Submitted on November 22, 2004
Accepted on March 29, 2005
Paracrine mitogenic effect of human endothelial progenitor cells - Role of interleukin-8
Tongrong He1, Timothy E Peterson1, and Zvonimir S Katusic2*
1 Department of Anesthesiology, Mayo Clinic, Rochester, MN, USA
2 Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA
* To whom correspondence should be addressed. E-mail: katusic.zvonimir{at}mayo.edu.
Endothelial progenitor cells (EPCs) play an important role in repair of vascular injury and neovascularization. Molecular mechanisms underlying vascular effects of EPCs are not fully understood. The present study was designed to test the hypothesis that human EPCs exert strong paracrine mitogenic effect on mature endothelial cells. Levels of interlukin-8 (IL-8) in conditioned media (CM) collected from EPCs were significantly higher than IL-8 levels in CM derived from mature endothelial cells [umbilical vein endothelial cells (HUVECs) and coronary artery endothelial cells (CAECs)]. CM of EPCs stimulated proliferation of HUVECs and CAECs. This mitogenic effect was partially inhibited by IL-8 neutralizing antibody. In contrast, CM of HUVECs and CAECs had a weak or no mitogenic effect on mature endothelial cells. Our results demonstrate that human EPCs secrete significantly higher levels of interleukin-8 (IL-8) as compared with mature endothelial cells. IL-8 appears to be an important mediator of EPCs paracrine mitogenic effect.
