Skin wound repair is critically regulated by peripheral nerves. Injury or dysfunction of these nerves represents a key factor impairing the healing of pathological wounds, such as diabetic ulcers and deep burns. The mechanisms by which peripheral nerves participate in cutaneous wound healing primarily involve modulation of immune responses, construction of stem cell niches, and promotion of angiogenesis. Sensory neurons initiate and mediate essential local immune responses, contribute to the epidermal stem cell microenvironment, and support regenerative potential. Sympathetic nerves bidirectionally regulate immune homeostasis via the release of various neuromodulators and precisely control the activation of hair follicle stem cells as well as the homeostasis of melanocyte stem cells. Schwann cells also play pivotal roles in immune modulation, balancing repair processes and mitigating scar formation. During revascularization, sensory and autonomic nerve terminals release neurotransmitters that precisely regulate vasomotor activity and angiogenesis, while Schwann cells facilitate the reconstruction of functional vascular networks via potent paracrine signaling. This review systematically summarizes the crucial roles of peripheral nerves in skin wound repair, with emphasis on their regulatory mechanisms in immune responses, stem cell activation and homeostasis, and vascular dynamics, thereby providing insights into the development of novel therapeutic strategies targeting peripheral nerve regulation.
Humans ; Wound Healing/physiology* ; Peripheral Nerves/physiology* ; Schwann Cells/physiology* ; Skin/injuries* ; Animals

Perineural invasion (PNI) by tumor cells is a key phenotype of highly-invasive oral squamous cell carcinoma (OSCC). Since Schwann cells (SCs) and fibroblasts maintain the physiological homeostasis of the peripheral nervous system, and we have focused on cancer-associated fibroblasts (CAFs) for decades, it's imperative to elucidate the impact of CAFs on SCs in PNI⁺ OSCCs. We describe a disease progression-driven shift of PNI^- towards PNI⁺ during the progression of early-stage OSCC (31%, n = 125) to late-stage OSCC (53%, n = 97), characterized by abundant CAFs and nerve demyelination. CAFs inhibited SC proliferation/migration and reduced neurotrophic factors and myelin in vitro, and this involved up-regulated ER stress and decreased MAPK signals. Moreover, CAFs also aggravated the paralysis of the hind limb and PNI in vivo. Unexpectedly, leukemia inhibitory factor (LIF) was exclusively expressed on CAFs and up-regulated in metastatic OSCC. The LIF inhibitor EC330 restored CAF-induced SC inactivation. Thus, OSCC-derived CAFs inactivate SCs to aggravate nerve injury and PNI development.
Schwann Cells/metabolism* ; Mouth Neoplasms/metabolism* ; Humans ; Cancer-Associated Fibroblasts/metabolism* ; Animals ; Carcinoma, Squamous Cell/metabolism* ; Neoplasm Invasiveness/pathology* ; Male ; Female ; Mice ; Cell Movement/physiology* ; Cell Proliferation/physiology* ; Cell Line, Tumor ; Leukemia Inhibitory Factor/metabolism* ; Middle Aged

Demyelination and remyelination play key roles in spinal cord injury (SCI), affecting the recovery of motor and sensory functions. Research in rodent models is extensive, but the study of these processes in non-human primates is limited. Therefore, our goal was to thoroughly study the histological features of demyelination and remyelination after contusion injury of the cervical spinal cord in Macaca fascicularis. In a previous study, we created an SCI model in M. fascicularis by controlling the contusion displacement. We used Eriochrome Cyanine staining, immunohistochemical analysis, and toluidine blue staining to evaluate demyelination and remyelination. The results showed demyelination ipsilateral to the injury epicenter both rostrally and caudally, the former mainly impacting sensory pathways, while the latter primarily affected motor pathways. Toluidine blue staining showed myelin loss and axonal distension at the injury site. Schwann cell-derived myelin sheaths were only found at the center, while thinner myelin sheaths from oligodendrocytes were seen at the center and surrounding areas. Our study showed that long-lasting demyelination occurs in the spinal cord of M. fascicularis after SCI, with oligodendrocytes and Schwann cells playing a significant role in myelin sheath formation at the injury site.
Animals ; Spinal Cord Injuries/physiopathology* ; Demyelinating Diseases/etiology* ; Remyelination/physiology* ; Macaca fascicularis ; Disease Models, Animal ; Myelin Sheath/pathology* ; Oligodendroglia/pathology* ; Schwann Cells/pathology* ; Female ; Spinal Cord/pathology* ; Axons/pathology*

Schwann cells and macrophages are the main immune cells involved in peripheral nerve injury. After injury, Schwann cells produce an inflammatory response and secrete various chemokines, inflammatory factors, and some other cytokines to promote the recruitment and M2 polarization of blood-derived macrophages, enhancing their phagocytotic ability, and thus play an important role in promoting nerve regeneration. Macrophages have also been found to promote vascular regeneration after injury, promote the migration and proliferation of Schwann cells along blood vessels, and facilitate myelination and axon regeneration. Therefore, there is a close interaction between Schwann cells and macrophages during peripheral nerve regeneration, but this has not been systematically summarized. In this review, the mechanisms of action of Schwann cells and macrophages in each other's migration and phenotypic transformation are reviewed from the perspective of each other, to provide directions for research on accelerating nerve injury repair.
Schwann Cells/metabolism* ; Peripheral Nerve Injuries/physiopathology* ; Animals ; Macrophages/immunology* ; Nerve Regeneration/physiology* ; Humans ; Cell Movement/physiology*

Dorsal root ganglia (DRG) is an essential part of the peripheral nervous system and the hub of the peripheral sensory afferent. The dynamic changes of neuronal cells and their gene expression during the development of dorsal root ganglion have been studied through single-cell RNAseq analysis, while the dynamic changes of non-neuronal cells have not been systematically studied. Using single cell RNA sequencing technology, we conducted a research on the non-neuronal cells in the dorsal root ganglia of rats at different developmental stage. In this study, primary cell suspension was obtained from using the dorsal root ganglions (DRGs, L4-L5) of ten 7-day-old rats and three 3-month-old rats. The 10×Genomics platform was used for single cell dissociation and RNA sequencing. Twenty cell subsets were acquired through cluster dimension reduction analysis, and the marker genes of different types of cells in DRG were identified according to previous researches about DRG single cell transcriptome sequencing. In order to find out the non-neuronal cell subsets with significant differences at different development stage, the cells were classified into different cell types according to markers collected from previous researches. We performed pseudotime analysis of 4 types Schwann cells. It was found that subtype Ⅱ Schwann cells emerged firstly, and then were subtype Ⅲ Schwann cells and subtype Ⅳ Schwann cells, while subtype Ⅰ Schwann cells existed during the whole development procedure. Pseudotime analysis indicated the essential genes influencing cell fate of different subtypes of Schwann cell in DRG, such as Ntrk2 and Pmp2, which affected cell fate of Schwann cells during the development period. GO analysis of differential expressed genes showed that the up-regulated genes, such as Cst3 and Spp1, were closely related to biological process of tissue homeostasis and multi-multicellular organism process. The down regulated key genes, such as Col3a1 and Col4a1, had close relationship with the progress of extracellular structure organization and negative regulation of cell adhesion. This suggested that the expression of genes enhancing cell homestasis increased, while the expression of related genes regulating ECM-receptor interaction pathway decreased during the development. The discovery provided valuable information and brand-new perspectives for the study on the physical and developmental mechanism of Schwann cell as well as the non-neuronal cell changes in DRG at different developmental stage. The differential gene expression results provided crucial references for the mechanism of somatosensory maturation during development.
Rats ; Animals ; Ganglia, Spinal/metabolism* ; Rats, Sprague-Dawley ; Transcriptome ; Neurons/metabolism* ; Schwann Cells/physiology*

Enhancing remyelination after injury is of utmost importance for optimizing the recovery of nerve function. While the formation of myelin by Schwann cells (SCs) is critical for the function of the peripheral nervous system, the temporal dynamics and regulatory mechanisms that control the progress of the SC lineage through myelination require further elucidation. Here, using in vitro co-culture models, gene expression profiling of laser capture-microdissected SCs at various stages of myelination, and multilevel bioinformatic analysis, we demonstrated that SCs exhibit three distinct transcriptional characteristics during myelination: the immature, promyelinating, and myelinating states. We showed that suppressor interacting 3a (Sin3A) and 16 other transcription factors and chromatin regulators play important roles in the progress of myelination. Sin3A knockdown in the sciatic nerve or specifically in SCs reduced or delayed the myelination of regenerating axons in a rat crushed sciatic nerve model, while overexpression of Sin3A greatly promoted the remyelination of axons. Further, in vitro experiments revealed that Sin3A silencing inhibited SC migration and differentiation at the promyelination stage and promoted SC proliferation at the immature stage. In addition, SC differentiation and maturation may be regulated by the Sin3A/histone deacetylase2 (HDAC2) complex functionally cooperating with Sox10, as demonstrated by rescue assays. Together, these results complement the recent genome and proteome analyses of SCs during peripheral nerve myelin formation. The results also reveal a key role of Sin3A-dependent chromatin organization in promoting myelinogenic programs and SC differentiation to control peripheral myelination and repair. These findings may inform new treatments for enhancing remyelination and nerve regeneration.
Animals ; Axons ; Chromatin/metabolism* ; Gene Expression Profiling ; Myelin Sheath/metabolism* ; Nerve Regeneration/physiology* ; Rats ; Schwann Cells/metabolism* ; Sciatic Nerve/injuries*

OBJECTIVETo observe the effect of Draconis Sanguis-containing serum on the expressions of NGF, BDNF, CNTF, LNG-FR, TrkA, GDNF, GAP-43 and NF-H in Schwann cells, and investigate the possible mechanism of Draconis Sanguis to promote peripheral nerve regeneration.

METHODSD rats were randomly divided into 2 groups: the Draconis Sanguis group (orally administered with Draconis Sanguis-containing balm solution) and the blank group (equivoluminal balm) to prepare Draconis Sanguis-containing serum and blank control serum. Schwann cells were extracted from double sciatic nerves of three-day-old SD rats, divided into 2 groups: the Draconis Sanguis group and the blank control group, and respectively cultured with 10% Draconis Sanguis-containing serum or blank control serum. The mRNA expressions of NGF, BDNF, CNTF and other genes in Schwann cells were measured by RT-PCR analysis 48 hours later.

RESULTMost of the Schwann cells were bipolar spindle and arranged shoulder to shoulder or end to end under the microscope and identified to be positive with the immunocytochemical method. To compare with the blank group, mRNA expressions of NGF, LNGFR, GDNF and GAP-43 significantly increased (P < 0.01). Whereas that of BDNF decreased significantly (P < 0.05), and so did that of TrkA, CNTF (P < 0.01), with no remarkable difference in NF-H-mRNA.

CONCLUSIONTraditional Chinese medicine Draconis Sanguis may show effect in nerve regeneration by up-regulating mRNA expressions of NGF, LNGFR, GDNF and GAP-43 and down-regulating mRNA expressions of TrkA, BDNF and CNTF.

Animals ; Arecaceae ; chemistry ; Brain-Derived Neurotrophic Factor ; genetics ; metabolism ; Cells, Cultured ; Ciliary Neurotrophic Factor ; genetics ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; GAP-43 Protein ; genetics ; metabolism ; Gene Expression ; drug effects ; Glial Cell Line-Derived Neurotrophic Factor ; genetics ; metabolism ; Male ; Nerve Growth Factor ; genetics ; metabolism ; Nerve Regeneration ; drug effects ; Neurofilament Proteins ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptor, trkA ; genetics ; metabolism ; Schwann Cells ; drug effects ; physiology ; Serum ; chemistry

OBJECTIVETo study the role and effect of Schwann cells (SCs) remyelination in contused spinal cord.

METHODSGreen fluorescence protein expressing-SCs were transplanted into the epicenter, rostral and caudal tissues of the injury site at 1 week after the spinal cords were contused. At 6 weeks, the spinal cords were removed for cryosections, semithin sections and ultrathin sections, and then immunocytochemical staining of myelin basic protein (MBP), P0 protein (P0) and S100 protein (S100) was carried out on the cryosections. Qualitative and semiquantitative analyses were performed on the cryosections and semithin sections. Ultrastructure of myelinated fibers was observed on the ultrathin sections under electron microscope.

RESULTSTransplanted SCs and myelinated fibers immunocytochemically labeled by MBP, P0 as well as S100 distributed in whole injured area. The quantity of myelinated fibers labeled by the three myelin proteins showed no statistical difference, however, which was significantly larger than that of controls. On the semithin sections, the experimental group demonstrated more myelinated fibers in the injured area than the controls, but the fibers had smaller diameter and thinner myelin sheath under electron microscope.

CONCLUSIONSCs can promote regeneration of injured nerve fibers and enhance remyelination, which may be histological basis of SCs-mediated functional repair of injured spinal cords.

Animals ; Immunohistochemistry ; Microscopy, Electron ; Myelin Basic Protein ; metabolism ; Myelin P0 Protein ; metabolism ; Nerve Regeneration ; physiology ; Rats ; Rats, Sprague-Dawley ; S100 Proteins ; metabolism ; Schwann Cells ; physiology ; ultrastructure ; Spinal Cord Injuries ; metabolism ; physiopathology

BACKGROUNDVarious tissue engineering strategies have been developed to facilitate axonal regeneration after spinal cord injury. This study aimed to investigate whether neural stem cells (NSCs) could survive in poly(L-lactic-co-glycolic acid) (PLGA) scaffolds and, when cografted with Schwann cells (SCs), could be induced to differentiate towards neurons which form synaptic connection and eventually facilitate axonal regeneration and myelination and motor function.

METHODSNSCs and SCs which were seeded within the directional PLGA scaffolds were implanted in hemisected adult rat spinal cord. Control rats were similarly injured and implanted of scaffolds with or without NSCs. Survival, migration, differentiation, synaptic formation of NSCs, axonal regeneration and myelination and motor function were analyzed. Student's t test was used to determine differences in surviving percentage of NSCs. One-way analysis of variance (ANOVA) was used to determine the differences in the number of axons myelinated in the scaffolds, the mean latency and amplitude of cortical motor evoked potentials (CMEPs) and Basso, Beattie & Bresnahan locomotor rating scale (BBB) score. The χ(2) test was used to determine the differences in recovery percentage of CMEPs.

RESULTSNSCs survived, but the majority migrated into adjacent host cord and died mostly. Survival rate of NSCs with SCs was higher than that of NSCs without SCs ((1.7831 ± 0.0402)% vs. (1.4911 ± 0.0313)%, P < 0.001). Cografted with SCs, NSCs were induced to differentiate towards neurons and might form synaptic connection. The mean number of myelinated axons in PLGA + NSCs + SCs group was more than that in PLGA + NSCs group and in PLGA group ((110.25 ± 30.46) vs. (18.25 ± 3.30) and (11.25 ± 5.54), P < 0.01). The percentage of CMEPs recovery in PLGA + NSCs + SCs group was higher than in the other groups (84.8% vs. 50.0% and 37.5%, P < 0.05). The amplitude of CMEPs in PLGA + NSCs + SCs group was higher than in the other groups ((1452.63 ± 331.70) µV vs. (428.84 ± 193.01) µV and (117.33 ± 14.40) µV, P < 0.05). Ipsilateral retransection resulted in disappearance again and functional loss of CMEPs for a few days. But contralateral retransection completely damaged the bilateral motor function.

CONCLUSIONSNSCs can survive in PLGA scaffolds, and SCs promote NSCs to survive and differentiate towards neurons in vivo which even might form synaptic connection. The scaffolds seeded with cells facilitate axonal regeneration and myelination and motor function recovery. But regenerating axons have limited contribution to motor function recovery.

Animals ; Axons ; physiology ; Cells, Cultured ; Electrophysiology ; Female ; Fluorescent Antibody Technique ; Lactic Acid ; chemistry ; Nerve Regeneration ; physiology ; Neural Stem Cells ; cytology ; Polyglycolic Acid ; chemistry ; Pregnancy ; Rats ; Rats, Wistar ; Schwann Cells ; cytology ; Spinal Cord Injuries ; therapy ; Tissue Engineering ; methods ; Tissue Scaffolds ; chemistry

Olfactory ensheathing cells (OECs) are a unique type of glia with common properties of astrocyte and Schwann cells. Cultured OECs have two morphological phenotypes, astrocyte-like OECs and Schwann cell-like OECs. Reversible changes have been found between these two morphological phenotypes. However, the molecular mechanism underlying the regulation of these reversible changes is still unknown. The aim of this paper is to establish a method for the morphology plasticity of cultured OECs, and investigate the underlying mechanism. Using the primary culture of OECs and immunocytochemistry, the morphology of OECs was observed under serum, serum free media or dB-cAMP drug treatment. Statistical analysis was performed to test differences among the percentages of OEC subtypes under these conditions. The results showed that under serum free media, (95.2±3.7)% of OECs showed Schwann cell-like morphology, and (4.8±3.7)% of OECs showed astrocyte-like morphology; however, under 10% serum media, (42.5±10.4)% of OECs exhibited Schwann cell-like morphology, and (57.5±10.4)% of OECs exhibited astrocyte-like morphology. When media was changed back to serum free media for 24 h, (94.8±5.0)% of OECs showed Schwann cell-like morphology, and (5.2±5.0)% of OECs showed astrocyte-like morphology. Furthermore, culture condition with or without serum did not affect the expression of OEC cell marker, p-75 and S-100. Finally, dB-cAMP, an analog of cAMP, through inhibiting the formation of F-actin stress fibers and focal adhesion, induced the morphology switch from astrocyte-like to Schwann cell-like morphology under serum condition, promoted the branches and the growth of processes. These results suggest that serum induces the morphology plasticity of cultured OECs, which is mediated by cytoplasmic cAMP level through regulating the formation of F-actin stress fibers and focal adhesion.
Animals ; Astrocytes ; cytology ; physiology ; Cells, Cultured ; Culture Media ; pharmacology ; Cyclic AMP ; physiology ; Male ; Neuroglia ; cytology ; physiology ; Olfactory Bulb ; cytology ; physiology ; Rats ; Rats, Sprague-Dawley ; Schwann Cells ; cytology ; physiology ; Serum ; physiology