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Neurotrophic keratitis or keratopathy (NK) is a degenerative corneal disease induced by impairment of the trigeminal nerve function. This condition may lead to persistent epithelial defects, corneal ulceration, and perforation. The diagnosis of NK requires a careful investigation of any ocular and systemic condition associated with the disease and ocular surface and corneal sensitivity examinations. In the past, several medical and surgical procedures were used to treat this condition with different clinical effectiveness. Cenegermin is a recombinant human nerve growth factor (rh-NGF) that supports corneal reinnervation. Different clinical trials have demonstrated the safety and efficacy of topical cenegermin in patients with moderate to severe neurotrophic keratitis. In this review, we report the literature on clinical results regarding the treatment of NK with cenegermin since its approval by the European Medicines Agency (EMA) and the Food and Drug Administration (FDA) in 2017 and 2018, respectively.

Immune checkpoint inhibitors (ICIs) have been increasingly used in combination for cancer treatment but are associated with myocarditis. Here, we report that tumor-bearing mice exhibited response to treatment with combinatorial anti-programmed cell death 1 and anti-cytotoxic T lymphocyte antigen-4 antibodies but also presented with cardiovascular toxicities observed clinically with ICI therapy, including myocarditis and arrhythmia. Female mice were preferentially affected with myocarditis compared to male mice, consistent with a previously described genetic model of ICI myocarditis and emerging clinical data. Mechanistically, myocardial tissue from ICI-treated mice, the genetic mouse model, and human heart tissue from affected patients with ICI myocarditis all exhibited down-regulation of MANF (mesencephalic astrocyte-derived neurotrophic factor) and HSPA5 (heat shock 70-kDa protein 5) in the heart; this down-regulation was particularly notable in female mice. ICI myocarditis was amplified by heart-specific genetic deletion of mouse Manf and was attenuated by administration of recombinant MANF protein, suggesting a causal role. Ironically, both MANF and HSPA5 were transcriptionally induced by liganded estrogen receptor β and inhibited by androgen receptor. However, ICI treatment reduced serum estradiol concentration to a greater extent in female compared to male mice. Treatment with an estrogen receptor β-specific agonist and androgen depletion therapy attenuated ICI-associated cardiac effects. Together, our data suggest that ICI treatment inhibits estradiol-dependent expression of MANF/HSPA5 in the heart, curtailing the cardiomyocyte response to immune injury. This endocrine-cardiac-immune pathway offers new insights into the mechanisms of sex differences in cardiac disease and may offer treatment strategies for ICI myocarditis.

Rett syndrome is a rare genetic neurodevelopmental disease, affecting 1 in over 10 000 females born worldwide, caused by de novo mutations in the X-chromosome-located methyl-CpG-binding protein 2 (MeCP2) gene. Despite the great effort put forth by the scientific community, a therapy for this devastating disease is still needed. Here, we tested the therapeutic effects of a painless mutein of the nerve growth factor (NGF), called human NGF painless (hNGFp), via a non-invasive intranasal delivery in female MeCP2 +/− mice. Of note, previous work had demonstrated a broad biodistribution of hNGFp in the mouse brain by the nasal delivery route. We report that (i) the long-term lifelong treatment of MeCP2 +/− mice with hNGFp, starting at 2 months of age, increased the chance of survival while also greatly improving behavioural parameters. Furthermore, when we assessed the phenotypic changes brought forth by (ii) a short-term 1-month-long hNGFp-treatment, starting at 3 months of age (right after the initial presentation of symptoms), we observed the rescue of a well known neuronal target population of NGF, cholinergic neurons in the medial septum. Moreover, we reveal a deficit in microglial morphology in MeCP2 +/− mice, completely reversed in treated animals. This effect on microglia is in line with reports showing microglia to be a TrkA-dependent non-neuronal target cell population of NGF in the brain. To understand the immunomodulatory activity of hNGFp, we analysed the cytokine profile after hNGFp treatment in MeCP2 +/− mice, to discover that the treatment recovered the altered expression of key neuroimmune-communication molecules, such as fractalkine. The overall conclusion is that hNGFp delivered intranasally can ameliorate symptoms in the MeCP2 +/− model of Rett syndrome, by exerting strong neuroprotection with a dual mechanism of action: directly on target neurons and indirectly via microglia. [ABSTRACT FROM AUTHOR]

Background Learning and memory impairment is a common dysfunction after stroke, which seriously affects the overall recovery of patients. Electroacupuncture at Shenting and Baihui has definite efficacy in patients with cognitive dysfunction after stroke, but its mechanism of action remains uncertain. Objective To observe the effect of electroacupuncture on hippocampal neuronal protection and brain-derived nerve growth factor (BDNF) /tyrosine receptor kinase B (TrkB) /phosphatidylinositol-3-hydroxykinase (PI3K) /protein kinase B (Akt) signaling pathway in rats with learning and memory impairment after middle cerebral artery occlusion reperfusion (MCAO/R) . Methods A total of 60 8-week-old healthy male SD rats were selected from May 2021 to March 2022, and 24 rats were divided into the blank group (n=12) and sham operation group (n=12), and the other 36 rats were constructed as MCAO/R model. The 24 rats with successful modeling were randomly divided into the model group (n=12) and electroacupuncture group (n=12). The electroacupuncture treatment was performed at Shenting and Baihui points in the electroacupuncture group. Zea-Longa score was used to observe the degree of neurological impairment in each group. Spatial probe test was used to evaluate the spatial learning and memory ability of the rats. TTC staining was used to observe the volume of brain infarction in rats. RT-PCR was used to measure the mRNA levels of BDNF, TrkB, PI3K and Akt, Western blotting was used to detect the protein levels of BDNF and TrkB and the levels of p-PI3K/PI3K and p-Akt/Akt. Results Zea-Longa score of the model group and electroacupuncture group was significantly different from the blank group and sham operation group at 2 h after surgery (P

Neuron navigator 1 (Nav1) is a cytoskeleton-associated protein expressed during brain development that is necessary for proper neuritogenesis, but the underlying mechanisms are poorly understood. Here we show that Nav1 is present in elongating axon tracts during mouse brain embryogenesis. We found that depletion of Nav1 in cultured neurons disrupts growth cone morphology and neurotrophin-stimulated neuritogenesis. In addition to regulating both F-actin and microtubule properties, Nav1 promotes actin-rich membrane ruffles in the growth cone and promotes macropinocytosis at those membrane ruffles, including internalization of the TrkB receptor for the neurotrophin brain-derived neurotropic factor (BDNF). Growth cone macropinocytosis is important for downstream signaling, neurite targeting, and membrane recycling, implicating Nav1 in one or more of these processes. Depletion of Nav1 also induces transient membrane blebbing via disruption of signaling in the Rho GTPase signaling pathway, supporting the novel role of Nav1 in dynamic actin-based membrane regulation at the cell periphery. These data demonstrate that Nav1 works at the interface of microtubules, actin, and plasma membrane to organize the cell periphery and promote uptake of growth and guidance cues to facilitate neural morphogenesis during development.

IntroductionThe Management of Myelomeningocele Study demonstrated that in utero repair of myelomeningocele improved motor outcomes compared with postnatal repair. However, even after in utero repair, many children were still unable to walk. We have previously demonstrated that augmentation of in utero repair with early-gestation placental mesenchymal stromal cells (PMSCs) improves motor outcomes in lambs compared with standard in utero repair. The neuroprotective potential of PMSCs of all gestational ages has not been evaluated previously.MethodsPMSCs were isolated from discarded first trimester (n = 3), second trimester (n = 3), and term (n = 3) placentas by explant culture. Cytokine array analysis was performed. Secretion of two neurotrophic factors, brain-derived neurotrophic factor and hepatocyte growth factor, was evaluated by enzyme-linked immunosorbent assay. An in vitro neuroprotective assay demonstrated to be associated with in vivo function was performed.ResultsAll cell lines secreted immunomodulatory and neuroprotective cytokines and secreted the neurotrophic factors evaluated. Increased neuroprotective capabilities relative to no PMSCs were demonstrated in two of the three first trimester cell lines (5.61, 4.96-6.85, P

Introduction/aimsAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative illness with great unmet patient need. We aimed to evaluate whether mesenchymal stem cells induced to secrete high levels of neurotrophic factors (MSC-NTF), a novel autologous cell-therapy capable of targeting multiple pathways, could safely slow ALS disease progression.MethodsThis randomized, double-blind, placebo-controlled study enrolled ALS participants meeting revised El Escorial criteria, revised ALS Functional Rating Scale (ALSFRS-R) ≥25 (screening) and ≥3 ALSFRS-R points decline prior to randomization. Participants received three treatments of MSC-NTF or placebo intrathecally. The primary endpoint evaluated efficacy of MSC-NTF through a responder analysis and safety. A change in disease progression post-treatment of ≥1.25 points/mo defines a clinical response. A pre-specified analysis leveraged baseline ALSFRS-R of 35 as a subgroup threshold.ResultsOverall, MSC-NTF treatment was well tolerated; there were no safety concerns. Thirty-three percent of MSC-NTF and 28% of placebo participants met clinical response criteria at 28 wk (odds ratio [OR] = 1.33, P = .45); thus, the primary endpoint was not met. A pre-specified analysis of participants with baseline ALSFRS-R ≥ 35 (n = 58) showed a clinical response rate at 28 wk of 35% MSC-NTF and 16% placebo (OR = 2.6, P = .29). Significant improvements in cerebrospinal biomarkers of neuroinflammation, neurodegeneration, and neurotrophic factor support were observed with MSC-NTF, with placebo unchanged.DiscussionThe study did not reach statistical significance on the primary endpoint. However, a pre-specified subgroup suggests that MSC-NTF participants with less severe disease may have retained more function compared to placebo. Given the unmet patient need, the results of this trial warrant further investigation.

One of the most prevalent causes of olfactory loss includes traumatic brain injury with subsequent shearing of olfactory axons at the level of the cribriform plate (anterior skull base). Scar tissue at this level may prevent axonal regrowth toward the olfactory bulb. Currently, there is no cure for this debilitating and often permanent condition. One promising therapeutic concept is to implant a synthetic scaffold with growth factors through the cribriform plate/scar tissue to induce neuroregeneration. The first step toward this goal is to investigate the optimum conditions (growth factors, extracellular matrix proteins) to boost this regeneration. However, the lack of a specifically tailored in vitro model and an automated procedure for quantifying axonal length limits our ability to address this issue. The aim of this study is to create an automated quantification tool to measure axonal length and to determine the ideal growth factors and extracellular proteins to enhance axonal regrowth of olfactory sensory neurons in a mouse organotypic 2D model. We harvested olfactory epithelium (OE) of C57BL/6 mice and cultured them during 15 days on coverslips coated with various extracellular matrix proteins (Fibronectin, Collagen IV, Laminin, none) and different growth factors: fibroblast growth factor 2 (FGF2), brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), nerve growth factor (NGF), retinoic acid (RA), transforming growth factor β (TGFβ), and none. We measured the attachment rate on coverslips, the presence of cellular and axonal outgrowth, and finally, the total axonal length with a newly developed automated high-throughput quantification tool. Whereas the coatings did not influence attachment and neuronal outgrowth rates, the total axonal length was enhanced on fibronectin and collagen IV (p = 0.001). The optimum growth factor supplementation media to culture OE compared to the control condition were as follows: FGF2 alone and FGF2 from day 0 to 7 followed by FGF2 in combination with NGF from day 7 to 15 (p < 0.0001). The automated quantification tool to measure axonal length outperformed the standard Neuron J application by reducing the average analysis time from 22 to 3 min per specimen. In conclusion, robust regeneration of murine olfactory neurons in vitro can be induced, controlled, and efficiently measured using an automated quantification tool. These results will help advance the therapeutic concept closer toward preclinical studies. [ABSTRACT FROM AUTHOR]

Age-related macular degeneration (AMD) is the primary cause of blindness in adults over 60 years of age, and clinical trials are currently assessing the therapeutic potential of retinal pigmented epithelial (RPE) cell monolayers on implantable scaffolds to treat this disease. However, challenges related to the culture, long-term storage, and long-distance transport of such implants currently limit the widespread use of adherent RPE cells as therapeutics. Here we report a xeno-free protocol to cryopreserve a confluent monolayer of clinical-grade, human embryonic stem cell-derived RPE cells on a parylene scaffold (REPS) that yields viable, polarized, and functional RPE cells post-thaw. Thawed cells exhibit ≥ 95% viability, have morphology, pigmentation, and gene expression characteristic of mature RPE cells, and secrete the neuroprotective protein, pigment epithelium-derived factor (PEDF). Stability under liquid nitrogen (LN2) storage has been confirmed through one year. REPS were administered immediately post-thaw into the subretinal space of a mammalian model, the Royal College of Surgeons (RCS)/nude rat. Implanted REPS were assessed at 30, 60, and 90 days post-implantation, and thawed cells demonstrate survival as an intact monolayer on the parylene scaffold. Furthermore, immunoreactivity for the maturation marker, RPE65, significantly increased over the post-implantation period in vivo, and cells demonstrated functional attributes similar to non-cryopreserved controls. The capacity to cryopreserve adherent cellular therapeutics permits extended storage and stable transport to surgical sites, enabling broad distribution for the treatment of prevalent diseases such as AMD.

Strabismus is a genetically heterogeneous disorder with complex molecular and neurophysiological causes. Evidence in the literature suggests a strong role for motor innervation in the etiology of strabismus, which connects central neural processes to the peripheral extraocular muscles. Current treatments of strabismus through surgery show that an inherent sensorimotor plasticity in the ocular motor system decreases the effectiveness of treatment, often driving eye alignment back toward its misaligned pre-surgical state by altering extraocular muscle tonus. There is recent interest in capitalizing on existing biological processes in extraocular muscles to overcome these compensatory mechanisms. Neurotrophins are trophic factors that regulate survival and development in neurons and muscle, including extraocular muscles. Local administration of neurotrophins to extraocular muscles partially reversed strabismus in an animal model of strabismus. The hypothesis is that sustained release of neurotrophins gives more time for the ocular motor system to adapt to a slow change in alignment in the desired direction. The effect of neurotrophins on extraocular muscles is complex, as different neurotrophic factors have diverse effects on extraocular muscle contraction profiles, patterns of innervation, and density of extraocular muscle precursor cells. Neurotrophic factors show promise as a therapeutic option for strabismus, which may help to improve treatment outcomes and offset devastating amblyopia and psychosocial effects of disease in strabismus patients.

In this review, an attempt was made to substantiate the possibility for neurotrophins to be involved in the development of immune tolerance based on data accumulated on neurotrophin content and receptor expression in the trophoblast and immune cells, in particular, in natural killer cells. Numerous research results are reviewed to show that the expression and localization of neurotrophins along with their high‐affinity tyrosine kinase receptors and low‐affinity p75NTR receptor in the mother‐placenta‐fetus system indicate the important role of neurotrophins as binding molecules in regulating the crosstalk between the nervous, endocrine, and immune systems in pregnancy. An imbalance between these systems can occur with tumor growth and pathological processes observed in pregnancy complications and fetal development anomalies. [ABSTRACT FROM AUTHOR]

One million estimated cases of spinal cord injury (SCI) have been reported in the United States and repairing an injury has constituted a difficult clinical challenge. The complex, dynamic, inhibitory microenvironment postinjury, which is characterized by proinflammatory signaling from invading leukocytes and lack of sufficient factors that promote axonal survival and elongation, limits regeneration. Herein, we investigated the delivery of polycistronic vectors, which have the potential to coexpress factors that target distinct barriers to regeneration, from a multiple channel poly(lactide-co-glycolide) (PLG) bridge to enhance spinal cord regeneration. In this study, we investigated polycistronic delivery of IL-10 that targets proinflammatory signaling, and NT-3 that targets axonal survival and elongation. A significant increase was observed in the density of regenerative macrophages for IL-10+NT-3 condition relative to conditions without IL-10. Furthermore, combined delivery of IL-10+NT-3 produced a significant increase of axonal density and notably myelinated axons compared with all other conditions. A significant increase in functional recovery was observed for IL-10+NT-3 delivery at 12 weeks postinjury that was positively correlated to oligodendrocyte myelinated axon density, suggesting oligodendrocyte-mediated myelination as an important target to improve functional recovery. These results further support the use of multiple channel PLG bridges as a growth supportive substrate and platform to deliver bioactive agents to modulate the SCI microenvironment and promote regeneration and functional recovery. Impact statement Spinal cord injury (SCI) results in a complex microenvironment that contains multiple barriers to regeneration and functional recovery. Multiple factors are necessary to address these barriers to regeneration, and polycistronic lentiviral gene therapy represents a strategy to locally express multiple factors simultaneously. A bicistronic vector encoding IL-10 and NT-3 was delivered from a poly(lactide-co-glycolide) bridge, which provides structural support that guides regeneration, resulting in increased axonal growth, myelination, and subsequent functional recovery. These results demonstrate the opportunity of targeting multiple barriers to SCI regeneration for additive effects.

Axon initial segments (AISs) initiate action potentials and regulate the trafficking of vesicles between somatodendritic and axonal compartments. However, the mechanisms controlling AIS assembly remain poorly defined. We performed differential proteomics and found nuclear mitotic apparatus protein 1 (NuMA1) is downregulated in AIS-deficient neonatal mouse brains and neurons. NuMA1 is transiently located at the AIS during development where it interacts with the scaffolding protein 4.1B and the dynein regulator lissencephaly 1 (Lis1). Silencing NuMA1 or protein 4.1B by shRNA disrupts AIS assembly, but not maintenance. Silencing Lis1 or overexpressing NuMA1 during AIS assembly increased the density of AIS proteins, including ankyrinG and neurofascin-186 (NF186). NuMA1 inhibits the endocytosis of AIS NF186 by impeding Lis1's interaction with doublecortin, a potent facilitator of NF186 endocytosis. Our results indicate the transient expression and AIS localization of NuMA1 stabilizes the developing AIS by inhibiting endocytosis and removal of AIS proteins.

BackgroundTreatments for autoimmune diseases aim to dampen autoreactivity while preserving normal immune function. In CD4+ T cells, the transcription factor Oct1/Pou2f1 is a dispensable transcription factor for T cell development and response to primary infection, but promotes expression of target genes, including Il2 and Ifng, under conditions of antigen reencounter. As a result, they are more strongly expressed upon secondary stimulation. Such repeated antigen encounters occur in memory recall responses, in autoimmunity where self-antigen can be recognized multiple times, and in chronic infection where foreign antigen is persistent. Based on these previous findings, we hypothesized that Oct1 loss would protect animals from autoimmunity but maintain normal responses to pathogens in the CNS.ObjectiveWe used a conditional mouse Oct1 (Pou2f1) allele and a CD4-Cre driver to determine the effect of T cell-specific Oct1 loss on autoimmune- and viral-induced neuroinflammation using an autoantigen-driven EAE model of autoimmunity and a JHMV model of viral infection.ResultsOct1 conditional deletion mitigated clinical scores and reduced infiltrating T cells and cytokine production in the EAE model. Consistently, Oct1-deficient CD4+ T cells stimulated in vitro showed increased expression of markers associated with T cell anergy, particularly in the absence of co-stimulatory signals. In contrast, anti-viral T cell effector functions are intact in the absence of Oct1, with no changes in neuroinflammation, infiltrating T cells or cytokine production.ConclusionOur findings uncover a significant difference between the effect of Oct1 loss on autoimmune and anti-pathogen responses, which potentially could be exploited for therapeutic benefit.

Simple Summary: A 3D scaffold developed for inguinal hernia repair has been designed to overcome the multiple incongruences of currently used flat meshes. Conventional hernia implants, positioned in a high-motile environment, are static, need fixation and, instead of healing the degenerative source of hernia disease, produce a granuloma of low-quality scar tissue. On the contrary, the new 3D scaffold, endowed with centrifugal expansion, avoids fixation, reacts dynamically to the motile impulses of the groin and attracts tissue growth factors, promoting the development of newly formed tissue structures. Despite being made of the same polypropylene material as conventional flat meshes, the dynamic behavior of the 3D scaffold that moves in tune with inguinal movements proves that modifying the design and kinetic attitude turns the biological response into tissue regeneration. Surgical repair of groin protrusions is one of the most frequently performed procedures. Currently, open or laparoscopic repair of inguinal hernias with flat meshes deployed over the hernial defect is considered the gold standard. However, fixation of the implant, poor quality biologic response to meshes and defective management of the defect represent sources of continuous debates. To overcome these issues, a different treatment concept has recently been proposed. It is based on a 3D scaffold named ProFlor, a flower shaped multilamellar device compressible on all planes. This 3D device is introduced into the hernial opening and, thanks to its inherent centrifugal expansion, permanently obliterates the defect in fixation-free fashion. While being made of the same polypropylene material as conventional hernia implants, the 3D design of ProFlor confers a proprietary dynamic responsivity, which unlike the foreign body reaction of flat/static meshes, promotes a true regenerative response. A long series of scientific evidence confirms that, moving in compliance with the physiologic cyclical load of the groin, ProFlor attracts tissue growth factors inducing the development of newly formed muscular, vascular and nervous structures, thus re-establishing the inguinal barrier formerly wasted by hernia disease. The development up to complete maturation of these highly specialized tissue elements was followed thanks to biopsies excised from ProFlor from the short-term up to years post implantation. Immunohistochemistry made it possible to document the concurrence of specific growth factors in the regenerative phenomena. The results achieved with ProFlor likely demonstrate that modifying the two-dimensional design of hernia meshes into a 3D outline and arranging the device to respond to kinetic stresses turns a conventional regressive foreign body response into advanced probiotic tissue regeneration. [ABSTRACT FROM AUTHOR]

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Identification of conditions for guided and specific differentiation of human stem cell and progenitor cells is important for continued development and engineering of in vitro cell culture systems for use in regenerative medicine, drug discovery, and human toxicology. Three-dimensional (3D) and organotypic cell culture models have been used increasingly for in vitro cell culture because they may better model endogenous tissue environments. However, detailed studies of stem cell differentiation within 3D cultures remain limited, particularly with respect to high-throughput screening. Herein, we demonstrate the use of a microarray chip-based platform to screen, in high-throughput, individual and paired effects of 12 soluble factors on the neuronal differentiation of a human neural progenitor cell line (ReNcell VM) encapsulated in microscale 3D Matrigel cultures. Dose-response analysis of selected combinations from the initial combinatorial screen revealed that the combined treatment of all-trans retinoic acid (RA) with the glycogen synthase kinase 3 inhibitor CHIR-99021 (CHIR) enhances neurogenesis while simultaneously decreases astrocyte differentiation, whereas the combined treatment of brain-derived neurotrophic factor and the small azide neuropathiazol enhances the differentiation into neurons and astrocytes. Subtype specification analysis of RA- and CHIR-differentiated cultures revealed that enhanced neurogenesis was not biased toward a specific neuronal subtype. Together, these results demonstrate a high-throughput screening platform for rapid evaluation of differentiation conditions in a 3D environment, which will aid the development and application of 3D stem cell culture models.

Retinitis pigmentosa is the most common form of inherited blindness and can be caused by a multitude of different genetic mutations that lead to similar phenotypes. Specifically, mutations in ubiquitously expressed splicing factor proteins are known to cause an autosomal dominant form of the disease, but the retina-specific pathology of these mutations is not well understood. Fibroblasts from a patient with splicing factor retinitis pigmentosa caused by a missense mutation in the PRPF8 splicing factor were used to produce three diseased and three CRISPR/Cas9-corrected induced pluripotent stem cell (iPSC) clones. We differentiated each of these clones into retinal pigment epithelial (RPE) cells via directed differentiation and analyzed the RPE cells in terms of gene and protein expression, apicobasal polarity, and phagocytic ability. We demonstrate that RPE cells can be produced from patient-derived and corrected cells and they exhibit morphology and functionality similar but not identical to wild-type RPE cells in vitro. Functionally, the RPE cells were able to establish apicobasal polarity and phagocytose photoreceptor outer segments at the same capacity as wild-type cells. These data suggest that patient-derived iPSCs, both diseased and corrected, are able to differentiate into RPE cells with a near normal phenotype and without differences in phagocytosis, a result that differs from previous mouse models. These RPE cells can now be studied to establish a disease-in-a-dish system relevant to retinitis pigmentosa.

We have described a novel cytokine encoded by a gene called Meteorin-like (Metrnl). Metrnl is a small (∼28 kDa) secreted protein expressed by activated macrophages and barrier tissues (mucosa and skin). Metrnl production by bone marrow macrophages is induced by several cytokines including TNF-α, IL-17α, IL-12, and IL-4 and inhibited by IFN-γ and TGF-β. Metrnl expression in macrophages is also induced by LPS, and its levels in circulation are associated with inflammatory responses in vivo. Furthermore, Metrnl regulates the production of several cytokines and chemokines in macrophages. We have produced a Metrnl-/- mouse, which is viable and shows normal development. However, it exhibits dysregulated cytokine production, alterations in IgG production, and is highly susceptible to LPS in a sepsis model. Furthermore, older Metrnl-/- mice develop inflammatory lesions, suggesting that Metrnl participates in the control of inflammatory responses. Taken together, these observations indicate that Metrnl encodes a novel immunoregulatory cytokine associated with inflammatory responses that we have designated Meteorin-β.

Spider silks have outstanding potential as biomaterials due to their sought‐after mechanical properties and low immunogenicity. The toughest spider silk is aciniform silk, which is used by spiders to wrap prey and produce egg sacs. A variety of recombinant aciniform silk constructs are now been developed, including hybrid silks with domains from multiple spider silk proteins fused together. In this study, an engineered aciniform silk construct, termed NBSilk, fused both N‐ and C‐terminally to heptapeptide motifs that bind the neurotrophic factor and nerve growth factor‐β (NGF) is introduced. NBSilk is shown to be amenable to casting into robust films that remain intact while sequestering and maintaining bioactive NGF at the film surface for at least 7 days. These films support cell survival while enhancing differentiation and neurite density and outgrowth in neuron‐like PC12 cells, with elevation of signaling through both the mitogen‐activated protein kinase (MAPK) and protein kinase B (AKT) signaling pathways. Strikingly, preloading of NBSilk films with NGF enhances neuritogenesis even over conditions where cells are grown with NGF supplementation in the culture medium. NBSilk scaffolds, thus, warrant future development and evaluation as biomaterials for nerve regeneration. [ABSTRACT FROM AUTHOR]

Wangseok Do,1 Jiseok Baik,1,2 Soeun Jeon,1 Chang-Min You,1 Dahyun Kang,1 Young-Hoon Jung,1 Jiyoon Lee,3 Hae-Kyu Kim1,2 1Department of Anesthesia and Pain Medicine and Biomedical Research Institute Pusan National University Hospital, Busan, Republic of Korea; 2Department of Anesthesia and Pain Medicine, School of Medicine, Pusan National University, Busan, Republic of Korea; 3Department of Anesthesia and Pain Medicine, Seoul National University Bundang Hospital, Seongnam-si, Gyeonggi-do, Republic of KoreaCorrespondence: Jiseok BaikDepartment of Anesthesia and Pain Medicine and Biomedical Research Institute Pusan National University Hospital, 179 Gudeok-Ro, Seo-gu, Busan, 49241, Republic of Korea, Tel +82-51-240-7499, Fax +82-51-242-7466, Email jidal75@naver.comBackground: The present study aimed to develop a rat model for mechanical allodynia after traumatic brain injury (TBI) and to investigate the expression of brain-derived neurotrophic factor (BDNF) in the cerebrospinal fluid (CSF) using this model.Methods: A total of 180 rats were randomly allocated into three groups: a control group (group C), a sham-operated group (group S), and a controlled cortical impact induced TBI group (group T), 60 in each group. Von Frey test was performed to evaluate mechanical withdrawal thresholds. An enzyme-linked immunosorbent assay was performed to quantify BDNF level in CSF.Results: The 50% withdrawal thresholds of group T were lower than those of group C and group S at all measuring points except for the preoperative period (P = 0.026, < 0.001, and < 0.001 for POD1, POD7, and POD14, respectively). The BDNF level of group T was higher than those of group C and group S at POD1 (P = 0.005).Conclusion: Upregulation of the BDNF expression in CSF was observed in rats who developed mechanical allodynia on the day after TBI. Based on our findings, to elucidate the relationship between TBI-induced neuropathic pain and BDNF expression in CSF, further research should be carried out through a multifaceted approach to a broad spectrum of pain behavior models.Keywords: brain injuries, traumatic, brain injuries, brain-derived neurotrophic factor, nerve growth factors, neuralgia, models, animal

One of the most prevalent causes of olfactory loss includes traumatic brain injury with subsequent shearing of olfactory axons at the level of the cribriform plate (anterior skull base). Scar tissue at this level may prevent axonal regrowth toward the olfactory bulb. Currently, there is no cure for this debilitating and often permanent condition. One promising therapeutic concept is to implant a synthetic scaffold with growth factors through the cribriform plate/scar tissue to induce neuroregeneration. The first step toward this goal is to investigate the optimum conditions (growth factors, extracellular matrix proteins) to boost this regeneration. However, the lack of a specifically tailored in vitro model and an automated procedure for quantifying axonal length limits our ability to address this issue. The aim of this study is to create an automated quantification tool to measure axonal length and to determine the ideal growth factors and extracellular proteins to enhance axonal regrowth of olfactory sensory neurons in a mouse organotypic 2D model. We harvested olfactory epithelium (OE) of C57BL/6 mice and cultured them during 15 days on coverslips coated with various extracellular matrix proteins (Fibronectin, Collagen IV, Laminin, none) and different growth factors: fibroblast growth factor 2 (FGF2), brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), nerve growth factor (NGF), retinoic acid (RA), transforming growth factor β (TGFβ), and none. We measured the attachment rate on coverslips, the presence of cellular and axonal outgrowth, and finally, the total axonal length with a newly developed automated high-throughput quantification tool. Whereas the coatings did not influence attachment and neuronal outgrowth rates, the total axonal length was enhanced on fibronectin and collagen IV (p = 0.001). The optimum growth factor supplementation media to culture OE compared to the control condition were as follows: FGF2 alone and FGF2 from day 0 to 7 followed by FGF2 in combination with NGF from day 7 to 15 (p < 0.0001). The automated quantification tool to measure axonal length outperformed the standard Neuron J application by reducing the average analysis time from 22 to 3 min per specimen. In conclusion, robust regeneration of murine olfactory neurons in vitro can be induced, controlled, and efficiently measured using an automated quantification tool. These results will help advance the therapeutic concept closer toward preclinical studies.

Numerous genetic and functional studies implicate variants of Neuregulin-1 (NRG1) and its neuronal receptor ErbB4 in schizophrenia and many of its endophenotypes. Although the neurophysiological and behavioral phenotypes of NRG1 mutant mice have been investigated extensively, practically nothing is known about the function of NRG2, the closest NRG1 homolog. We found that NRG2 expression in the adult rodent brain does not overlap with NRG1 and is more extensive than originally reported, including expression in the striatum and medial prefrontal cortex (mPFC), and therefore generated NRG2 knockout mice (KO) to study its function. NRG2 KOs have higher extracellular dopamine levels in the dorsal striatum but lower levels in the mPFC; a pattern with similarities to dopamine dysbalance in schizophrenia. Like ErbB4 KO mice, NRG2 KOs performed abnormally in a battery of behavioral tasks relevant to psychiatric disorders. NRG2 KOs exhibit hyperactivity in a novelty-induced open field, deficits in prepulse inhibition, hypersensitivity to amphetamine, antisocial behaviors, reduced anxiety-like behavior in the elevated plus maze and deficits in the T-maze alteration reward test-a task dependent on hippocampal and mPFC function. Acute administration of clozapine rapidly increased extracellular dopamine levels in the mPFC and improved alternation T-maze performance. Similar to mice treated chronically with N-methyl-d-aspartate receptor (NMDAR) antagonists, we demonstrate that NMDAR synaptic currents in NRG2 KOs are augmented at hippocampal glutamatergic synapses and are more sensitive to ifenprodil, indicating an increased contribution of GluN2B-containing NMDARs. Our findings reveal a novel role for NRG2 in the modulation of behaviors with relevance to psychiatric disorders.

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER) protein that can be secreted and protects dopamine neurons and cardiomyocytes from ER stress and apoptosis. The mechanism of action of extracellular MANF has long been elusive. From a genetic screen for mutants with abnormal ER stress response, we identified the gene Y54G2A.23 as the evolutionarily conserved C. elegans MANF orthologue. We find that MANF binds to the lipid sulfatide, also known as 3-O-sulfogalactosylceramide present in serum and outer-cell membrane leaflets, directly in isolated forms and in reconstituted lipid micelles. Sulfatide binding promotes cellular MANF uptake and cytoprotection from hypoxia-induced cell death. Heightened ER stress responses of MANF-null C. elegans mutants and mammalian cells are alleviated by human MANF in a sulfatide-dependent manner. Our results demonstrate conserved roles of MANF in sulfatide binding and ER stress response, supporting sulfatide as a long-sought lipid mediator of MANF's cytoprotection.

Neurotrophic factors, including the members of the neurotrophin family, play important roles in the development and maintenance of the nervous system. Trophic factor signals must be transmitted over long distances from axons and dendrites to the cell bodies of neurons. A mode of signaling well suited to the challenge of robust long distance signaling is the signaling endosome. We review the biology of signaling endosomes and the "signaling endosome hypothesis". Evidence for disruption of signaling endosome function in disorders of the nervous system is also reviewed. Changes in endosome structure in Alzheimer disease (AD) and Down syndrome (DS) are present early in these disorders. Data for the APP products responsible are reviewed and the consequent changes in signaling from endosomes discussed. We conclude by pointing to the need for additional studies to explore the biology of signaling endosomes in normal neurons and to elucidate their role in the pathogenesis of neurodegeneration.

Objective The purpose of this study is to investigate apoptosis of hippocampal neurons and the expression of glial cell line⁃derived neurotrophic factor (GDNF) and brain⁃derived neurotrophic factor (BDNF) in neonatal pups with EDNRB gene deficiency. Methods The infant rats (2-3 d after birth) with EDNRB gene defect caused by congenital base deletion were divided into wild (+/+), heterozygous (+/sl) and homozygous (sl/sl), 6-8 rats were included in each group. Apoptosis of hippocampal nerve cells was detected by TUNEL staining. The number of apoptotosic cells was calculated by confocal fluorescence microscopy, and the levels of GDNF and BDNF in hippocampus was determined by enzyme⁃linked immunsorbent assay (ELISA). Results The number of apoptotic cells in hippocampus of the three genotypes was significantly different (F=24.315, P=0.000), the number of apoptotic cells in sl/sl was higher than that in +/+ (t=⁃6.780, P=0.000) and +/sl (t=4.801, P=0.000). The number of apoptotic cells was the highest in hippocampal CA1 region, followed by CA3 region, and the lowest in dentate gyrus. However, there was no significant difference in the levels of BDNF (F=0.766, P=0.479) and GDNF (F=2.538, P=0.107) in the hippocampus between different genotypes. Conclusions In rat with EDNRB gene defect, compared with the heterozygote and wild rats, the neural apoptosis were increased in hippocampal CA1, CA3 regions. But the levels of neurotrophic factors BDNF and GDNF were not significantly changed.

WT p53 is critical for tumor suppression, whereas mutant p53 promotes tumor progression. Nerve injury-induced protein 1 (Ninj1) is a target of p53 and forms a feedback loop with p53 by repressing p53 mRNA translation. Here, we show that loss of Ninj1 increased mutant p53 expression and, subsequently, enhanced cell growth and migration in cells carrying a mutant p53. In contrast, loss of Ninj1 inhibited cell growth and migration in cells carrying a WT p53. To explore the biological significance of Ninj1, we generated a cohort of Ninj1-deficient mice and found that Ninj1+/- mice were prone to systemic inflammation and insulitis, but not to spontaneous tumors. We also found that loss of Ninj1 altered the tumor susceptibility in both mutant p53 and p53-null background. Specifically, in a mutant p53(R270H) background, Ninj1 deficiency shortened the lifespan, altered the tumor spectrum, and increased tumor burden, likely via enhanced expression of mutant p53. In a p53-null background, Ninj1 deficiency significantly increased the incidence of T-lymphoblastic lymphoma. Taken together, our data suggest that depending on p53 genetic status, Ninj1 has two opposing functions in tumorigenesis and that the Ninj1-p53 loop may be targeted to manage inflammatory diseases and cancer.

The canonical model for netrin1 function proposed that it acted as a long-range chemotropic axon guidance cue. In the developing spinal cord, floor-plate (FP)-derived netrin1 was thought to act as a diffusible attractant to draw commissural axons to the ventral midline. However, our recent studies have shown that netrin1 is dispensable in the FP for axon guidance. We have rather found that netrin1 acts locally: netrin1 is produced by neural progenitor cells (NPCs) in the ventricular zone (VZ), and deposited on the pial surface as a haptotactic adhesive substrate that guides Dcc+ axon growth. Here, we further demonstrate that this netrin1 pial-substrate has an early role orienting pioneering spinal axons, directing them to extend ventrally. However, as development proceeds, commissural axons choose to grow around a boundary of netrin1 expressing cells in VZ, instead of continuing to extend alongside the netrin1 pial-substrate in the ventral spinal cord. This observation suggests netrin1 may supply a more complex activity than pure adhesion, with netrin1-expressing cells also supplying a growth boundary for axons. Supporting this possibility, we have observed that additional domains of netrin1 expression arise adjacent to the dorsal root entry zone (DREZ) in E12.5 mice that are also required to sculpt axonal growth. Together, our studies suggest that netrin1 provides "hederal" boundaries: a local growth substrate that promotes axon extension, while also preventing local innervation of netrin1-expressing domains.

The septin cytoskeleton is primarily known for roles in cell division and host defense against bacterial infection. Despite recent insights, the full breadth of roles for septins in host defense is poorly understood. In macrophages, Shigella induces pyroptosis, a pro-inflammatory form of cell death dependent upon gasdermin D (GSDMD) pores at the plasma membrane and cell surface protein ninjurin-1 (NINJ1) for membrane rupture. Here, we discover that septins promote macrophage pyroptosis induced by lipopolysaccharide (LPS)/nigericin and Shigella infection, but do not affect cytokine expression or release. We observe that septin filaments assemble at the plasma membrane, and cleavage of GSDMD is impaired in septin-depleted cells. We found that septins regulate mitochondrial dynamics and the expression of NINJ1. Using a Shigella-zebrafish infection model, we show that septin-mediated pyroptosis is an in vivo mechanism of infection control. The discovery of septins as a mediator of pyroptosis may inspire innovative anti-bacterial and anti-inflammatory treatments., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: In the current study, it was aimed to evaluate neurotrophic factor levels and their relationship with executive functions in high-risk children and adolescents (high-risk group) whose parents were diagnosed with bipolar disorder (BD) but not affected by any psychiatric disease,and in order to determine possible vulnerability factors related to the disease., Methods: The study sample consisted of 32 high-risk group and 34 healthy controls. The Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version-Turkish Adaptation (KSADS-PL-T), Stroop Test, Serial Digit Learning Test (SDLT) and Cancellation Test to evaluate executive functions were administered to all participants by the clinician.Serum levels of neurotrophic factors were measured using commercial enzyme linked immunosorbent assay kits., Results: Serum BDNF, NT-3, NT-4 levels and SDLT scores were significantly lower in the high-risk group for BD compared to the healthy control group. A moderate negative correlation was found between BDNF levels and the Cancellation Test scores in the high-risk group. In addition to these results, the odds ratios of age, NT-4, SDLT scores for being in the risky group in terms of BD diagnosis were 1.26, 0.99 and 0.86 respectively., Limitations: This was a cross-sectional study. Causality between study results is therefore difficult to establish. The relatively small sample size of the study is another limitation., Conclusion: The results of the present study suggest that BDNF, NT-3, NT-4 may play a role in the physiopathology of BD and may be associated with impaired executive function areas such as attention and response inhibition in the high-risk group., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Financial disclosure Supported by Selcuk University Scientific Research Projects Coordination Office with the project number 21122019., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: To analyze the clinical features of anti-neurofascin-155 (NF155) antibody positive autoimmune nodopathy in children. Methods: This was a case series study. A total of 6 children who were diagnosed accurately as anti-NF155 antibody positive autoimmune nodopathy by cell immunofluorescence assay at the Children's Hospital of Fudan University from January 2020 to December 2023 were collected. This study retrospectively analyzed 6 pediatric children's clinical manifestations, laboratory and electrophysiological examination results, and treatment outcomes. Results: Among 6 children with anti-NF155 antibody positive autoimmune nodopathy, there were 4 boys and 2 girls. The onset age of 6 children ranged from 3 years and 8 months to 12 years. All 6 children had extremity weakness (more severe in the distal and the lower extremities than in the upper extremities), 5 children had sensory deficits such as numbness or pain in the extremities, 4 children had tremors and ataxia, 3 children had cranial nerve involvement. Among the 6 children, 4 children had protein-cell separation in cerebrospinal fluid examinations. Among the 6 children, 1 child had central nervous system demyelination, the brain magnetic resonance imaging showed multiple abnormal signals in the bilateral cerebral hemispheres. Four children showed motor and sensory nerve damage in electrophysiological examination, and 2 children only showed motor nerve damage. Three children showed myelin and axonal damage, and 3 children only showed axonal damage. Among the 6 children, 5 children were treated with intravenous immunoglobulin and steroids. Among them, 2 children underwent plasma exchange due to poor efficacy, and subsequently, rituximab was added. There was 1 child changed the treatment with olfatomumab since the symptoms did not significantly improve after using rituximab. After treatment for 4-15 months, 2 children had no clinical symptoms, 1 child had improvement in clinical symptoms, 2 children had no significant improvement in clinical symptoms, and 1 child who did not receive the immunotherapy had no significant change in clinical symptoms. Conclusions: Anti-NF155 antibody positive autoimmune nodopathy in children presents with varying degrees of clinical manifestations. It is mainly characterized by extremity weakness, numbness and pain, often accompanied bytremorsand ataxia. Some pediatric patients may also have central nervous system demyelination. Cerebrospinal fluid and electrophysiological examination are important auxiliary examination methods. If steroid therapy is not effective, plasma exchange and rituximab treatment should be used as soon as possible.

Abdominal aortic aneurysm (AAA) is a common and potentially life-threatening condition. Chronic aortic inflammation is closely associated with the pathogenesis of AAA. Nerve injury-induced protein 1 (NINJ1) is increasingly acknowledged as a significant regulator of the inflammatory process. However, the precise involvement of NINJ1 in AAA formation remains largely unexplored. The present study finds that the expression level of NINJ1 is elevated, along with the specific expression level in macrophages within human and angiotensin II (Ang II)-induced murine AAA lesions. Furthermore, Ninj1 flox/flox and Ninj1 flox/flox Lyz2-Cre mice on an ApoE -/- background are generated, and macrophage NINJ1 deficiency inhibits AAA formation and reduces macrophage infiltration in mice infused with Ang II. Consistently, in vitro suppressing the expression level of NINJ1 in macrophages significantly restricts macrophage adhesion and migration, while attenuating macrophage pro-inflammatory responses. Bulk RNA-sequencing and pathway analysis uncover that NINJ1 can modulate macrophage infiltration through the TLR4/NF-κB/CCR2 signaling pathway. Protein-protein interaction analysis indicates that NINJ1 can activate TLR4 by competitively binding with ANXA2, an inhibitory interacting protein of TLR4. These findings reveal that NINJ1 can modulate AAA formation by promoting macrophage infiltration and pro-inflammatory responses, highlighting the potential of NINJ1 as a therapeutic target for AAA., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Acetaminophen (APAP), a widely used pain and fever reliever, is a major contributor to drug-induced liver injury, as its toxic metabolites such as NAPQI induce oxidative stress and hepatic necrosis. While N-acetylcysteine serves as the primary treatment for APAP-induced liver injury (AILI), its efficacy is confined to a narrow window of 8-24 h post-APAP overdose. Beyond this window, liver transplantation emerges as the final recourse, prompting ongoing research to pinpoint novel therapeutic targets aimed at enhancing AILI treatment outcomes. Nerve injury-induced protein 1 (Ninjurin1; Ninj1), initially recognized as an adhesion molecule, has been implicated in liver damage stemming from factors like TNFα and ischemia-reperfusion. Nonetheless, its role in oxidative stress-related liver diseases, including AILI, remains unexplored. In this study, we observed up-regulation of Ninj1 expression in the livers of both human DILI patients and the AILI mouse model. Through the utilization of Ninj1 null mice, hepatocyte-specific Ninj1 KO mice, and myeloid-specific Ninj1 KO mice, we unveiled that the loss of Ninj1 in hepatocytes, rather than myeloid cells, exerts alleviative effects on AILI irrespective of sex dependency. Further in vitro experiments demonstrated that Ninj1 deficiency shields hepatocytes from APAP-induced oxidative stress, mitochondrial dysfunctions, and cell death by bolstering NRF2 stability via activation of AMPKα. In summary, our findings imply that Ninj1 likely plays a role in AILI, and its deficiency confers protection against APAP-induced hepatotoxicity through the AMPKα-NRF2 pathway., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024. Published by Elsevier Inc.)

Neurotrophic keratitis or keratopathy (NK) is a degenerative corneal disease induced by impairment of the trigeminal nerve function. This condition may lead to persistent epithelial defects, corneal ulceration, and perforation. The diagnosis of NK requires a careful investigation of any ocular and systemic condition associated with the disease and ocular surface and corneal sensitivity examinations. In the past, several medical and surgical procedures were used to treat this condition with different clinical effectiveness. Cenegermin is a recombinant human nerve growth factor (rh-NGF) that supports corneal reinnervation. Different clinical trials have demonstrated the safety and efficacy of topical cenegermin in patients with moderate to severe neurotrophic keratitis. In this review, we report the literature on clinical results regarding the treatment of NK with cenegermin since its approval by the European Medicines Agency (EMA) and the Food and Drug Administration (FDA) in 2017 and 2018, respectively., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer IA declared a past co-authorship with the author JA to the handling editor., (Copyright © 2024 Roszkowska, Spinella, Calderone, Sindoni, Wowra, Kozak, Sajak-Hydzik and Aliò.)

Abstract Pancreatic ductal adenocarcinoma (PDAC), with its extremely poor prognosis, presents a substantial health problem worldwide. Outcomes have improved thanks to progress in surgical technique, chemotherapy, pre‐/postoperative management, and centralization of patient care to high‐volume centers. However, our goals are yet to be met. Recently, exome sequencing using PDAC surgical specimens has demonstrated that the most frequently altered genes were the axon guidance genes, indicating involvement of the nervous system in PDAC carcinogenesis. Moreover, perineural invasion has been widely identified as one poor prognostic factor. The combination of innovative technologies and extensive clinician experience with the nervous system come together here to create a new treatment option. However, evidence has emerged that suggests that the relationship between cancer and nerves in PDAC, the underlying mechanism, is not fully understood. In an attempt to tackle this lethal cancer, this review summarizes the anatomy and physiology of the pancreas and discusses the role of the nervous system in the pathophysiology of PDAC.

Objective(s): Adrenomedullin (AM) has high expression in the spinal cord. In this study, we investigated the expression of AM and its receptor components, including calcitonin receptor-like receptor (CLR) and receptor activity modifying proteins (RAMPs) in dorsal root ganglion (DRG) and spinal motor (SM) neurons. Furthermore, the effects of AM on cAMP/cAMP response element-binding protein (CREB), AKT/glycogen synthase kinase-3 beta (GSK-3β) signaling pathways, and expressions of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) were evaluated. Materials and Methods: Rat embryonic DRG and SM neurons were isolated, purified, and cultured. Real-time PCR was used to assess expressions of AM, CLR, and RAMPs. cAMP levels, p-CREB, BDNF, and NT-3 were determined using an enzyme-linked immunosorbent assay. p-AKT and p-GSK-3β levels were determined by western blotting. Real-time PCR showed expressions of AM, CLR, RAMP2, and RAMP3 in both DRG and SM neurons. Results: AM increased cAMP accumulation and p-CREB levels in DRG and SM neurons. AM increased p-AKT and p-GSK-3β in DRG, but not SM neurons. AM significantly increased BDNF expression in both DRG and SM neurons. There was also an increase in NT-3 level in both DRG and SM neurons, which is statistically significant in SM neurons. Conclusion: These results showed both DRG and SM neurons are targets of AM actions in the spinal cord. An increase in BDNF expression by AM in both DRG and SM neurons suggests the possible beneficial role of AM in protecting, survival, and regeneration of sensory and motor neurons.

Background: The authors established an in vitro model of diabetic neuropathy based on the culture system of primary neurons and Schwann cells (SCs) to mimic similar symptoms observed in in vivo models of this complication, such as impaired neurite extension and impaired myelination. The model was then utilized to investigate the effects of insulin on enhancing neurite extension and myelination of diabetic neurons. Methods: SCs and primary neurons were cultured under conditions mimicking hyperglycemia prepared by adding glucose to the basal culture medium. In a single culture, the proliferation and maturation of SCs and the neurite extension of neurons were evaluated. In a co-culture, the percentage of myelination of diabetic neurons was investigated. Insulin at different concentrations was supplemented to culture media to examine its effects on neurite extension and myelination. Results: The cells showed similar symptoms observed in in vivo models of this complication. In a single culture, hyperglycemia attenuated the proliferation and maturation of SCs, induced apoptosis, and impaired neurite extension of both sensory and motor neurons. In a co-culture of SCs and neurons, the percentage of myelinated neurites in the hyperglycemia-treated group was significantly lower than that in the control group. This impaired neurite extension and myelination was reversed by the introduction of insulin to the hyperglycemic culture media. Conclusions: Insulin may be a potential candidate for improving diabetic neuropathy. Insulin can function as a neurotrophic factor to support both neurons and SCs. Further research is needed to discover the potential of insulin in improving diabetic neuropathy. [ABSTRACT FROM AUTHOR]