Comparison of biodegradable conduits within aged rat sciatic nerve defects

Background: Considering that little is known about the peripheral nerve regenerative capacity of elderly patients, the authors studied nerve regenerative capacity in aged rats and compared the effect of three synthetic nerve guides with different material characteristics and porosity. The authors hypothesized that the use of a biodegradable composite nerve guide (CultiGuides) would promote nerve regeneration and functional recovery in a manner similar to treatment with autografts or U.S. Food and Drug Administration-approved polyglycolic acid Neurotubes in an aged rat sciatic nerve defect model. Methods: Aged Sprague-Dawley rats (11 months old) underwent a I-cm sciatic nerve resection in the right leg [group 1, control (contralateral leg samples), n = 10; group 2, negative (nerve gap defect), n = 6; group 3, autograft, n = 10; group 4, polycaprolactone, n = 10; group 5, CultiGuides, n = 10; and group 6, Neurotube, n = 10]. Results: After 12 weeks, the negative group did not demonstrate any nerve regeneration. In the regenerated and distal nerve, all treated groups had increased myelinated areas compared with the negative control. In the regenerated nerve, there was a significant increase in myelination in the Neurotube group compared with the polycaprolactone group (p < 0.001). However, in the distal nerve, there were no differences among the treatment groups. Walking track analyses and gastrocnemius muscle weight ratios were not different among treatment groups 3 through 6. Conclusions: The results showed differences in myelination; Neurotubes promoted the highest degree of myelination (p < 0.001) as compared with all groups. The authors found no improvement in function of the repaired nerve as measured by percentage of autotomy, the sciatic function index, and gastrocnemius muscle weight. No group was able to recover function in this aged model.