Neuron-Schwann cell interactions in peripheral nervous system homeostasis, disease, and preclinical treatment.

Schwann cells (SCs) have a critical role in the peripheral nervous system. These cells are able to support axons during homeostasis and after injury. However, mutations in genes associated with the SCs repair program or myelination result in dysfunctional SCs. Several neuropathies such as Charcot-Marie-Tooth (CMT) disease, diabetic neuropathy and Guillain-Barré syndrome show abnormal SC functions and an impaired regeneration process. Thus, understanding SCs-axon interaction and the nerve environment in the context of homeostasis as well as post-injury and disease onset is necessary. Several neurotrophic factors, cytokines, and regulators of signaling pathways associated with proliferation, survival and regeneration are involved in this process. Preclinical studies have focused on the discovery of therapeutic targets for peripheral neuropathies and injuries. To study the effect of new therapeutic targets, modeling neuropathies and peripheral nerve injuries (PNIs) in vitro and in vivo are useful tools. Furthermore, several in vitro protocols have been designed using SCs and neuron cell lines to evaluate these targets in the regeneration process. SCs lines have been used to generate effective myelinating SCs without success. Alternative options have been investigated using direct conversion from somatic cells to SCs or SCs derived from pluripotent stem cells to generate functional SCs. This review will go over the advantages of these systems and the problems associated with them. In addition, there have been challenges in establishing adequate and reproducible protocols in vitro to recapitulate repair SC-neuron interactions observed in vivo. So, we also discuss the mechanisms of repair SCs-axon interactions in the context of peripheral neuropathies and nerve injury (PNI) in vitro and in vivo. Finally, we summarize current preclinical studies evaluating transgenes, drug, and novel compounds with translational potential into clinical studies.

Genotoxicity and Anticancer Effects of the Aminothiophene Derivatives SB-44, SB- 83, and SB-200 in Cancer Cells.

INTRODUCTION: Thiophene derivatives have been widely studied as promising options for the treatment of solid tumors. Previous studies have shown that thiophene derivatives have antileishmanial activity and cytotoxic activity against breast, colon, and ovarian cancer cells. METHODS: In our study, we evaluated the anticancer activities of three aminothiophene derivatives: SB-44, SB-83, and SB-200, in prostate and cervical adenocarcinoma cells. Several in vitro methods were performed, including cytotoxicity, clonogenic migration, mutagenic, and cleaved Poly (ADP-ribose) polymerase (PARP) assays and annexin V staining. RESULTS: Significant cytotoxicity was observed in cell lines with IC50 values less than 35 µM (15.38-34.04 µM). All aminothiophene derivatives significantly reduced clone formation but had no effect on cell motility. SB-83 and SB-44 induced a significant increase in the percentage of cells in the sub-G1 phase, while SB-200 derivatives significantly decreased the percentage of S/G2/M as well as induced apoptosis, with an increase of cleaved PARP. SBs compounds also showed significant mutagenic potential. Beyond that, in silico analyses revealed that all three thiophene derivatives fulfilled the criteria for oral druggability, which underscores the potential of using them in anticancer therapies. CONCLUSION: Our findings show that the thiophene nucleus may be used to treat solid tumors, including prostate cancer and cervical adenocarcinoma.

Metabolic activation enhances the cytotoxicity, genotoxicity and mutagenicity of two synthetic alkaloids with selective effects against human tumour cell lines.

The pharmacological potential of drugs must be evaluated to establish their potential therapeutic benefits and side effects. This evaluation includes assessment of the effects of hepatic enzymes that catalyse their metabolic activation. Previously, our research group synthesized and characterized a set of synthetic 3-alkyl pyridine alkaloid (3-APA) analogues that cause in vitro cytotoxic, genotoxic, and mutagenic effects in various human cancer cell lines. The present study aimed to evaluate these activities with the two most promising synthetic 3-APAs (3-APA 1 and 3-APA 2) against cell lines derived from breast cancer (MDA-MB-231), ovarian cancer (TOV-21 G) and lung fibroblasts (WI-26-VA4) with and without metabolic activation (S9 fraction). The cytotoxicity of the compounds was evaluated employing MTT and clonogenic assays. In addition, comet assays, γH2AX immunocytochemistry labelling assays and cytokinesis-block micronucleus tests were carried out to evaluate the potential of these compounds to induce chromosomal damage. The results obtained in the MTT assay showed that compound 3-APA 2 exhibited high selectivity index (SI) values (ranging between 21.0 and 92.6). In addition, the cytotoxicity of the compounds was clearly enhanced by metabolic activation. Moreover, both compounds were genotoxic and induced double-strand breaks in DNA and chromosomal lesions with and without S9. The cancer cell lines tested showed higher genotoxic sensitivity to the compounds than did the non-tumour cell line used as a reference. The genotoxic and mutagenic effects of the compounds were potentiated in experiments with metabolic activation. The data obtained in this study indicate that compound 3-APA 2 is more active against the human cancer cell lines tested, both with and without metabolic activation, and can therefore be considered a candidate drug to treat human ovarian and breast cancer.

Myelination of regenerating optic nerve axons occurs in conjunction with an increase of the oligodendrocyte precursor cell population in the adult mice.

Recently, regeneration of CNS tracts has been partially accomplished by strategies of intrinsic neuronal growth stimulation. However, restoration of function is dependent on proper myelination of regenerating axons. Previous work from our group (Goulart et al., 2018) has shown an increase in oligodendrocyte staining in the regenerating optic nerve, 2 weeks after crush, in animals that were submitted to conditional deletion of pten gene in retinal ganglion cells and intravitreal injection of zymosan + cAMP. Thus, in the present study we aimed to investigate the maturation of the oligodendroglial lineage and myelination during the regeneration of the optic nerve under the same conditions of our previous work. We showed that the combined treatment promoted an increase of myelinated fibers within the optic nerve, 12 weeks after lesion, as well as an increase in Sox10 positive cells. Early-OPCs, positive to A2B5, were also increased at 12 weeks, whereas O4 positive, late-OPCs, were increased from 2 until 12 weeks after crush. At 12 weeks after crush, the optic nerve of Regenerating group presented more CC1 positive oligodendrocytes and increased MRF positive myelinating oligodendrocytes, culminating in CTB traced regenerating axons superimposed to MBP staining, suggestive of myelination. Thus, our work showed that conditional deletion of pten gene in retinal ganglion cells and intravitreal inflammatory stimuli + cAMP stimulate full maturation of the olidodendroglial lineage, from OPC proliferation and differentiation to myelination of regenerating CNS axons.

Ultrasound elastography in patients with fatty liver disease.

Hepatic steatosis, or fatty liver disease, occurs due to the accumulation of lipids in hepatocytes. When it becomes chronic, lobular inflammation develops and the disease can evolve to hepatic fibrosis, liver cirrhosis, or hepatocellular carcinoma. Early diagnosis is desirable because patients diagnosed in the early stage of the disease respond better to treatment. In the early stages of fatty liver disease, the physical examination is often unremarkable. Fatty liver disease and hepatic fibrosis can be diagnosed and monitored through laboratory tests, imaging, and biopsy. Among the imaging methods, ultrasound stands out as an effective means of diagnosing and following patients with liver disease. Ultrasound used in conjunction with elastography (ultrasound elastography) has recently shown great utility in the follow-up of such patients. Ultrasound elastography studies the degree of deformation (stiffness) of an organ or lesion, so that when there is hardening, fibrosis, or cirrhosis of the liver, those alterations are well demonstrated. In this review article, we discuss the application of the different types of ultrasound elastography for liver studies: transient elastography, point shear wave elastography, and two-dimensional shear wave elastography. Although magnetic resonance elastography may also be used in the analysis of liver fibrosis, it will not be addressed in this article.

Ultrasound elastography in patients with fatty liver disease / Análise da elastografia por ultrassonografia em pacientes com esteatose hepática

Abstract Hepatic steatosis, or fatty liver disease, occurs due to the accumulation of lipids in hepatocytes. When it becomes chronic, lobular inflammation develops and the disease can evolve to hepatic fibrosis, liver cirrhosis, or hepatocellular carcinoma. Early diagnosis is desirable because patients diagnosed in the early stage of the disease respond better to treatment. In the early stages of fatty liver disease, the physical examination is often unremarkable. Fatty liver disease and hepatic fibrosis can be diagnosed and monitored through laboratory tests, imaging, and biopsy. Among the imaging methods, ultrasound stands out as an effective means of diagnosing and following patients with liver disease. Ultrasound used in conjunction with elastography (ultrasound elastography) has recently shown great utility in the follow-up of such patients. Ultrasound elastography studies the degree of deformation (stiffness) of an organ or lesion, so that when there is hardening, fibrosis, or cirrhosis of the liver, those alterations are well demonstrated. In this review article, we discuss the application of the different types of ultrasound elastography for liver studies: transient elastography, point shear wave elastography, and two-dimensional shear wave elastography. Although magnetic resonance elastography may also be used in the analysis of liver fibrosis, it will not be addressed in this article.

Resumo Esteatose hepática ocorre pelo acúmulo de lipídios nos hepatócitos, sua cronificação cursa com inflamação lobular e evolui com fibrose hepática, cirrose e carcinoma hepatocelular. O diagnóstico precoce do acometimento hepático é desejável em razão da melhor resposta terapêutica dos pacientes na fase inicial da doença. O exame físico nas fases iniciais da doença não apresenta alterações. O diagnóstico e o controle evolutivo da esteatose e fibrose hepática podem ser realizados por exames laboratoriais, exames de imagens e biópsia. Entre os exames de imagem, destaca-se a ultrassonografia (US) no diagnóstico e acompanhamento dos pacientes com doença hepática. Atualmente, a US associada à elastografia vem se destacando para acompanhamento desses pacientes. A elastografia por US estuda o grau de deformação (ou dureza) do órgão ou lesão, de modo que quando há endurecimento do fígado, por fibrose ou cirrose, essa alteração é bem demonstrada na elastografia por US. Neste artigo de revisão nos propusemos a discutir a aplicação dos diversos tipos de elastografia por US para estudo do fígado: elastografia transitória, point-shear wave elastography e 2D-shear wave elastography. A elastografia por ressonância magnética também pode ser utilizada na análise de fibrose hepática, mas não será abordada neste artigo.

Repulsive Environment Attenuation during Adult Mouse Optic Nerve Regeneration.

The regenerative capacity of CNS tracts has ever been a great hurdle to regenerative medicine. Although recent studies have described strategies to stimulate retinal ganglion cells (RGCs) to regenerate axons through the optic nerve, it still remains to be elucidated how these therapies modulate the inhibitory environment of CNS. Thus, the present work investigated the environmental content of the repulsive axon guidance cues, such as Sema3D and its receptors, myelin debris, and astrogliosis, within the regenerating optic nerve of mice submitted to intraocular inflammation + cAMP combined to conditional deletion of PTEN in RGC after optic nerve crush. We show here that treatment was able to promote axonal regeneration through the optic nerve and reach visual targets at twelve weeks after injury. The Regenerating group presented reduced MBP levels, increased microglia/macrophage number, and reduced astrocyte reactivity and CSPG content following optic nerve injury. In addition, Sema3D content and its receptors are reduced in the Regenerating group. Together, our results provide, for the first time, evidence that several regenerative repulsive signals are reduced in regenerating optic nerve fibers following a combined therapy. Therefore, the treatment used made the CNS microenvironment more permissive to regeneration.

Comparison of morphological and functional outcomes of mouse sciatic nerve repair with three biodegradable polymer conduits containing poly(lactic acid).

Poly(lactic acid) (PLA)-containing nerve guidance conduits (NGCs) are currently being investigated for nerve repair as an alternative to autograft, which leads to permanent functional impairment in the territory innervated by the removed nerve. Combination of polymers modifies the physical properties of the conduits, altering their nerve-guidance properties. Conduits made from PLA-only or combined with other polymers have been used successfully for nerve repair, but their efficiency has not been compared. We compared the morphological and functional outcomes of peripheral nerve repair by using NGCs made of poly(lactic acid) and combined or not with polycaprolactone (PLA/PCL) or polyvinylpyrrolidone (PLA/PVP). To assess the functional recovery, we employed a mechanical hyperalgesia analysis, sciatic functional index (SFI), and electroneuromyography. The mechanical hyperalgesia analysis showed that the PLA group improved more rapidly than the PLA/PVP and PLA/PCL groups; similarly, in the electroneuromyography assay, the PLA group exhibited higher amplitude than the PLA/PCL and PLA/PVP groups. However, the SFI improvement rates did not differ among the groups. Morphologically, the PLA group showed more vascularization, while the nerve fiber regeneration did not differ among the groups. In conclusion, the PLA-only conduits were superior to the other NGCs tested for nerve repair.

Ortho-nitrobenzyl derivatives as potential anti-schistosomal agents

ABSTRACT In the search for new anti-schistosomal agents, a series of fifteen ortho-nitrobenzyl derivatives was assayed in vitro against both the schistosomulum (somule) and adult forms of Schistosoma mansoni. Compounds 8 and 12 showed significant activity against somules at low micromolar concentrations, but none was active against adults. The SAR demonstrated that the compounds most active against the parasite were mutagenic to the human cell line RKO-AS45-1 only at concentrations 10- to 40-fold higher than the worm-killing dose. Given their electrophilicity, compounds were also screened as inhibitors of the S. mansoni cysteine protease (cathepsin B1) in vitro. Amides 5 and 15 exhibited a modest inhibition activity with values of 55.7 and 50.6 % at 100 µM, respectively. The nitrobenzyl compounds evaluated in this work can be regarded as hits in the search for more active and safe anti-schistosomal agents.

Blockade of ATP P2X7 receptor enhances ischiatic nerve regeneration in mice following a crush injury.

Preventing damage caused by nerve degeneration is a great challenge. There is a growing body of evidence implicating extracellular nucleotides and their P2 receptors in many pathophysiological mechanisms. In this work we aimed to investigate the effects of the administration of Brilliant Blue G (BBG) and Pyridoxalphosphate-6-azophenyl-2', 4'- disulphonic acid (PPADS), P2X7 and P2 non-selective receptor antagonists, respectively, on sciatic nerve regeneration. Four groups of mice that underwent nerve crush lesion were used: two control groups treated with vehicle (saline), a group treated with BBG and a group treated with PPADS during 28days. Gastrocnemius muscle weight was evaluated. For functional evaluation we used the Sciatic Functional Index (SFI) and the horizontal ladder walking test. Nerves, dorsal root ganglia and spinal cords were processed for light and electron microscopy. Antinoceptive effects of BBG and PPADS were evaluated through von Frey E, and the levels of IL-1ß and TNF-α were analyzed by ELISA. BBG promoted an increase in the number of myelinated fibers and on axon, fiber and myelin areas. BBG and PPADS led to an increase of TNF-α and IL-1ß in the nerve on day 1 and PPADS caused a decrease of IL-1ß on day 7. Mechanical allodynia was reversed on day 7 in the groups treated with BBG and PPADS. We concluded that BBG promoted a better morphological regeneration after ischiatic crush injury, but this was not followed by anticipation of functional improvement. In addition, both PPADS and BBG presented anti-inflammatory as well as antinociceptive effects.

Digoxin reduces the mutagenic effects of Mitomycin C in human and rodent cell lines.

Digoxin is a drug widely used to treat heart failure and studies have demonstrated its potential as anticancer agent. In addition, digoxin presents the potential to interact with a series of other compounds used in medicine. The aim of the present study was to evaluate in vitro the cytotoxicity, genotoxicity and mutagenicity of digoxin and its potential to interact with the mutagen Mitomycin C (MMC). The cytotoxicity of digoxin was assessed by employing the MTT method and the comet assay was performed to assess the genotoxicity of this medicine in CHO-K1 and HeLa cell lines. Besides, the cytokinesis-block micronucleus assay was performed to assess the mutagenicity and the antimutagenicity of this drug. The Ames assay was also performed with TA98 and TA100 strains of S. typhimurium. Results showed that digoxin was cytotoxic, genotoxic and mutagenic for HeLa and CHO-K1 cell lines at concentrations many times higher than those observed in human therapeutic conditions. Nevertheless, an antimutagenic effect against the mutagen MMC was observed on both cell lines in concentrations near those used therapeutically in humans. This chemoprotective effect observed is an interesting finding that should be better explored regarding its impact in anticancer chemotherapy.

Olfactory ensheathing glia cell therapy and tubular conduit enhance nerve regeneration after mouse sciatic nerve transection.

The regenerative potential of the peripheral nervous system (PNS) is widely known, but functional recovery, particularly in humans, is seldom complete. Therefore, it is necessary to resort to strategies that induce or potentiate the PNS regeneration. Our main objective was to test the effectiveness of Olfactory Ensheathing Cells (OEC) transplantation into a biodegradable conduit as a therapeutic strategy to improve the repair outcome after nerve injury. Sciatic nerve transection was performed in C57BL/6 mice; proximal and distal stumps of the nerve were sutured into the collagen conduit. Two groups were analyzed: DMEM (acellular grafts) and OEC (1×105/2µL). Locomotor function was assessed weekly by Sciatic Function Index (SFI) and Global Mobility Test (GMT). After eight weeks the sciatic nerve was dissected for morphological analysis. Our results showed that the OEC group exhibited many clusters of regenerated nerve fibers, a higher number of myelinated fibers and myelin area compared to DMEM group. The G-ratio analysis of the OEC group showed significantly more fibers on the most suitable sciatic nerve G-ratio index. Motor recovery was accelerated in the OEC group. These data provide evidence that the OEC therapy can improve sciatic nerve functional and morphological recovery and can be potentially translated to the clinical setting.

Evaluation of biodegradable polymer conduits--poly(L-lactic acid)--for guiding sciatic nerve regeneration in mice.

Polymeric biomaterials are often used for stimulating nerve regeneration. Among different conduits, poly(lactide acid) - PLA polymer is considered to be a good substrate due to its biocompatibility and resorbable characteristics. This polymer is an aliphatic polyester which has been mostly used in biomedical application. It is an organic compound with low allergenic potential, low toxicity, high biocompatibility and predictable kinetics of degradation. In this study we fabricated and evaluated a PLA microporous hollow fiber as a conduit for its ability to bridge a nerve gap in a mouse sciatic nerve injury model. The PLA conduit was prepared from a polymer solution, throughout extrusion technique. The left sciatic nerve of C57BL/6 mouse was transected and the nerve stumps were placed into a resorbable PLA (PLA group) or a PCL conduit (PCL group), n=5 each group. We have also used another group in which the nerves were repaired by autograft (autograft group, n=5). Motor function was analyzed according to sciatic functional index (SFI). After 56days, the regenerated nerves were processed for light and electron microscopy and morphometric analyses were performed. A quantitative analysis of regenerated nerves showed significant increase in the number of myelinated fibers and blood vessels in animals that received PLA conduit. The PLA group exhibited better overall tissue organization compared to other groups. Presenting well-organized bundles, many regenerating clusters composed of preserved nerve fibers surrounded by layers of compacted perineurium-like cells. Also the SFI revealed a significant improvement in functional recovery. This work suggests that PLA conduits are suitable substrate for cell survival and it provides an effective strategy to be used to support axonal growth becoming a potential alternative to autograft.

A combination of Schwann-cell grafts and aerobic exercise enhances sciatic nerve regeneration.

BACKGROUND: Despite the regenerative potential of the peripheral nervous system, severe nerve lesions lead to loss of target-organ innervation, making complete functional recovery a challenge. Few studies have given attention to combining different approaches in order to accelerate the regenerative process. OBJECTIVE: Test the effectiveness of combining Schwann-cells transplantation into a biodegradable conduit, with treadmill training as a therapeutic strategy to improve the outcome of repair after mouse nerve injury. METHODS: Sciatic nerve transection was performed in adult C57BL/6 mice; the proximal and distal stumps of the nerve were sutured into the conduit. Four groups were analyzed: acellular grafts (DMEM group), Schwann cell grafts (3×105/2 µL; SC group), treadmill training (TMT group), and treadmill training and Schwann cell grafts (TMT + SC group). Locomotor function was assessed weekly by Sciatic Function Index and Global Mobility Test. Animals were anesthetized after eight weeks and dissected for morphological analysis. RESULTS: Combined therapies improved nerve regeneration, and increased the number of myelinated fibers and myelin area compared to the DMEM group. Motor recovery was accelerated in the TMT + SC group, which showed significantly better values in sciatic function index and in global mobility test than in the other groups. The TMT + SC group showed increased levels of trophic-factor expression compared to DMEM, contributing to the better functional outcome observed in the former group. The number of neurons in L4 segments was significantly higher in the SC and TMT + SC groups when compared to DMEM group. Counts of dorsal root ganglion sensory neurons revealed that TMT group had a significant increased number of neurons compared to DMEM group, while the SC and TMT + SC groups had a slight but not significant increase in the total number of motor neurons. CONCLUSION: These data provide evidence that this combination of therapeutic strategies can significantly improve functional and morphological recovery after sciatic injury.

Synthesis and biological evaluation of novel 3-alkylpyridine marine alkaloid analogs with promising anticancer activity.

Cancer continues to be one of the most important health problems worldwide, and the identification of novel drugs and treatments to address this disease is urgent. During recent years, marine organisms have proven to be a promising source of new compounds with action against tumoral cell lines. Here, we describe the synthesis and anticancer activity of eight new 3-alkylpyridine alkaloid (3-APA) analogs in four steps and with good yields. The key step for the synthesis of these compounds is a Williamson etherification under phase-transfer conditions. We investigated the influence of the length of the alkyl chain attached to position 3 of the pyridine ring on the cytotoxicity of these compounds. Biological assays demonstrated that compounds with an alkyl chain of ten carbon atoms (4c and 5c) were the most active against two tumoral cell lines: RKO-AS-45-1 and HeLa. Micronucleus and TUNEL assays showed that both compounds are mutagenic and induce apoptosis. In addition, Compound 5c altered the cellular actin cytoskeleton in RKO-AS-45-1 cells. The results suggest that Compounds 4c and 5c may be novel prototype anticancer agents.

Neurotrauma and mesenchymal stem cells treatment: From experimental studies to clinical trials.

Mesenchymal stem cell (MSC) therapy has attracted the attention of scientists and clinicians around the world. Basic and pre-clinical experimental studies have highlighted the positive effects of MSC treatment after spinal cord and peripheral nerve injury. These effects are believed to be due to their ability to differentiate into other cell lineages, modulate inflammatory and immunomodulatory responses, reduce cell apoptosis, secrete several neurotrophic factors and respond to tissue injury, among others. There are many pre-clinical studies on MSC treatment for spinal cord injury (SCI) and peripheral nerve injuries. However, the same is not true for clinical trials, particularly those concerned with nerve trauma, indicating the necessity of more well-constructed studies showing the benefits that cell therapy can provide for individuals suffering the consequences of nerve lesions. As for clinical trials for SCI treatment the results obtained so far are not as beneficial as those described in experimental studies. For these reasons basic and pre-clinical studies dealing with MSC therapy should emphasize the standardization of protocols that could be translated to the clinical set with consistent and positive outcomes. This review is based on pre-clinical studies and clinical trials available in the literature from 2010 until now. At the time of writing this article there were 43 and 36 pre-clinical and 19 and 1 clinical trials on injured spinal cord and peripheral nerves, respectively.

Bone marrow mesenchymal stem cell transplantation for improving nerve regeneration.

Although the peripheral nervous system has an inherent capacity for regeneration, injuries to nerves still result in considerable disabilities. The persistence of these disabilities along with the underlying problem of nerve reconstruction has motivated neuroscientists worldwide to seek additional therapeutic strategies. In recent years, cell-based therapy has emerged as a promising therapeutic tool. Schwann cells (SCs) are the main supportive cells for peripheral nerve regeneration; however, there are several technical limitations regarding its application for cell-based therapy. In this context, bone marrow mesenchymal stem cells (BM-MSCs) have been used as alternatives to SCs for treating peripheral neuropathies, showing great promise. Several studies have been trying to shed light on the mechanisms behind the nerve regeneration-promotion potential of BM-MSCs. Although not completely clarified, understanding how BM-MSCs exert tissue repair effects will facilitate their development as therapeutic agents before they become a clinically viable tool for encouraging peripheral nerve regeneration.

Full-length axon regeneration in the adult mouse optic nerve and partial recovery of simple visual behaviors.

The mature optic nerve cannot regenerate when injured, leaving victims of traumatic nerve damage or diseases such as glaucoma with irreversible visual losses. Recent studies have identified ways to stimulate retinal ganglion cells to regenerate axons part-way through the optic nerve, but it remains unknown whether mature axons can reenter the brain, navigate to appropriate target areas, or restore vision. We show here that with adequate stimulation, retinal ganglion cells are able to regenerate axons the full length of the visual pathway and on into the lateral geniculate nucleus, superior colliculus, and other visual centers. Regeneration partially restores the optomotor response, depth perception, and circadian photoentrainment, demonstrating the feasibility of reconstructing central circuitry for vision after optic nerve damage in mature mammals.

PEMF fails to enhance nerve regeneration after sciatic nerve crush lesion.

The use of electromagnetic fields has been reported to enhance peripheral nerve regeneration. This study aimed to identify the effects of a prolonged protocol of low-frequency pulsed electromagnetic field (PEMF) on peripheral nerve regeneration. Thirty-four male Swiss mice (Mus musculus) were divided into PEMF (n = 17) and control (n = 17) groups. All animals underwent a unilateral sciatic-crush lesion, and the PEMF group was exposed to a 72-Hz, 2-G electromagnetic field for 30 min, five days a week, for three weeks. Functional analysis was carried out weekly. After three weeks, the animals were euthanized, and histological, morphometric, oxidative stress, and TGF-beta1 analyses were performed. Functional analysis showed no differences between the groups. Histological appearance was similar between PEMF and control nerves. Morphometric assessment showed that the PEMF nerves trended toward decreased regeneration. The levels of free radicals were more pronounced in PEMF nerves, but were not associated with an increase in the content of the TGF-beta1/Smad signaling pathway. Prolonged PEMF regimen leads to delayed histological peripheral nerve regeneration and increased oxidative stress but no loss of function recovery.