Aims and objectives: To investigate and compare the effects of hyaluronic acid (HA), tacrolimus (FK-506) and saline on peripheral nerve regeneration in vivo after topical application at the site of nerve repair.
Materials and methods: In the present study, 48 adult male European rabbits (Oryctolagus cuniculus), ranging in weight from 2.5 to 3 kg, were randomly assigned to three experimental groups: Group I (saline), Group II (HA) and Group III (FK-506). After transection and immediate repair of the right sciatic nerve of each rabbit, the nerve repair sites were wrapped with an absorbable gelatin sponge soaked that contained saline, HA and FK-506 in Groups I, II and III, respectively. The left hind leg was used as a control. To evaluate the effects of HA and FK-506 on nerve regeneration, electrophysiological measurements were acquired at 6 and 12 weeks after nerve repair and toe-spreading index (TSI) experiments were conducted at 4, 8 and 12 weeks after nerve repair.
Results: Motor nerve conduction velocity (MNCV) was improved in Groups II and III compared to Group I, but no differences between Groups II and III were observed. After 12 weeks, however, the MNCV in Groups I, II and III was 40.04%, 51.16% and 50.42%, respectively, of that in the control group (100%). In addition, at 12 weeks, Grade 4 TSI scores were observed in Groups II and III.
Conclusion: Electrophysiological analyses and functional evaluations based on the TSI indicate that HA and FK-506 exert similar, positive effects on nerve regeneration that are superior to those observed in response to saline treatment.