Relevance and Recent Developments of Chitosan in Peripheral Nerve Surgery

Abstract

Developments in tissue engineering yield biomaterials with different supporting strategies to promote nerve regeneration. One promising material is the naturally occurring chitin derivate chitosan. Chitosan has become increasingly important in various tissue engineering approaches for peripheral nerve reconstruction, as it has demonstrated its potential to interact with regeneration associated cells and the neural microenvironment, leading to improved axonal regeneration and less neuroma formation. Moreover, the physiological properties of its polysaccharide structure provide safe biodegradation behavior in the absence of negative side effects or toxic metabolites. Beneficial interactions with Schwann cells (SC), inducing differentiation of mesenchymal stromal cells to SC-like cells or creating supportive conditions during axonal recovery are only a small part of the effects of chitosan. As a result, an extensive body of literature addresses a variety of experimental strategies for the different types of nerve lesions. The different concepts include chitosan nanofibers, hydrogels, hollow nerve tubes, nerve conduits with an inner chitosan layer as well as hybrid architectures containing collagen or polyglycolic acid nerve conduits. Furthermore, various cell seeding concepts have been introduced in the preclinical setting. First translational concepts with hollow tubes following nerve surgery already transferred the promising experimental approach into clinical practice. However, conclusive analyses of the available data and the proposed impact on the recovery process following nerve surgery are currently lacking. This review aims to give an overview on the physiologic properties of chitosan, to evaluate its effect on peripheral nerve regeneration and discuss the future translation into clinical practice.

Keywords: chitosan; microsurgery; nerve growth factors; nerve reconstruction; nerve regeneration; nerve surgery; peripheral nerve injuries.

FIGURE 1

Chemical structure of Chitin and Chitosan. The chemical structure of Chitin based on a linear homopolymer of N-acetyl-D-glucosamine units (A). After partial deacetylation chitin becomes chitosan mainly used in peripheral nerve surgery (B).

FIGURE 2

Translational Concepts in daily clinical practice. Chitosan nerve tube protects the epineural nerve coaptation (A). Magnification of the chitosan-based nerve tube for covering the epineural suture of the third proper palmar digital (B). Protection of the epineural nerve coaptation by a chitosan-based nerve tube in a model (C). (A,B) has been taken during clinical routine care.