Perivascular fat-derived leptin: a potential role in improved vein graft performance in coronary artery bypass surgery.

Perivascular tissue (PVT) surrounding many blood vessels, including those used as bypass conduits, is the source of adipocyte-derived relaxing factors, one of which is leptin. Here, we assessed leptin levels and identified leptin localization in the cushion of fat surrounding 'no-touch-harvested' saphenous veins (SVs) used as grafts in 15 patients undergoing coronary artery bypass surgery (CABG). Leptin protein was identified in perivascular fat (PVF) extracts by Western blot analysis and leptin levels were 2.2 (0.5-4.2) ng/mg protein [mean (range), n=10] as assessed by ELISA. There was dense leptin immunostaining of fat and adipocyte membranes surrounding these no-touch SV grafts. PVT-derived factors are suggested to play an important role in the superior patency rate of the internal thoracic artery used as a bypass graft. Our findings suggest that, as a potent vasodilator, PVF-derived leptin may also play an important role both at harvesting and in the improved long-term performance of no-touch SVs in patients undergoing CABG.