Cold-Stored Venous Allografts In Different Preserving Solutions: A Study On Changes In Vein Wall Morphology.

Background: The saphenous vein is the most frequently used bypass conduit for vascular reconstructions, which may need to be stored for a prolonged time. The aim of this study was to compare the effect of different preservation solutions on the morphology of saphenous veins during the long-term cold storage. Design: An in vitro study Material and Methods: Saphenous vein samples, collected from 29 patients undergoing varicose vein surgery, were stored at +4 degrees C in (1) 10% formalin, (2) isotonic saline with heparin and antibiotic, (3) phosphate-buffered saline, (4) 2.5% glutaraldehyde+phosphate-buffered saline, and (5) Custodiol (histidine-tryptophan-ketoglutarate). Changes in the vein wall were histologically investigated up to day 35. Possible retention of the capacity of endothelial function was evaluated by immunohistochemical detection of endothelial nitric oxide synthase. Results: Formalin as the control medium well preserved the vein wall morphology, but endothelial nitric oxide synthase immunostaining was very weak. Phosphate-buffered saline and isotonic saline with heparin and antibiotic poorly preserved vein wall morphology. Phosphate-buffered saline endothelial nitric oxide synthase staining decreased dramatically throughout the study period. Compared to phosphate-buffered saline, stronger isotonic saline with heparin and antibiotic endothelial nitric oxide synthase staining was noted at day 35 (p<0.001). Custodiol and glutaraldehyde better preserved vein morphology compared to ISHA and PBS at day 5 and later (p<0.001), but compared to stronger isotonic saline with heparin and antibiotic their endothelial nitric oxide synthase staining was weaker. Conclusion: In terms of preserving the morphology of saphenous veins, phosphate-buffered saline and isotonic saline with heparin and antibiotic were the poorest, while Custodiol and glutaraldehyde were the best. Demonstrating good retention of endothelial nitric oxide synthase staining throughout the study period, isotonic saline with heparin and antibiotic seems to have the best potential to retain vein wall functionality, despite relatively poor morphological preservation.