Vascularized Nerve Flap for Spinal Cord Repair—A Preliminary Study

Object: By making the “vascularized nerve flap for complete spinal cord gap” model, we assessed the histological effect of this method. Method: Eight female Sprague-Dawley rats were divided into 2 groups: group A and group B. Group A included “nonvascularized nerve flap” models, whereas group B consisted of “vascularized nerve flap” models. In each group, we transferred peripheral nerves to fill the void made by complete surgical transection of the spinal cord. Postoperatively, we administered intravenous antibiotics and performed urethral catheterization and disimpaction everyday. Tissue sampling was done on postoperative day 10. Results: No necrosis occurred in group B, vascularized models. In group A, nonvascularized models, necrosis of the grafted nerves was observed in 2 of the 4 rats. As for the specimens of Kluver-Barrera's method for selective myelin sheath staining, in group B, all specimens were stained with Kluver-Barrera's method for selective myelin sheath staining, whereas in group A, 2 specimens with successful engraftment were not stained. With type IV collagen immunostaining, the increase of type IV collagen around the grafted area was not so severe, compared with that of normal region in vascularized cases. In nonvascularized cases, the appearance of type IV collagen was prominent. Therefore, in the vascularized cases, it was made clear that Schwann cells survived in vascularized models and that fibrotic scar formation was inhibited. Conclusion: Histological comparison between vascularized and nonvascularized peripheral nerve transfer for complete spinal cord gap showed significant differences in 10 days. A longer follow-up period is necessary for observation of functional differences.