An Experimental Study of Cryopreservation of Aortic Valve Allograft with Maintenance of Cell Viability / 日本心臓血管外科学会雑誌

ABSTRACT

Aortic valve allografts have been used extensively for aortic valve replacement, aortic root replacement and relief of right ventricular outflow tract obstruction. Some investigators consider that the degree of cellular viability is important in determining allograft durability. In order to evaluate cell viability and histological changes of cryopreserved aortic valve allograft in a pig model, porcine aortic and pulmonary valves are subjected to cryopreservation. Porcine aortic valves were obtained from a slaughterhouse in a non-sterile condition. The dissected valves together with vascular walls were kept in a solution of antibiotics (CFX, IPM/CS, PCG, SM) for 6hr, at 37°C. After sterilization, no growth of aerobic and anaerobic bacteria, as well as fungi was seen in pieces of valves. For cryopreservation, the program freezing method (control freezing at a rate of -1°C/min) and the rapid freezing method (simple immersion in liquid nitrogen), with and without 10% dimethylsulfoxide (DMSO) for cryoprotective agents, were tested. Cell viability was assesed by cell growth from pieces of valves and vascular walls. Histological changes and cell viability were evaluated after storage periods of 1 week, 1 month and 3 months. By the program freezing method with 10% DMSO, cell viability was well preserved and no histological change was detected after 3 months storage. By the rapid freezing method with 10% DMSO, cell viability of valves and vascular walls, except for aorta, were preserved and histological changes were slight. The valves and vascular walls cryopreserved without DMSO showed no cell growth after storage of 1 week. The result suggests that the program freezing method with 10% DMSO is applicable in a clinical use.