PURPOSE:
Reconstruction of peripheral nerves when a gap exists remains a difficult problem. The current standard of care for repairing defects in peripheral nerves involves the use of autologous nerve grafts. However the use of nerve grafts is associated with donor site morbidity, limited availability, and suboptimal clinical efficacy.
Synthetic nerve conduits have been proposed to reconstruct defects in peripheral nerves. Limitations using such conduits include mechanical compression of regenerating axons, inflammatory reactions, and impairment of vascular in-growth. To overcome these obstacles we have assessed the efficacy of electrospun tissue engineered polymer conduits in a rat sciatic nerve model.
METHODS:
In this study, using a rat sciatic nerve model, electrospun polymer conduits were inserted to span gaps of 10 mm. Two experimental groups of rats (n=6) each, had nerve regeneration assessed at 1 and 3 months. A control group (n=3) had reverse nerve grafts inserted and assessed at the same time periods. The sciatic nerve was exposed through a posterior gluteal muscle splitting incision and transected at the mid thigh level using straight micro dissecting scissors. A 1 cm segment was removed and guides were implanted in the gap with two 10’0 nylon sutures, inserting the proximal and distal nerve stumps into the guides. The muscle wound was sutured with 3’0 chromic sutures and skin was closed with 4’0 Dexon subcuticular closure.
After harvest and fixation, nerve regeneration was assessed by histology to determine quantitative axon counts, electrophysiology, and walking track analysis.
RESULTS:
Quantitative axon analysis revealed that both at 1 and 3 months the total number of axons were equivalent in both groups. At 3 months there were statistically significant increases in the number of unmyelinated axons in the experimental group (p=0.014). Functional analysis assessed by walking tack analysis, showed no statistical significance at 1 month but slight improvement in controls at 3 months. Electrophysiological analysis revealed no difference between groups 1 and 3 in amplitude or velocity. Vascular in growth was found to be excellent in both types of conduits, and was not statistically significant between the 2 groups
CONCLUSION:
Electrospun polymer conduits demonstrated equivalence to nerve grafts in this model, and may enhance unmyelinated axon regeneration compared to controls. These polymer conduits permitted the same degree of vascular in-growth as nerve grafts, and did not elicit an inflammatory response.
In conclusion, electrospun polymer conduits were equal and possibly superior to nerve grafts without the disadvantage of donor site morbidity.