Study On Autogenous Nerve Regeneration Accelerated By Temporary Immunosuppression With FK506

Clinical study on human hand allotransplantation show that nerve of the allograft grew 2-3 mm/day, after using immunosuppressant. The speed is faster than that in autologous replantation of severed hand at the same level (about 1mm/day). So it is necessary to study the mechanism of nerve injury, repair and regeneration under immunosuppressive state. In the present study, we examined nerve regeneration and functional recovery in rats receiving FK506 (tacrolimus) 1.0mg/kg per day, comparing with untreated control animals. Morphometric analysis of the regenerating fiber was evaluated by light and electron microscopy. Weight of soleus muscle and contractility of triceps leg muscle was measured in comparison with the unoperated contralateral leg. Sciatic function index (SF1) and Somato-Sensory Evoked Potentials (SSEP) evaluated recovery of function. Besides, 10 cases of clinical volunteer were treated with FK506, and regular examination were done for functional evaluation. Preliminary results: 1. Rat model of autogenous nerve regeneration under immunosuppression was established. All the operated animals were divided into two groups: the experimental group was immunosuppressed with FK506 systemically, while the other untreated-group as control group. 2. Nerve regeneration receiving immunosuppression showed significant difference, compared with control group by light and electron microscopy. Axonal amount and area demonstrated a good recovery in the FK5 06-treated animals, and a more advanced stage of myelination could be seen as well. 3. Recovery rates of soleus muscle weight and contractility of triceps leg 6 muscle in animals given FK506 were significantly higher than that in control group. 4. SF1 demonstrated better functional recovery of the injuried leg in FK5 06.-treated animals. 5. No significant difference of functional recovery could be seen between animals treated with FK506 temporarily and continuously. 6. Mortality in two groups showed no significant difference. 7. Clinical volunteers showed excellent functional recovery with improved velocity of nerve regeneration. Conclusions: 1. Jmmunosuppressant FK506 is benefit to nerve regeneration, muscle and function recovery. 2. Temporary usage of FK506 has the same effect as continuous usage, with no significant influence on survivaL 3. FK506 could be used as a novel drug for peripheral nerve treatment by accelerating nerve regeneration.