Effect of preservation media on cellular apoptosis in autologous saphenous vein grafts procured for coronary revascularization

Purpose: Ischemic injury of the saphenous vein graft (SVG) during temporary storage prior to implantation in coronary bypass grafting (CABG) is believed to contribute to SVG thrombosis and stenosis. We aimed to show that; cellular apoptosis in endothelial and smooth muscle cells of the SVG is amplified by the short-term preservation, and that pyruvate-based preservation reduces the degree of cellular apoptosis as compared to other media. Methods: 5-cm SVG segments were taken from 14 patients undergoing CABG. Each 5-cm segment was then subdivided into five 1-cm units (totalling 70 units). For each patient, the first of the five subunits became the control and was immediately examined for apoptosis. These units did not undergo storage. The other four segments were stored at 20°C for 1-hour in one of the following solutions: Normal saline, Euro-Collins (EC), University of Wisconsin solution (UWS) or a 10mM pyruvate solution. Apoptotic cells were detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL assay) and the Student’s t-test was used for comparison. To minimize variability, each patient served as his/her own control. Results: Mean (SEM) number of TUNEL positive cells was similar in segments preserved with pyruvate when compared to Controls (4.00 ± 0.47% versus 4.03 ± 0.40%). When these compared by Student’s t-test, there was no significant difference in the number of apoptotic cells among 10/14 patients (71%). Pyruvate preserved segments had significantly less apoptosis (p < 0.05) in 10/14 patients (71%) when compared to normal saline, in 7/14 patients (50%) when compared to EC, and in 3/14 patients when compared to UWS. Conclusions: Procurement of SVGs is associated with a measurable degree of cellular apoptosis and cellular apoptosis is amplified by the short-term preservation. However, pyruvate preserved SVGs had less cell damage when compared to those preserved in other media and where similar to controls.