Abstract 3749: Interleukin-11 has a Novel Role in Proliferation and Migration of Cultured Endothelial Progenitor Cells in Vitro And Mobilization of Endothelial Progenitor Cells in Vivo
Endothelial progenitor cells (EPC) have the capacity to differentiate into endothelial cells or secrete growth factors that can enhance post-ischemic angiogenesis. Under normal physiological conditions, very low percentage of EPCs circulates in blood, thus enhanced mobilization of EPCs from bone marrow to ischemic myocardium is intensely studied for therapeutic use. We isolated, cultured, and characterized EPCs from normal human subjects. Cultured EPCs Human Blood Outgrowth Endothelial Cells (HBOEC) were identified by their differential expression of CD31+CD34+CD45-CD133- and Dil-Ac-LDL uptake. Stimulation of HBOEC with recombinant human IL-11 (rHIL-11) caused 2.5-fold increase in cell migration and 3-fold increase cell proliferation. In 3-D spheroid angiogenesis assay using HBOEC, rHIL-11 stimulation caused 6-fold increase in cumulative sprout length and 4-fold increase in number of sprouts per spheroid. To find the effect of IL-11 on HBOEC at molecular level, we performed western blot, gene expression and cytokine array analysis. rHIL-11 stimulated phosphorylation of STAT3 and ERK1/2 in a dose and time dependent manner. Gene expression profile of rHIL-11-stimulated HBOEC showed differential expression of many genes, 19 of which showed putative binding site for HIF-1 regulator. Furthermore, cytokine array analysis of rHIL-11-stimulated HBOEC resulted in secretion TGF-β1, G-CSF, RANTES and angiopoietin-1 with a concomitant reduction of angiostatin secretion which suggests that rHIL-11-stimulated HBOEC may mediate repair of ischemic tissues through secretion of pro-angiogenic cytokines. To confirm our observations in vivo, we showed that in C57BL6 mice stimulation with rHIL-11 leads to a 5-fold increase in circulating EPC levels detected by their specific expression of CD31+, VEGFR2+, CD34bright and CD45+ by flow cytometry. Taken together, our study showed that rHIL-11 stimulates pro-angiogenic response in HBOEC in vitro and increase EPC mobilization in vivo, suggesting a potential adjunctive therapeutic use of rHIL-11 in the treatment of ischemic heart or peripheral vascular disease.