Enhanced Peripheral Nerve Regeneration by a High Surface Area to Volume Ratio of Nerve Conduits Fabricated from Hydroxyethyl Cellulose/Soy Protein Composite Sponges.

Abstract

Multichannel nerve guide conduits (MCNGCs) have been widely studied and exhibited outstanding nerve repair function. However, the effect of the geometric structure of MCNGCs on the nerve repair function was still not clear. Herein, we postulated that MCNGCs with different inner surface area-to-volume ratios (ISA/V) of the channels inside the nerve guide conduits (NGCs) would show different nerve repair functions. Therefore, in current work, we constructed a series of hydroxyethyl cellulose/soy protein sponge-based nerve conduit (HSSN) with low, medium, and high ISA/V from hydroxyethyl cellulose (HEC)/soy protein isolate (SPI) composite sponges, which were abbreviated as HSSN-L, HSSN-M and HSSN-H, respectively. These NGCs were applied to bridge and repair a 10 mm long sciatic nerve defect in a rat model. Finally, the influence of ISA/V on nerve repair function was evaluated by electrophysiological assessment, histological investigation, and in vivo biodegradability testing. The results of electrophysiological assessment and histological investigation showed that the regenerative nerve tissues bridged with HSSN-H and HSSN-M had higher compound muscle action potential amplitude ratio, higher percentage of positive NF200 and S100 staining, larger axon diameter, lower G-ratio, and greater myelination thickness. Furthermore, the regenerative nerve tissues bridged with HSSN-H also showed higher density of regenerated myelinated nerve fibers and more number of myelin sheath layers. On the whole, the repair efficiency of the peripheral nerve in HSSN-H and HSSN-M groups might be better than that in HSSN-L. These results indicated that higher ISA/V based on HEC/SPI composite sponge may result in greater nerve repair functions. The conclusion provided a probable guiding principle for the structural designs of NGCs in the future.