Regeneration After Peripheral Nerve Repair With NerbridgeŽ In Segmental Sciatic Nerve Defects In Rats
Shunsuke Nishimoto, MD, PhD1; Hiroyuki Tanaka, MD, PhD2; Tsuyoshi Murase, MD, PhD2; Hideki Yoshikawa, MD, PhD2
1Kansai Rosai Hospital, Amagasaki, Hyogo, Japan, 2Osaka University, Suita, Osaka, Japan
Introduction
NerbridgeŽ, an artificial nerve graft that was put on the market in Japan recently, is a polyglycolic acid (PGA) conduit filled with collagen matrix. Although there has been many reports with respect to the effect of artificial nerve conduits on segmental nerve defect injuries, the influence of the collagen matrix filled in the conduit upon the regeneration remains to be elucidated. We compared outcomes treated with NerbridgeŽ and hollow NerbridgeŽ, which is processed with collagenase to get rid of inner collagen, for a rat segmental nerve defect model.
Methods
A unilateral 10-mm sciatic nerve defect was created in adult male Wistar rats (ave weight 200 g). Rats were randomly divided into four groups based on the type of repair: sham, autograft, hollow NerbridgeŽ, and NerbridgeŽ groups. Motor function recovery was evaluated at twelve weeks postoperatively on the basis of the wet muscle weight, compound muscle action potential (CMAP), terminal latency, and maximum isometric tetanic force of the tibialis anterior (TA) muscle. For histological evaluation, cross-sections of each nerve of a group were prepared and myelination was assessed by immunofluorescence for neurofilament 200 and myelin basic protein (MBP).
Results
The mean wet muscle weight of the TA muscle was two times greater in NerbridgeŽ group (502 mg) than that in hollow NerbridgeŽ group (254 mg). Terminal latency in NerbridgeŽ group (4.2 ms) was shortened compared to that in hollow NerbridgeŽ group (4.8 ms), whereas no difference in CMAP was observed between these two groups. The isometric tetanic force in NerbridgeŽ group (59.2 g) was six times greater than that in hollow NerbridgeŽ group (10.1 g) and almost the same as that in autograft group. Histologically, NerbridgeŽ group showed the increasing number of MBP-positive axons by approximately four-fold compared with that in hollow NerbridgeŽ group.
Conclusion
The artificial nerve grafts available for clinical application so far have hollow structures except for allografts. In this study, we proposed that NerbridgeŽ, composed of outer PGA conduit and inner collagen, had the greater ability to regenerate after peripheral nerve injury than hollow NerbridgeŽ. NerbridgeŽ has a potential to bring more effective outcomes after peripheral nerve injury compared with artificial nerve grafts with hollow structures commercially available so far.
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