Schwann Cells Research Articles

Loss of YAP in Schwann cells improves HNPP pathophysiology.

Rapid nerve conduction in the peripheral nervous system (PNS) is facilitated by the multilamellar myelin sheath encasing many axons of peripheral nerves. Charcot-Marie-Tooth type 1A (CMT1A), and hereditary neuropathy with liability to pressure palsy (HNPP) are common demyelinating inherited peripheral neuropathies and are caused by mutations in the peripheral myelin protein 22 (PMP22) gene. Duplication of PMP22 leads to its overexpression and causes CMT1A, while its deletion results in PMP22 under expression and causes HNPP. Here, we investigated novel targets for modulating the protein level of PMP22 in HNPP. We found that genetic attenuation of the transcriptional coactivator Yap in Schwann cells reduces p-TAZ levels, increased TAZ activity, and increases PMP22 in peripheral nerves. Based on these findings, we ablated Yap alleles in Schwann cells of the Pmp22-haploinsufficient mouse model of HNPP and identified fewer tomacula on morphological assessment and improved nerve conduction in peripheral nerves. These findings suggest YAP modulation may be a new avenue for treatment of HNPP.

Perineural invasion in prostate cancer is associated with Schwann cells and disruption of circadian rhythm-related gene expression: A bioinformatics approach

Schwann cells in the tumor microenvironment are reportedly involved in the production of several factors that benefit cancer cell growth. During this process, Schwann cells are dedifferentiated and facilitate cancer cellular proliferation. The cells then migrate to the region close to the tumor tissue and assist the development of the neoplastic cells. Accordingly, the present study was designed to evaluate the perineural invasion in prostate cancer, in association with disrupted circadian rhythm-related gene expression in Schwann cells. Initially, we identified a database reporting gene expression in Schwann cells in a neoplastic context from the GEO Datasets platform in the GEO repository. The database contains the expression results from experiments in which two factors produced by tumor cells were added to cell cultures. Comparisons were made between samples from the first and third passages. Then, these data were used in differential gene expression analysis and combined with differential expression data of genes upregulated in perineural invasion-negative and -positive prostate cancers. We observed that the “axon guidance” pathway was upregulated in perineural invasion-negative prostate cancers. Meanwhile, upregulated mRNAs activated the “axon guidance” pathway and, together with ROBO1 and MPZ upregulation, inhibited perineural invasion pathways. Both genes are also associated with inhibition of Schwann cell migration. PER3, NR3C1, PPARGC1A, TIMP3, ID2, PDE6B, and CAVIN1 were upregulated in perineural invasion-negative tumors, while SLC25A10 was upregulated. We also observed upregulated expression in perineural invasion-positive tumors for genes such as PPARGC1A, TIMP3, S100A8, ID2, DEFB1, AQP3, ASS1, PDE6B, NEFH, and CAVIN1. AQP3 and NEFH were upregulated only in perineural invasion-positive tumors and PER3 and NR3C1 were upregulated only in perineural invasion-negative samples. The findings revealed that circadian rhythm and/or melatonin disruption are associated with dedifferentiation of Schwann cells, which consequently produce a set of factors that drive tumor progression. These processes may also be involved in tumor invasion into the perineural tissue in prostate cancer.

Roles for PMP22 in Schwann cell cholesterol homeostasis in health and disease.

Underexpression, overexpression, and point mutations in peripheral myelin protein 22 (PMP22) cause most cases of Charcot-Marie-Tooth disease (CMTD). While its exact functions remain unclear, PMP22 is clearly essential for formation and maintenance of healthy myelin in the peripheral nervous system. This review explores emerging evidence for roles of PMP22 in cholesterol homeostasis. First, we highlight dysregulation of lipid metabolism in PMP22-based forms of CMTD and recently-discovered interactions between PMP22 and cholesterol biosynthesis machinery. We then examine data that demonstrates PMP22 and cholesterol co-traffic in cells and co-localize in lipid rafts, including how disease-causing PMP22 mutations result in aberrations in cholesterol localization. Finally, we examine roles for interactions between PMP22 and ABCA1 in cholesterol efflux. Together, this emerging body of evidence suggests that PMP22 plays a role in facilitating enhanced cholesterol synthesis and trafficking necessary for production and maintenance of healthy myelin.

Role of Piezo2 in Schwann Cell Volume Regulation and Its Impact on Neurotrophic Release Regulation.

Tactile perception relies on mechanoreceptors and nerve fibers, including c-fibers, Aβ-fibers and Aδ-fibers. Schwann cells (SCs) play a crucial role in supporting nerve fibers, with non-myelinating SCs enwrapping c-fibers and myelinating SCs ensheathing Aβ and Aδ fibers. Recent research has unveiled new functions for cutaneous sensory SCs, highlighting the involvement of nociceptive SCs in pain perception and Meissner corpuscle SCs in tactile sensation. Furthermore, Piezo2, previously associated with Merkel cell tactile sensitivity, has been identified in SCs. The goal of this study was to investigate the channels implicated in SC mechanosensitivity and the release process of neurotrophic factor secretion. Immortalized IFRS1 SCs and human primary SCs generated two distinct subtypes of SCs: undifferentiated and differentiated SCs. Quantitative PCR was employed to evaluate the expression of differentiation markers and mechanosensitive channels, including TRP channels (TRPV4, TRPM7 and TRPA1) and Piezo channels (Piezo1 and Piezo2). To validate the functionality of specific mechanosensitive channels, Ca2+ imaging and electronic cell sizing experiments were conducted under hypotonic conditions, and inhibitors and siRNAs were used. Protein expression was assessed by Western blotting and immunostaining. Additionally, secretome analysis was performed to evaluate the release of neurotrophic factors in response to hypotonic stimulation, with BDNF, a representative trophic factor, quantified using ELISA. Induction of differentiation increased Piezo2 mRNA expression levels both in IFRS1 and in human primary SCs. Both cell types were responsive to hypotonic solutions, with differentiated SCs displaying a more pronounced response. Gd3+ and FM1-43 effectively inhibited hypotonicity-induced Ca2+ transients in differentiated SCs, implicating Piezo2 channels. Conversely, inhibitors of Piezo1 and TRPM7 (Dooku1 and NS8593, respectively) had no discernible impact. Moreover, Piezo2 in differentiated SCs appeared to participate in regulatory volume decreases (RVD) after cell swelling induced by hypotonic stimulation. A Piezo2 deficiency correlated with reduced RVD and prolonged cell swelling, leading to heightened release of the neurotrophic factor BDNF by upregulating the function of endogenously expressed Ca2+-permeable TRPV4. Our study unveils the mechanosensitivity of SCs and implicates Piezo2 channels in the release of neurotrophic factors from SCs. These results suggest that Piezo2 may contribute to RVD, thereby maintaining cellular homeostasis, and may also serve as a negative regulator of neurotrophic factor release. These findings underscore the need for further investigation into the role of Piezo2 in SC function and neurotrophic regulation.

Postoperative hemorrhages in vestibular schwannoma surgery pontine hemorrhage. Clinical case report

Vestibular schwannoma (acoustic neuroma) is a benign tumor that develops from Schwann cells and can be life-threatening. Nowadays, surgical treatment is the method of choice in the management of patients with this type of tumor. We present a clinical case report of 71 y.o. patient with vestibular schwannoma (Koos grade IV, Samii grade 4B) with severe compression of the pons and the left cerebellar hemisphere. Microsurgical removal of the tumor was performed via the retrosigmoid approach. Starting from postoperative day 1, signs of respiratory distress developed. Control multislice spiral computed tomography (MSCT) of the brain revealed the area of hemorrhage in the left regions of the pons. On postoperative day 24 the patient's condition rapidly worsened progressing to coma with pronounced arterial hypotonia and cardiac arrest. Hemorrhage in the brain stem structures is a rare and life-threatening postoperative complication in vestibular schwannoma surgery. The incidence of postoperative hemorrhage is 2–11% of cases. Vascular complications are the leading cause of mortality. The key predisposing factors are older age, large and giant size of the tumor, tumor invasion into the pia mater of the brainstem, and vascularization of the tumor stroma. Comprehensive assessment of the tumor blood supply status, the state of the brainstem, intra- and postoperative clinical and neurophysiological monitoring, careful and thorough dissection of the tumor capsule and strict control of blood pressure in the postoperative period are the basis for the prevention of these complications.

Regeneration of Propriospinal Axons in Rat Transected Spinal Cord Injury through a Growth-Promoting Pathway Constructed by Schwann Cells Overexpressing GDNF.

Unsuccessful axonal regeneration in transected spinal cord injury (SCI) is mainly attributed to shortage of growth factors, inhibitory glial scar, and low intrinsic regenerating capacity of severely injured neurons. Previously, we constructed an axonal growth permissive pathway in a thoracic hemisected injury by transplantation of Schwann cells overexpressing glial-cell-derived neurotrophic factor (SCs-GDNF) into the lesion gap as well as the caudal cord and proved that this novel permissive bridge promoted the regeneration of descending propriospinal tract (dPST) axons across and beyond the lesion. In the current study, we subjected rats to complete thoracic (T11) spinal cord transections and examined whether these combinatorial treatments can support dPST axons' regeneration beyond the transected injury. The results indicated that GDNF significantly improved graft-host interface by promoting integration between SCs and astrocytes, especially the migration of reactive astrocyte into SCs-GDNF territory. The glial response in the caudal graft area has been significantly attenuated. The astrocytes inside the grafted area were morphologically characterized by elongated and slim process and bipolar orientation accompanied by dramatically reduced expression of glial fibrillary acidic protein. Tremendous dPST axons have been found to regenerate across the lesion and back to the caudal spinal cord which were otherwise difficult to see in control groups. The caudal synaptic connections were formed, and regenerated axons were remyelinated. The hindlimb locomotor function has been improved.

Identification of cellular and noncellular components of mature intact human peripheral nerve.

The goal of this study was to define basic constituents of the adult peripheral nervous system (PNS) using intact human nerve tissues. We combined fluorescent and chromogenic immunostaining methods, myelin-selective fluorophores, and routine histological stains to identify common cellular and noncellular elements in aldehyde-fixed nerve tissue sections. We employed Schwann cell (SC)-specific markers, such as S100β, NGFR, Sox10, and myelin protein zero (MPZ), together with axonal, extracellular matrix (collagen IV, laminin, fibronectin), and fibroblast markers to assess the SC's relationship to myelin sheaths, axons, other cell types, and the acellular environment. Whereas S100β and Sox10 revealed mature SCs in the absence of other stains, discrimination between myelinating and non-myelinating (Remak) SCs required immunodetection of NGFR along with axonal and/or myelin markers. Surprisingly, our analysis of NGFR+ profiles uncovered the existence of at least 3 different novel populations of NGFR+/S100β- cells, herein referred to as nonglial cells, residing in the stroma and perivascular areas of all nerve compartments. An important proportion of the nerve's cellular content, including circa 30% of endoneurial cells, consisted of heterogenous S100β negative cells that were not associated with axons. Useful markers to identify the localization and diversity of nonglial cell types across different compartments were Thy1, CD34, SMA, and Glut1, a perineurial cell marker. Our optimized methods revealed additional detailed information to update our understanding of the complexity and spatial orientation of PNS-resident cell types in humans.

Anisotropic topological scaffolds synergizing non-invasive wireless magnetic stimulation for accelerating long-distance peripheral nerve regeneration

Long-distance peripheral nerve regeneration is the challenging clinical problem that needs to be resolved urgently. In this study, an anisotropic topological Chitosan@Artemisia sphaerocephala (CS@AS) scaffold containing Fe3O4 nanoparticles for achieving non-invasive wireless magnetic stimulation on nerve regeneration process under external static magnetic field (SMF) was developed using surface modification and micro-molding method, aiming to provide a synergistic stimulus for the repair of long-distance peripheral nerve injury. The results showed that the anisotropic topological scaffolds and non-invasive wireless magnetic stimulation under exogenous SMF could synergistically regulate the morphological change, proliferation and oriented growth of Schwann cells. In vivo experiments confirmed that magnetic CS@AS nerve conduit could better promote the functional recovery and reconstruction of the long-distance injured sciatic nerve under SMF, close to that of the autograft transplantation. Further on, the scaffolds were found to activate the magnetic induction receptors, promote the gene expression related to proliferation, migration and myelin formation, regulate the homeostasis of intracellular Ca2+ and enhance the signal transduction via cGMP-PKG, VEGF, MAPK, and TNF signaling pathways. Therefore, the combination of anisotropic topological nerve grafts and non-invasive wireless magnetic stimulation under external SMF can promote the repair and functional recovery of long-distance nerve injury, providing a new strategy for the treatment of peripheral nerve injury.

Humidity-Responsive Amorphous Calcium-Magnesium Pyrophosphate/Cassava Starch Scaffold for Enhanced Neurovascular Bone Regeneration.

Developing a neurovascular bone repair scaffold with an appropriate mechanical strength remains a challenge. Calcium phosphate (CaP) is similar to human bone, but its scaffolds are inherently brittle and inactive, which require recombination with active ions and polymers for bioactivity and suitable strength. This work discussed the synthesis of amorphous magnesium-calcium pyrophosphate (AMCP) and the subsequent development of a humidity-responsive AMCP/cassava starch (CS) scaffold. The scaffold demonstrated enhanced mechanical properties by strengthening the intermolecular hydrogen bonds and ionic bonds between AMCP and CS during the gelatinization and freeze-thawing processes. The release of active ions was rapid initially and stabilized into a long-term stable release after 3 days, which is well-matched with new bone growth. The release of pyrophosphate ions endowed the scaffold with antibacterial properties. At the cellular level, the released active ions simultaneously promoted the proliferation and mineralization of osteoblasts, the proliferation and migration of endothelial cells, and the proliferation of Schwann cells. At the animal level, the scaffold was demonstrated to promote vascular growth and peripheral nerve regeneration in a rat skull defect experiment, ultimately resulting in the significant and rapid repair of bone defects. The construction of the AMCP/CS scaffold offers practical suggestions and references for neurovascular bone repair.

The impact of artificial intelligence in the diagnosis and management of acoustic neuroma: A systematic review.

Schwann cell sheaths are the source of benign, slowly expanding tumours known as acoustic neuromas (AN). The diagnostic and treatment approaches for AN must be patient-centered, taking into account unique factors and preferences. The purpose of this study is to investigate how machine learning and artificial intelligence (AI) can revolutionise AN management and diagnostic procedures. A thorough systematic review that included peer-reviewed material from public databases was carried out. Publications on AN, AI, and deep learning up until December 2023 were included in the review's purview. Based on our analysis, AI models for volume estimation, segmentation, tumour type differentiation, and separation from healthy tissues have been developed successfully. Developments in computational biology imply that AI can be used effectively in a variety of fields, including quality of life evaluations, monitoring, robotic-assisted surgery, feature extraction, radiomics, image analysis, clinical decision support systems, and treatment planning. For better AN diagnosis and treatment, a variety of imaging modalities require the development of strong, flexible AI models that can handle heterogeneous imaging data. Subsequent investigations ought to concentrate on reproducing findings in order to standardise AI approaches, which could transform their use in medical environments.

Robust differentiation of human pluripotent stem cells into Schwann cells

Research into Schwann cell (SC)-related diseases has been hampered by the difficulty of obtaining human-derived SCs, which have limited proliferative capacity. This has resulted in a delay in progress in drug discovery and cell therapy targeting SCs. To overcome these limitations, we developed a robust method for inducing the differentiation of human induced pluripotent stem cells (hiPSCs) into SCs. We established hiPSC lines and successfully generated high-purity Schwann cell precursors (SCPs) from size-controlled hiPSC aggregates by precisely timed treatment with our proprietary enzyme solution. Such SCPs were successfully expanded and further differentiated into myelin basic protein (MBP) expressing SC populations when treated with an appropriate medium containing dibutyryl-cAMP (db-cAMP). These differentiated cells secreted factors that induced neurite outgrowth in vitro. Our method allows for the efficient and stable production of SCPs and SCs from hiPSCs. This robust induction and maturation method has the potential to be a valuable tool in drug discovery and cell therapy targeting SC-related diseases.

The cytoplasmic tail of myelin protein zero induces morphological changes in lipid membranes

The major myelin protein expressed by the peripheral nervous system Schwann cells is protein zero (P0), which represents 50% of the total protein content in myelin. This 30-kDa integral membrane protein consists of an immunoglobulin (Ig)-like domain, a transmembrane helix, and a 69-residue C-terminal cytoplasmic tail (P0ct). The basic residues in P0ct contribute to the tight packing of myelin lipid bilayers, and alterations in the tail affect how P0 functions as an adhesion molecule necessary for the stability of compact myelin. Several neurodegenerative neuropathies are related to P0, including the more common Charcot-Marie-Tooth disease (CMT) and Dejerine-Sottas syndrome (DSS) as well as rare cases of motor and sensory polyneuropathy. We found that high P0ct concentrations affected the membrane properties of bicelles and induced a lamellar-to-inverted hexagonal phase transition, which caused bicelles to fuse into long, protein-containing filament-like structures. These structures likely reflect the formation of semicrystalline lipid domains with potential relevance for myelination. Not only is P0ct important for stacking lipid membranes, but time-lapse fluorescence microscopy also shows that it might affect membrane properties during myelination. We further describe recombinant production and low-resolution structural characterization of full-length human P0. Our findings shed light on P0ct effects on membrane properties, and with the successful purification of full-length P0, we have new tools to study the role of P0 in myelin formation and maintenance in vitro.

Pancreatic Schwann cell reprogramming supports cancer-associated neuronal remodeling.

The peripheral nervous system is a key regulator of cancer progression. In pancreatic ductal adenocarcinoma (PDAC), the sympathetic branch of the autonomic nervous system inhibits cancer development. This inhibition is associated with extensive sympathetic nerve sprouting in early pancreatic cancer precursor lesions. However, the underlying mechanisms behind this process remain unclear. This study aimed to investigate the roles of pancreatic Schwann cells in the structural plasticity of sympathetic neurons. We examined the changes in the number and distribution of Schwann cells in a transgenic mouse model of PDAC and in a model of metaplastic pancreatic lesions induced by chronic inflammation. Schwann cells proliferated and expanded simultaneously with new sympathetic nerve sprouts in metaplastic/neoplastic pancreatic lesions. Sparse genetic labeling showed that individual Schwann cells in these lesions had a more elongated and branched structure than those under physiological conditions. Schwann cells overexpressed neurotrophic factors, including glial cell-derived neurotrophic factor (GDNF). Sympathetic neurons upregulated the GDNF receptors and exhibited enhanced neurite growth in response to GDNF in vitro. Selective genetic deletion of Gdnf in Schwann cells completely blocked sympathetic nerve sprouting in metaplastic pancreatic lesions in vivo. This study demonstrated that pancreatic Schwann cells underwent adaptive reprogramming during early cancer development, supporting a protective antitumor neuronal response. These finding could help to develop new strategies to modulate cancer associated neural plasticity.

A novel induced pluripotent stem cell model of Schwann cell differentiation reveals NF2 - related gene regulatory networks of the extracellular matrix.

Schwann cells are vital to development and maintenance of the peripheral nervous system and their dysfunction has been implicated in a range of neurological and neoplastic disorders, including NF2 -related schwannomatosis. We developed a novel human induced pluripotent stem cell (hiPSC) model to study Schwann cell differentiation in health and disease. We performed transcriptomic, immunofluorescence, and morphological analysis of hiPSC derived Schwann cell precursors (SPCs) and terminally differentiated Schwann cells (SCs) representing distinct stages of development. To validate our findings, we performed integrated, cross-species analyses across multiple external datasets at bulk and single cell resolution. Our hiPSC model of Schwann cell development shared overlapping gene expression signatures with human amniotic mesenchymal stem cell (hAMSCs) derived SCs and in vivo mouse models, but also revealed unique features that may reflect species-specific aspects of Schwann cell biology. Moreover, we identified gene co-expression modules that are dynamically regulated during hiPSC to SC differentiation associated with ear and neural development, cell fate determination, the NF2 gene, and extracellular matrix (ECM) organization. By cross-referencing results between multiple datasets, we identified new genes potentially associated with NF2 expression. Our hiPSC model further provides a tractable platform for studying Schwann cell development in the context of human disease.

63 Developing a 3D in Vitro Schwann Cell Model of Myelination for Peripheral Nerve Injury

Abstract Aim This study investigated the effectiveness of fabricating engineered neural tissue (EngNT) to develop a 3D in vitro model of myelination for peripheral nerve injury. Additionally, the effect of metformin and sulindac sulfide in nerve regeneration was evaluated by assessing neurite growth in both monolayer and 3D co-culture systems. Method Neuronal cells (NG108-15 and SH-SY5Y cell lines) were treated with metformin for 72 hrs in an Incucyte® live-cell analysis system. EngNT cellular collagen gels were fabricated using Schwann cells (SCL4.1/F7), SCL4.1/F7:NG108-15 (1:1) cells or harvested rat dorsal root ganglion cells. NG108–15 cells were co-cultured with SCL4.1/F7 cellular gels. 3D EngNT co-cultures were treated with metformin and sulindac sulfide for 72 hrs. EngNT cellular gels were analysed with transmission electron microscopy (TEM). Results TEM evaluation of EngNT co-cultures demonstrated the enfoldment of neurones by Schwann cells resulting in cell-cell contacts and myelination was identified. NG108-15 and SH-SY5Y cells exhibited significant neurite growth with 100 μM metformin being the optimal dose (151.4 ± 3 μM and 108.0 ± 12 μM respectively). Increased neurite growth of NG108-15 neurones was demonstrated with 100 μM (179.3 ± 2 μM) metformin treatment in 3D EngNT. Additionally, significant neurite growth was demonstrated following treatment with 100 μM (203.9 ± 32 μM) sulindac sulfide. Conclusions A 3D EngNT in vitro co-culture model of Schwann cell myelination was developed illustrating the cell-cell interaction between Schwann cells and neurones and the formation of myelin in the peripheral nervous system. Metformin elicits significant positive results on neurite growth in vitro highlighting its therapeutic potential in PNI.

Image features and clinical analysis of retroperitoneal pelvic schwannoma: a case report

BackgroundSchwannomas are benign usually encapsulated nerve sheath tumors derived from the Schwann cells, and affecting single or multiple nerves. The tumors commonly arise from the cranial nerves as acoustic neurinomas but they are extremely rare in the pelvis and the retroperitoneal area. Retroperitoneal pelvic schwannomas often present with non-specific symptoms leading to misdiagnosis and prolonged morbidity.Case presentationWe report the case of a 59-year-old woman presenting with a feeling of heaviness in the lower abdomen who was found to have a retroperitoneal pelvic schwannoma originating from the right femoral nerve. She had a history of two resections of peripheral schwannomas at four different sites of limbs. After conducting magnetic resonance imaging, this pelvic schwannoma was misdiagnosed as a gynecological malignancy. The tumor was successfully removed by laparoscopic surgery. Pathological analysis of the mass revealed a benign schwannoma of the femoral nerve sheath with demonstrating strong, diffuse positivity for S-100 protein.ConclusionsAlthough retroperitoneal pelvic schwannoma is rare, it should be considered in the differential diagnosis of pelvic masses, especially in patients with a history of neurogenic mass or the presence of neurogenic mass elsewhere.

GRT-X Stimulates Dorsal Root Ganglia Axonal Growth in Culture via TSPO and Kv7.2/3 Potassium Channel Activation.

GRT-X, which targets both the mitochondrial translocator protein (TSPO) and the Kv7.2/3 (KCNQ2/3) potassium channels, has been shown to efficiently promote recovery from cervical spine injury. In the present work, we investigate the role of GRT-X and its two targets in the axonal growth of dorsal root ganglion (DRG) neurons. Neurite outgrowth was quantified in DRG explant cultures prepared from wild-type C57BL6/J and TSPO-KO mice. TSPO was pharmacologically targeted with the agonist XBD173 and the Kv7 channels with the activator ICA-27243 and the inhibitor XE991. GRT-X efficiently stimulated DRG axonal growth at 4 and 8 days after its single administration. XBD173 also promoted axonal elongation, but only after 8 days and its repeated administration. In contrast, both ICA27243 and XE991 tended to decrease axonal elongation. In dissociated DRG neuron/Schwann cell co-cultures, GRT-X upregulated the expression of genes associated with axonal growth and myelination. In the TSPO-KO DRG cultures, the stimulatory effect of GRT-X on axonal growth was completely lost. However, GRT-X and XBD173 activated neuronal and Schwann cell gene expression after TSPO knockout, indicating the presence of additional targets warranting further investigation. These findings uncover a key role of the dual mode of action of GRT-X in the axonal elongation of DRG neurons.

Immobilized NRG1 Accelerates Neural Crest like Cell Differentiation Toward Functional Schwann Cells Through Sustained Erk1/2 Activation and YAP/TAZ Nuclear Translocation.

Neural Crest cells (NC) are a multipotent cell population that give rise to a multitude of cell types including Schwann cells (SC) in the peripheral nervous system (PNS). Immature SC interact with neuronal axons via the neuregulin 1 (NRG1) ligand present on the neuronal surface and ultimately form the myelin sheath. Multiple attempts to derive functional SC from pluripotent stem cells have met challenges with respect to expression of mature markers and axonal sorting. Here, they hypothesized that sustained signaling from immobilized NRG1 (iNRG1) might enhance the differentiation of NC derived from glabrous neonatal epidermis towards a SC phenotype. Using this strategy, NC derived SC expressed mature markers to similar levels as compared to explanted rat sciatic SC. Signaling studies revealed that sustained NRG1 signaling led to yes-associated protein 1 (YAP) activation and nuclear translocation. Furthermore, NC derived SC on iNRG1 exhibited mature SC function as they aligned with rat dorsal root ganglia (DRG) neurons in an in vitro coculture model; and most notably, aligned on neuronal axons upon implantation in a chick embryo model in vivo. Taken together their work demonstrated the importance of signaling dynamics in SC differentiation, aiming towards development of drug testing platforms for de-myelinating disorders.

Decellularized porcine peripheral nerve based injectable hydrogels as a Schwann cell carrier for injured spinal cord regeneration

Objective. To develop a clinically relevant injectable hydrogel derived from decellularized porcine peripheral nerves and with mechanical properties comparable to native central nervous system (CNS) tissue to be used as a delivery vehicle for Schwann cell transplantation to treat spinal cord injury (SCI). Approach. Porcine peripheral nerves (sciatic and peroneal) were decellularized by chemical decellularization using a sodium deoxycholate and DNase (SDD) method previously developed by our group. The decellularized nerves were delipidated using dichloromethane and ethanol solvent and then digested using pepsin enzyme to form injectable hydrogel formulations. Genipin was used as a crosslinker to enhance mechanical properties. The injectability, mechanical properties, and gelation kinetics of the hydrogels were further analyzed using rheology. Schwann cells encapsulated within the injectable hydrogel formulations were passed through a 25-gauge needle and cell viability was assessed using live/dead staining. The ability of the hydrogel to maintain Schwann cell viability against an inflammatory milieu was assessed in vitro using inflamed astrocytes co-cultured with Schwann cells. Main results. The SDD method effectively removes cells and retains extracellular matrix in decellularized tissues. Using rheological studies, we found that delipidation of decellularized porcine peripheral nerves using dichloromethane and ethanol solvent improves gelation kinetics and mechanical strength of hydrogels. The delipidated and decellularized hydrogels crosslinked using genipin mimicked the mechanical strength of CNS tissue. The hydrogels were found to have shear thinning properties desirable for injectable formulations and they also maintained higher Schwann cell viability during injection compared to saline controls. Using in vitro co-culture experiments, we found that the genipin-crosslinked hydrogels also protected Schwann cells from astrocyte-mediated inflammation. Significance. Injectable hydrogels developed using delipidated and decellularized porcine peripheral nerves are a potential clinically relevant solution to deliver Schwann cells, and possibly other therapeutic cells, at the SCI site by maintaining higher cellular viability and increasing therapeutic efficacy for SCI treatment.

Three-Dimensional Ultrastructure of Flower-Spray Nerve Endings in the Rat Carotid Sinus.

The flower-spray nerve endings are afferent nerve terminals in the carotid sinus that arise from carotid sinus nerve of glossopharyngeal nerve. However, the three-dimensional ultrastructural characteristics of flower-spray nerve endings and spatial relationships between the terminal parts and other cellular elements have not been fully understood. To elucidate their detailed relationship, backscattered electron imaging of serial sections was performed with a scanning electron microscope to produce a three-dimensional reconstruction of the flower-spray endings. The terminal parts of flower-spray endings were distributed horizontally approximately 5µm outside the external elastic membrane in the tunica adventitia of the internal carotid artery. The three-dimensional reconstruction showed that the terminal parts of flower-spray endings were flat with irregular contours and were partially covered by the thin cytoplasmic processes of Schwann cells. The complex consisting of the nerve terminals and associated Schwann cells was surrounded by a multilayered basement membrane. The terminal parts of the endings were also surrounded by fibroblasts with elastic fibers and collagen fibrils. Secretory vesicles without an electron-dense core were observed in the terminal parts of the endings. The accumulation of vesicles just below the axonal membrane was observed in terminal parts not covered by Schwann cell cytoplasmic processes on both the luminal and basal sides. Swollen mitochondria, concentric membranous structures, and glycogen granule-like electron-dense materials were often noted in some of the terminal parts of the endings and the parent axon. Collectively, the present results suggest that flower-spray endings are baroreceptors because their morphology was similar to other mechanoreceptors. Furthermore, flower-spray endings may be affected by glutamate secreted in an autocrine manner.