Rewarming Rate On The Cryopreservation Of The Vascular Effects Of Experimental Research

ObjectiveTo match the clinical application, compare the effect of different thawing rate on the function and structure of cryopreserved vessels.Methods32 bilateral carotid segments were obtained from 8 rabbits, 24 specimens of which were all first cooling to - 100℃by procedure, after 4 weeks preserving in liquid nitrogen, then rewarmed them in different rates and divided these carotids into group A, B and C on average according to the rate of speed, 100℃/min, 30℃/min, 15℃/min, and each group consists of 8 carotid segments, The rest 8 similar segments without any dealings were used as control. Observing the alteration of the vascular structure under the light microscope and electron microscope respectively, then by the TUNEL to compare the apoptosis rates of the vessel wall cells in each group. we assessed the endodermis-dependent relaxation and nonendodermis-dependent relaxation of different vessel in organ bath.Results Under the light microscope and electron microscope respectively, group A showed a loss of endotheliocyte (EC) and cytomorphosis of SMC, and bulk vacuolus were observed in kytoplasm while only mild alteration of the endotheliocyte and SMC were presented in Group B and C. There were also significant diversity among these groups regarding apoptosis rates of the vascular cells and the endodermis-dependent relaxation and nonendodermis-dependent relaxation. Group A, B and C compared control had increased apoptosis rates(P<0.05),and Group A compared Group B, C had increased apoptosis rates(P<0.05). There were no diversity between Group B and C(P>0.05). Group A, B and C compared control had decreased max percentage of endodermis dependent relaxation by 40%, 23% and 19% (P< 0.05). Group A compared Group B, C had decreased (P<0.05). Group A compared control had decreased max percentage of nonendodermis dependent relaxation by 29% (P<0.05). There were no diversity between Group B, C and control(P>0.05).ConclusionRewarming gradually and slowly can improve the structure and efficiency of the carotids , which were cryopreservated.