[show abstract][hide abstract] ABSTRACT: The aim of this study was to evaluate long-term regenerative capacity over a 15-mm nerve gap of an autologous nerve conduit, the biogenic conduit (BC), 16 weeks after sciatic nerve transection in the rat.
A 19-mm long polyvinyl chloride (PVC) tube was implanted parallely to the sciatic nerve. After implantation, a connective tissue cover developed around the PVC-tube, the so-called BC. After removal of the PVC-tube the BCs filled with fibrin (n = 8) were compared to autologous nerve grafts (n = 8). Sciatic functional index (SFI) was evaluated every 4 weeks, histological evaluation was performed at 16 weeks postimplantation. Regenerating axons were visualized by retrograde labelling.
SFI revealed no significant differences. Nerve area and axon number in the BC group were significantly lower than in the autologous nerve group (P < 0.05; P < 0.01). Analysis of myelin formation showed no significant difference in both groups. Analysis of N-ratio revealed lower values in the BC group (P < 0.001).
This study reveals the suitability of BC for nerve gap bridging over a period of 16 weeks with functional recovery to comparable extent as the autologous nerve graft despite impaired histomorphometric parameters.
[show abstract][hide abstract] ABSTRACT: Several types of nerve conduits have been used for peripheral nerve gap bridging. This study investigated the in vivo engineering of a biological nerve conduit and its suitability for nerve gap bridging.
A 19-mm long polyvinyl chloride (PVC) tube was implanted parallely to the sciatic nerve. After implantation, a connective tissue cover developed around the PVC-tube, the so-called biogenic conduit. Histological cross-sections were performed after 1, 2, 3, and 4 weeks. Wall thicknesses were measured and all vessels per cross-section were counted. The biogenic conduit filled with fibrin was used to bridge a 15-mm long nerve gap in the sciatic lesion model of the rat (n = 8). The results of nerve repair with the conduit were compared to the autologous nerve graft (n = 8). Sciatic functional index (SFI), nerve area, axon count, myelination index, and ratio of total myelinated fiber area/nerve area (N-ratio) were analyzed after 4 weeks.
The wall thickness of biogenic conduits increased over the 4 weeks implantation time. Biogenic conduits revealed highest number of vessels per cross-section after 4 weeks. The results of SFI analysis did not show significant difference between the repairs with biogenic conduit and autologous nerve graft. Nerve area and axon count in the biogenic conduit group were significantly lower than in the autologous nerve group (P < 0.001). The biogenic conduit group showed significant higher myelination values, but lower N-ratio when compared to the nerve graft group (P < 0.001).
The in vivo engineered conduits allow nerve gap bridging of 15 mm. However, quality of regeneration after 4 weeks observation time is not comparable to autologous nerve grafts. Whether biogenic conduits might be a suitable alternative to artificial and biological conduits for gap bridging will have to be evaluated in further studies.