The Experimental Study Of Vascular Allografts' Cold Storage/Cryopreservation

IntroductionIn the recent 20 years, Vascular allograft plays a crucial role in the treatment of Vascular-borne diseases and Revascularization of organ transplantation. Clinical needs of vascular substitutes are more and more, according to alternative sources of these vessels they can be divided into three categories:autologous blood vessels, artificial blood vessels and the allograft. Allograft, in theory, have the same structure, Easily obtained and are easy to match the diameter of advantages, with a large number of available donor organs to obtain. With the development of tissue preservation technology, people gradually increased the use of allograft vascular.The preservation of allograft vascular methods are:cryopreservation and low temperature cold storage method (0-4℃), and glutaraldehyde preservation, and the first two methods are more commonly used. Cold storage method is simple, equipment and advantages of less demanding conditions, but the save time is short, and less research-related; Cryopreservation method has effective long-term preservation, but the operation is relatively complicated and requires a higher costs and equipment. Also, There is no unified, generally accepted standards to determine the vitality of blood vessels after thawing. In clinical practice, due to various factors, the graft which has been kept at 4℃may still not be used in the short term, at this point the vessel can re-cryopreserved to prolong storage time of blood vessels? In this study, by observing the low-temperature graft after cryopreservation of cell metabolic activity and changes in organizational structure, and effect and graft preservation time of 4℃UW liquid cooling, vascular preservation effects of -80℃cryopreservation and the feasibility and safety limit of low temperature-cryopreservation sequential grafts preservation. ObjectiveTo explore the optimal time limit and result of vascular allografts preserved both at 4℃UW solution and -80℃cryopreservation processes, the feasibility and secure cold storage time limit during sequentially cold-cryopreservation through experimental research.MethodsHuman iliac and splenic arteries were stored for 72 hours,1 week,2 weeks,3 weeks and 4 weeks in UW solution at 4℃. After the cold storage procedure, half of the vascular allografts are investigated by NBT dye method, electron and light microscope. The other vascular allografts continued to be stored by -80℃cryopreservation procedure for 4 weeks, after which the vascular allografts were investigated by NBT dye method, electron and light microscope.ResultsThere was no statistic difference in NBT dyeing time between the groups stored by UW solution within 2 weeks and fresh group at 4℃. After -80℃cryopreservation, the NBT dyeing time between the groups stored by UW solution within 1 week and fresh group at 4℃was also no statistic difference. Along with the cold storage time extension, the destruction of ultrastructue aggravated. When vascular allograft was stored over 2 weeks at 4℃, the destruction was more obvious. As the cold storage time prolonged, the ultrastructural destruction of vascular allografts was aggravated, especially those stored over 1 week.ConclusionsThe optimal time limit for arteries stored at 4℃by UW solution is 2 weeks. Cryopreservation at -80℃kept the arteries satisfactory metabolic activity and organizational structure. The arteries stored with 1 week at 4℃by UW solution, which restored at -80℃, could maintain satisfactory metabolic activity and organizational structure.