Pores in synthetic nerve conduits are beneficial to regeneration

Abstract

Current opinion holds that pores in synthetic nerve guides facilitate nerve regeneration. Solid factual support for this opinion, however, is absent; most of the relevant studies assessed only morphological parameters and results have been contradictory. To evaluate the effect of pores, the rat sciatic nerve was either autografted or grafted with nonporous, macroporous (10-230 mum), and microporous (1-10 microm) biodegradable epsilon-caprolactone grafts. Twelve weeks later, the grafted nerves were resected, and the electrophysiological properties were determined in vitro. Subsequently midgraft-level sections were inspected, and peroneal nerve sections were evaluated morphometrically. Finally, the gastrocnemic and tibial muscle morphometrical properties were quantified. The microporous nerve graft performed much better than the nonporous and macroporous grafts with respect to most parameters: it was bridged by a free floating bundle that contained myelinated nerve fibers, there were more nerve fibers present distal to the graft, the electrophysiological response rate was higher, and the decrease in muscle cross-sectional area was markedly smaller. Hence, the present study demonstrates the beneficial effect of synthetic nerve guide pores on nerve regeneration, although with the caveat that not pores per se, but only small (1-10 microm) pores were effective.

Scaffolds for Peripheral Nerve Regeneration, the Importance of In Vitro and In Vivo Studies for the Development of Cell-Based Therapies and Biomaterials: State of the Art

“…Controlling the architecture of the conduit wall is possible to develop a microporous inner layer and macroporous outer layer and obtain a bidirectional permeability [86,103]. The diameter of the pores plays a critical role in the efficiency of the scaffolds since it influences cell attachment, axon regeneration and diffusion of nutrients [183,184]. Electrospinning is a frequently used technique in bioengineering to produce imprinted micropatterns and can be used as a luminal guidance strategy.…”

Enhanced Femoral Nerve Regeneration After Tubulization with a Tyrosine-Derived Polycarbonate Terpolymer: Effects of Protein Adsorption and Independence of Conduit Porosity

“…Some reports demonstrate benefits of using porous nerve conduits, which are hypothesized to facilitate the flow of nutrients and factors that enhances cell migration and fibrin cable formation, 74,75 while others show the benefits of using nonporous conduits, which better contain the fluid and cells secreted by the nerve stumps at the injury site, in direct association with the regenerating axons. 76 However, very few studies directly compare porous to nonporous nerve conduits.…”

Design of Oriented Porous PHBV Scaffold as a Neural Guide

“…In the SEM image in Figure 3B the maximum pore size observed on the patterned film is around 2 mm, and therefore, it is smaller than the size of most neural cells. Similarly, a 1-10 mm pore size was reported in the construction of nerve guides [33]. Thus, this level of pore size on the micropatterned film would allow the nutrients to permeate, however, it would not allow the permeation of the cells forcing the cells to remain in the tube, align, and migrate along the axis of the micropatterns.…”