely unknown. In vitro studies suggest that GLP-1 may promote endothelial cell proliferation, but no study to date has evaluated a potential direct effect of GLP-1 on angiogenesis.

Specific Aim

To evaluate whether GLP-1 affects angiogenesis in humans and to elucidate underlying molecular mechanisms.

Material and Methods

We utilized a 3D culture system where spherules of human umbilical vein endothelial cells (HUVECs) embedded in a collagen scaffold were treated with escalating doses of human recombinant GLP-1 (50–2000nmol/L) and the formation of new vessels was observed and quantified. Signaling inhibitors were utilized to identify molecular pathways through which GLP-1 promotes angiogenesis.

Results

We demonstrate that GLP-1 promotes angiogenesis in a dose-dependent manner. The maximum effect on angiogenesis was observed at a GLP-1 dose of 500nmol/L, while increased angiogenesis occurred in response to doses ranging from 200nmol/L to 1000nmol/L. Pre-treatment of the system with Akt inhibitor IV, Bisindolylmaleimide (PKC inhibitor) and src inhibitor I resulted in a significant decrease of the GLP-1 induced angiogenesis.

Conclusions

This is the first study to demonstrate that GLP-1 promotes angiogenesis in a HUVEC three dimensional in vitro model. This effect requires pharmacological doses and is mediated through the Akt, PKC and src pathways.