Hydroxyapatite coated magnesium alloy for peripheral nerve regeneration

Abstract

Magnesium (Mg) has been used as a neuroprotective agent and for orthopedic and cardiovascular stent applications for a long time. Mg is a promising material for neural regeneration own to its metallic nature, biodegradability, and biocompatibility. To evaluate the benefit of hydroxyapatite (HA) coated Mg alloy (WE43) nerve conduit in peripheral nerve injury regeneration. In vitro cell adhesion and proliferation of PC12 cells and Schwann cells over pure Mg, WE43, HA coated pure Mg (HA-Mg), and HA coated WE43 (HA-WE43) disks were assessed using scanning electron microscope and EZ-CYTOX assay. In vivo study was also performed for sham, silicone nerve conduits, and HA-WE43 nerve conduits to evaluate rat sciatic nerve regeneration over 10 mm gap. These rats were observed for three months with weekly functional assessment using sciatic functional index. Regeneration was evaluated through retrograde neuron labeling and histomorphometric analysis at the end of the experiment. Non-coated pure Mg and WE43 conduits showed fast resorption rate and high gas formation. Higher adhesion and proliferation of PC12 cells were found in HA-WE43 disks. At the end of three months, HA-WE43 nerve conduit showed mild resorption without detectable gas formation in the surrounding tissue. However, only scanty regenerated neural tissue was found within the conduit. HA-WE43 nerve conduit showed controlled degradation and absence of gas formation with scanty regenerated neural tissue.