The effects of picric acid (2,4,6-trinitrophenol) and a bite-deterrent chemical (denatonium benzoate) on autotomy in rats after peripheral nerve lesion

Electrical stimulation enhances sciatic nerve regeneration using a silk-based conductive scaffold beyond traditional nerve guide conduits

Despite recent advancements in peripheral nerve regeneration, the creation of nerve conduits with chemical and physical cues to enhance glial cell function and support axonal growth remains challenging. This study aimed to assess the impact of electrical stimulation (ES) using a conductive nerve conduit on sciatic nerve regeneration in a rat model with transection injury. The study involved the fabrication of conductive nerve conduits using silk fibroin and Au nanoparticles (AuNPs). Collagen hydrogel loaded with green fluorescent protein (GFP)-positive adipose-derived mesenchymal stem cells (ADSCs) served as the filling for the conduit. Both conductive and non-conductive conduits were applied with and without ES in rat models. Locomotor recovery was assessed using walking track analysis. Histological evaluations were performed using H&E, luxol fast blue staining and immunohistochemistry. Moreover, TEM analysis was conducted to distinguish various ultrastructural aspects of sciatic tissue. In the ES + conductive conduit group, higher S100 (p < 0.0001) and neurofilament (p < 0.001) expression was seen after 6 weeks. Ultrastructural evaluations showed that conductive scaffolds with ES minimized Wallerian degeneration. Furthermore, the conductive conduit with ES group demonstrated significantly increased myelin sheet thickness and decreased G. ratio compared to the autograft. Immunofluorescent images confirmed the presence of GFP-positive ADSCs by the 6th week. Locomotor recovery assessments revealed improved function in the conductive conduit with ES group compared to the control group and groups without ES. These results show that a Silk/AuNPs conduit filled with ADSC-seeded collagen hydrogel can function as a nerve conduit, aiding in the restoration of substantial gaps in the sciatic nerve with ES. Histological and locomotor evaluations indicated that ES had a greater impact on functional recovery compared to using a conductive conduit alone, although the use of conductive conduits did enhance the effects of ES.

Chitin scaffold combined with autologous small nerve repairs sciatic nerve defects

Although autologous nerve transplantation is the gold standard for treating peripheral nerve defects, it has many clinical limitations. As an alternative, various tissue-engineered nerve grafts have been developed to substitute for autologous nerves. In this study, a novel nerve graft composed of chitin scaffolds and a small autologous nerve was used to repair sciatic nerve defects in rats. The novel nerve graft greatly facilitated regeneration of the sciatic nerve and myelin sheath, reduced atrophy of the target muscle, and effectively restored neurological function. When the epineurium of the small autogenous nerve was removed, the degree of nerve regeneration was similar to that which occurs after autogenous nerve transplantation. These findings suggest that our novel nerve graft might eventually be a new option for the construction of tissue-engineered nerve scaffolds. The study was approved by the Research Ethics Committee of Peking University People's Hospital (approval No. 2019PHE27) on October 18, 2019.

Biopolymer-nanotube nerve guidance conduit drug delivery for peripheral nerve regeneration: In vivo structural and functional assessment

Peripheral nerve injuries account for roughly 3% of all trauma patients with over 900,000 repair procedures annually in the US. Of all extremity peripheral nerve injuries, 51% require nerve repair with a transected gap. The current gold-standard treatment for peripheral nerve injuries, autograft repair, has several shortcomings. Engineered constructs are currently only suitable for short gaps or small diameter nerves. Here, we investigate novel nerve guidance conduits with aligned microchannel porosity that deliver sustained-release of neurogenic 4-aminopyridine (4-AP) for peripheral nerve regeneration in a critical-size (15 mm) rat sciatic nerve transection model. The results of functional walking track analysis, morphometric evaluations of myelin development, and histological assessments of various markers confirmed the equivalency of our drug-conduit with autograft controls. Repaired nerves showed formation of thick myelin, presence of S100 and neurofilament markers, and promising functional recovery. The conduit's aligned microchannel architecture may play a vital role in physically guiding axons for distal target reinnervation, while the sustained release of 4-AP may increase nerve conduction, and in turn synaptic neurotransmitter release and upregulation of critical Schwann cell neurotrophic factors. Overall, our nerve construct design facilitates efficient and efficacious peripheral nerve regeneration via a drug delivery system that is feasible for clinical applications.

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Nerve guidance conduit platform with tunable scaffold properties for repair and regeneration of large-gap nerve injuries.

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Sustained 4-aminopyridine release amplifies neurotrophic factor release by Schwann cells to promote axon regeneration.

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Longitudinally aligned scaffold pores and controllable physicochemical properties provide guidance for axon regeneration.

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Critical-size rat sciatic nerve defect healing both structurally and functionally resembled autograft control treatment.

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Innovative and transformative scaffold technology imbued with structural and functional features for tissue regeneration.

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Scaffold enable tailorable release profiles for small molecules proteins and electrical stimulation for tissue regeneration.