Fabrication of GDNF-Gel/HA-Mg nerve conduit and its role in repairing peripheral nerve defects.

BACKGROUND

Magnesium (Mg) and its alloys are receiving increasing attention in peripheral nerve regeneration, but they were limited due to the low corrosion resistance and rapid degradation. In this study, GDNF-Gel/HA-Mg was prepared and its value in peripheral nerve defects repairment was explored both and .

METHODS

A hydroxyapatite (HA) coating was first applied to the pure Mg surface, followed by the formation of gelatin methacrylate (GelMA) loaded with glial cell-derived neurotrophic factor (GDNF) on the HA-coated Mg surface. GDNF-Gel/HA-Mg corrosion resistance was explored. The effect of GDNF-Gel/HA-Mg conduit on Schwann cell proliferation and migration abilities were investigated. And sciatic nerve defects models were established to explored the role of GDNF-Gel/HA-Mg conduit in peripheral nerve defects repairment.

FINDINGS

The electrochemical, immersion, and hydrogen evolution experiments indicated that the corrosion resistance in phosphate buffer saline (PBS) of pure Mg was significantly improved by the GDNF-Gel/HA coating. Cell cycle, Cell Count Kit-8 (CCK-8), and clone formation assays indicated that GDNF-Gel/HA-Mg promoted the proliferation of Schwann cells. Scratch and Transwell assay results demonstrated that GDNF-Gel/HA-Mg promoted Schwann cell migration ability dose-dependently. GDNF-Gel/HA-Mg was found to enhance the secretion of nerve growth factor (NGF) and the expression of p75. Flow cytometry results showed that GDNF-Gel/HA-Mg could reduce HO-induced oxidative stress and Schwann cell apoptosis. GDNF-Gel/HA-Mg inhibited M1 macrophage polarization while facilitated M2 macrophage polarization in a concentration-dependent manner. The studies demonstrated that GDNF-Gel/HA-Mg conduit could significantly promote the regeneration and myelination of sciatic nerve, as well as the recovery of denervated gastrocnemius atrophy.

INTERPRETATION

The GDNF-Gel/HA-Mg conduit prepared in this study exhibited good hydrophilicity and corrosion resistance and greatly enhanced the proliferation, migration, and invasion abilities of Schwann cells, as well as peripheral nerve regeneration.