β2-Adrenergic Receptor Stimulation Improves Endothelial Progenitor Cells Mediated Ischemic Neoangiogenesis
Rationale: Endothelial progenitor cells (EPCs) are present in the systemic circulation and home to sites of ischemic injury where they promote neoangiogenesis. β2 Adrenergic Receptor (β2AR) play a critical role in vascular tone regulation and neoangiogenesis.
Objective: We aimed to evaluate the role of β2AR on EPCs function.
Methods and Results: We firstly performed in vitro analysis showing the expression of β2AR on EPCs. Stimulation of wild type EPCs with β-agonist Isoproterenol (ISO) induced a significant increase of Flk-1 expression on EPCs as assessed by FACS. Moreover, β2AR stimulation induced a significant increase of cell proliferation, improved the EPCs migratory activity and enhanced the EPCs ability to promote endothelial cell networks formation in vitro. Then we performed in vivo studies in animals model of hindlimb ischemia. Consistent with our in vitro results, in vivo EPCs treatment resulted in an improvement of impaired angiogenic phenotype in β2AR KO mice after induction of ischemia, whereas no significant amelioration was observed when β2AR KO EPCs were injected. Indeed, WT derived EPCs injection resulted in a significantly higher blood flow restoration in ischemic hindlimb and higher capillaries density at histological analysis as compared with not treated or β2AR KO EPCs treated mice.
Conclusions: The present study provides the first evidence that EPCs express a functional β2AR. Moreover, β2AR stimulation results in EPCs proliferation, migration and differentiation, enhancing their angiogenic ability, both in vitro and in vivo, leading to an improved response to ischemic injury in animal models of hindlimb ischemia.
- Received September 21, 2012.
- Revision received February 13, 2013.
- Accepted February 15, 2013.
- Copyright © 2013, Circulation Research