Neurite outgrowth is directed by Schwann cell alignment in the absence of other guidance cues

Schwann cells enhance axonal regeneration following nerve injury in vivo and provide a favorable substrate for neurite outgrowth in vitro. However, much remains unknown about the nature of interactions that occur between Schwann cells and growing neurites. In this paper, we describe direct evidence of the ability of Schwann cell alignment alone to direct neurite outgrowth. Previously, we reported that laminin micropatterns can be used to align Schwann cells and thus create oriented Schwann cell monolayers. In the current study, dissociated rat spinal neurons were seeded onto oriented Schwann cell monolayers, whose alignment provided the only directional cue for growing neurites, and neurite alignment with the underlying Schwann cells was analyzed. The orientation of neurite outgrowth mimicked that of the Schwann cells. Associations observed between neurites and Schwann cells suggest that Schwann cells may guide neurite outgrowth through both topographical and molecular mechanisms. This work demonstrates that Schwann cell alignment can direct neurite outgrowth in the absence of other directional cues, and provides a new method for examining neuronal-Schwann cell interactions in vitro.