Chitosan Films with varying Degrees of Acetylation for application in Peripheral Nerve Regeneration

Damage to the Peripheral Nervous System (PNS) is remarkably common and occurs mainly as a result from trauma or complications 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]. As consequence, this issue has been raising major concerns in regenerative medicine for several years as unsatisfactory recovery continues to be a significant clinical challenge [3]

Chitosan, because of its good biocompatibility and physicochemical properties has been proposed as a biomaterial for tackling peripheral nerve injuries [4]. The Degree of Acetylation (DA) is a key parameter that can be controlled and has a major impact on material properties [5, 6]. According to the literature, decreasing DA leads to greater Schwann cell adhesion [6-8]. In this study, chitosan films with three low and different DAs (DA I ~ 1%; DA II ~ 2% and DA III ~ 5%) were produced from Altakitin medical grade chitosan powders. Surface and bulk properties of the films were investigated by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Contact angle and Surface Energy measurements, FTIR, X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Degradation and Water Uptake, Bioactivity and Mechanical Properties. Biological assays using a L929 cell line and Immortalized Schwann cells were also seeded on the materials in order to assess cell viability, adhesion and proliferation of these two cell types in the films. Results showed that by means of controlling DA of chitosan films it is possible to tune material characteristics, even at a molecular level which can be beneficial for adequately developing novel nerve conduits for peripheral nerve regeneration.