Multilayered spraying and gradient dotting of nanodiamond–polycaprolactone guidance channels for restoration of immune homeostasis

Abstract

AbstractThe major problem in peripheral nerve repair is restoration of the microenvironment rather than traditional structural reconstruction. Nanodiamonds (NDs), highly biocompatible carbon nanoparticles, are widely applied in medical engineering. They may alleviate inflammatory insults in peripheral nerve injury because they can induce macrophage polarization from a proinflammatory to an anti-inflammatory state. Here we report a concentric multilayered spraying manufacturing process to fabricate microporous ND/polycaprolactone (PCL) nerve bridges. We investigated the proliferative, adhesive, and glioprotective role of these bridges in Schwann cells in vitro. We further evaluated their long-term in vivo performance in a 20-mm sciatic nerve defect rat model. ND/PCL nerve bridges are comparable to autografts in functional, electrophysiological, and morphological sciatic nerve repair. They ameliorate the immune milieu by inducing M1 to M2 macrophage polarization. In addition, they pose no harm to major organs after 4 months of implantation. These findings show the promising roles of ND-based nanotechnology in neuroengineering.Biomaterials: Bridging the gap in damaged nervesA method for spray-manufacturing implants that could aid the repair of damaged nerves has been developed by researchers in China. Peripheral nerves link the brain and spinal cord to the rest of the body but are easily damaged. Cunyi Fan and Wei-En Yuan from the Shanghai Jiao Tong University and colleagues created structures that could serve as a scaffold that enables new nerve cells to regrow around, or bridge, any defect. They sprayed multilayers of a combination of nanodiamond and a biodegradable polyester onto a tubular mold. Nanodiamond is widely used in medical engineering because of its biocompatibility. The team observed the successful proliferation of Schwann cells, cells that support and protect nerve cells, in their nanodiamond scaffold in culture. They also demonstrated its effectiveness in bridging a 20-mm sciatic nerve defect in a rat model.Schematic introduction of nanodiamond/polycaprolactone nerve bridge manufacturing process and in vivo performance. The nanodiamond incorporated into concentrical triple-layered structure provided appropriate elasticity and receptivity. In addition, this scaffold regenerated peripheral nerves and induced macrophage polarization in vivo.\n