RESUMO
The peripheral nervous system consists of ganglia, nerve trunks, plexuses, and nerve endings, that transmit afferent and efferent information. Regeneration after a peripheral nerve damage is sluggish and imperfect. Peripheral nerve injury frequently causes partial or complete loss of motor and sensory function, physical impairment, and neuropathic pain, all of which have a negative impact on patients' quality of life. Because the mechanism of peripheral nerve injury and healing is still unclear, the therapeutic efficacy is limited. As peripheral nerve injury research has processed, an increasing number of studies have revealed that biological scaffolds work in tandem with progenitor cells to repair peripheral nerve injury. Here, we fabricated collagen chitosan nerve conduit bioscaffolds together with collagen and then filled neuroepithelial stem cells (NESCs). Scanning electron microscopy showed that the NESCs grew well on the scaffold surface. Compared to the control group, the NESCs group contained more cells with bigger diameters and myelinated structures around the axons. Our findings indicated that a combination of chitosan-collagen bioscaffold and neural stem cell transplantation can facilitate the functional restoration of peripheral nerve tissue, with promising future applications and research implications.
Assuntos
Quitosana , Colágeno , Regeneração Nervosa , Traumatismos dos Nervos Periféricos , Alicerces Teciduais , Quitosana/química , Regeneração Nervosa/fisiologia , Colágeno/química , Animais , Alicerces Teciduais/química , Traumatismos dos Nervos Periféricos/terapia , Ratos , Células Neuroepiteliais/citologia , Células-Tronco Neurais/citologia , Nervos Periféricos/fisiologia , Nervo Isquiático/fisiologiaRESUMO
The development of biomaterials such as synthetic scaffolds for peripheral nerve regeneration requires a precise knowledge of the mechanical properties of the nerve in physiological-like conditions. Mechanical properties (Young's modulus, maximum stress and strain at break) for peripheral nerves are scarce and large discrepancies are observed in between reports. This is due in part to the absence of a robust testing device for nerves. To overcome this limitation, a custom-made tensile device (CMTD) has been built. To evaluate its reproducibility and accuracy, the imposed speed and distance over measured speed and distance was performed, followed by a validation using poly(dimethylsiloxane) (PDMS), a commercial polymer with established mechanical properties. Finally, the mechanical characterization of rodents (mice and rats) sciatic nerves using the CMTD was performed. Mouse and rat sciatic nerves Young's modulus were 4.57 ± 2.04 and 19.2 ± 0.86 MPa respectively. Maximum stress was 1.26 ± 0.56 MPa for mice and 3.81 ± 1.84 MPa for rats. Strain at break was 53 ± 17% for mice and 32 ± 12% for rats. The number of axons per sciatic nerve was found to be twice higher for rats. Statistical analysis of the measured mechanical properties revealed no sex-related trends, for both mice and rats (except for mouse maximum stress with p=0.03). Histological evaluation of rat sciatic nerve corroborated these findings. By developing a robust CMTD to establish the key mechanical properties (Young's modulus, maximum stress and strain at break) values for rodents sciatic nerves, our work represent an essential step toward the development of better synthetic scaffolds for peripheral nerve regeneration.
Assuntos
Teste de Materiais , Nervo Isquiático , Resistência à Tração , Animais , Nervo Isquiático/fisiologia , Camundongos , Ratos , Masculino , Feminino , Fenômenos Biomecânicos , Módulo de Elasticidade , Estresse Mecânico , Dimetilpolisiloxanos/química , Ratos Sprague-Dawley , Fenômenos MecânicosRESUMO
The low electrical conductivity of conductive hydrogels limits their applications as soft conductors in bioelectronics. This low conductivity originates from the high water content of hydrogels, which impedes facile carrier transport between conductive fillers. This study presents a highly conductive and stretchable hydrogel nanocomposite comprising whiskered gold nanosheets. A dry network of whiskered gold nanosheets is fabricated and then incorporated into the wet hydrogel matrices. The whiskered gold nanosheets preserve their tight interconnection in hydrogels despite the high water content, providing a high-quality percolation network even under stretched states. Regardless of the type of hydrogel matrix, the gold-hydrogel nanocomposites exhibit a conductivity of ≈520 S cm-1 and a stretchability of ≈300% without requiring a dehydration process. The conductivity reaches a maximum of ≈3304 S cm-1 when the density of the dry gold network is controlled. A gold-adhesive hydrogel nanocomposite, which can achieve conformal adhesion to moving organ surfaces, is fabricated for bioelectronics demonstrations. The adhesive hydrogel electrode outperforms elastomer-based electrodes in in vivo epicardial electrogram recording, epicardial pacing, and sciatic nerve stimulation.
Assuntos
Condutividade Elétrica , Ouro , Hidrogéis , Nanocompostos , Ouro/química , Nanocompostos/química , Hidrogéis/química , Eletrodos , Animais , Nanopartículas Metálicas/química , Nervo Isquiático/fisiologiaRESUMO
The rat sciatic nerve model is commonly used to test novel therapies for nerve injury repair. The static sciatic index (SSI) is a useful metric for quantifying functional recovery, and involves comparing an operated paw versus a control paw using a weighted ratio between the toe spread and the internal toe spread. To calculate it, rats are placed in a transparent box, photos are taken from underneath and the toe distances measured manually. This is labour intensive and subject to human error due to the challenge of consistently taking photos, identifying digits and making manual measurements. Although several commercial kits have been developed to address this challenge, they have seen little dissemination due to cost. Here we develop a novel algorithm for automatic measurement of SSI metrics based on video data using casted U-Nets. The algorithm consists of three U-Nets, one to segment the hind paws and two for the two pairs of digits which input into the SSI calculation. A training intersection over union error of 60 % and 80 % was achieved for the back paws and for both digit segmentation U-Nets, respectfully. The algorithm was tested against video data from three separate experiments. Compared to manual measurements, the algorithm provides the same profile of recovery for every experiment but with a tighter standard deviation in the SSI measure. Through the open-source release of this algorithm, we aim to provide an inexpensive tool to more reliably quantify functional recovery metrics to the nerve repair research community.
Assuntos
Algoritmos , Modelos Animais de Doenças , Traumatismos dos Nervos Periféricos , Animais , Ratos , Traumatismos dos Nervos Periféricos/fisiopatologia , Simulação por Computador , Nervo Isquiático/fisiologia , Nervo Isquiático/lesões , Ratos Sprague-DawleyRESUMO
The therapeutic benefits of photobiomodulation (PBM) in pain management, although well documented, are accompanied by concerns about potential risks, including pain, particularly at higher laser intensities. This study investigated the effects of laser intensity on pain perception using behavioral and electrophysiological evaluations in rats. Our results show that direct laser irradiation of 1000 mW/cm2 to the sciatic nerve transiently increases the frequency of spontaneous firing in the superficial layer without affecting the deep layer of the spinal dorsal horn, and this effect reverses to pre-irradiation levels after irradiation. Interestingly, laser irradiation at 1000 mW/cm2, which led to an increase in spontaneous firing, did not prompt escape behavior. Furthermore, a significant reduction in the time to initiate escape behavior was observed only at 9500 mW/cm2 compared to 15, 510, 1000, and 4300 mW/cm2. This suggests that 1000 mW/cm2, the laser intensity at which an increase in spontaneous firing was observed, corresponds to a stimulus that did not cause pain. It is expected that a detailed understanding of the risks and mechanisms of PBM from a neurophysiological perspective will lead to safer and more effective use of PBM.
Assuntos
Terapia com Luz de Baixa Intensidade , Ratos Sprague-Dawley , Corno Dorsal da Medula Espinal , Animais , Terapia com Luz de Baixa Intensidade/métodos , Masculino , Ratos , Corno Dorsal da Medula Espinal/efeitos da radiação , Nervo Isquiático/efeitos da radiação , Nervo Isquiático/fisiologia , Potenciais de Ação/efeitos da radiaçãoRESUMO
Peripheral nerve injury (PNI) poses a significant public health issue, often leading to muscle atrophy and persistent neuropathic pain, which can drastically impact the quality of life for patients. Electrical stimulation represents an effective and non-pharmacological treatment to promote nerve regeneration. Yet, the postoperative application of electrical stimulation remains a challenge. Here, we propose a fully biodegradable, self-powered nerve guidance conduit (NGC) based on dissolvable zinc-molybdenum batteries. The conduit can offer topographic guidance for nerve regeneration and deliver sustained electrical cues between both ends of a transected nerve stump, extending beyond the surgical window. Schwann cell proliferation and adenosine triphosphate (ATP) production are enhanced by the introduction of the zinc-molybdenum batteries. In rodent models with 10-mm sciatic nerve damage, the device effectively enhances nerve regeneration and motor function recovery. This study offers innovative strategies for creating biodegradable and electroactive devices that hold important promise to optimize therapeutic outcomes for nerve regeneration.
Assuntos
Regeneração Nervosa , Traumatismos dos Nervos Periféricos , Nervo Isquiático , Zinco , Animais , Traumatismos dos Nervos Periféricos/terapia , Zinco/química , Nervo Isquiático/fisiologia , Nervo Isquiático/lesões , Ratos , Fontes de Energia Elétrica , Molibdênio/química , Células de Schwann , Ratos Sprague-Dawley , Humanos , Regeneração Tecidual Guiada/instrumentação , Regeneração Tecidual Guiada/métodos , Técnicas Biossensoriais , Implantes AbsorvíveisRESUMO
Photochemical sealing of a nerve wrap over the repair site isolates and optimizes the regenerating nerve microenvironment. To facilitate clinical adoption of the technology, we investigated photosealed autologous tissue in a rodent sciatic nerve transection and repair model. Rats underwent transection of the sciatic nerve with repair performed in three groups: standard microsurgical neurorrhaphy (SN) and photochemical sealing with a crosslinked human amnion (xHAM) or autologous vein. Functional recovery was assessed at four-week intervals using footprint analysis. Gastrocnemius muscle mass preservation, histology, and nerve histomorphometry were evaluated at 120 days. Nerves treated with a PTB-sealed autologous vein improved functional recovery at 120 days although the comparison between groups was not significantly different (SN: -58.4 +/- 10.9; XHAM: -57.9 +/- 8.7; Vein: -52.4 +/- 17.1). Good muscle mass preservation was observed in all groups, with no statistical differences between groups (SN: 69 +/- 7%; XHAM: 70 +/- 7%; Vein: 70 +/- 7%). Histomorphometry showed good axonal regeneration in all repair techniques. These results demonstrate that peripheral nerve repair using photosealed autologous veins produced regeneration at least equivalent to current gold-standard microsurgery. The use of autologous veins removes costs and foreign body concerns and would be readily available during surgery. This study illustrates a new repair method that could restore normal endoneurial homeostasis with minimal trauma following severe nerve injury.
Assuntos
Regeneração Nervosa , Nervo Isquiático , Animais , Ratos , Regeneração Nervosa/fisiologia , Nervo Isquiático/lesões , Nervo Isquiático/cirurgia , Nervo Isquiático/fisiologia , Humanos , Âmnio , Transplante Autólogo/métodos , Músculo Esquelético , Recuperação de Função Fisiológica , Masculino , Procedimentos Neurocirúrgicos/métodos , Veias/cirurgiaRESUMO
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.
Assuntos
Regeneração Nervosa , Nervo Isquiático , Alicerces Teciduais , Animais , Nervo Isquiático/fisiologia , Ratos , Alicerces Teciduais/química , Ouro/química , Ratos Sprague-Dawley , Seda/química , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Estimulação Elétrica/métodos , Fibroínas/química , Nanopartículas Metálicas/química , Masculino , Recuperação de Função Fisiológica , Regeneração Tecidual Guiada/métodos , Hidrogéis/químicaRESUMO
Three-dimensional (3D) printing is an emerging tool for creating patient-specific tissue constructs analogous to the native tissue microarchitecture. In this study, anatomically equivalent 3D nerve conduits were developed using thermoplastic polyurethane (TPU) by combining reverse engineering and material extrusion (i.e. fused deposition modeling) technique. Printing parameters were optimized to fabricate nerve-equivalent TPU constructs. The TPU constructs printed with different infill densities supported the adhesion, proliferation, and gene expression of neuronal cells. Subcutaneous implantation of the TPU constructs for three months in rats showed neovascularization with negligible local tissue inflammatory reactions and was classified as a non-irritant biomaterial as per ISO 10993-6. To performin vivoefficacy studies, nerve conduits equivalent to rat's sciatic nerve were fabricated and bridged in a 10 mm sciatic nerve transection model. After four months of implantation, the sensorimotor function and histological assessments revealed that the 3D printed TPU conduits promoted the regeneration in critical-sized peripheral nerve defects equivalent to autografts. This study proved that TPU-based 3D printed nerve guidance conduits can be created to replicate the complicated features of natural nerves that can promote the regeneration of peripheral nerve defects and also show the potential to be extended to several other tissues for regenerative medicine applications.
Assuntos
Regeneração Nervosa , Poliuretanos , Impressão Tridimensional , Nervo Isquiático , Alicerces Teciduais , Animais , Poliuretanos/química , Poliuretanos/farmacologia , Regeneração Nervosa/efeitos dos fármacos , Ratos , Nervo Isquiático/fisiologia , Nervo Isquiático/lesões , Nervo Isquiático/efeitos dos fármacos , Alicerces Teciduais/química , Ratos Sprague-Dawley , Traumatismos dos Nervos Periféricos/terapia , Traumatismos dos Nervos Periféricos/patologia , Masculino , Regeneração Tecidual Guiada/instrumentação , Regeneração Tecidual Guiada/métodos , Engenharia Tecidual/métodos , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologiaRESUMO
Complicated peripheral nerve injuries or defects, especially at branching sites, remain a prominent clinical challenge after the application of different treatment strategies. Current nerve grafts fail to match the expected shape and size for delicate and precise branched nerve repair on a case-by-case basis, and there is a lack of geometrical and microscale regenerative navigation. In this study, we develop a sugar painting-inspired individualized multilevel epi-/peri-/endoneurium-mimetic device (SpinMed) to customize natural cues, featuring a selectively protective outer sheath and an instructive core, to support rapid vascular reconstruction and consequent efficient neurite extension along the defect area. The biomimetic perineurium dictates host-guest crosslinking in which new vessels secrete multimerin 1 binding to the fibroin filler surface as an anchor, contributing to the biological endoneurium that promotes Schwann cell homing and remyelination. SpinMed implantation into rat sciatic nerve defects yields a satisfactory outcome in terms of structural reconstruction, with sensory and locomotive function restoration. We further customize SpinMed grafts based on anatomy and digital imaging, achieving rapid repair of the nerve trunk and branches superior to that achieved by autografts and decellularized grafts in a specific beagle nerve defect model, with reliable biosafety. Overall, this intelligent art-inspired biomimetic design offers a facile way to customize sophisticated high-performance nerve grafts and holds great potential for application in translational regenerative medicine.
Assuntos
Regeneração Nervosa , Células de Schwann , Nervo Isquiático , Animais , Regeneração Nervosa/efeitos dos fármacos , Ratos , Nervo Isquiático/lesões , Nervo Isquiático/fisiologia , Células de Schwann/metabolismo , Cães , Traumatismos dos Nervos Periféricos/terapia , Traumatismos dos Nervos Periféricos/cirurgia , Ratos Sprague-Dawley , Masculino , Alicerces Teciduais/química , Materiais Biomiméticos/química , Materiais Biomiméticos/farmacologia , Biomimética/métodos , Fibroínas/química , Fibroínas/farmacologia , Engenharia Tecidual/métodosRESUMO
PURPOSE: To evaluate the effects on peripheral neural regeneration of the end-to-side embracing repair technique compared to the autograft repair technique in Wistar rats. METHODS: Fifteen male Wistar rats were divided into three groups with five animals each: denervated group (GD), autograft group (GA), and embracing group (EG). For the evaluation, the grasping test, electroneuromyography (ENMG), and muscle weight assessment were used. RESULTS: Muscle weight assessment and ENMG did not show significant neural regeneration at the end of 12 weeks in the DG and GE groups, but only in GA. The grasping test showed an increase in strength between the surgery and the fourth week in all groups, and only the GA maintained this trend until the 12th week. CONCLUSIONS: The present study indicates that the neural regeneration observed in the end-to-side embracing neurorrhaphy technique, in the repair of segmental neural loss, is inferior to autograft repair in Wistar rats.
Assuntos
Regeneração Nervosa , Ratos Wistar , Animais , Masculino , Regeneração Nervosa/fisiologia , Eletromiografia , Ratos , Procedimentos Neurocirúrgicos/métodos , Músculo Esquelético/inervação , Traumatismos dos Nervos Periféricos/cirurgia , Transplante Autólogo/métodos , Fatores de Tempo , Reprodutibilidade dos Testes , Nervo Isquiático/cirurgia , Nervo Isquiático/lesões , Nervo Isquiático/fisiologiaRESUMO
BACKGROUND: Nerve guide conduits are a promising strategy for reconstructing peripheral nerve defects. Improving the survival rate of seed cells in nerve conduits is still a challenge and microcarriers are an excellent three-dimensional (3D) culture scaffold. Here, we investigate the effect of the 3D culture of microcarriers on the biological characteristics of adipose mesenchymal stem cells (ADSCs) and to evaluate the efficacy of chitosan nerve conduits filled with microcarriers loaded with ADSCs in repairing nerve defects. METHODS: In vitro, we prepared porous chitosan microspheres by a modified emulsion cross-linking method for loading ADSCs and evaluated the growth status and function of ADSCs. In vivo, ADSCs-loaded microcarriers were injected into chitosan nerve conduits to repair a 12 mm sciatic nerve defect in rats. RESULTS: Compared to the conventional two-dimensional (2D) culture, the prepared microcarriers were more conducive to the proliferation, migration, and secretion of trophic factors of ADSCs. In addition, gait analysis, neuro-electrophysiology, and histological evaluation of nerves and muscles showed that the ADSC microcarrier-loaded nerve conduits were more effective in improving nerve regeneration. CONCLUSIONS: The ADSCs-loaded chitosan porous microcarrier prepared in this study has a high cell engraftment rate and good potential for peripheral nerve repair.
Assuntos
Tecido Adiposo , Quitosana , Células-Tronco Mesenquimais , Microesferas , Regeneração Nervosa , Ratos Sprague-Dawley , Quitosana/química , Regeneração Nervosa/fisiologia , Animais , Ratos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Tecido Adiposo/citologia , Nervo Isquiático/fisiologia , Porosidade , Alicerces Teciduais/química , Masculino , Transplante de Células-Tronco Mesenquimais/métodos , Proliferação de Células , Células CultivadasRESUMO
BACKGROUND: Molybdenum disulfide (MoS2) has excellent physical and chemical properties. Further, chiral MoS2 (CMS) exhibits excellent chiroptical and enantioselective effects, and the enantioselective properties of CMS have been studied for the treatment of neurodegenerative diseases. Intriguingly, left- and right-handed materials have different effects on promoting the differentiation of neural stem cells into neurons. However, the effect of the enantioselectivity of chiral materials on peripheral nerve regeneration remains unclear. METHODS: In this study, CMS@bacterial cellulose (BC) scaffolds were fabricated using a hydrothermal approach. The CMS@BC films synthesized with L-2-amino-3-phenyl-1-propanol was defined as L-CMS. The CMS@BC films synthesized with D-2-amino-3-phenyl-1-propanol was defined as D-CMS. The biocompatibility of CMS@BC scaffolds and their effect on Schwann cells (SCs) were validated by cellular experiments. In addition, these scaffolds were implanted in rat sciatic nerve defect sites for three months. RESULTS: These chiral scaffolds displayed high hydrophilicity, good mechanical properties, and low cytotoxicity. Further, we found that the L-CMS scaffolds were superior to the D-CMS scaffolds in promoting SCs proliferation. After three months, the scaffolds showed good biocompatibility in vivo, and the nerve conducting velocities of the L-CMS and D-CMS scaffolds were 51.2 m/s and 26.8 m/s, respectively. The L-CMS scaffolds showed a better regenerative effect than the D-CMS scaffolds. Similarly, the sciatic nerve function index and effects on the motor and electrophysiological functions were higher for the L-CMS scaffolds than the D-CMS scaffolds. Finally, the axon diameter and myelin sheath thickness of the regenerated nerves were improved in the L-CMS group. CONCLUSION: We found that the CMS@BC can promote peripheral nerve regeneration, and in general, the L-CMS group exhibited superior repair performance. Overall, the findings of this study reveal that CMS@BC can be used as a chiral nanomaterial nerve scaffold for peripheral nerve repair.
Assuntos
Celulose , Dissulfetos , Molibdênio , Regeneração Nervosa , Células de Schwann , Alicerces Teciduais , Regeneração Nervosa/efeitos dos fármacos , Animais , Ratos , Alicerces Teciduais/química , Dissulfetos/química , Dissulfetos/farmacologia , Células de Schwann/efeitos dos fármacos , Molibdênio/química , Molibdênio/farmacologia , Celulose/química , Celulose/farmacologia , Celulose/análogos & derivados , Ratos Sprague-Dawley , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Nervo Isquiático/efeitos dos fármacos , Nervo Isquiático/fisiologia , Proliferação de Células/efeitos dos fármacos , Engenharia Tecidual/métodos , Masculino , Traumatismos dos Nervos Periféricos , EstereoisomerismoRESUMO
Optoelectronic neural interfaces can leverage the photovoltaic effect to convert light into electrical current, inducing charge redistribution and enabling nerve stimulation. This method offers a non-genetic and remote approach for neuromodulation. Developing biodegradable and efficient optoelectronic neural interfaces is important for achieving transdermal stimulation while minimizing infection risks associated with device retrieval, thereby maximizing therapeutic outcomes. We propose a biodegradable, flexible, and miniaturized silicon-based neural interface capable of transdermal optoelectronic stimulation for neural modulation and nerve regeneration. Enhancing the device interface with thin-film molybdenum significantly improves the efficacy of neural stimulation. Our study demonstrates successful activation of the sciatic nerve in rodents and the facial nerve in rabbits. Moreover, transdermal optoelectronic stimulation accelerates the functional recovery of injured facial nerves.
Assuntos
Regeneração Nervosa , Nervo Isquiático , Animais , Coelhos , Regeneração Nervosa/fisiologia , Regeneração Nervosa/efeitos dos fármacos , Nervo Isquiático/fisiologia , Nervo Facial/fisiologia , Nervos Periféricos/fisiologia , Masculino , Ratos , Silício/química , Ratos Sprague-Dawley , Estimulação ElétricaRESUMO
Repairing larger defects (>5 mm) in peripheral nerve injuries (PNIs) remains a significant challenge when using traditional artificial nerve guidance conduits (NGCs). A novel approach that combines 4D printing technology with poly(L-lactide-co-trimethylene carbonate) (PLATMC) and Ti3C2Tx MXene nanosheets is proposed, thereby imparting shape memory properties to the NGCs. Upon body temperature activation, the printed sheet-like structure can quickly self-roll into a conduit-like structure, enabling optimal wrapping around nerve stumps. This design enhances nerve fixation and simplifies surgical procedures. Moreover, the integration of microchannel expertly crafted through 4D printing, along with the incorporation of MXene nanosheets, introduces electrical conductivity. This feature facilitates the guided and directional migration of nerve cells, rapidly accelerating the healing of the PNI. By leveraging these advanced technologies, the developed NGCs demonstrate remarkable potential in promoting peripheral nerve regeneration, leading to substantial improvements in muscle morphology and restored sciatic nerve function, comparable to outcomes achieved through autogenous nerve transplantation.
Assuntos
Regeneração Nervosa , Traumatismos dos Nervos Periféricos , Impressão Tridimensional , Regeneração Nervosa/fisiologia , Regeneração Nervosa/efeitos dos fármacos , Traumatismos dos Nervos Periféricos/terapia , Animais , Ratos , Ratos Sprague-Dawley , Nervo Isquiático/lesões , Nervo Isquiático/fisiologia , Titânio/química , Alicerces Teciduais/química , Regeneração Tecidual Guiada/métodos , Regeneração Tecidual Guiada/instrumentação , Dioxanos/química , MasculinoRESUMO
Carbon nanotube (CNT) fiber electrodes have demonstrated exceptional spatial selectivity and sustained reliability in the context of intrafascicular electrical stimulation, as evidenced through rigorous animal experimentation. A significant presence of unmyelinated C fibers, known to induce uncomfortable somatosensory experiences, exists within peripheral nerves. This presence poses a considerable challenge to the excitation of myelinated Aß fibers, which are crucial for tactile sensation. To achieve nuanced tactile sensory feedback utilizing CNT fiber electrodes, the selective stimulation of Aß sensory afferents emerges as a critical factor. In confronting this challenge, the present investigation sought to refine and apply a rat sciatic-nerve model leveraging the capabilities of the COMSOL-NEURON framework. This approach enables a systematic evaluation of the influence exerted by stimulation parameters and electrode geometry on the activation dynamics of both myelinated Aß and unmyelinated C fibers. The findings advocate for the utilization of current pulses featuring a pulse width of 600 µs, alongside the deployment of CNT fibers characterized by a diminutive diameter of 10 µm, with an exclusively exposed cross-sectional area, to facilitate reduced activation current thresholds. Comparative analysis under monopolar and bipolar electrical stimulation conditions revealed proximate activation thresholds, albeit with bipolar stimulation exhibiting superior fiber selectivity relative to its monopolar counterpart. Concerning pulse waveform characteristics, the adoption of an anodic-first biphasic stimulation modality is favored, taking into account the dual criteria of activation threshold and fiber selectivity optimization. Consequently, this investigation furnishes an efficacious stimulation paradigm for the selective activation of touch-related nerve fibers, alongside provisioning a comprehensive theoretical foundation for the realization of natural tactile feedback within the domain of prosthetic hand applications.
Assuntos
Estimulação Elétrica , Fibras Nervosas Mielinizadas , Fibras Nervosas Amielínicas , Animais , Fibras Nervosas Mielinizadas/fisiologia , Fibras Nervosas Amielínicas/fisiologia , Ratos , Nanotubos de Carbono/química , Modelos Neurológicos , Nervo Isquiático/fisiologia , EletrodosRESUMO
Nerve guidance conduits (NGCs) are considered as promising treatment strategy and frontier trend for peripheral nerve regeneration, while their therapeutic outcomes are limited by the lack of controllable drug delivery and available physicochemical cues. Herein, novel aligned piezoelectric nanofibers derived hydrogel NGCs with ultrasound (US)-triggered electrical stimulation (ES) and controllable drug release for repairing peripheral nerve injury are proposed. The inner layer of the NGCs is the barium titanate piezoelectric nanoparticles (BTNPs)-doped polyvinylidene fluoride-trifluoroethylene [BTNPs/P(VDF-TrFE)] electrospinning nanofibers with improved piezoelectricity and aligned orientation. The outer side of the NGCs is the thermoresponsive poly(N-isopropylacrylamide) hybrid hydrogel with bioactive drug encapsulation. Such NGCs can not only induce neuronal-oriented extension and promote neurite outgrowth with US-triggered wireless ES, but also realize the controllable nerve growth factor release with the hydrogel shrinkage under US-triggered heating. Thus, the NGC can positively accelerate the functional recovery and nerve axonal regeneration of rat models with long sciatic nerve defects. It is believed that the proposed US-responsive aligned piezoelectric nanofibers derived hydrogel NGCs will find important applications in clinic neural tissue engineering.
Assuntos
Hidrogéis , Nanofibras , Regeneração Nervosa , Animais , Regeneração Nervosa/efeitos dos fármacos , Hidrogéis/química , Nanofibras/química , Ratos , Ondas Ultrassônicas , Compostos de Bário/química , Nervo Isquiático/fisiologia , Nervo Isquiático/efeitos dos fármacos , Titânio/química , Polivinil/química , Alicerces Teciduais/química , Resinas Acrílicas/química , Traumatismos dos Nervos Periféricos/terapia , Ratos Sprague-Dawley , Fator de Crescimento Neural/química , Fator de Crescimento Neural/farmacologia , Liberação Controlada de Fármacos , Estimulação Elétrica , Nanopartículas/química , Engenharia Tecidual/métodosRESUMO
Peripheral nerve injuries can lead to sensory or motor deficits that have a serious impact on a patient's mental health and quality of life. Nevertheless, it remains a major clinical challenge to develop functional nerve conduits as an alternative to autologous grafts. We applied reduced graphene oxide (rGO) as a bioactive conductive material to impart electrophysiological properties to a 3D printed scaffold and the application of a pulsed magnetic field to excite the formation of microcurrents and induce nerve regeneration.In vitrostudies showed that the nerve scaffold and the pulsed magnetic field made no effect on cell survival, increased S-100ßprotein expression, enhanced cell adhesion, and increased the expression level of nerve regeneration-related mRNAs.In vivoexperiments suggested that the protocol was effective in promoting nerve regeneration, resulting in functional recovery of sciatic nerves in rats, when they were damaged close to that of the autologous nerve graft, and increased expression of S-100ß, NF200, and GAP43. These results indicate that rGO composite nerve scaffolds combined with pulsed magnetic field stimulation have great potential for peripheral nerve rehabilitation.
Assuntos
Campos Eletromagnéticos , Grafite , Regeneração Nervosa , Impressão Tridimensional , Ratos Sprague-Dawley , Nervo Isquiático , Alicerces Teciduais , Animais , Grafite/química , Nervo Isquiático/fisiologia , Nervo Isquiático/lesões , Regeneração Nervosa/efeitos dos fármacos , Alicerces Teciduais/química , Ratos , MasculinoRESUMO
The structural and functional features of lymphatic vessels in the peripheral nervous system (pLVs) is still unclear. Here, we clarify the existence of pLVs in rats, PROX1-EGFP transgenic mice and human, and exhibit a clear three-dimensional structure for helping understand its structural features. Moreover, two specific phenotypes of lymphatics endothelial cells (Rnd1Hi LECs and Ccl21Hi LECs) in peripheral nerves are well characterized by single-cell sequencing. Subsequently, the ability of trans-lymphatic delivery to peripheral nerves via pLVs has been dynamically demonstrated. After peripheral nerve injury (PNI), extensive lymphangiogenesis occurs in the lesion area and further enhances the efficiency of retrograde lymphatic-nerve transport. In PNI animal models, subcutaneously footpad-injected exosomes are efficiently delivered to sciatic nerve via pLVs which can promote nerve regeneration. The trans-lymphatic delivery to peripheral nerves via pLVs can subtly bypass BNB which provides an easy and alternative delivery route for PNI treatment.
Assuntos
Vasos Linfáticos , Camundongos Transgênicos , Regeneração Nervosa , Traumatismos dos Nervos Periféricos , Animais , Regeneração Nervosa/fisiologia , Vasos Linfáticos/fisiologia , Camundongos , Traumatismos dos Nervos Periféricos/patologia , Ratos , Humanos , Sistema Nervoso Periférico , Ratos Sprague-Dawley , Masculino , Nervo Isquiático/fisiologia , Nervo Isquiático/lesões , Linfangiogênese/fisiologia , Células Endoteliais/fisiologia , Exossomos/metabolismoRESUMO
Nerve guidance conduits (NGCs) are widely developed using various materials for the functional repair of injured or diseased peripheral nerves. Especially, hydrogels are considered highly suitable for the fabrication of NGCs due to their beneficial tissue-mimicking characteristics (e.g., high water content, softness, and porosity). However, the practical applications of hydrogel-based NGCs are hindered due to their poor mechanical properties and complicated fabrication processes. To bridge this gap, a novel double-network (DN) hydrogel using alginate and gelatin by a two-step crosslinking process involving chemical-free gamma irradiation and ionic crosslinking, is developed. DN hydrogels (1% alginate and 15% gelatin), crosslinked with 30 kGy gamma irradiation and barium ions, exhibit substantially improved mechanical properties, including tensile strength, elastic modulus, and fracture stain, compared to single network (SN) gelatin hydrogels. Additionally, the DN hydrogel NGC exhibits excellent kink resistance, mechanical stability to successive compression, suture retention, and enzymatic degradability. In vivo studies with a sciatic defect rat model indicate substantially improved nerve function recovery with the DN hydrogel NGC compared to SN gelatin and commercial silicone NGCs, as confirm footprint analysis, electromyography, and muscle weight measurement. Histological examination reveals that, in the DN NGC group, the expression of Schwann cell and neuronal markers, myelin sheath, and exon diameter are superior to the other controls. Furthermore, the DN NGC group demonstrates increased muscle fiber formation and reduced fibrotic scarring. These findings suggest that the mechanically robust, degradable, and biocompatible DN hydrogel NGC can serve as a novel platform for peripheral nerve regeneration and other biomedical applications, such as implantable tissue constructs.