Effects Of Schwann Cells' Viability On Regeneration Of Facial Nerve In Allotransplantation Of Rats

Objectives1.To explore a simple and precise method to modulate the viability of Schwann cell (SC) in Facial Nerve.2.Facial nerves with different SCs' viability are allotransplanted in SD rats and observe nerve regeneration to evaluate the effects of SCs' viability on nerve transplantation.Methods1.The effects of freeze-thaw method on SCs' viability of Facial Nerve were measured. SD rats were assigned to flesh nerve group(Group F),freeze-thaw-one -time group (Group FTI) and freeze-thaw-five -time group(Group FTV).2.Three nerves in each group were stained with Calcein-AM,and fluorescent strengths were measured by confocal microscope to reflect the viability of SC.Nine SD rats in each group were received unilateral facial nerve allotransplantation.3.The middle grafts of 3 rats in each group were stained with osmic acid to observe the regeneration of axons and were counted regenerated axons in 2,4 and 8 weeks after transplantation.The amplitude of action potential and neural conducting velocity (NCV) of transplanted facial nerve and contralateral facial nerve were measured in 8 weeks after transplantation.Results1.The mean fluorescent strength of Group F was 140.93±17.55/μm~2,that of Group FTI was 56.99±7.10/μm~2,and Group FTV 28.46±4.11/μm~2.2.The axons counts of Group F,Group FTI and Group FTV in Week 8 after transplantation were356.60±75.57,334.41±93.71 and 301.60±95.67 respectively,the difference was not statistically significant.There was also no significant statistical difference in the amplitude of action potential and NCV of three groups.3.The distribution of regenerative axons of Group FTI in Week 8 after transplantation was more even than that of Group FTV and Group F,and the thickness of myelin and transactional area of axons were larger,myelin was more mature.Conclusion1.The viability of SC can be effectively and precisely modulated by fast freeze-thaw method,it can be decreased to 40%of fresh nerve by freeze-thaw for one time,while 20%by freeze-thaw for 5 times.2.Under conditions of this experiment,no significant statistical differences were found about effects of Schwann cells' viability on regeneration of facial nerve allotransplantation.But the morphology of regenerated axons in Group FTI was better than that of Group FTV and Group F.It is suggested that lower viability of SC in certain range may be beneficial for regeneration of facial nerve.