Cultured peripheral nervous system cells support peripheral nerve regeneration through tubes in the absence of distal nerve stump

Axons of a cut peripheral nerve will grow across a gap (less than or equal to 10 mm in adult rodents) formed when the proximal and distal stumps are placed at opposite ends of an impermeable, inert tube, but will not grow to the end of a blind-ended tube in the absence of the distal stump [Williams et al, 1984]. Work reported here demonstrates that cultured peripheral nervous system (PNS) cells suspended in a collagen matrix will provide an effective milieu that directs and supports axonal regeneration from a severed nerve into a blind-ended tube in the absence of a distal stump. Adult mouse sciatic nerves were cut and the proximal stumps were inserted into close-ended tubes that contained either a collagen matrix containing dissociated cells from embryonic mouse dorsal root ganglia (DRG), a collagen matrix saturated with medium conditioned by cultured DRG cells, or a collagen matrix saturated with fresh medium. In all three cases cellular cables formed that ran the full length of the tubes, but myelinated and unmyelinated axons regenerated the length of the tubes only when cultured cells had been added. The critical factor in influencing axonal regeneration through the length of the tubes was the presence of cultured cells, since collagen alone or collagen saturated with conditioned medium did not support axonal regrowth even though cells had migrated into the chambers from the proximal stumps in all cases. Ordered structure was not a requisite for axonal growth, since the cultures consisted of random arrays of dissociated cells.