Materials for Peripheral Nerve Regeneration

Abstract

Recent efforts in scientific research in the field of peripheral nerve regeneration have been directed towards the development of artificial nerve guides. We have studied various materials with the aim of obtaining a biocompatible and biodegradable two layer guide for nerve repair. The candidate materials for use as an external layer for the nerve guides were poly(caprolactone) (PCL), a biosynthetic blend between PCL and chitosan (CS) and a synthesised poly(ester-urethane) (PU). Blending PCL, which is a biocompatible synthetic polymer, with a natural polymer enhanced the system biocompatibility and biomimetics, fastened the degradation rates and reduced the production costs. Various novel block poly(ester-urethane)s are being synthesised by our group with tailored properties for specific tissue engineering applications. One of these poly(ester-urethane)s, based on a low molecular weight poly(caprolactone) as the macrodiol, cycloesandimethanol as the chain extender and hexamethylene diisocyanate as the chain linker, was investigated for the production of melt extruded nerve guides. We studied natural polymers such as gelatin (G), poly(L-lysine) (PL) and blends between chitosan and gelatin (CS/G) as internal coatings for nerve guides. In vitro and in vivo tests were performed on PCL guides internally coated either with G or PL to determine the differences in the quality of nerve regeneration associated with the type of adhesion protein. CS/G natural blends combined the good cell adhesion properties of the protein phase with the ability to promote nerve regeneration of the polysaccharide phase. Natural blends were crosslinked both by physical and chemical crosslinking methods. In vitro neuroblast adhesion tests were performed on CS/G film samples, PCL/CS and PU guides internally coated with G to evaluate the ability of such materials towards nerve repair.

Application of conductive polymers, scaffolds and electrical stimulation for nerve tissue engineering

“…Neurodegenerative disorders of the spinal cord and brain after injury, stroke or multiple sclerosis have increased over the past few years (Prabhakaran et al, 2009). Peripheral nerve lesions are also common, with serious injuries affecting 2.8% of trauma patients annually, leading to lifelong disability (Ciardelli and Chiono, 2006). In the USA, 360 000 people suffer from upper extremity paralytic syndromes on an annual basis and approximately 253 000 people in the USA live with the after-effects of spinal cord injury.…”

“…In the USA, 360 000 people suffer from upper extremity paralytic syndromes on an annual basis and approximately 253 000 people in the USA live with the after-effects of spinal cord injury. Moreover, each year this number grows by an estimated 11 000 people in the USA (Willerth and Sakiyama-Elbert, 2007) and in Europe more than 300 000 cases of peripheral nerve injury are reported annually (Ciardelli and Chiono, 2006;Bueno and Shah, 2008).…”

Synthesis and characterization of electrospun polyvinyl alcohol nanofibrous scaffolds modified by blending with chitosan for neural tissue engineering

“…It has been shown that chitosan has quite positive effects on nerve tissue regeneration. [31][32][33] Here, we tried to modify the physicochemical and biological properties of PVA polymer by blending it with chitosan, and used electrospinning for fabrication of a neurocompatible scaffold.…”

Local Administration of Nimodipine and Improvement of Functional Recovery of the Transected Sciatic Nerve after Bridging with Inside-out Artery Graft

“…Nevertheless, these non-biodegradable tubes induce fibrous capsule formation, leading to chronic nerve compression and an inflammatory response (Merle et al, 1989). In order to avoid problems associated with non-degradable guides, recent research has been focused on the production of biodegradable nerve guides (Ciardelli and Chiono 2006). Copolymer of 50% DL-lactide and 50% _ caprolactone (Polyganics B.V.) is a biodegradable guide that is effective in supporting the outgrowth of axons and allows faster axonal regeneration and better recovery (Meek et al, 2001).…”