Multifunctional wet-adhesive chitosan/acrylic conduit for sutureless repair of peripheral nerve injuries.

The incidence of peripheral nerve injury (PNI) is high worldwide, and a poor prognosis is common. Surgical closure and repair of the affected area are crucial to ensure the effective treatment of peripheral nerve injuries. Despite being the standard treatment approach, reliance on sutures to seal the severed nerve ends introduces several limitations and restrictions. This technique is intricate and time-consuming, and the application of threading and punctate sutures may lead to tissue damage and heightened tension concentrations, thus increasing the risk of fixation failure and local inflammation. This study aimed to develop easily implantable chitosan-based peripheral nerve repair conduits that combine acrylic acid and cleavable N-hydroxysuccinimide to reduce nerve damage during repair. In ex vivo tissue adhesion tests, the conduit achieved maximal interfacial toughness of 705 J m-2 ± 30 J m-2, allowing continuous bridging of the severed nerve ends. Adhesive repair significantly reduces local inflammation caused by conventional sutures, and the positive charge of chitosan disrupts the bacterial cell wall and reduces implant-related infections. This promises to open new avenues for sutureless nerve repair and reliable medical implants.

Micron track chitosan conduit fabricated by 3D-printed model topography provides bionic microenvironment for peripheral nerve regeneration.

The micron track conduit (MTC) and nerve factor provide a physical and biological model for simulating peripheral nerve growth and have potential applications for nerve injury. However, it has rarely been reported that they synergize on peripheral nerves. In this study, we used bioderived chitosan as a substrate to design and construct a neural repair conduit with micron track topography using threedimensional (3D) printing topography. We loaded the MTC with neurotrophin-3 (NT-3) to promote the regeneration of sensory and sympathetic neurons in the peripheral nervous system. We found that the MTC@NT3 composite nerve conduit mimicked the microenvironment of peripheral nerves and promoted axonal regeneration while inducing the targeted growth of Schwann cells, which would promote functional recovery in rats with peripheral nerve injury. Artificial nerve implants with functional properties can be developed using the strategy presented in this study.

Polydopamine-modified chitin conduits with sustained release of bioactive peptides enhance peripheral nerve regeneration in rats.

The introduction of neurotrophic factors into injured peripheral nerve sites is beneficial to peripheral nerve regeneration. However, neurotrophic factors are rapidly degraded in vivo and obstruct axonal regeneration when used at a supraphysiological dose, which limits their clinical benefits. Bioactive mimetic peptides have been developed to be used in place of neurotrophic factors because they have a similar mode of action to the original growth factors and can activate the equivalent receptors but have simplified sequences and structures. In this study, we created polydopamine-modified chitin conduits loaded with brain-derived neurotrophic factor mimetic peptides and vascular endothelial growth factor mimetic peptides (Chi/PDA-Ps). We found that the Chi/PDA-Ps conduits were less cytotoxic in vitro than chitin conduits alone and provided sustained release of functional peptides. In this study, we evaluated the biocompatibility of the Chi/PDA-Ps conduits. Brain-derived neurotrophic factor mimetic peptide and vascular endothelial growth factor mimetic peptide synergistically promoted proliferation of Schwann cells and secretion of neurotrophic factors by Schwann cells and attachment and migration of endothelial cells in vitro. The Chi/PDA-Ps conduits were used to bridge a 2 mm gap between the nerve stumps in rat models of sciatic nerve injury. We found that the application of Chi/PDA-Ps conduits could improve the motor function of rats and reduce gastrocnemius atrophy. The electrophysiological results and the microstructure of regenerative nerves showed that the nerve conduction function and remyelination was further restored. These findings suggest that the Chi/PDA-Ps conduits have great potential in peripheral nerve injury repair.