199. Circulating Endothelial Progenitor Cells Restore Endothelial Function of Balloon Injured Rabbit Carotid Artery

Abstract

Existing evidence suggests that circulating endothelial progenitor cells (EPCs) play an important protective role against vascular injury. The present study was designed to determine the effect of autologous EPCs transplantation on endothelial dysfunction of rabbit carotid artery induced by balloon injury. Rabbit EPCs were isolated from peripheral blood by density gradient centrifugation and cultured in endothelial growth medium for 7 days. Balloon injury of rabbit common carotid artery was used as a model to study the effect or EPCs on vascular morphology and function. Two groups of rabbits (n = 3 - 5/group) were subjected to injury of the common carotid artery using 3F fogarty balloon catheter. Immediately after injury, autologous EPCs (~ 50,000 in 200 m l saline) were instilled into the injured vessel segment and incubated for 20 min. Control animals received an equivalent volume of saline. The animals were sacrificed 4 weeks after balloon injury, and carotid arteries were harvested for morphological and functional analysis. The presence of DiI-labeled EPCs in vascular wall was detected by fluorescent microscopy. In vivo Evans blue staining demonstrated accelerated re-endothelialization of injured arteries treated with EPCs. Studies of vasomotor function by isometric force recording indicated that contractions to phenylephrine (10-9-10-5 M) were not affected by vascular injury or treatment with EPCs. In contrast, endothelium-dependent relaxations to acetylcholine (Ach; 10-9-10-5M) were significantly impaired by balloon injury (maximal relaxation to Ach = 44.73 ± 22.73 %, n = 3, P< 0.05). Treatment with EPCs normalized endothelium-dependent relaxations to Ach (maximal relaxation = 95.3 ± 2.9%, n = 5). Endothelium-independent relaxations to nitric oxide were not affected by balloon injury or by treatment with EPCs (n = 3 - 5). Cytokine protein array showed that EPC cultured for 7 days secreted angiogenic cytokines: vascular endothelial growth factor, interleukin-8, epidermal growth factor, fibroblast growth factors, transforming growth factor-beta 2, macrophage colony stimulating factor, oncostatin M, thrombopoietin, placenta growth factor, and macrophage migration inhibitory factor. These EPCs also produced pro-inflammatory cytokines such as macrophage inflammatory protein-1, monocyte chemoattratant protein-2, neutrophil activating peptide-2, pulmonary and activation-regulated chemokine. These findings demonstrate that in carotid artery, treatment with EPCs selectively accelerate recovery of endothelial function after balloon injury, and that cytokines secreted by EPCs may contribute to the restoration of endothelium of injured artery. We speculate that transplantation of autologous EPCs may provide novel therapeutic approach in prevention and treatment of endothelial dysfunction.