Protective effect of biodegradable nerve conduit against peripheral nerve adhesion after neurolysis

Abstract

OBJECTIVE Peripheral nerve adhesion caused by extraneural and intraneural scar formation after neurolysis leads to nerve dysfunction. The authors previously developed a novel very flexible biodegradable nerve conduit composed of poly(L-lactide) and poly(ε-caprolactone) for use in peripheral nerve regeneration. In the present study, they investigated the effect of protective nerve wrapping on preventing adhesion in a rat sciatic nerve adhesion model. METHODS Rat sciatic nerves were randomly assigned to one of the following four groups: a no-adhesion group, which involved neurolysis alone without an adhesion procedure; an adhesion group, in which the adhesion procedure was performed after neurolysis, but no treatment was subsequently administered; a nerve wrap group, in which the adhesion procedure was performed after neurolysis and protective nerve wrapping was then performed with the nerve conduit; and a hyaluronic acid (HA) group, in which the adhesion procedure was performed after neurolysis and nerve wrapping was then performed with a 1% sodium HA viscous solution. Six weeks postoperatively, the authors evaluated the extent of scar formation using adhesion scores and biomechanical and histological examinations and assessed nerve function with electrophysiological examination and gastrocnemius muscle weight measurement. RESULTS In the adhesion group, prominent scar tissue surrounded the nerve and strongly adhered to the nerve biomechanically and histologically. The motor nerve conduction velocity and gastrocnemius muscle weight were the lowest in this group. Conversely, the adhesion scores were significantly lower, motor nerve conduction velocity was significantly higher, and gastrocnemius muscle weight was significantly higher in the nerve wrap group than in the adhesion group. Additionally, the biomechanical breaking strength was significantly lower in the nerve wrap group than in the adhesion group and HA group. The morphological properties of axons in the nerve wrap group were preserved. Intraneural macrophage invasion, as assessed by the number of CD68- and CCR7-positive cells, was less severe in the nerve wrap group than in the adhesion group. CONCLUSIONS The nerve conduit prevented post-neurolysis peripheral nerves from developing adhesion and allowed them to maintain their nerve function because it effectively blocked scarring and prevented adhesion-related damage in the peripheral nerves.

3D melatonin nerve scaffold reduces oxidative stress and inflammation and increases autophagy in peripheral nerve regeneration

“…Traditional polymeric nerve conduits like polyglycolic acid and polycaprolactone (PCL) are widely used in clinical practice. However, they are not excellent enough for long‐range nerve defects …”

Electrospun polycaprolactone (PCL)-amnion nanofibrous membrane prevents adhesions and promotes nerve repair in a rat model of sciatic nerve compression

“…To prevent adhesion and scar formation, a variety of surgical methods have been developed, such as nerve transfer [7], fascial fat transplantation [8], venous encapsulation [9], and muscle flap transplantation [10]. However, even fine surgical techniques cannot completely rule out postoperative adhesions, and the tissues may still need to be obtained from different body parts [11]. Many natural and synthetic polymers are used to prevent adhesion, such as polyethylene films, silica gel patches [12], hyaluronic acid [13], and collagen [14].…”

Histologic and Functional Outcomes of Conduit Wrapping for Peripheral Nerve Repair: Early Results in a Rat Model

“…27 In a rat model designed to assess the use of nerve wraps to prevent adhesions, Shintani et al demonstrated improved electrophysiologic outcomes at 6 weeks when a polycaprolactone conduit was used as a nerve wrap in an intact nerve, compared with no wrap in an adhesion model. 28 However, this model did not evaluate the response to nerve transection and recovery, and therefore, is most applicable to the clinical situation of an external neurolysis and decompression. Kim et al wrapped bovine collagen around rat sciatic nerve repairs and evaluated fibrosis and nerve regeneration at 3 months.…”