Nanobiotechnology is an emerging field that has recently been explored for peripheral neural regeneration (PNR). Being a public-health problem, peripheral nerve injuries (PNIs) should be treated by the therapiesthat ensure swift functional recovery. The autologous nerve grafts (standard treatment for PNIs) are rarely available and also cause morbidity and neuroma formation at the harvest site, hence an alternative approach with minimum complications is required for the treatment of serious PNIs. Although nerve guidance conduits (NGCs) provide microenvironment for axonal regeneration but they are as yet imperfect solutions. Nanoparticles (e.g., metallic and metallic oxide nanoparticles) have properties which are interesting to include in biomaterials developed for peripheral nervous system regeneration including potential theranostic function. It is important to get an insight into the fundamental mechanisms of reconstruction of peripheral nerves for clinical translation of pre-clinical outcomes of the use of nanoparticles in PNR. Moreover, the combination of nanotechnological strategies is expected to provide transition from bed to bench-side and beyond to the patients, clinicians, and researchers.
- Article type
Clinical repair of a nerve defect is one of the most challenging surgical problems. Autologous nerve grafting remains the gold standard treatment in addressing peripheral nerve injuries that cannot be bridged by direct epineural suturing. However, the autologous nerve graft is not readily available, and the process of harvesting autologous nerve graft results in several complications. Thus, it is necessary to explore an alternative to autologous nerve graft. In the last few decades, with significant advances in the life sciences and biotechnology, a lot of artificial nerve grafts have been developed to aim at the treatment of peripheral nerve disruptions. Artificial nerve grafts range from biological tubes to synthetic tubes and from nondegradable tubes to degradable tubes. Among them, acellular nerve allografts and artificial nerve repair conduits are two kinds of the most promising substitutes for nerve autografts. The history, research status, and prospect of acellular nerve allografts and artificial nerve repair conduits are described briefly in this review.
The reconstruction after peripheral nerve damage, especially for long-segment nerve defects, remains a clinical challenge. Autologous nerve graft transplantation is an efficient method for the repair of peripheral nerve defects, but the involved complications and shortcomings have greatly limited the clinical efficacy of treatments offered to patients with nerve defects. Thus, there is an urgent need to develop new therapeutic strategies and explore alternatives to autologous nerve transplantation in clinical practice, based on the knowledge of the peripheral nerve regeneration mechanism and biological histocompatibility principles. With significant advances in the research and application of nerve conduits, they have been used to repair peripheral nerve injury for several decades. In this paper, the study background of nerve conduits, their applications in clinic, status of conduit material research and construction of tissue-engineered artificial nerves were reviewed.
Nerve regeneration after peripheral nerve injury is a slow process with a limited degree of functional recovery, resulting in a high disability rate. Thus, accelerating the rate of nerve regeneration and improving the degree of nerve repair is a clinical challenge. This study aimed to investigate the role of growth factor gel combined with small-gap nerve anastomosis in the regeneration of sciatic nerve injury in rats. This was achieved by injecting nerve growth factor (NGF) and basic fibroblast growth factor (bFGF) gel into a silicon chamber that bridged the transection of the nerve.
In 27 randomly chosen Sprague Dawley rats, a sharp blade was used to transect the right hind leg sciatic nerve. The rats were divided into 3 groups: in groups A and B, silicon tubes containing NGF and bFGF gel or saline, respectively, were used to bridge the nerve proximal and distal ends (3-mm gap), and in group C, the nerve proximal and distal ends were directly sutured. Eight weeks after surgery, the sciatic nerve function index, neural electrophysiology, and muscle wet weight as well as histological, ultrastructural, and immunohistochemical parameters were evaluated.
The sciatic nerve function index, nerve conduction velocity, muscle wet weight, density of regenerated nerve fibers, and myelination in group A were better than those in group B or C, but the sciatic nerve function index, muscle wet weight, and thickness of myelination in the 3 groups were not significantly different (P > 0.05). There were no significant differences innerve conduction velocity between groups A and B (P > 0.05), but it was higher in both groups than that of group C (P < 0.05). The regenerated nerve fiber density in the 3 groups showed significant differences (P < 0.05).
Small-gap nerve anastomosis can provide a good regenerative microenvironment for rat sciatic nerve regeneration, and the combined strategy of growth factor gel with small-gap nerve anastomosis appears to have a superior effect on nerve repair.