Gradient galectin-1 coating technology: bionic multichannel nerve guidance conduits promote neural cell migration

Engineered nerve guidance conduits have been widely used to repair peripheral nerve injuries. Galectin-1 is an important biological cue that promotes axon regeneration and Schwann cell migration. In this study, a series of polycaprolactone-based nerve guidance conduits were prepared. First, we determined the concentration of galectin-1 (a member of the galactose lectin family) via the proliferation and morphology of Schwann cells and the viability, morphology, and axon length of PC12 cells. On this basis, nanofiber yarns coated with a uniform or unidirectionally linear gradient coating layer of galectin-1 were prepared by electrospinning to investigate the viability and migration of Schwann cells and neural stem cells on the surfaces. The unidirectional linear gradient coating with increasing galectin-1 content was found to promote the migration of both Schwann cells and neural stem cells. To construct nerve guidance conduits with encapsulated nanofiber yarns, we fabricated nerve guidance conduit walls composed of conjugately electrospun nanofiber yarns and random polycaprolactone nanofibers as the inner and outer layers. With a biocompatible light-absorbing dye, the nanofibers can be sealed via light welding to obtain a hollow polycaprolactone conduit. Finally, we prepared nerve guidance conduits containing nanofiber yarns coated with graded galectin-1 as well as hyaluronic acid methacryloyl hydrogel in the lumen. We found that the topology (nanofiber yarns and hyaluronic acid methacryloyl) and biological cues (gradient galectin-1 coating) synergistically accelerated the migration of Schwann cells and neural stem cells along multiple channels of nerve guidance conduits.