Background

Although there have used a lot of methods, autogenous nerve grafting has been the standart technique for repairing nerve defect, but it causes significant donor site morbidity. In a preliminary study, we thought that the alternative conduit material to avoid donor side morbidity should be as similar as the autogenous nerve graft. In that study, we carried out nerve prefabrication by using autogenous vein as conduit between two healthy nerves, in addition making partial incision on the nerves and performing VEGF gene therapy, thus we created a new alternative of autogenous nerve graft. The purpose of this current study was to evaluate the effectivity of prefabricated nerve grafts in the repairing nerve defect, and to compare them with the autogenous nerve graft and vein graft.

Material and Methods

Four groups were created, each containing 10 rats. Firstly, nerve prefabrication was carried out as described in our previously study during eight weeks in group I (partial incision group) and group II (gene therapy group), and then a 1 cm long nerve gap was created by sectioning on the peroneal nerve in all groups. Prefabricated nerve graft with partial incision sectioned from the right side was sutured to the peroneal nerve defect in group I. Prefabricated nerve graft with gene therapy sectioned from the right side was sutured to the peroneal nerve defect in group II. Nerve defect was repaired by using autogenous nerve graft sectioned from same localization on the peroneal nerve in group III (nerve group). Nerve defect was repaired by using jugular vein graft in group IV (vein group). Nerve conduction studies and histologic evaluation were performed for assessment of the results.

Results

According to electromyographic studies peak amplitude of the group I, II and III, were significantly higher than group IV. The latency of group I, II, and III were significantly shorter than group IV. According to microscopic evaluation of semithin sections, there were so many myelinated fibers had large diameters in group III (nerve group) as predicted (Figure 1A). The myelinated fibers of group IV (vein group) were less organized and fewer than other groups, while the results of microscopic evaluation in both group I (partial incision group) and group II (gene therapy group) were similar to group III (nerve group).

The electron microscopic evaluation of nerve, partial incision and gene therapy groups (group I, II, and III) showed that quite regularity in the myelin sheath, and no or mild lacuna formation in the axon. The electron microscopic results revealed large lacuna formation in the axons, and irregularity in the myelin sheath in the vein group (group IV).

Conclusions

We carried out nerve prefabrication by using autogenous vein as conduit between two healthy nerves, in addition making partial incision on the nerves and performing gene therapy, thus we created a new alternative of autogenous nerve graft. In addition, we showed that this prefabricated nerve grafts as effective as autogenous nerve graft but it doesn’t cause donor site morbidity.