Schwann Cells Research Articles

MicroRNA-301a knockout attenuates peripheral nerve regeneration by delaying Wallerian degeneration.

Our recent study demonstrated that knockout of microRNA-301a attenuates migration and phagocytosis in macrophages. Considering that macrophages and Schwann cells synergistically clear the debris of degraded axons and myelin during Wallerian degeneration, which is a prerequisite for nerve regeneration, we hypothesized that microRNA-301a regulates Wallerian degeneration and nerve regeneration via impacts on Schwann cell migration and phagocytosis. Herein, we found low expression of microRNA-301a in intact sciatic nerves, with no impact of the microRNA-301a knockout on nerve structure and function. By contrast, we found significant upregulation of microRNA- 301a in injured sciatic nerves. We established a sciatic nerve crush model in microRNA-301a knockout mice, which exhibited attenuated morphological and functional regeneration following sciatic nerve crush injury. The microRNA-301a knockout also led to significantly inhibited Wallerian degeneration in an in vivo sciatic nerve-transection model and in an in vitro nerve explant block model. Schwann cells with the microRNA-301a knockout showed inhibition of phagocytosis and migration, which was reversible under transfection with microRNA-301a mimics. Rescue experiments involving transfection of microRNA-301a-knockout Schwann cells with microRNA-301a mimics or treatment with the C-X-C motif receptor 4 inhibitor WZ811 indicated the mechanistic involvement of the Yin Yang 1/C-X-C motif receptor 4 pathway in the role of microRNA-301a. Combined with our previous findings in macrophages, we conclude that microRNA-301a plays a key role in peripheral nerve injury and repair by regulating the migratory and phagocytic capabilities of Schwann cells and macrophages via the Yin Yang 1/C-X-C motif receptor 4 pathway.

Myelin debris phagocytosis in demyelinating disease.

Demyelinating diseases are often caused by a variety of triggers, including immune responses, viral infections, malnutrition, hypoxia, or genetic factors, all of which result in the loss of myelin in the nervous system. The accumulation of myelin debris at the lesion site leads to neuroinflammation and inhibits remyelination; therefore, it is crucial to promptly remove the myelin debris. Initially, Fc and complement receptors on cellular surfaces were the primary clearance receptors responsible for removing myelin debris. However, subsequent studies have unveiled the involvement of additional receptors, including Mac-2, TAM receptors, and the low-density lipoprotein receptor-related protein 1, in facilitating the removal process. In addition to microglia and macrophages, which serve as the primary effector cells in the disease phase, a variety of other cell types such as astrocytes, Schwann cells, and vascular endothelial cells have been demonstrated to engage in the phagocytosis of myelin debris. Furthermore, we have concluded that oligodendrocyte precursor cells, as myelination precursor cells, also exhibit this phagocytic capability. Moreover, our research group has innovatively identified the low-density lipoprotein receptor as a potential phagocytic receptor for myelin debris. In this article, we discuss the functional processes of various phagocytes in demyelinating diseases. We also highlight the alterations in signaling pathways triggered by phagocytosis, and provide a comprehensive overview of the various phagocytic receptors involved. Such insights are invaluable for pinpointing potential therapeutic strategies for the treatment of demyelinating diseases by targeting phagocytosis.

Quantitative proteomics unveils known and previously unrecognized alterations in neuropathic nerves.

Charcot-Marie-Tooth disease type 1E (CMT1E) is an inherited autosomal dominant peripheral neuropathy caused by mutations in the peripheral myelin protein 22 (PMP22) gene. The identical leucine-to-proline (L16P) amino acid substitution in PMP22 is carried by the Trembler J (TrJ) mouse and is found in CMT1E patients presenting with early-onset disease. Peripheral nerves of patients diagnosed with CMT1E display a complex and varied histopathology, including Schwann cell hyperproliferation, abnormally thin myelin, axonal degeneration, and subaxonal morphological changes. Here, we have taken an unbiased data-independent analysis (DIA) mass spectrometry (MS) approach to quantify proteins from nerves of 3-week-old, age and genetic strain-matched wild-type (Wt) and heterozygous TrJ mice. Nerve proteins were dissolved in lysis buffer and digested into peptide fragments, and protein groups were quantified by liquid chromatography-mass spectrometry (LC-MS). A linear model determined statistically significant differences between the study groups, and proteins with an adjusted p-value of less than 0.05 were deemed significant. This untargeted proteomics approach identified 3759 quality-controlled protein groups, of which 884 demonstrated differential expression between the two genotypes. Gene ontology (GO) terms related to myelin and myelin maintenance confirm published data while revealing a previously undetected prominent decrease in peripheral myelin protein 2. The dataset corroborates the described pathophysiology of TrJ nerves, including elevated activity in the proteasome-lysosomal pathways, alterations in protein trafficking, and an increase in three macrophage-associated proteins. Previously unrecognized perturbations in RNA processing pathways and GO terms were also discovered. Proteomic abnormalities that overlap with other human neurological disorders besides CMT include Lafora Disease and Amyotrophic Lateral Sclerosis. Overall, this study confirms and extends current knowledge on the cellular pathophysiology in TrJ neuropathic nerves and provides novel insights for future examinations. Recognition of shared pathomechanisms across discrete neurological disorders offers opportunities for innovative disease-modifying therapeutics that could be effective for distinct neuropathies.

Novel miRNA-inducing drugs enable differentiation of retinoic acid-resistant neuroblastoma cells.

Tumor cell heterogeneity in neuroblastoma, a pediatric cancer arising from neural crest-derived progenitor cells, poses a significant clinical challenge. In particular, unlike adrenergic (ADRN) neuroblastoma cells, mesenchymal (MES) cells are resistant to chemotherapy and retinoid therapy and thereby significantly contribute to relapses and treatment failures. Previous research suggested that overexpression or activation of miR-124, a neurogenic microRNA with tumor suppressor activity, can induce the differentiation of retinoic acid-resistant neuroblastoma cells. Leveraging our established screen for miRNA-modulatory small molecules, we validated PP121, a dual inhibitor of tyrosine and phosphoinositide kinases, as a robust inducer of miR-124. A combination of PP121 and BDNF-activating bufalin synergistically arrests proliferation, induces differentiation, and maintains the differentiated state of MES SK-N-AS cells for 8 weeks. RNA-seq and deconvolution analyses revealed a collapse of the ADRN core regulatory circuitry (CRC) and the emergence of novel CRCs associated with chromaffin cells and Schwann cell precursors. Using a similar protocol, we differentiated and maintained MES neuroblastoma GI-ME-N and SH-EP cell lines, as well as glioblastoma LN-229 and U-251 cell lines, for over 16 weeks. In conclusion, our novel protocol suggests a promising treatment for therapy-resistant cancers of the nervous system. Moreover, these long-lived, differentiated cells provide valuable models for studying mechanisms underlying differentiation, maturation, and senescence.

LncRNA GAS5 modulates Schwann cell function and enhances facial nerve injury repair via the miR-138-5p/CXCL12 axis.

Facial nerve is an integral part of peripheral nerve. Schwann cells are important microglia involved in the repair and regulation of facial nerve injury. LncRNA growth arrest‑specific transcript 5 (GAS5) is involved in the behavioral regulation of Schwann cell and the regeneration of peripheral nervous system. However, there is little research about the effect of GAS5 on the repair of facial nerve injury (FNI) by regulating Schwann cells. This study aimed to investigate the role of GAS5 in Schwann cell function and FNI repair, focusing on the miR-138-5p/CXCL12 axis. Hematoxylin and eosin staining, Luxol fast blue staining, transmission electron microscope, and immunofluorescence (IF) experiments were used to verify the effect of GAS5 on FNI rats. Reverse transcription real-time polymerase chain reaction was performed to detect GAS5, miR-138-5p, and C-X-C motif chemokine ligand 12 (CXCL12) mRNA expression. IF staining was used to detect the inflorescence of S100 calcium binding protein B (S100β), SRY-box transcription factor 10 (SOX10), and tubulin beta 3 class III (β-Tubulin III). Glial fibrillary acidic protein (GFAP), nerve growth factor receptor (NGFR), S100β, brain derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), and CXCL12 proteins were detected using western blot. The5-bromo-2'-deoxyuridine staining, Transwell, and flow cytometry assays were conducted to detect Schwann cell function. Dual-luciferase, RNA immunoprecipitation, and RNA pulldown assaywere used to identify the interaction among GAS5, miR-138-5p, and CXCL12. Results found thatGAS5 was downregulated in facial nerve tissues of FNI rats. Overexpressed GAS5 decreased facial grading, inhibited demyelination, and promoted proliferation, migration, and suppressed apoptosis of Schwann cells. Mechanistically, GAS5 was a sponge of miR-138-5p and positively regulated CXCL12 expression. GAS5 inhibition repressed CXCL12 expression and decreased cell proliferationand migration, increased apoptosis rate of Schwann cells by sponging miR-138-5p. In conclusion,overexpression of GAS5 accelerates facial nerve repair in FNI rats by regulating miR-138-5p/CXCL12 axis.

Promoting neurovascularized bone regeneration with a novel 3D printed inorganic-organic magnesium silicate/PLA composite scaffold

Critical-size bone defect repair presents multiple challenges, such as osteogenesis, vascularization, and neurogenesis. Current biomaterials for bone repair need more consideration for the above functions. Organic-inorganic composites combined with bioactive ions offer significant advantages in bone regeneration. In our work, we prepared an organic-inorganic composite material by blending polylactic acid (PLA) with 3-aminopropyltriethoxysilane (APTES)-modified magnesium silicate (A-M2S) and fabricated it by 3D printing. With the increase of A-M2S proportion, the hydrophilicity and mineralization ability showed an enhanced trend, and the compressive strength and elastic modulus were increased from 15.29MPa and 94.61MPa to 44.30MPa and 435.77MPa, respectively. Furthermore, A-M2S/PLA scaffolds not only exhibited good cytocompatibility of bone marrow mesenchymal stem cells (BMSCs), human umbilical vein endothelial cells (HUVECs), and Schwann cells (SCs), but also effectively promoted osteogenesis, angiogenesis, and neurogenesis in vitro. After implanting 10% A-M2S/PLA scaffolds in vivo, the scaffolds showed the most effective repair of cranium defects compared to the blank and control group (PLA). Additionally, they promoted the secretion of proteins related to bone regeneration and neurovascular formation. These results provided the basis for expanding the application of A-M2S and PLA in bone tissue engineering and presented a novel concept for neurovascularized bone repair.

Piezo1 promotes peripheral nerve fibrotic scar formation through Schwann cell senescence

After peripheral nerve injury (PNI), the long-term healing process at the injury site involves a progressive accumulation of collagen fibers and the development of localized scar tissue. Excessive formation of scar tissue within nerves hinders the process of nerve repair. In this study, we demonstrate that scar formation following nerve injury induces alterations in the local physical microenvironment, specifically an increase in nerve stiffness. Recent research has indicated heightened expression of Piezo1 in Schwann cells (SCs). Our findings also indicate Piezo1 expression in SCs and its association with suppressed proliferation and migration. Transcriptomic data suggests that activation of Piezo1 results in elevated expression of senescence-associated genes. GO enrichment analysis reveals upregulation of the TGF-β pathway. Overall, our study highlights the potential for Piezo1-induced signaling to regulate SC senescence and its potential significance in the pathophysiology of fibrotic scar formation surrounding peripheral nerves.

Reconceiving Perineural Invasion in Cutaneous Squamous Cell Carcinoma: From Biological to Histopathological Assessment.

Perineural invasion (PNI) is a complex molecular process histologically represented by the presence of tumor cells within the peripheral nerve sheath and defined when infiltration into the 3 nerve sheath layers can be clearly identified. Several molecular pathways have been implicated in cSCC. PNI is a well-recognized risk factor in cutaneous squamous cell carcinoma (cSCC) and its accurate assessment represents a challenging field in pathology daily practice. As a highly intricate and dynamic process, PNI involves a contingent on bidirectional signaling interactions between the tumor and various nerve components, such as Schwann cells and neurons. The current staging systems recommend the identification of PNI as a dichotomous variable (presence vs. absence) to identify a subgroup of high-risk patients. However, recent further insights revealed that the evaluation of morphological PNI-related features in cSCC may enhance the prognostic stratification of patients and may optimize the current staging guidelines for recurrence risk assessment and improvement of patient selection for postoperative adjuvant treatments. Furthermore, recent emerging biomarkers could redefine early PNI detection. This review provides updated insights into cSCC with PNI, focusing on molecular and cellular pathogenic processes, and aims to increase knowledge on prognostic relevant PNI-related histological features.

Novel Technologies to Address the Lower Motor Neuron Injury and Augment Reconstruction in Spinal Cord Injury.

Lower motor neuron (LMN) damage results in denervation of the associated muscle targets and is a significant yet under-appreciated component of spinal cord injury (SCI). Denervated muscle undergoes a progressive degeneration and fibro-fatty infiltration that eventually renders the muscle non-viable unless reinnervated within a limited time window. The distal nerve deprived of axons also undergoes degeneration and fibrosis making it less receptive to axons. In this review, we describe the LMN injury associated with SCI and its clinical consequences. The process of degeneration of the muscle and nerve is broken down into the primary components of the neuromuscular circuit and reviewed, including the nerve and Schwann cells, the neuromuscular junction, and the muscle. Finally, we discuss three promising strategies to reverse denervation atrophy. These include providing surrogate axons from local sources; introducing stem cell-derived spinal motor neurons into the nerve to provide the missing axons; and finally, instituting a training program of high-energy electrical stimulation to directly rehabilitate these muscles. Successful interventions for denervation atrophy would significantly expand reconstructive options for cervical SCI and could be transformative for the predominantly LMN injuries of the conus medullaris and cauda equina.

Fully biodegradable and self-powered nerve guidance conduit based on zinc-molybdenum batteries for peripheral nerve repair

Peripheral nerve injury (PNI) poses a significant public health issue, often leading to muscle atrophy and persistent neuropathic pain, which can drastically impact the quality of life for patients. Electrical stimulation represents an effective and non-pharmacological treatment to promote nerve regeneration. Yet, the postoperative application of electrical stimulation remains a challenge. Here, we propose a fully biodegradable, self-powered nerve guidance conduit (NGC) based on dissolvable zinc-molybdenum batteries. The conduit can offer topographic guidance for nerve regeneration and deliver sustained electrical cues between both ends of a transected nerve stump, extending beyond the surgical window. Schwann cell proliferation and adenosine triphosphate (ATP) production are enhanced by the introduction of the zinc-molybdenum batteries. In rodent models with 10-mm sciatic nerve damage, the device effectively enhances nerve regeneration and motor function recovery. This study offers innovative strategies for creating biodegradable and electroactive devices that hold important promise to optimize therapeutic outcomes for nerve regeneration.

Combining single-cell spatial transcriptomics and molecular simulation to develop in vivo probes targeting the perineural invasion region of adenoid cystic carcinoma

Background and objectivesPerineural invasion (PNI) refers to the invasion, encasement, or penetration of tumor cells around or through nerves. Various malignant tumors, including pancreatic cancer, head and neck tumors, and bile duct cancer, exhibit the characteristic of PNI. Particularly, in head and neck-skull base tumors such as adenoid cystic carcinoma (ACC), PNI is a significant factor leading to incomplete surgical resection and postoperative recurrence. MethodsSpatial transcriptomic and single-cell transcriptomic sequencing were conducted on a case of ACC tissue with PNI to identify potential probes targeting PNI. The efficacy of the probes was validated through in vivo and in vitro experiments. ResultsSpatial transcriptomic and single-cell RNA sequencing revealed phenotypic changes in Schwann cells within the PNI region of ACC. Peptide probes were designed based on the antigen-presenting characteristics of Schwann cells in the PNI region, which are dependent on Major Histocompatibility Complex II (MHC-II) molecules. Successful validation in vitro and in vivo experiments confirmed that these probes can label viable Schwann cells in the PNI region, serving as a tool for dynamic in vivo marking of tumor invasion into nerves. ConclusionsPeptide probes targeting Schwann cells' MHC-II molecules have the potential to demonstrate the occurrence of PNI in patients with ACC

MicroRNAs Associated with IgLON Cell Adhesion Molecule Expression.

The IgLON family of cell adhesion molecules consists of five members (LSAMP, OPCML, neurotrimin, NEGR1, and IgLON5) discovered as supporters of neuronal development, axon growth and guidance, and synapse formation and maintenance. Tumour suppression properties have recently been emerging based on antiproliferative effects through the modulation of oncogenic pathways. Available evidence endorses a role for non-coding RNAs or microRNAs as relevant controllers of IgLON molecule expression that can impact their critical physiological and pathological roles. Current findings support a function for long non-coding RNAs and microRNAs in the modulation of LSAMP expression in cell senescence, cancer biogenesis, addiction, and pulmonary hypertension. For OPCML, data point to a role for several microRNAs in the control of tumorigenesis. MicroRNAs were detected in neurotrimin-mediated functions in cancer biogenesis and in Schwann cell responses to peripheral nerve injury. For NEGR1, studies have mainly investigated microRNA involvement in neuronal responses to ischaemic injury, although data also exist about tumorigenesis and endothelial cell dysfunction. For IgLON5, information is only available about microRNA involved in myocardial infarction. In conclusion, despite much information being still missing and further research needed, the emerging picture favours a model in which non-coding RNAs exert a crucial role in modulating IgLON expression, ultimately affecting their important physiological functions.

Efficacy of using adipose-derived stem cells and PRP on regeneration of 40 -mm long sciatic nerve defect bridged by polyglycolic-polypropylene mesh in canine model

BackgroundSciatic nerve repair becomes a focus of research in neurological aspect to restore the normal physical ability of the animal to stand and walk. Tissue engineered nerve grafts (TENGs) provide a promising alternative therapy for regeneration of large gap defects. The present study investigates the regenerative capacity of PRP, ADSCs, and PRP mixed ADSCs on a long sciatic nerve defect (40-mm) bridged by a polyglycolic polypropylene (PGA-PRL) mesh which acts as a neural scaffold.Materials and methodsThe study was conducted on 12 adult male mongrel dogs that were randomly divided into 4 groups: Group I (scaffold group); where the sciatic defect was bridged by a (PGA-PRL) mesh only while the mesh was injected with ADSCs in Group II (ADSCs group), PRP in Group III (PRP group). Mixture of PRP and ADSCs was allocated in Group IV (PRP + ADSCs group). Monthly, all animals were monitored for improvement in their gait and a numerical lameness score was recorded for all groups. 6 months-post surgery, the structural and functional recovery of sciatic nerve was evaluated electrophysiologically, and on the level of gene expression, and both sciatic nerve and the gastrocnemius muscle were evaluated morphometrically, histopathologically.ResultsNumerical lameness score showed improvement in the motor activities of both Group II and Group III followed by Group IV and the scaffold group showed mild improvement even after 6 months. Histopathologically, all treated groups showed axonal sprouting and numerous regenerated fascicles with obvious angiogenesis in proximal cut, and distal portion where Group IV exhibited a significant remyelination with the MCOOL technique. The regenerative ratio of gastrocnemius muscle was 23.81%, 56.68%, 52.06% and 40.69% for Group I, II, III and IV; respectively. The expression of NGF showed significant up regulation in the proximal portion for both Group III and Group IV (P ≤ 0.0001) while Group II showed no significant difference. PDGF-A, and VEGF expressions were up-regulated in Group II, III, and IV whereas Group I showed significant down-regulation for NGF, PDGF-A, and VEGF (P ≤ 0.0001).ConclusionADSCs have a great role in restoring the damaged nerve fibers by secreting several types of growth factors like NGF that have a proliferative effect on Schwann cells and their migration. In addition, PRP therapy potentiates the effect of ADSCs by synthesis another growth factors such as PDGF-A, VEGF, NGF for better healing of large sciatic gap defects.

Cilostazol Ameliorates Motor Dysfunction and Schwann Cell Impairment in Streptozotocin-Induced Diabetic Rats.

This study investigated the effects of cilostazol on motor dysfunction, spinal motor neuron abnormalities, and schwannopathy in rats with diabetes. Diabetes mellitus (DM) was induced in rats via femoral intravenous streptozotocin (STZ) injection (60 mg/kg). After successful DM induction, cilostazol was administered on day 15 via oral gavage (100 mg/kg/day) for 6 weeks until sacrifice. Behavioral assays, including motor function, were performed weekly. The sciatic nerve, L5 spinal cord, and spinal ventral root were collected to evaluate the expression of the glial fibrillary acidic protein (GFAP), myelin protein zero (P0), and choline acetyltransferase (ChAT) by immunofluorescence and Western blotting. DM rats displayed decreased running speeds, running distances, and toe spread but increased foot pressure. In addition, loss of non-myelinating Schwann cells and myelin sheaths was observed in the sciatic nerve and L5 spinal ventral root. Reduced numbers of motor neurons were also found in the L5 spinal ventral horn. Cilostazol administration significantly potentiated running speed and distance; increased hind paw toe spread; and decreased foot pressure. In the sciatic nerve and L5 spinal ventral root, cilostazol treatment significantly improved non-myelinated Schwann cells and increased myelin mass. ChAT expression in motor neurons in the spinal ventral horn was improved, but not significantly. Cilostazol administration may protect sensorimotor function in diabetic rats.

GDNF-induced phosphorylation of MUC21 promotes pancreatic cancer perineural invasion and metastasis by activating RAC2 GTPase.

Perineural invasion (PNI) is an adverse prognostic feature of pancreatic ductal adenocarcinoma (PDAC). However, the understanding of the interactions between tumors and neural signaling within the tumor microenvironment is limited. In the present study, we found that MUC21 servers as an independent risk factor for poor prognosis in PDAC. Furthermore, we demonstrated that MUC21 promoted the metastasis and PNI of PDAC cells by activating JNK and inducing epithelial-mesenchymal transition (EMT). Mechanistically, glial cell-derived neurotrophic factor, secreted by Schwann cells, phosphorylates the intracellular domain S543 of MUC21 via CDK1 in PDAC cells, facilitating the interaction between MUC21 and RAC2. This interaction leads to membrane anchoring and activation of RAC2, which in turn activates the JNK/ZEB1/EMT axis, ultimately enhancing the metastasis and PNI of PDAC cells. Our results present a novel mechanism of PNI, suggesting that MUC21 is a potential prognostic marker and therapeutic target for PDAC.

Overview of Granular Cell Tumor General Hospitals in Iraq over 11-years

Granular cell tumor is rare tumors from Schwann cells with clinicopathological feature results, which may be showed in both benign and malignant tumor. Several tumors commonly appear in the oral cavity, gastrointestinal tract and skin. This must be appropriately treated to avoid repetition or metastatic cancer lesions. The aim study is to search clinicopathological aspects of granular cell tumor diagnosed at different general hospitals in Iraq and to compare these findings with epidemiological findings from different governorates positions. The data was collected from different Iraq governorates in mouth and tongue area from 2010 to 2020 years. Different parameters were displayed like age group, gender, topography, morphology and distribution of annual patients of the tumor. According to the available of the all information about these characteristics was revealed the inclusion criteria. The factors frequencies were calculated from descriptive analysis of the data. The total (101) cases of granular cell tumor in mouth and tongue location were found. (17) cases was the maximum value in 2015 year and it followed by (15) cases in 2019 year as compared to other years. Baghdad governorate (95) cases has a greatly patients than other governorates. (59) Cases with (58.40 %) of female gender and (42) cases with (41.60) of male and the female to male ratio was (1.38:1).

Intradural Melanotic Schwannoma of the Sacral Spine: An Illustrated Case Report of Diagnostic Conundrum

Schwannomas are benign and slow-growing peripheral nerve sheath neoplasms of Schwann cells. These are generally encountered in the neck, head, and flexor areas of the extremities. Even though many schwannomas are easily diagnosable, their variable morphology can occasionally create difficulty in diagnosis. In this study, we present a rare case of melanotic schwannoma of the sacrum, emphasizing the need for routine biopsy to understand the etiology. A 46-year-old man presented to the Department of Neurosurgery, Taipei Medical University Hospital, with buttock pain in the sacrum area for 1 year, which worsened in the last 1–2 months. The patient had no known history of trauma or malignancy. We evidenced an intradural extramedullary neurogenic tumor at the caudal end from S1 to S3. Histologic analysis revealed melanin deposition in the tumor cells. Round to oval tumor cells were positive for HMB-45 and S-100 proteins, suggestive of melanotic Schwannoma, which were removed by laminectomy. After 1 month, the tumor recurred and was further removed surgically. Conclusively, we observed the sacrum as an unusual anatomic site for the possible occurrence of melanotic schwannoma, especially in patients with no known history of trauma and malignancy. The possibility of melanotic schwannoma is very high. We hypothesize that melanotic schwannoma was possible because it occurred in the intradural and extramedullary regions of the spine. Hence, a routine biopsy should be performed to corroborate the exact cause and prevent incorrect presumptions.

Appendicular schwannoma: Case report of a rare differential of a right iliac fossa mass

Schwannomas are slow growing, mostly benign tumors arising from the Schwann cells of the nerve sheath. They usually arise from the nerves of the head-and-neck region. They are rare in the gastrointestinal tract. The stomach is the most common site for gastrointestinal schwannomas. Appendicular schwannomas are even a rarer entity that may present as a right iliac fossa mass. The final diagnosis is by histopathology and immunohistochemistry. Treatment is essentially surgical. Such entities may present as diagnostic dilemmas presenting as the not-so-common cause of iliac fossa mass and hence deserve reporting and discussion. We report our experience of treating a case of appendicular schwannoma in a 70-year-old lady with a short discussion on its characteristics and management.

Sarm1-Dependent Metabolic Reprogramming of Schwann Cells Following Nerve Injury.

Schwann cells (SCs) transition into a repair phenotype after peripheral nerve injury, which is crucial for supporting axon regeneration. However, the early SC injury response preceding the repair state remains poorly understood. Here, we demonstrate that Sarm1, a key regulator of axon degeneration, is expressed in SCs and has a critical role in the early SC injury response. Leveraging the fact that Sarm1 deletion impairs the SC transition to the repair state, we used single-nucleus RNA sequencing to compare the transcriptional responses of wild-type and Sarm1 knockout SCs 24 hours after nerve injury. Remarkably, Sarm1-deficient SCs, unlike wild-type SCs, showed increased expression of genes involved in oxidative phosphorylation and the TCA cycle. These findings were functionally validated, revealing that Sarm1 knockout SCs displayed increased mitochondrial respiration in response to injury. Intriguingly, Sarm1 knockout SCs also exhibited enhanced axon protection compared to wild-type SCs in an in vitro model of axon degeneration. We propose that Sarm1 gates the transition of SCs from a protective, oxidative phosphorylation-dependent state (which we term Protection Associated Schwann Cells or PASCs) to a glycolytic, pro-regenerative repair phenotype after injury. Our findings challenge the prevailing view of Sarm1 as an exclusively axon-autonomous regulator of degeneration and reveal a paradigm shift in understanding the role of Sarm1 in the SC injury response, with broad implications for the treatment of peripheral neuropathies and neurodegenerative diseases.

Fabrication of ECM protein coated hollow collagen channels to study peripheral nerve regeneration

Peripheral nerve injury is a prevalent clinical problem that often leads to lifelong disability and reduced quality of life. Although peripheral nerves can regenerate, recovery after severe injury is slow and incomplete. The current gold standard treatment, autologous nerve transplantation, has limitations including donor site morbidity and poor functional outcomes, highlighting the need for improved repair strategies. We developed a reproducible in vitro hollow channel collagen gel construct to investigate peripheral nerve regeneration (PNR) by exploring the influence of key extracellular matrix (ECM) proteins on axonal growth and regeneration. Channels were coated with ECM proteins: collagen IV, laminin, or fibronectin and seeded with dorsal root ganglia (DRG) collected from E16 rat embryos to compare the ability of the ECM proteins to enhance axonal growth. Robust axonal extension and Schwann cell (SC) infiltration were observed in fibronectin-coated channels, suggesting its superiority over other ECM proteins. Differential effects of ECM proteins on axons and SCs indicated direct growth stimulation beyond SC-mediated guidance. In vitro laceration injury modeling further confirmed fibronectin’s superior pro-regenerative effects, showcasing its potential in enhancing axonal regrowth post-injury. Advancing in vitro modeling that closely replicates native microenvironments will accelerate progress in overcoming the limitations of current nerve repair approaches.