ABSTRACT
Objective To study the effect of magnetic rewarming on the morphology and biomechanical properties of vitrified umbilical artery. Methods The vitrified umbilical artery was rewarmed by magnetothermal method and traditional water bath. The temperature distribution and stress in the solution system were analyzed, and the rewarming effect was evaluated by tissue staining and mechanical test. Results Compared with water bath rewarming, the temperature gradient and thermal stress generated by magnetic rewarming were smaller, which could effectively reduce the thermal stress damage during the rewarming stage and achieve rapid and uniform rewarming. Magnetic rewarming could effectively avoid umbilical artery fractures and micro-cracks. After rewarming, the extracellular matrix, collagen fibers, elastic fibers and muscle fibers of the umbilical artery were evenly distributed, which preserved the macro and micro structures of the umbilical artery. The umbilical artery showed different degrees of hardening after water bath and magnetic rewarming, but the elastic modulus and limit stress of the latter were not significantly different from those of fresh umbilical artery, and the latter had unidirectional stretching characteristics similar to that of fresh umbilical artery, showing good elasticity and toughness. Conclusions Compared with water bath rewarming, magnetothermal method can effectively reduce the damage of rewarming stage, ensure the macroscopic, microscopic structure integrity of umbilical artery and better biomechanical properties. The research findings provide important references for cryopreservation of large tissues or organs such as umbilical artery.
ABSTRACT
Objective: To investigate the feasibility of improving sciatic nerve vitrification preservation using Shenfu Injection in rats. Methods: At -80℃, SPF male SD rat sciatic nerve segments were preserved in the vitrification solution containing Shenfu Injection (0%, 5%, 10%, 30%, groups A, B, C and D) for 4 weeks. The sciatic nerves were observed by transmission electron microscope (TEM), the biological activity of the nerve was detected by laser scanning confocal microscope (LSCM) after Calcein-AM and PI double staining, and the expressions of Bcl-2 and Bax of the sciatic nerves were tested by Western blotting. 10 mm sciatic nerve defect of the Wistar rats (groups A', B', C' and D') was repaired using the corresponding SD rats sciatic nerves preserved for 4 weeks, the gross appearance and sciatic nerve function index (SFI) were detected at different periods after the surgery, the histological and electrophysiological changes of regenerating nerve were detected at 16 weeks post transplantation. Results: The results of TEM showed that demyelination of the sciatic nerve in group A was severe, and in groups B, C and D were mild. The results of LSCM showed that there were strong green fluorescent and weak red fluorescent in groups B, C and D, and weak green fluorescent and strong red fluorescent in group A. The expression of Bcl-2 and Bax of the sciatic nerves, there were significant differences between groups B, C, D and group A, and between groups C, D and group B (P 0.05). The SFI at different periods after the transplantation, the results of electrophysiological detection, the number of myelinated nerve fibers, and the thickness of myelin at 16 weeks after the surgery, there were significant differences between groups C', D' and groups A', B' (P 0.05). At 16 weeks after the surgery, the results by TEM observation showed that there were fewer fibers, smaller diameter, sparse distribution, thinner myelin sheath in group A' and group B', but the number of regenerated fibers was more, the distribution was extensive, and the myelin sheath was thicker in group C' and group D'. Conclusion: Shenfu Injection has protective effect on sciatic nerve preserved by vitrification, and can improve nerve regeneration after allograft in rats.
