Abstract 5110: The Inhibition of Poly(ADP-ribose) Polymerase-1 (PARP-1) Significantly Accelerates the Vasculogenesis in a Model of Hind Limb Ischemia

Abstract

Background: Cardiovascular and metabolic diseases are associated with impaired vasculogenesis in response to ischemia. PARP-1, an abundant nuclear enzyme involved in DNA repair and transcriptional regulation and recognized as a key regulator of cell survival and cell death in response to noxious stimuli in various forms of cardiovascular and metabolic disease. Our hypothesis is to determine whether PARP-1 has a key role in vasculogensis in response to ischemia. Methods and Results: Hind limb ischemia was performed in C57/Bl6 mice for 15 days with and without PARP-1 inhibition using TIQ (PARP-1 inhibitor) or local injection of lentivirus-PARP-1-siRNA. We also used microvascular cultured endothelial cells stimulated with hypoxia with and without PARP-1 inhibition (TIQ and lentivirus-PARP-1-siRNA) and determined the expression of VEGF. Mice treated with TIQ significantly accelerated the recovery of blood flow, as determined with MoorLDI-Laser and X-ray, by 50 – 60% the first week and complete recovery at the second week compared to control. Interestingly, mice locally injected with lentivirus-PARP-1-siRNA significantly accelerated blood flow recovery compared to control. Western blot analysis revealed an increase in VEGF level in muscle from mice treated with TIQ or injected with lentivirus-PARP-1-siRNA compared to control. VEGF release in the conditioned media was increased when cultured endothelial cells were stimulated with hypoxia. In addition, endothelial cells pre-treated with TIQ or transfected with lentivirus-PARP-1-siRNA and then stimulated with hypoxia significantly increased VEGF release in the conditioned media compared control and to cells stimulated with hypoxia. Conclusion: Our novel data provide evidence that PARP-1 plays a key role in the regulation of vasculogenesis in response to ischemia. We demonstrated that the inhibition of PARP-1 enhances earlier the formation of new vessels in response to ischemia through the increase of VEGF release. The inhibition of PARP-1 would be interesting in model of altered vasculogenesis such cardiovascular and metabolic diseases.