Arterial graft preservation with an endothelial damage inhibitor reduces vascular dysfunction in a rat model of in vitro ischemia/reperfusion injury

Abstract

Coronary artery bypass grafting (CABG) with autologous conduits is a common surgical operation to redirect blood flow to the ischemic myocardium. Vascular ischemia/reperfusion injury (IR) occurs during graft harvest and implantation, and can lead to endothelial dysfunction. DuraGraft®, a novel one-time intraoperative vascular graft treatment, has been shown to protect integrity and function in saphenous vein grafts against IRI. We compared the effect of DuraGraft® to saline solution on arterial grafts submitted to IRI. Rat thoracic aorta was harvested, prepared, and immediately mounted in organ bath chambers (control, n = 7 rats) or underwent 24-hour cold ischemic preservation (4 °C) either in physiological saline (IR, n = 9 rats) or DuraGraft® (IR + Dura, n = 9 rats). Reperfusion-associated endothelial injury was simulated by hypochlorite. Vascular function was measured ex vivo and immunohistochemistry was performed. Impaired maximal vasorelaxation (Rmax) to acetylcholine (ACh) in the IR-group compared to controls was ameliorated by DuraGraft®, indicating an improvement in endothelial function (Rmax to ACh (%): IR + Dura 73 ± 2 vs. IR 48 ± 3, P < 0.05). Additionally, decreased aortic ring sensitivity to ACh (pD2-value: -log 50% maximum response) seen after IR in the saline group was increased by DuraGraft® (pD2 to ACh: IR + Dura 7.1 ± 0.1 vs. IR 6.3 ± 0.2, P < 0.05). Impaired maximum contractile response to phenylephrine and high K+-induced depolarization in the IR-group compared to controls was improved by DuraGraft®. Immunohistochemical analysis for ICAM-1 showed positivity confined to the endothelial layer in the IR group compared to controls, which was decreased by the preservation of aortic rings with DuraGraft®. Furthermore, DuraGraft® decreased nitrotyrosine immunoreactivity in the IR + DuraGraft® compared to both control and IR groups. Also, endothelial PECAM-1 immunoreactivity was significantly reduced in the IR rings compared to controls, whereas a similar pattern was observed between control and IR + Duragraft® groups. DuraGraft® alleviates vascular dysfunction following in vitro IR injury, in part, by reducing nitro-oxidative stress and by lowering inflammatory response through ICAM-1.