Animal experiment of nerve regeneration promoted by predegenerated nerve graft

Cunxiao LI; Rensheng LI; Qi YIN

ABSTRACT

BACKGROUND:

Many studies thought that predegenerated nerve graft (PNG) is superior to fresh nerve graft (FNG).

OBJECTIVE:

To observe the effect of predegeneration on nerve functional recovery from histological,immunocytochemical,electrophysiological and microstructural aspects based on predegenerated nerve graft to common peroneal nerve at different time periods.

DESIGN:

Grouping and controlled experiment

SETTING:

General Center of Department of Orthopaedics, Tangdu Hospital, Fourth Military Medical University of Chinese PLA MATERIALS Totally 42 rabbits, with body mass ranged from 2.3 to 2.6 kg,of either gender, were used in this experiment

METHODS:

This experiment was conducted at the General Center of Department of Orthopaedics, Xijing Hospital, Fourth Military Medical University of Chinese PLA in 1996. Totally 42 rabbits were divided into 7experiment groups A, B, C, D, E, F, G for nerve grafts of different predegenerated periods. In groups A, B, C, D, E, F, both side of the rabbits peroneal nerves were allowed to undergo predegeneration for 0, 4, 7, 14,21, 28 days; common peroneal nerve of the rabbits in the Groups B, C, D,E and F were cut off; The skin of the animals in Group A was cut open,exposed but the nerve was not cut off. Only the right common peroneal nerve in Group G was cut off. The cut nerve in Groups B, C, D, E and F were re-exposed respectively at 4,7,14,21 and 28 days after operation. 1.5 cm-length degenerated distal nerve segment was chosen for transplantation and reparation contrafateral nerve. Two sides were transplanted mutually. Common peroneal nerve in Group A was re-exposed 2 weeks later, 1.5 cm-length nerve segment was cut in the same way for mutual transplantation. In Group G, the predegenerated nerve segment of the right side was transplanted to the fresh receptor of the left side 2weeks later. The fresh nerve segment of left segment was transplanted to degenerated receptor of the right side.Histological observation, passing rate of axon counting shortened significantly the initial delay period of axonal regeneration (from 3.04 to 0.04 day), accelerated the axonal growing rate (1.73-2.59 mm/d)as compared with FNG; Electrophysiological study showed that N-MCV in the Groups D, C and B was the fastest, followed by Group A and Group E,Group F was the slowest; there was no significant difference in passing rate appeared in the animals of Group D after operation, middle-quantity of myelin sheaths appeared in the Group C and few myelin sheaths in the Groups A, B, and F.

CONCLUSION:

PNG excels FNG at decreasing initial delay period of axonal regeneration, promoting regeneration velocity of axon, boosting up passing rate of axon and enhancing N-MCV. Nerve grafting for predegenerated for 14 days can enhance significantly nerve regeneration than fresh nerve grafts, then grafts degenerated for 7 days. Grafts degenerated for 4 and 21 days can also enhance axonal regeneration lightly.