Abstract 80: Modulating the Vascular Healing Response via SIRT1 Transgene Delivery

Abstract

Bypass graft procedures are commonly performed to treat narrowing or blocked vessels. However, damage to the vascular wall from the surgical intervention can lead to pro-inflammatory events and oxidative stress that promote intimal hyperplasia and may eventually lead to restenosis. Therefore, strategies that seek to reduce inflammation and oxidative stress during the initial stages of wound healing at the graft anastomoses are expected to inhibit intimal hyperplasia and reduce graft failure rates. Sirtuin-1 (Sirt1), an NAD+-dependent lysine deacetylase, protects against inflammation and oxidative stress by deacetylating the RelA/p65 subunit of NF-kB and FOXO transcription factors. We hypothesize that the localized overexpression of Sirt1 at the perivascular wall via lentivirus entrapped in a thermoresponsive gel referred to as nanonets will lead to an improved vascular healing response at the graft anastomoses and attenuate intimal hyperplasia via reduced tissue inflammation and oxidative stress. Human aortic adventitial fibroblasts (AoAFs) were transduced with lentiviruses encoding for Sirt1 and assessed for NF-kB activity, cytokine expression, senescence, and upregulation of antioxidant genes. To assess perivascular transgene delivery, nanonets containing lentiviruses encoding GFP were applied perivascularly around the aortas of rats. After one week of in vivo transduction, aortas were explanted and probed for GFP positive cells. Upon TNFα stimulation, NF-kB activity and cytokine expression levels were decreased when compared to non-transduced and empty vector-transduced AoAFs. Furthermore, Sirt1-overexpression prevented cellular senescence and protected against oxidative stress. Nanonets containing lentiviruses effectively transduced adventitial fibroblasts in vivo. In conclusion, Sirt1 overexpression in AoAFs may be protective against inflammation and oxidative stress.