Abstract 655: Protecting The Saphenous Vein Endothelium During Bypass Surgery

Abstract

Coronary artery bypass graft surgeries commonly use saphenous vein grafts to revascularize diseased coronary arteries. Despite surgical and pharmacological advancements, graft failure rates remain high. Loss of endothelial cells (EC) during saphenous vein harvest and preservation likely contributes to the high incidence of graft failure. Standard methods of saphenous vein preparation and preservation during surgery include perfusion with heparinized saline solutions, a practice known to induce EC damage. As such, improved methods of saphenous vein storage may be the key to preserving EC and reducing graft failure rates. Here, we assessed the hypothesis that maintaining saphenous veins in autologous heparinized blood would preserve EC coverage and reduce cellular damage compared to standard of care, heparinized saline. To investigate this, saphenous vein tissues from 12 patients undergoing coronary artery bypass graft surgery were split into 2 treatment groups, 1) standard maintenance in heparin-saline (n=6) and 2) maintenance in heparin-blood (n=6). At the end of the surgeries, excess saphenous vein tissues were immediately fixed in 4% PFA to analyze endothelial coverage and DNA damage. In heparin-saline veins, histological analysis by H&E and Movat pentachrome staining revealed a broken or absent luminal layer and exposed lamina matrix, suggesting a loss of endothelial cell coverage. Luminal cell coverage was notably increased in heparin-blood samples. Immunofluorescent staining of endothelial markers VE-cadherin and endothelial nitric oxide identified a significant improvement in endothelial coverage in the heparin-blood group compared to heparin-saline. To determine the health of remaining endothelial cells, DNA damage was measured using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. Our data show that most of the endothelium (VE-cadherin positive) in heparin-saline tissues was TUNEL positive compared with heparin-blood. In conclusion, our data indicate that maintaining saphenous vein tissues in solutions containing autologous heparinized blood helps preserve the endothelium and maintains vein graft health which has the potential to improve vein graft patency rates in patients.