Reinnervation of a denervated skeletal muscle by spinal axons regenerating through a collagen channel directly implanted into the rat spinal cord

In the present study, the continuity between the central nervous system (CNS) and the peripheral nervous system (PNS) was restored by mean of a collagen channel in order to reinnervate a skeletal muscle. Three groups of animals were considered. In the first group, one end of the collagen channel was implanted in the cervical spinal cord of adult rats. The other end was connected to a 30-mm autologous peripheral nerve graft (PNG) implanted into the denervated biceps brachii muscle. The gap between the spinal cord and the proximal nerve stump varied from 3 to 7 mm. In the second group of animals, the distal end of the PNG graft was ligatured in order to compare the survival of the growing axons in the presence and in the absence of a muscular target. In the third group of animals, the extraspinal stump of the collagen channel was ligatured. Our study demonstrates that spinal neurons and dorsal root ganglion (DRG) neurons can grow long axons through the collagen channel over a 7-mm gap and reinnervate a denervated skeletal muscle. The results also indicate that the presence of a PNG at the extraspinal stump of the collagen channel is essential for axonal regrowth and that the muscle target contributes to the long-term maintenance of the regenerating axons. These data might be interesting for clinical application when the continuity between the CNS and PNS is interrupted such as in root avulsion. (C) 2001 Elsevier Science B.V. All rights reserved.