Effect of FK506 nanospheres on regeneration of allogeneic nerve after transplant

Objective: To discuss effect of FK506 nanospheres used at different time on the regeneration of allogeneic nerve after transplant. Methods: Single emulsion solvent evaporation method (O/W) was adopted to prepare the FK506 nanospheres and the tibial nerve of rats after allogeneic transplantation. FK506 nanospheres were used in group A after operation immediately, in group B in 24 h after operation, and in group C in 3 d after operation while FK506 nanospheres were not used in group D; in the 4th, 8th and 12th week after operation respectively, general observation of transplanted nerves, histological examination, image analysis of myelinated fibers, wet-weight determination of musculi triceps surae, retrogradely labeling of neurons by the fluorescein and electrophysiological comparison of bilateral tibial nerve were carried out. Results: FK506 nanospheres can be degraded and absorbed quickly. The neural regenerations in group A and B were similar, which were both much better than those in group C and D. The difference was statistically significant and so was the difference between group C and D. Conclusions: Drug release rate of FK506 nanospheres is accordant with the regeneration law of damaged nerves and the local application can promote the regenerations of nerves. The effect would be better if the drug is used in earlier period (within 24h).