Repair of peripheral nerve defects with acellular allogeneic grafts combined with triiodothyronine

Objective To study role of acellular allogeneic grafts(removed of the allogeneic nerve myelin sheath and Schwann cells by chemical method) combined with triiodothyronine(T_3) in bridging 1.0 cm long sciatic nerve gap and observe the regenerative effect of the sciatic nerves.(Methods) Acellular nerve segments containing Schwann cell basal lamina tubes were obtained from sciatic nerves of normal SD rats via chemical extraction.T_3 solution for 500 μl(0.5 mg of T_3 was dissolved in 0.5 ml 0.01 N NaOH and then the solution was neutralized with 0.01 N HCl,with final PH of 7.8) was impregnated in 0.5 ml gelatin hydrogels(0.3 g of gelatin was dissolved in 2 ml distilled water).The SD rats were divided randomly into three Groups(10 rats in each group): Group A(acellular basal lamina tubes grafting combined with T_3),Group B(allogeneic nerve grafting) and Group C(autogenous nerve grafting).The sciatic nerve function index(SFI),electrophysiological test,light and electron microscopic and image analysis were done postoperatively.Results At the 8th week postoperatively,SFI was-36.36±1.91 in Group C,higher than-41.58±2.98 in Group A and-41.89±3.65 in Group B,with significantly statistical difference(P0.01) but insignificantly statistical difference between Group A and Group B(P(0.05)).However,at the 12th week postoperatively,SFI was-31.38±1.87 in Group A and-30.03±1.73 in Group C,both higher than-36.74±1.63 in Group B,with significantly statistical difference (P0.01),but with insignificantly statistical difference between Group A and Group C(P0.05).Motor nerve conductive velocity(NCV) and recovery rate of the cross area of myelinated nerve fibers in both Groups A and C were significantly better than those in Group B at the 8th and 12th weeks respectively postoperatively,with significantly statistical difference(P0.01),but insignificantly statistical difference between Group A and Group C(P0.05).Conclusions The acellular basal lamina tubes grafting combined with T_3 is better than the acellular basal lamina tubes grafting in improving nerve regeneration and is a good substitute for nerve grafts.