The Role of Magnesium Biodegradable Material in Peripheral Nerve Repair

Abstract

Peripheral nerve injuries can greatly diminish a patient’s quality of life. The use of permanent metallic material implants, including stainless steel, introduce a toxicity risk, due to release of allergenic particles upon chronic use, The significant difference in hardness versus bodily tissues is also unsatisfactory for long‐time placement. Biodegradable biomaterial scaffolds are an innovative alternative therapeutic methodology to enhance tissue repair. Magnesium is a biodegradable metal which has received significant interest recently because it is both closer in hardness to tissues and it biodegrades safely, releasing Mg ions, playing many beneficial roles in the human body. Mg ions regulate ion channel opening, DNA replication, protein synthesis and are a crucial cofactor for >300 enzymes. Serum deficiencies of Mg result in general inflammation and are implicated in disorders such as Parkinson’s and Alzheimer’s diseases. Thus, Mg metal biodegradable implants have great promise as a new generation of tissue repair materials. In vivo studies in the Pixley lab have shown that peripheral nerve axons regenerating across an injury gap, react positively to the presence of the Mg, including giving indications that they may be drawn towards the magnesium wire within the tissue. The long term goal is to understand cellular reactions to magnesium (Mg) metal, which will aid the development of a clinical application in peripheral nerve repair.ObjectivesToward investigating the underlying cellular mechanisms, this study sought to 1) design in vitro cell culture systems to determine the effects of selected types of Mg metal wires being tested for use in clinical practice. Then, 2) we sought to determine the in vitro responses to Mg metal by two cell types that are important in peripheral nerve repair: Schwann cells and the class of immune cells, macrophages, that are the first to attach to any implant material and that also play a large role in nerve repair.Materials and MethodsCellular interactions with the selected Mg wires were studied in vitro using immunostaining and phagocytosis assays. The cells analyzed were mouse Schwannoma cells (RT4‐D6P2T) and a mouse macrophage cell line (RAW264.7).ResultsSchwannoma cells showed aggregates around the edge of the immobilized Mg wires, though, no significant migration towards/away from Mg wires, but macrophages appear to react to the Mg wires. The research is continuing to determine the mechanism of cellular interactions with the Mg metal, and whether these interactions would influence the quality of the peripheral nerve repair.Support or Funding InformationFunding was provided by the NSF ERC RMB EEC‐0812348