Functional and morphological evaluation of canine veins following preservation in different storage media

Injuries of endothelial and smooth muscle cells of autologous vein due to preservation in standard storage media may be responsible for graft failure. The effects of vein preservation with University of Wisconsin solution (UWs) on endothelial and smooth muscle cell function and morphology were compared to the effects of preservation with autologous whole blood (AWB) and normal saline (NS), which are frequently used in cardiovascular surgery. Canine external jugular and common femoral vein segments were preserved in the different solutions at 4°C for 45 min and 24 hr. Rings (4- 5 mm in length) from control and preserved veins were evaluated by isometric tension studies at 37°C and by scanning and transmission electron microscopy. Differences between groups were evaluated by Student's t test or Mann-Whitney U test and by analysis of the variance, and considered to be significant at P < 0.05. Sensitivities to norepinephrine (NE) showed that a 45-min vein storage in AWB (5.7 ± 0.2 μmol/L) but not in NS (5.8 ± 0.2 μmol/L) or UWs (6.5 ± 0.2 μmol/L) had a deleterious effect on function of smooth muscle (P < 0.05) when compared to control veins (6.6 ± 0.2 μmol/L). Maximum contractile responses and sensitivities to NE were significantly altered (P < 0.05) after 24-hr vein storage in AWB (0.09 ± 0.02 g/mm² and 5.4 ± 0.07 mmol/L) and NS (0.12 ± 0.03 g/mm² and 5.6 ± 0.08 μmol/L) but not in UWs (0.36 ± 0.06 g/mm² and 6.4 ± 0.07 μmol/L). With both storage times, acetylcholine-induced endothelium-dependent maximum relaxations and sensitivities were significantly reduced (P < 0.05) in veins stored in AWB and NS, but not in UWs, compared with controls. Similarly, transmission electron microscopy revealed marked neutrophil migration beneath the intimal surface of vessels and extensive separation and desquamation of endothelial cells with exposure of subendothelial structures in veins stored in AWB and NS. The results suggest that UWs is a suitable storage medium when compared to AWB and NS.