Objective To investigate the effect of tetramethylpyrazine (TMP) with a certain concentration added to vitrification solution on peripheral nerve allografts regeneration. Methods Forty-eight healthy clean SD male rats were selected as donors, and 96 healthy clean Wistar male rats as recipients, all rats being 3 months old and weighing 200-250 g. The sciatic nerves segments of 15 mm were removed from the donors, then randomly divided into 4 groups according to vitrificationsolution containing TMP. No TMP was used in group A as the control group; 100 mg/L, 200 mg/L and 400 mg/L TMP were used in group B, group C and group D, respectively. Then them were cryo-preserved at — 196 ℃ for 3 weeks. Nerve defect of 10 mm in length was made in the sciatic nerves of recipients. After rewarming, the allografts were transplanted to the corresponding rats. The gross appearance, the morphological and electrophysiological changes, the image analysis of axons and motor end-plate were detected at 4, 8, 12 and 16 weeks. Results All rates survived to the end of the experiment. The adhesion and edema of allografts in group A and group B were obvious 4 weeks after operation; then adhesion and edema was obvious in group A and were improved in the other groups 8 weeks after operation. Adhesion was observed in groups A and B; no adhesion was observed in groups C and D at 12 weeks. The number of regeneration nerve, the latent, the ampl itude, the nerve conduction velocity, the medullary sheath/μm2, the medullary sheath density/μm2 and the image analysis of axons and motor end-plate in groups A and B were significantly lower than those in groups C and D (P lt; 0.01); and there were no significant differences between groups C and D (P gt; 0.05). The observation of transmission electron microscope showed that medullated nerve fibers and myel in sheath of groups C and D were thicker than groups A and B, layers of groups C and D were clear. Conclusion The vitrification solution with 200 mg/L tetramethylpyrazine has protective effect on regeneration of peripheral nerve allografts．
Objective To evaluate the feasibility of preservation of arteriesby vitrification and the effectiveness of vitrified arteries as allografts. Methods Sixty rabbits were used in the research. Forty-eight femoral arteries wereharvested from 24 rabbits as the transplanted materials，and 24 femoral arteries were preserved by vitrification, 24 by freezing for 14 days，respectively. Theother 36 rabbits were used as the transplanted subjects，and were divided into three groups， 12 rabbits including 24 femoral arteries per group: Group A(fresharterial autografts), Group B(vitrified arterial allografts) and Group C(frozen arterial allografts). The morphologic changes of arterial grafts were observed macroscopically and histologically. The patent rate of arterial grafts were measured by angiography, and the rabbits were sacrificed on the 14th day, the 30th day, the 60th day and the 120th day after transplantation respectively. Arterial grafts were harvested to observe the morphological changes，and the immunological rejection was evaluated by measuring the ratio of tunica intima and tunica media. The results were compared between these groups. Results Before transplantation，theintegrated rate of Group B was 91.67%，which was significantly better than that of Group C（54.17%, Plt;0.01）. After transplantation, the accumulative patent rate of Group B was 87.50%，which was significantly better than that of Group C（66.67%, Plt;0.05）. There was statistically significant difference in the ratioof tunica intima and tunica media between Group B and Groups A, C（Plt;0.05）.Conclusion The above results show that vitrification does less damage to cells and tissues because of ice-free in the process of cryopreservation. So vitrification can be used to preserve arteries， and the arterial allografts preserved by vitrification are better than those preserved by freezing.