Schwann Cells Research Articles

Concurrent spinal schwannoma and meningioma without neurofibromatosis: case presentation and review of literature

Abstract Background Concurrent multiple tumors developing in the spinal cord are rare, except for in genetic disorders, such as neurofibromatosis and von Hippel–Lindau disease. The presence of multiple histologically different spinal tumors in the absence of NF-2 is extremely rare. Schwannoma and meningioma can be explained partly by their common origin from the same mesenchymal cell, there is currently no explanation for the simultaneous existence of different spinal tumors other than simple coincidence. Case presentation After review of literature, there are thirteen such cases reported in the literature in addition to the present case. The current patient presents with lower limb weakness, and the patient radiology revealed intradural mass opposite the fourth lumbar vertebra with contrast enhancement and intradural extramedullary mass opposite the tenth dorsal vertebra with contrast enhancement in MRI spine. The coexistence of these tumors may be coincidental or might be due to a common histological origin of the Schwann cells and the meningocytes. Conclusion Schwannoma and meningioma have different radiological characteristics and require different managing procedures such as dural base coagulation in meningiomas and rootlet sacrifice in schwannomas.

Abstract IA019: Regulation of EMT tumor states by stromal cells

Abstract Epithelial-to-mesenchymal transition (EMT) is a reversible process during which epithelial cells lose their epithelial characteristics and acquire mesenchymal features, that are important for tumor initiation, progression, stemness, metastasis, and therapy resistance. Different EMT states, each with distinct functional properties, have been identified across various tumor models. These EMT states reside within specific physical niches, characterized by unique stromal cell populations. Understanding the cellular interactions within the tumor microenvironment (TME) and their influence on EMT could lead to novel therapeutic strategies. To understand how the TME regulates the distinct tumor states, we performed single-cell RNA sequencing of the tumor cells and their TME in mouse cancer models presenting EMT. We identified distinct subsets of cancer-associated fibroblasts (CAFs), macrophages, neutrophils, endothelial cells, pericytes, adipocytes, dendritic cells, mast cells, Schwann cells, and T cells in different tumor types. To unravel how TME-tumor cell interactions regulates EMT, we used different bioinformatic approaches to identify ligand-receptor pairs that are likely to organize the tumor niche and to regulate tumor transition states. In vitro treatment of tumor cells with some of these ligands demonstrated their EMT-promoting effects. These findings provide novel mechanistic insights on the crosstalk between tumor cells and the surrounding TME, that may have important implications for anti-cancer therapy. Citation Format: Cédric Blanpain. Regulation of EMT tumor states by stromal cells [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr IA019.

Complement activation by IgM autoantibodies linked to immune-mediated neuropathies depends on C2.

Complement factor C2 is a potential therapeutic target in immune-mediated neuropathies. However, literature suggests that classical complement pathway activation may proceed to C3 in the absence of C2, a so-called "C2 bypass." Here, we evaluated a C2 bypass mechanism during complement activation by pathogenic human IgM from patients with immune-mediated neuropathies. IgM autoantibodies from 51 patients with multifocal motor neuropathy (MMN) or anti-myelin-associated glycoprotein (MAG) neuropathy (AMN) were used to activate complement in exvivo disease models. C2 bypass was evaluated using C2-depleted (C2D) serum and a therapeutic anti-C2 antibody. In two different disease models of MMN, IgM anti-GM1 and IgM anti-GM2 autoantibodies from MMN patients were bound to induced pluripotent stem cell-derived motor neurons and Schwann cells, respectively, and fixed C3 upon incubation with fresh serum. C3 fixation was inhibited by anti-C2 and did not occur with C2D serum. Similarly, in an AMN model, IgM anti-MAG antibodies were incubated with fresh serum fixed C3, which in all cases was abrogated in the absence of C2 or in the presence of anti-C2. In exvivo disease models of MMN and AMN, complement activation by IgM autoantibodies from 51 patients was in all cases dependent on C2 and was inhibited by an antihuman C2 antibody. No evidence of a C2 bypass mechanism was found.

Role of the Egr2 Promoter Antisense RNA in Modulating the Schwann Cell Chromatin Landscape

Background: Schwann cells (SCs) and their plasticity contribute to the peripheral nervous system’s capacity for nerve regeneration after injury. The Egr2/Krox20 promoter antisense RNA (Egr2-AS) recruits chromatin remodeling complexes to inhibit Egr2 transcription following peripheral nerve injury. Methods: RNA-seq and ATAC-seq were performed on control cells, Lenti-GFP-transduced cells, and cells overexpressing Egr2-AS (Lenti-AS). Egr2 AS-RNA was cloned into the pLVX-DsRed-Express2-N1 lentiviral expression vector (Clontech, Mountain View, CA, USA), and the levels of AS-RNA expression were determined. Ezh2 and Wdr5 were immunoprecipitated from rat SCs and RT-qPCR was performed against AS-Egr2 RNA. ChIP followed by DNA purification columns was used to perform qPCR for relevant promoters. Hi-C, HiC-DC+, R, Bioconductor, and TOBIAS were used for significant and differential loop analysis, identifications of COREs and CORE-promotor loops, comparisons of TF activity at promoter sites, and identification of site-specific TF footprints. OnTAD was used to detect TADs, and Juicer was used to identify A/B compartments. Results: Here we show that a Neuregulin-ErbB2/3 signaling axis mediates binding of the Egr2-AS to YY1Ser184 and regulates its expression. Egr2-AS modulates the chromatin accessibility of Schwann cells and interacts with two distinct histone modification complexes. It binds to EZH2 and WDR5 and enables targeting of H3K27me3 and H3K4me3 to promoters of Egr2 and C-JUN, respectively. Expression of the Egr2-AS results in reorganization of the global chromatin landscape and quantitative changes in the loop formation and contact frequency at domain boundaries exhibiting enrichment for AP-1 genes. In addition, the Egr2-AS induces changes in the hierarchical TADs and increases transcription factor binding scores on an inter-TAD loop between a super-enhancer regulatory hub and the promoter of mTOR. Conclusions: Our results show that Neuregulin-ErbB2/3-YY1 regulates the expression of Egr2-AS, which mediates remodeling of the chromatin landscape in Schwann cells.

Effect and mechanism of Tetramethylpyrazine in repair of sciatic nerve injury in rats.

Observing the effects of Tetramethylpyrazine (TMP) on the expression of Collagen IV and Laminin in neurovascular basement membrane and the apoptosis of vascular endothelial cells, and to study the mechanism of TMP in the treatment of sciatic nerve injury. Compared with the NS group, the TMP group had a significant increase in the sciatic nerve function index (P < 0.01).The miss times in TMP group was significantly lower than that in NS group (P < 0.01). The HE staining results of the TMP group showed irregular arrangement of some neuronal axons and Schwann cells, and more edema and rupture of cells. The proliferation of glial cells and inflammatory cells was significantly increased in TMP group. The results of immunohistochemistry showed that the expression of type IV collagen and laminin in the TMP group group was distributed around the blood vessels, vascular endothelial cells, basal membrane and glial cells after SNI. The expression of type IV collagen and laminin in TMP group increased significantly(P < 0.05). Immunofluorescence showed that compared with NS group, the apoptosis rate of TMP group was significantly decreased (P < 0.01). Flow cytometry results showed that compared with the NS group, the number of CECs in the TMP group was significantly decreased (P < 0.01). TMP can effectively improve the sciatic nerve functional index (SFI) of Sprague Dawley (SD) rats, enhance the proliferation of sciatic nerve vascular endothelial cells, reduce apoptosis, promote the expression of Collagen IV and Laminin in sciatic nerve microvascular basal membrane components, thereby promoting angiogenesis and improving lower limb function in rats.

Genomic and Phenotypic Variations Among Thai-53 and Mycobacterium leprae Clinical Isolates: Implications for Leprosy Pathogenesis and Research

Throughout Mycobacterium leprae’s (M. leprae) evolutionary trajectory, nearly half of its genome was converted into pseudogenes. Despite this drastic reduction in genetic content, the genome sequence identity among M. leprae isolates worldwide is remarkably high compared to other pathogens. In this study, we investigated the genotype and morphotype of three M. leprae strains: the reference strain Thai-53 (genotype 1A), and two clinical isolates from Brazilian leprosy relapse patients, which were Br014-03 (genotypes 3I) and Br014-01(4N). We compared their genome sequences and their interaction with human Schwann cells from the ST88-14 lineage and with human primary macrophages. On the genetic level, we observed over a hundred missense mutations in the three strains, translated into significant phenotypic changes such as: prolonged doubling time, altered cytokine induction, reduced interaction rates, and decreased intracellular viability in Schwann cells. Our findings underscore the concept that despite their 99.992% identity, even small genomic disparities in M. leprae genomes can elicit substantial alterations in bacilli interaction with host cells and subsequent immune responses. Consequently, our data could lead to better comprehension of correlation between pathogen mutations and the diverse clinical manifestations observed in leprosy patients.

Alternatively activated macrophages are associated with faster growth rate in vestibular schwannoma

Abstract The variability in vestibular schwannoma growth rates greatly complicates clinical treatment. Management options are limited to radiological observation, surgery, radiotherapy and, in specific cases, bevacizumab therapy. As such, there is a pressing requirement for growth restricting drugs for vestibular schwannoma. This study explored potential predictors of vestibular schwannoma growth in depth, highlighting differences between static and growing vestibular schwannoma to identify potential therapeutic targets. High dimensional imaging was used to characterise the tumour microenvironment of four static and five growing vestibular schwannoma (indicated by volumetric change &amp;lt; 20% or ≥ 20% per year, respectively). Single cell spatial information and protein expression data from a panel of 35 tumour immune-targeted antibodies identified specific cell populations, their expression profiles, and their spatial localisation within the tumour microenvironment. Growing vestibular schwannoma contained significantly more proliferative and non-proliferative alternatively activated tumour-associated macrophages per mm2 compared to static vestibular schwannoma. Furthermore, two additional proliferative cell types were identified in growing and static vestibular schwannoma: transitioning monocytes and Programmed Cell Death Ligand 1 (PD-L1+) Schwann cells. In agreement, growing vestibular schwannoma were characterised by a tumour microenvironment composed of immune-enriched, proliferative neighbourhoods, whereas static vestibular schwannoma were composed of tumour-enriched, non-proliferative neighbourhoods. Finally, classically activated macrophages significantly co-localised with alternatively activated macrophages in static vestibular schwannoma, but this sequestration was reduced in growing vestibular schwannoma. This study provides a novel, spatial characterisation of the immune landscape in growing vestibular schwannoma, whilst highlighting the need for new therapeutic targets that modulate the tumour immune microenvironment.

Role and Interplay of Different Signaling Pathways Involved in Sciatic Nerve Regeneration.

Regeneration of the sciatic nerve is a sophisticated process that involves the interplay of several signaling pathways that orchestrate the cellular responses critical to regeneration. Among the key pathways are the mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K)/AKT, cyclic adenosine monophosphate (cAMP), and Janus kinase/signal transducers and transcription activators (JAK/STAT) pathways. In particular, the cAMP pathway modulates neuronal survival and axonal regrowth. It influences various cellular behaviors and gene expression that are essential for nerve regeneration. MAPK is indispensable for Schwann cell differentiation and myelination, whereas PI3K/AKT is integral to the transcription, translation, and cell survival processes that are vital for nerve regeneration. Furthermore, GTP-binding proteins, including those of the Ras homolog gene family (Rho), regulate neural cell adhesion, migration, and survival. Notch signaling also appears to be effective in the early stages of nerve regeneration and in preventing skeletal muscle fibrosis after injury. Understanding the intricate mechanisms and interactions of these pathways is vital for the development of effective therapeutic strategies for sciatic nerve injuries. This review underscores the need for further research to fill existing knowledge gaps and improve therapeutic outcomes.

CSIG-19. IDENTIFICATION AND TARGETING OF TUMOR DRIVER SCHWANN(NF2LOSS) CELLS IN SPORADIC AND NF2-RELATED VESTIBULAR SCHWANNOMAS

Abstract Vestibular schwannomas (VS) arise from myelinating Schwann cells of CN VIII and are associated with severe morbidity due to local tumor growth. Sporadic and neurofibromatosis type 2 (NF2) associated VS are both characterized by NF2 (merlin) loss but the mechanisms remain unexplored. Using a multiomic approach, we dissected the role of NF2 loss in VS tumor formation and proliferation. We obtained surgical samples from 15 patients undergoing surgery for VS (sporadic, n=4; NF2, n=9), and performed single-cell or single-nucleus RNA sequencing (scRNAseq, n=4; snRNAseq, n=15), transposase-accessible chromatin (snATAC-seq, n=9), whole exome (n=12), and bulk DNA methylation assays (n=15). Transcription factor binding was assayed with ChIPseq. We validated our key findings with immunoblot, ELISA, RNAscope (n=8), and multiplex immunocytochemistry (mIHC; n=8). NF2fl/fl;Periostin-Cre+mice versus their Cre- control littermates treated with novel inhibitors of TEAD auto-palmitoylation (VTs). We mapped the VS transciptome and identified canonical Schwann cells, macrophages, T-cells and endothelial cells. Using the cells that had Chr22 loss (second hit deletions at the NF2 locus), we generated a NF2loss gene signature. We then identified Schwann(NF2loss) cells in all tumors, and found these enriched for YAP1/TAZ-TEAD, NRG1, and HIF-1α signaling pathways. Schwann(NF2loss) cells showed increased TEAD1 expression and chromatin accessibility for TEAD family transcription factor motifs. TEAD1 binding was observed at promoters of genes including VEGFA, EGFR, with strong enrichment for mitogenic pathways. We also found that VEFGA expression was restricted to Schwann(NF2loss) cells, and confirmed this with RNAscope and mIHC. Schwann(NF2loss) cells were key regulators of macrophages (M2-subtype, tissue resident) through M-CSF/IL-34 signaling. NF2fl/fl;Periostin-Cre+ mice showed increased VEGFA expression, and that was reversible by TEAD inhibition in-vivo with VTs. We report that Schwann(NF2loss) cells are key tumor drivers in VS. These cells are highly proliferative (YAP/TAZ-TEAD axis), drive angiogenesis (VEGFA expression), and promote tumor mass accretion (macrophage influx via M-CSF/IL-34 pathway) that can all be targeted via TEAD inhibition.

EPID-04. VESTIBULAR SCHWANNOMA IN PREGNANCY: A SYSTEMATIC REVIEW

Abstract INTRODUCTION Vestibular Schwannomas (VS) are intracranial tumors of the nervous system originating from peripherally myelinating Schwann cells. There are sparse reports of this tumor presenting in pregnant patients but many of the cardinal symptoms of pregnancy overlap with the presentation of VS. For this reason, we systematically reviewed reports of VS in pregnant patients to identify the most specific clinical symptoms to aid diagnosis of and address management considerations for this population. METHODS Our systematic review was performed according to PRISMA guidelines. The data extracted includes study characteristics, symptom presence and onset relative to tumor diagnosis, tumor size, treatment modality, complications, and maternal/fetal health outcomes. This data was analyzed for overlap with commonly presenting symptoms and current management trends. RESULTS Sixteen papers between 1967 and 2018 reported a total of 26 pregnant patients who met criteria for inclusion. The most common presenting symptoms were hearing loss (76.9%), ataxia (42.3%), headache (38.5%), and vomiting (38.5%). The symptoms that presented with the longest duration were dizziness/vertigo (145.33 weeks), tinnitus (155 weeks), and hearing loss (145.67 weeks). The most common complications were post-op facial paralysis (46.2%), hydrocephalus (23.1%), and post-op hearing loss (19.2%). CONCLUSIONS A heightened clinical suspicion for VS in pregnant patients is needed due to the large overlap of cardinal symptoms of pregnancy and VS presentation. The way pregnancy changes patients’ normal physiology should be considered when determining optimal management. We hope that this review will improve diagnostic accuracy and prevent complications in pregnant patients with VS.

CNSC-53. SHH ACTIVATION IN DEDIFFERENTIATION DURING TUMOR PROGRESSION IN MPNST

Abstract BACKGROUND Malignant peripheral nerve sheath tumors (MPNST) are highly aggressive sarcomas with little progress on outcomes and treatment strategies. Previously, unsupervised analyses of methylome and transcriptome profiles of 108 peripheral nerve sheath tumors uncovered two subgroups of MPNSTs that predict progression-free survival, MPNST-G1 (characterized by SHH-pathway activation) and MPNST-G2 (characterized by WNT/ß-catenin/CCND1-pathway activation). Further, single nuclear RNA sequencing revealed that MPNST-G1 and MPNST-G2 cells resemble neural crest-like and Schwann cell precursor-like cells, respectively. PURPOSE &amp; HYPOTHESIS To examine whether the activation of the SHH pathway in MPNST-G1 cell lines induces overexpression of factors known to play canonical roles in early neural crest cell specification (TWIST1, SNAI2, PAX3, PAX6, SOX9, OTX2) and to investigate the role of Src activation on SHH pathway-induced dedifferentiation. We hypothesize that MPNST-G1 cells will exhibit SHH pathway activation, synergizing with Src to induce the overexpression of early neural crest cell (ENCC) transcription factors. METHODS SHH pathway activation, expression of ENCC transcription factors, and effects of inhibitors were analyzed in MPNST-G1 cells using RT-PCR, western blotting, Alamar Blue assay, Trypan Blue assay, and Soft Agar Transformation assay. RESULTS Compared to MPNST-G2 cells, MPNST-G1 cells displayed SHH-pathway activation, SMO-dependent activation of Src, and elevated expression of the ENCC transcription factors. Sonidegib (SMO inhibitor) and Dasatinib (Src inhibitor) were able to revert dedifferentiation. CONCLUSIONS The SHH-pathway cooperates with Src to promote expression of important transcription factors in dedifferentiation. This finding provides insights into the transformation process of MPNST and novel therapeutic options.

TMOD-26. GENERATION OF A CHROMOSOME 8 GAIN;NF1-/- HIPSC-DERIVED SCHWANN CELL PRECURSOR MODEL

Abstract Neurofibromatosis type 1 (NF1) is an autosomal dominant cancer predisposition syndrome caused by a germline mutation in the NF1 gene. The loss of the second copy of NF1 within Schwann cell precursors (SCPs) contributes to the formation of plexiform neurofibromas (PNs) found in 30-50% of NF1 patients. PNs can progress into malignant peripheral sheath tumors (MPNSTs), an aggressive form of cancer and a leading cause of mortality in NF1 patients. Our lab previously demonstrated frequent chromosome 8 (Chr8) gain in NF1-MPNST patient-derived xenografts (PDX) and patient tumors. To investigate Chr8 gain’s role, we created isogenic NF1-/- iPSC cell lines with and without Chr8 gain. Trisomy 8 fibroblasts were obtained and single-cell cloned to establish wildtype (WT) and Chr8 gain populations. Washington University’s Genome Engineering &amp; Stem Cell Center (GESC@MGI) reprogrammed these cells into human induced pluripotent stem cells (hiPSCs). Using synthetic gRNA and CRISPR/Cas9, NF1 knockout lines were generated. Four iPSC cell lines were differentiated into SCPs, and cell survival and proliferation were assessed using Incucyte cell survival and CellTiter-Glo® Assay. Fluorescence in situ hybridization (FISH) and karyotyping validated the human iPSCs. qPCR revealed high expression of iPSC markers OCT3/4 and SOX2 in all iPSC lines. After differentiation, SCP markers (GAP43 and ITGA4) were upregulated in WT, NF1-/-, and Chr8 gain;NF1-/- SCP lines, demonstrating successful differentiation. Furthermore, Chr8 gain; NF1-/- SCPs displayed enhanced proliferation and increased cell survival compared to WT and NF1-/- SCPs, suggesting improved characteristics in the presence of Chr8 gain. In summary, our research provides insights into Chr8 gain and NF1 loss effects on SCP differentiation, proliferation, and survival. Understanding these molecular mechanisms may contribute to developing targeted therapies for NF1.

Wnt 3a-Modified Scaffolds Improve Nerve Regeneration by Boosting Schwann Cell Function.

A pivotal approach in engineering artificial peripheral nerve sheaths encompasses the augmentation of the regenerative microenvironment via the manipulation of Schwann cells (SCs). Our investigation employed single-cell sequencing analysis to elucidate the potential functions of Schwann cells and the Wnt pathway in facilitating peripheral nerve regeneration. In vitro studies showed that activating the Wnt signaling pathway promotes the transition to repair SCs, boosting their growth, movement, and immune functions. To better understand the peripheral nerve regeneration environment, we created a polymer scaffold using ammonization and electrospinning. The Wnt3a protein was incorporated into the polycaprolactone (PCL) electrospun fiber surface. In a rat sciatic nerve defect model, the Wnt3a-modified scaffold showed better nerve repair outcomes than traditional electrospun scaffolds. After a week, the test group showed better immune regulation and angiogenesis, with a significant increase in axon growth rate observed after 3 weeks. Three-month-long animal experiments revealed notable improvements in neuroelectrophysiology, reduced organ atrophy, and enhanced sciatic nerve recovery. In this nerve defect model, Wnt3a-modified neural scaffolds achieved repair effects.

Multiomic Analyses Reveal New Targets of Polycomb Repressor Complex 2 in Schwann Lineage Cells and Malignant Peripheral Nerve Sheath Tumors

Abstract Background Malignant peripheral nerve sheath tumors (MPNST) can arise from atypical neurofibromas (ANF). Loss of the polycomb repressor complex 2 (PRC2) is a common event. Previous studies on PRC2-regulated genes in MPNST used genetic addback experiments in highly aneuploid MPNST cell lines which may miss PRC2-regulated genes in NF1-mutant ANF-like precursor cells. A set of PRC2-regulated genes in human Schwann cells has not been defined. We hypothesized PRC2 loss has direct and indirect effects on gene expression resulting in MPNST, so we sought to identify PRC2-regulated genes in immortalized human Schwann cells (iHSCs). Methods We engineered NF1-deficient iHSCs with loss of function SUZ12 or EED mutations. RNA sequencing revealed 1,327 differentially expressed genes to define PRC2-regulated genes. To investigate MPNST pathogenesis we compared genes in iHSCs to consistent gene expression differences between ANF and MPNSTs. Chromatin immunoprecipitation sequencing was used to further define targets. Methylome and proteomic analyses were performed to further identify enriched pathways. Results We identified potential PRC2-regulated drivers of MPNST progression. Pathway analysis indicates many upregulated cancer-related pathways. We found transcriptional evidence for activated Notch and Sonic Hedgehog signaling in PRC2-deficient iHSCs. Functional studies confirm Notch signaling is active in MPNST cell lines, patient-derived xenografts, and transient cell models of PRC2 deficiency. A combination of MEK and γ-secretase inhibition shows synergy in MPNST cell lines. Conclusions We identified PRC2-regulated genes and potential drivers of MPNSTs. Our findings support the Notch pathway as a druggable target in MPNSTs. Our identification of PRC2-regulated genes and pathways could result in more novel therapeutic approaches.

Bioactive MgO/MgCO3/Polycaprolactone Multi-gradient Fibers Facilitate Peripheral Nerve Regeneration by Regulating Schwann Cell Function and Activating Wingless/Integrase-1 Signaling

AbstractPeripheral nerve defects present complex orthopedic challenges with limited efficacy of clinical interventions. The inadequate proliferation and dysfunction of Schwann cells within the nerve scaffold impede the effectiveness of nerve repair. Our previous studies suggested the effectiveness of a magnesium-encapsulated bioactive hydrogel in repairing nerve defects. However, its rapid release of magnesium ions limited its efficacy to long-term nerve regeneration, and its molecular mechanism remains unclear. This study utilized electrospinning technology to fabricate a MgO/MgCO3/polycaprolactone (PCL) multi-gradient nanofiber membrane for peripheral nerve regeneration. Our findings indicated that by carefully adjusting the concentration or proportion of rapidly degradable MgO and slowly degradable MgCO3, as well as the number of electrospun layers, the multi-gradient scaffold effectively sustained the release of Mg2+ over a period of 6 weeks. Additionally, this study provided insight into the mechanism of Mg2+-induced nerve regeneration and confirmed that Mg2+ effectively promoted Schwann cell proliferation, migration, and transition to a repair phenotype. By employing transcriptome sequencing technology, the study identified the Wingless/integrase-1 (Wnt) signaling pathway as a crucial mechanism influencing Schwann cell function during nerve regeneration. After implantation in 10 mm critically sized nerve defects in rats, the MgO/MgCO3/PCL multi-gradient nanofiber combined with a 3D-engineered PCL nerve conduit showed enhanced axonal regeneration, remyelination, and reinnervation of muscle tissue 12 weeks post-surgery. In conclusion, this study successfully developed an innovative multi-gradient long-acting MgO/MgCO3/PCL nanofiber with a tunable Mg2+ release property, which underscored the molecular mechanism of magnesium-encapsulated biomaterials in treating nervous system diseases and established a robust theoretical foundation for future clinical translation. Graphical abstract

Mesocolic schwannoma mimicking gastrointestinal stromal tumor: A case report and review of literature.

Schwannomas are common peripheral nerve tumors originating from Schwann cells, primarily occurring in the head and neck, limbs, and trunk. Schwannomas occurring in the mesocolon are rare and often have no specific manifestations. Abdominal schwannomas need to be differentiated from common abdominal tumors such as gastrointestinal stromal tumors. We report a case of a mesocolic schwannoma in a 59-year-old female presenting with gastrointestinal symptoms of acid reflux. At an outside hospital, gastroscopy, colonoscopy, and abdominal computed tomography scans revealed a soft tissue mass adjacent to the greater curvature of the stomach, leading to a suspicion of a gastric mesenchymal tumor. Mesocolic schwannoma. Laparoscopy was performed at our hospital. Intraoperatively, the tumor was found to be closely related to the transverse colon and was initially diagnosed as a mass originating from the transverse colon. Consequently, a resection of the mass along with the adherent portion of the transverse colon was performed. Postoperative pathology and immunohistochemistry confirmed that the tumor was a schwannoma of the mesentery and did not originate from the transverse colon. Schwannomas can be distinguished from gastrointestinal stromal tumors by immunohistochemical staining, and surgical treatment is effective for benign schwannomas.

Bcl2l12, a novel protein interacting with Arf6, triggers Schwann cell differentiation program.

Schwann cells are glial cells in the peripheral nervous system (PNS); they wrap neuronal axons with their differentiated plasma membranes called myelin sheaths. Although the physiological functions, such as generating saltatory conduction, have been well studied in the PNS, the molecular mechanisms by which Schwann cells undergo their differentiation program without apparent morphological changes before dynamic myelin sheath formation remain unclear. Here, for the first time, we report that Arf6, a small GTP/GDP-binding protein controlling morphological differentiation, and the guanine-nucleotide exchange factors cytohesin proteins are involved in the regulation of Schwann cell differentiation marker expression in primary Schwann cells. Specific inhibition of Arf6 and cytohesins by NAV-2729 and SecinH3, respectively, decreased expression of marker proteins 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and glial fibrillary acidic protein (GFAP). Similar results using promoter assays were observed using the IMS32 Schwann cell line. Furthermore, using an affinity-precipitation technique, we identified Bcl2-like 12 (Bcl2l12) as a novel GTP-bound Arf6-interacting protein. Knockdown of Bcl2l12 using a specific artificial miRNA decreased expression of marker proteins. The knockdown also led to decreased filamentous actin extents. These results suggest that Arf6 and Bcl2l12 can trigger Schwann cell differentiation, providing evidence for a molecular relay that underlies how Schwann cells differentiate.

The E3 ubiquitin ligase Nedd4 fosters developmental myelination in the mouse central and peripheral nervous system.

Ubiquitination is a major post-translational regulatory mechanism that tunes numerous aspects of ubiquitinated target proteins, including localization, stability, and function. During differentiation and myelination, Oligodendrocytes (OLs) in the central nervous system and Schwann cells (SCs) in the peripheral nervous system undergo major cellular changes, including the tightly controlled production of large and accurate amounts of proteins and lipids. Such processes have been implied to depend on regulatory aspects of ubiquitination, with E3 ubiquitin ligases being generally involved in the selection of specific ubiquitination substrates by ligating ubiquitin to targets and granting target selectivity. In this study, we have used multiple transgenic mouse lines to investigate the functional impact of the E3 ubiquitin ligase Nedd4 in the OL- and SC-lineages. Our findings in the developing spinal cord indicate that Nedd4 is required for the correct accumulation of differentiated OLs and ensures proper myelination, supporting and further expanding previously suggested conceptual models. In sciatic nerves, we found that Nedd4 is required for timely radial sorting of axons by SCs as a pre-requirement for correct onset of myelination. Moreover, Nedd4 ensures correct myelin thickness in both SCs and spinal cord OLs.

Innovative spiral nerve conduits: Addressing nutrient transport and cellular activity for critical-sized nerve defects

Large-gap nerve defects require nerve guide conduits (NGCs) for complete regeneration and muscle innervation. Many NGCs have been developed using various scaffold designs and tissue engineering strategies to promote axon regeneration. Still, most are tubular with inadequate pore sizes and lack surface cues for nutrient transport, cell attachment, and tissue infiltration. This study developed a porous spiral NGC to address these issues using a 3D-printed thermoplastic polyurethane (TPU) fiber lattice. The lattice was functionalized with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) electrospun aligned (aPHBV) and randomly (rPHBV) oriented nanofibers to enhance cellular activity. TPU lattices were made with 25 %, 35 %, and 50 % infill densities to create scaffolds with varied mechanical compliance. The fabricated TPU/PHBV spiral conduits had significantly higher surface areas (25 % TPU/PHBV: 698.97 mm2, 35 % TPU/PHBV: 500.06 mm2, 50 % TPU/PHBV: 327.61 mm2) compared to commercially available nerve conduits like Neurolac™ (205.26 mm2). Aligned PHBV nanofibers showed excellent Schwann cell (RSC96) adhesion, proliferation, and neurogenic gene expression for all infill densities. Spiral TPU/PHBV conduits with 25 % and 35 % infill densities exhibited Young's modulus values comparable to Neurotube® and ultimate tensile strength like acellular cadaveric human nerves. A 10 mm sciatic nerve defect in Wistar rats treated with TPU/aPHBV NGCs demonstrated muscle innervation and axon healing comparable to autografts over 4 months, as evaluated by gait analysis, functional recovery, and histology. The TPU/PHBV NGC developed in this study shows promise as a treatment for large-gap nerve defects.

AAV1.tMCK.NT-3 gene therapy improves phenotype in Sh3tc2-/- mouse model of Charcot-Marie-Tooth Type 4C.

Charcot-Marie-Tooth Type 4C (CMT4C) is associated with mutations in the SH3 domain and tetratricopeptide repeats 2 (SH3TC2) gene, primarily expressed in Schwann cells (SCs). Neurotrophin-3 (NT-3) is an important autocrine factor for SC survival and differentiation, and it stimulates neurite outgrowth and myelination. In this study, scAAV1.tMCK.NT-3 was delivered intramuscularly to 4-week-old Sh3tc2-/- mice, a model for CMT4C, and treatment efficacy was assessed at 6-month post-gene delivery. Efficient transgene production was verified with the detection of NT-3 in serum from the treated cohort. NT-3 gene therapy improved functional and electrophysiological outcomes including rotarod, grip strength and nerve conduction velocity. Qualitative and quantitative histopathological studies showed that hypomyelination of peripheral nerves and denervated status of neuromuscular junctions at lumbrical muscles were also improved in the NT-3-treated mice. Morphometric analysis in mid-sciatic and tibial nerves showed treatment-induced distally prominent regenerative activity in the nerve and an increase in the estimated SC density. This indicates that SC proliferation and differentiation, including the promyelination stage, are normal in the Sh3tc2-/- mice, consistent with the previous findings that Sh3tc2 is not involved in the early stages of myelination. Moreover, in size distribution histograms, the number of myelinated axons within the 3- to 6-µm diameter range increased, suggesting that treatment resulted in continuous radial growth of regenerating axons over time. In conclusion, this study demonstrates the efficacy of AAV1.NT-3 gene therapy in the Sh3tc2-/- mouse model of CMT4C, the most common recessively inherited demyelinating CMT subtype.