Chitosan nanofibers as scaffolds for peripheral nerve regeneration

Damage to the Peripheral Nervous System (PNS) is remarkably common and occurs mainly from trauma or a complication of surgery [1]. Although recovery of nerve function occurs in some mild injuries, outcomes are frequently poor following severe trauma, resulting in long-term impairment of limb function, dysaesthesia and pain, often with associated psychological effects [2]. In contrast to the central nervous system, the PNS includes an intrinsic capacity to regenerate. Currently, the gold standard autograft repair of the damaged peripheral nerve is far from optimal and is often disappointing. The alternative to the use of grafts is the use of a scaffold that consists in an artificial nerve guide, namely a hollow tube, combined with engineered biomaterials filling its interior in order to provide topographical cues as it has been postulated that axon elongation requires guidance by contact with appropriate substrates. In the scope of the Biohybrid project, chitosan (CS) powders from Altakitin were supplied and its cytotoxicity was assessed. According to cell viability percentage, no cytotoxicity was observed. Using these biomedical grade powders, biodegradable scaffolds were developed to support neuronal regeneration using the electrospinning technique to produce nanofibers from chitosan solutions. Random and aligned nanofibers were produced and characterized, using techniques such as FTIR, SEM, AFM, DSC and contact angle. To produce a mesh of random chitosan fibers with no beads or other defects, a 5% chitosan solution in trifluoroacetic-acid and dicloromethane as solvents, in the proportion of 70:30 was used. They are super hydrophilic, defect-free and have an average diameter of 184±36nm. Yarns of aligned chitosan fibers were obtained using the two blades placed in line set up, with the exact same conditions used to obtain random nanofibers. In vitro tests to characterize L929 cells viability (MTS assay) and proliferation (DNA quantification) on nanofibers scaffold were performed.