Comparison of Different Thawing Methods on Cryopreserved Aorta

Oh, Young Min; Sim, Sung Bo; Sa, Young Jo; Park, Jae Kil; Kwack, Moon Sub; Lee, Sun Hee

Abstract

BACKGROUND: The studies on cryopreserved arterial allograft have been focused on cooling methods, pre-treatment, cryoprotectant agents, and preservation temperature. But recently, several studies have reported that thawing methods also play an important role in the occurrence of macroscopic and microscopic cracks. This study was designed to investigate the cell injury after thawing, using a rabbit model to clarify the effect of thawing methods on cryopreserved arteries. MATERIAL AND METHOD: Segments of the rabbit aorta were obtained and divided into 3 groups (n=60) according to whether the specimens were fresh (control, n=20), cryopreserved and rapidly thawed (RT) at 37oC (n=20), or cryopreserved and subjected to controlled, automated slow thawing (ST)(n=20). Cell damage was established using the TUNEL method and the morphological changes were also evaluated. RESULT: In the group that was rapidly thawed, the expression of TUNEL (+) cells increased significantly more than in the slowly thawed group. In addition, the endothelial denudation, microvesicles and edema were significant in the rapidly thawed group compared with those changes in the slowly thawed group.
CONCLUSION
Our study suggests that the rapid thawing method may be one of the major causes of cellular damage and delayed rupture in cryopreserved arterial allografts. The expression of TUNEL (+) cells and structural changes were significantly low in the slowly thawed group, which might have contributed to the improvement of graft failure after transplantation.