凍結乾燥異種神経移植の実験的研究

Abstract

Experiments were performed to investigate regrowth of the rat sciatic nerve through lyophilized heterografts of 10mm length prepared from the rabbit or rat sciatic nerve. The results were as the following:1) Regenerating axons were able to extend through the grafted nerve in both the hetero and homografted lyophilized nerves. However, regrowth through the hetero grafts was delayed by about 4 weeks as assessed by the number of regenerating nerve fibers, latency of the EMG evoked by electrically stimulating the ipsilateral sciatic nerve, and time course of the concentration of γ-enolase in the nerve.2) Regeneration was apparently retarded by inflammatory responses, but once regenerated axons passed through the hetero graft in which intense connective tissue proliferation was noted, regeneration proceeded rapidly, eventually catching the recovery rate of the homo grafted group. At the end of the 48 week observation period no significant differences between hetero and homografted groups were noted in terms of evoked EMG latency, rate of myelinated fiber regeneration, and γ-enolase concentration in the nerve.3) In both the hetero and homografted groups, the recovery of β-enolase concentration of the muscles started from the 8 th postoperative week. The recovery of wet weight of the muscles on the operated side started from the 12 th postoperative week in the hetero grafted group, and from the 8 th postoperative week in the homografted group.4) The degree of recovery of the wet weight of the fast-twitch muscles was superior to that of the slow-twitch muscles. As to β-enolase concentrations the fast-twitch muscles recovered to near-normal levels, while the slow-twitch muscles increased to attain a level between normal fast-and slow-twitch muscle levels.To summarize, although there is a small difference in the period immediately after operation, lyophilized hetero and homografts can, within 48 postoperative weeks, have comparable properties measurable by histological, electrophysiological and biochemical methods.