The Artificial Nerve Graft: A Comparison of Blended Elastomer-Hydrogel with Polyglycolic Acid Conduits

Abstract

A study was undertaken to compare the regeneration of rat peroneal nerves across a 0.5-cm gap repaired with either a permanent, porous or a resorbable, non-porous artificial nerve graft. The resorbable, impermeable artificial nerve graft was a synthetic passive conduit made from polyglycolic acid (PGA). The permanent, porous artificial nerve graft conduit was manufactured from a hydrophilic elastomeric biopolymer (HEB), and four variations were tested. Qualitative histology on short-term animals revealed similar inflammatory reactions to HEB and PGA. Axonal regeneration was evaluated in longer-term animals after three, four, and six months by qualitative and quantitative histology. Qualitative histology on longer-term animals demonstrated both artificial nerve grafts to be anti-immunogenic. All PGA-artificial nerve graft repairs among three-, four-, and six-month rats contained myelinated axons, as did all HEB-1 repairs. However, three other HEB-graft varieties accounted for a 25 percent failed regeneration rate. Quantitative histologic comparison of repair-site cross-sections in viable PGA and HEB matched pairs demonstrated statistically equivalent myelinated axon counts but larger average myelinated fiber diameters in HEB repairs, with p = .001.