Blood vessels: the pathway used by Schwann cells to colonize nerve conduits

The repair of severe nerve injuries requires an autograft or conduit to bridge the gap and avoid axon dispersion. Several conduits are used routinely, but their effectiveness is comparable to that of the autograft only for short gaps. Understanding nerve regeneration within short con-duits could help improve their efficacy for longer gaps. Since Schwann cells are known to mi-grate on endothelial cells to colonize a nerve bridge - the new tissue spontaneously formed to connect the injured nerve stumps – here we aimed to investigate whether this migratory mecha-nism drive Schwann cells also to proceed within the nerve conduits used to repair large nerve gaps. Injured median nerves of adult female rat were repaired with 10mm chitosan conduits and the regenerated nerves within conduits were analysed at different time points by confocal im-aging of sequential thick sections. Our data show that endothelial cells form a dense capillary network used by Schwann cells to migrate from the two nerve stumps into the conduit. We con-clude that angiogenesis plays a key role in nerve conduits, not only by supporting cell survival, but also by providing a pathway for the migration of newly formed Schwann cells.