Identification of key genes involved in recovery from spinal cord injury in adult zebrafish

Zebrafish are an effective vertebrate model to study the mechanisms underlying recovery after spinal cord injury.The subacute phase after spinal cord injury is critical to the recovery of neurological function,which involves tissue bridging and axon regeneration.In this study,we found that zebrafish spontaneously recovered 44%of their swimming ability within the subacute phase(2 weeks)after spinal cord injury.During this period,we identified 7762 differentially expressed genes in spinal cord tissue:2950 were up-regulated and 4812 were down-regulated.These differentially expressed genes were primarily concentrated in the biological processes of the respiratory chain,axon regeneration,and cell-component morphogenesis.The genes were also mostly involved in the regulation of metabolic pathways,the cell cycle,and gene-regulation pathways.We verified the gene expression of two differentially expressed genes,clasp2 up-regulation and h1m down-regulation,in zebrafish spinal cord tissue in vitro.Pathway enrichment analysis revealed that up-regulated clasp2 functions similarly to microtubule-associated protein,which is responsible for axon extension regulated by microtubules.Down-regulated h1m controls endogenous stem cell differentiation after spinal cord injury.This study provides new candidate genes,clasp2 and h1m,as potential therapeutic intervention targets for spinal cord injury repair by neuroregeneration.All experimental procedures and protocols were approved by the Animal Ethics Committee of Tianjin Institute of Medical&Pharmaceutical Sciences(approval No.IMPS-EAEP-Q-2019-02)on September 24,2019.     

Epidural electrical stimulation effectively restores locomotion function in rats with complete spinal cord injury

Epidural electrical stimulation can restore limb motor function after spinal cord injury by reactivating the surviving neural circuits.In previous epidural electrical stimulation studies,single electrode sites and continuous tetanic stimulation have often been used.With this stimulation,the body is prone to declines in tolerance and locomotion coordination.In the present study,rat models of complete spinal cord injury were established by vertically cutting the spinal cord at the T8 level to eliminate disturbance from residual nerve fibers,and were then subjected to epidural electrical stimulation.The flexible extradural electrode had good anatomical topology and matched the shape of the spinal canal of the implanted segment.Simultaneously,the electrode stimulation site was able to be accurately applied to the L2–3 and S1 segments of the spinal cord.To evaluate the biocompatibility of the implanted epidural electrical stimulation electrodes,GFAP/Iba-1 doublelabeled immunofluorescence staining was performed on the spinal cord below the electrodes at 7 days after the electrode implantation.Immunofluorescence results revealed no significant differences in the numbers or morphologies of microglia and astrocytes in the spinal cord after electrode implantation,and there was no activated Iba-1~+ cell aggregation,indicating that the implant did not cause an inflammatory response in the spinal cord.Rat gait analysis showed that,at 3 days after surgery,gait became coordinated in rats with spinal cord injury under burst stimulation.The regained locomotion could clearly distinguish the support phase and the swing phase and dynamically adjust with the frequency of stimulus distribution.To evaluate the matching degree between the flexible epidural electrode(including three stimulation contacts),vertebral morphology,and the level of the epidural site of the stimulation electrode,micro-CT was used to scan the thoracolumbar vertebrae of rats before and after electrode implantation.Based on the experimental results of gait recovery using three-site stimulation electrodes at L2–3 and S1 combined with burst stimulation in a rat model of spinal cord injury,epidural electrical stimulation is a promising protocol that needs to be further explored.This study was approved by the Animal Ethics Committee of Chinese PLA General Hospital(approval No.2019-X15-39) on April 19,2019.     

Lymphokine mRNA expression in the spinal cords of Lewis rats with experimental autoimmune encephalomyelitis is associated with a host recruited CD45R hi/CD4 population during recovery

To evaluate CD4⁺ T cell subpopulations involved in the induction and recovery from experimental autoimmune encephalomyelitis (EAE), the CD45R phenotype and lymphokine mRNA profile was evaluated for encephalitogenic CD4⁺ T cell lines in vitro and compared to CD4^* T cells islated from the spinal cord of Lewis rats with EAE were > 90% of the myelin basic protein (MBP)-specific T cell lines and clones that adoptively transferred EAE were > 90% CD4⁺ and > 90% CD45R lo. A time course of EAE disease progression was monitored as a function of the percentage of CD45R hi/CD4⁺ T cells isolated from the spinal cords of diseased animals. The majority of CD4⁺ T cells found in the central nervous system during the early phase of passive EAE were CD45R lo (the same as the encephalitogenic lines/clones). A large increase of the CD45R hi/CD4⁺ T cells (up to 45%) was observed during the peak and recovery phases of EAE. Lymphokine mRNA production was analyzed from antigen-stimulated MBP-specific lines, and from spinal cord lymphocytes isolated from rats with EAE. The BP-specific lines produced Th1 lymphokines (IL-2, IFN-γ, and TNF-α), while the spinal cord lymphocytes produced the same Th1 lymphokines as well as IL-4 and IL-10. The CD45R hi/CD4⁺ T cells isolated from the spinal cords were larger and expressed more lymphokine RNA per cell than the CD45R lo/CD4⁺ T cells. The encephalitogenic cells (CD45R hi/CD4⁺ T detected in the spinal cords of rats with a fluorescent dye and by allelic transfers and all of the CD45R hi/CD4⁺ lymphocytes found in the spinal cells were found to be host recruited. Thus it appears that the CD45R hi/CD4⁺ lymphocytes found in the spinal cord represent a host-recruited, activated cellular infiltrate that increased in number in the recovery phase of EAE and synthesized both Th1 and Th2 lymphokines.     

Identification of potential oxidative stress biomarkers for spinal cord injury in erythrocytes using mass spectrometry

Oxidative stress is a hallmark of secondary injury associated with spinal cord injury.Identifying stable and specific oxidative biomarkers is of important significance for studying spinal cord injury-associated secondary injury.Mature erythrocytes do not contain nuclei and mitochondria and cannot be transcribed and translated.Therefore, mature erythrocytes are highly sensitive to oxidative stress and may become a valuable biomarker.In the present study, we revealed the proteome dynamics of protein expression in erythrocytes of beagle dogs in the acute and subacute phases of spinal cord injury using mass spectrometry-based approaches.We found 26 proteins that were differentially expressed in the acute(0–3 days) and subacute(7–21 days) phases of spinal cord injury.Bioinformatics analysis revealed that these differentially expressed proteins were involved in glutathione metabolism, lipid metabolism, and pentose phosphate and other oxidative stress pathways.Western blot assays validated the differential expression of glutathione synthetase, transaldolase, and myeloperoxidase.This result was consistent with mass spectrometry results, suggesting that erythrocytes can be used as a novel sample source of biological markers of oxidative stress in spinal cord injury.Glutathione synthetase, transaldolase, and myeloperoxidase sourced from erythrocytes are potential biomarkers of oxidative stress after spinal cord injury.This study was approved by the Experimental Animal Centre of Ningxia Medical University, China(approval No.2017-073) on February 13, 2017.     

A multi-channel collagen scaffold loaded with neural stem cells for the repair of spinal cord injury

Collagen scaffolds possess a three-dimensional porous structure that provides sufficient space for cell growth and proliferation,the passage of nutrients and oxygen,and the discharge of metabolites.In this study,a porous collagen scaffold with axially-aligned luminal conduits was prepared.In vitro biocompatibility analysis of the collagen scaffold revealed that it enhances the activity of neural stem cells and promotes cell extension,without affecting cell differentiation.The collagen scaffold loaded with neural stem cells improved the hindlimb motor function in the rat model of T8 complete transection and promoted nerve regeneration.The collagen scaffold was completely degraded in vivo within 5 weeks of implantation,exhibiting good biodegradability.Rectal temperature,C-reactive protein expression and CD68 staining demonstrated that rats with spinal cord injury that underwent implantation of the collagen scaffold had no notable inflammatory reaction.These findings suggest that this novel collagen scaffold is a good carrier for neural stem cell transplantation,thereby enhancing spinal cord repair following injury.This study was approved by the Animal Ethics Committee of Nanjing Drum Tower Hospital(the Affiliated Hospital of Nanjing University Medical School),China(approval No.2019AE02005)on June 15,2019.     

Temporal kinetics of macrophage polarization in the injured rat spinal cord

Local activated macrophages derived from infiltrating monocytes play an important role in the damage and repair process of spinal cord injury (SCI). The present study investigates the dynamic change of classically activated proinflammatory (M1) and alternatively activated anti‐inflammatory (M2) cells in a rat model with contusive SCI by flow cytometry (FCM) and immunohistochemistry. The macrophage subsets were immunophenotyped by using antibodies against cluster of differentiation (CD)?68, C‐C chemokine receptor type 7 (CCR7), CD163, and arginase 1 (Arg1). The CD68⁺CD163^– and CD68⁺CCR7⁺ cells were determined to be M1 subsets, whereas the CD68⁺CD163⁺ and CD68⁺Arg1⁺ cell subpopulations represented M2 cells. The subsets of macrophages in the injured spinal cord at 1, 3, 5, 7, 14, and 28 days postinjury (dpi) were examined. In the sham‐opened spinal cord, few M1 or M2 cells were found. After SCI, the phenotypes of both M1 and M2 cells were rapidly induced. However, M1 cells were detected and maintained at a high level for up to 28 dpi (the longest time evaluated in this study). In contrast, M2 cells were transiently detected at high levels before 7 dpi and returned to preinjury levels at 14 dpi. These results indicate that M1 cell response is rapidly induced and sustained, whereas M2 induction is transient after SCI in rat. Increasing the fraction of M2 cells and prolonging their residence time in the injured local microenvironment is a promising strategy for the repair of SCI. © 2015 Wiley Periodicals, Inc.     

CD133 cells from human umbilical cord blood reduce cortical damage and promote axonal growth in neonatal rat organ co-cultures exposed to hypoxia

To evaluate the effect of CD133⁺ cells (endothelial progenitor cells) on the hypoxia-induced suppression of axonal growth of cortical neurons and the destruction of blood vessels (endothelial cells), we used anterograde axonal tracing and immunofluorescence in organ co-cultures of the cortex and the spinal cord from 3-day-old neonatal rats. CD133⁺ cells prepared from human umbilical cord blood were added to the organ co-cultures after hypoxic insult, and axonal growth, vascular damage and apoptosis were evaluated. Anterograde axonal tracing with 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate was used to analyze axonal projections from the cortex to the spinal cord. Immunolabeling co-cultured tissues of the cortex and the spinal cord were used to investigate the effect of CD133⁺ cells on the survival of blood vessels and apoptosis in the brain cortex. Hypoxia remarkably suppressed axonal growth in organ co-cultures of the cortex and the spinal cord, and this suppression was significantly restored by the addition of CD133⁺ cells. CD133⁺ cells also reduced the hypoxia-induced destruction of the cortical blood vessels and apoptosis. CD133⁺ cells had protective effects on hypoxia-induced injury of neurons and blood vessels of the brain cortex in vitro. These results suggest that CD133⁺ cell transplantation may be a possible therapeutic intervention for perinatal hypoxia-induced brain injury.     

Inducing inflammation following subacute spinal cord injury in female rats: A double-edged sword to promote motor recovery

The inflammatory response following spinal cord injury is associated with increased tissue damage and impaired functional recovery. However, inflammation can also promote plasticity and the secretion of growth-promoting substances. Previously we have shown that inducing inflammation with a systemic injection of lipopolysaccharide in the chronic (8 weeks) stage of spinal cord injury enhances neuronal sprouting and the efficacy of rehabilitative training in rats. Here, we tested whether administration of lipopolysaccharide in female rats in the subacute (10 days) stage of spinal cord injury would have a similar effect. Since the lesioned environment is already in a pro-inflammatory state at this earlier time after injury, we hypothesized that triggering a second immune response may not be beneficial for recovery. Contrary to our hypothesis, we found that eliciting an inflammatory response 10 days after spinal cord injury enhanced the recovery of the ipsilesional forelimb in rehabilitative training. Compared to rats that received rehabilitative training without treatment, rats that received systemic lipopolysaccharide showed restored motor function without the use of compensatory strategies that translated beyond the trained task. Furthermore, lipopolysaccharide treatment paradoxically promoted the resolution of chronic neuroinflammation around the lesion site. Unfortunately, re-triggering a systemic immune response after spinal cord injury also resulted in a long-term increase in anxiety-like behaviour.     

Low-dose metformin treatment in the subacute phase improves the locomotor function of a mouse model of spinal cord injury

Metformin,a first-line drug for type-2 diabetes,has been shown to improve locomotor recovery after spinal cord injury.However,there are studies reporting no beneficial effect.Recently,we found that high dose of metformin(200 mg/kg,intraperitoneal)and acute phase administration(immediately after injury)led to increased mortality and limited locomotor function recovery.Consequently,we used a lower dose(100 mg/kg,i.p.)metformin in mice,and compared the effect of immediate administration after spinal cord injury(acute phase)with that of administration at 3 days post-injury(subacute phase).Our data showed that metformin treatment starting at the subacute phase significantly improved mouse locomotor function evaluated by Basso Mouse Scale(BMS)scoring.Immunohistochemical studies also revealed significant inhibitions of microglia/macrophage activation and astrogliosis at the lesion site.Furthermore,metformin treatment at the subacute phase reduced neutrophil infiltration.These changes were in parallel with the increased survival rate of spinal neurons in animals treated with metformin.These findings suggest that low-dose metformin treatment for subacute spinal cord injury can effectively improve the functional recovery possibly through anti-inflammation and neuroprotection.This study was approved by the Institute Animal Care and Use Committee at the University of Texas Medical Branch(approval No.1008041C)in 2010.     

Granzyme‐b mediated cell death in the spinal cord‐injured rat model

Spinal cord injury initiates a complex series of inflammatory and immune responses including the influx of monocytes, macrophages, T‐cells, NK cells and so on, into the injured area. In the present study, we found a significant increase in the levels of granzyme‐b (gra‐b) from the first day after the transection until the third day, with decrease in intensity thereafter. The chemokine IP‐10/CXCL10 was also found to be elevated along with gra‐b correlating with the infiltration of CD‐8⁺ cytotoxic T lymphocytes (CTLs) into the injured spinal cord. We observed an increase in the levels of the 64 kDa poly ADP ribose polymerase fragment, known to be a signature fragment produced by gra‐b. Localization of gra‐b in TUNEL positive neurons indicates that gra‐b might play a crucial role in neuronal death and contributes to the pathophysiology of spinal cord injury.     

VX-765 reduces neuroinflammation after spinal cord injury in mice

Inflammation is a major cause of neuronal injury after spinal cord injury. We hypothesized that inhibiting caspase-1 activation may reduce neuroinflammation after spinal cord injury, thus producing a protective effect in the injured spinal cord. A mouse model of T9 contusive spinal cord injury was established using an Infinite Horizon Impactor, and VX-765, a selective inhibitor of caspase-1, was administered for 7 successive days after spinal cord injury. The results showed that: (1) VX-765 inhibited spinal cord injury-induced caspase-1 activation and interleukin-1β and interleukin-18 secretion. (2) After spinal cord injury, an increase in M1 cells mainly came from local microglia rather than infiltrating macrophages. (3) Pro-inflammatory Th1Th17 cells were predominant in the Th subsets. VX-765 suppressed total macrophage infiltration, M1 macrophages/microglia, Th1 and Th1Th17 subset differentiation, and cytotoxic T cells activation; increased M2 microglia; and promoted Th2 and Treg differentiation. (4) VX-765 reduced the fibrotic area, promoted white matter myelination, alleviated motor neuron injury, and improved functional recovery. These findings suggest that VX-765 can reduce neuroinflammation and improve nerve function recovery after spinal cord injury by inhibiting caspase-1/interleukin-1β/interleukin-18. This may be a potential strategy for treating spinal cord injury. This study was approved by the Animal Care Ethics Committee of Bengbu Medical College (approval No. 2017-037) on February 23, 2017.

Chinese Library Classification No. R453; R392.3; R744     

Astrocytes initiate inflammation in the injured mouse spinal cord by promoting the entry of neutrophils and inflammatory monocytes in an IL-1 receptor/MyD88-dependent fashion

CNS injury stimulates the expression of several proinflammatory cytokines and chemokines, some of which including MCP-1 (also known as CCL2), KC (CXCL1), and MIP-2 (CXCL2) act to recruit Gr-1⁺ leukocytes at lesion sites. While earlier studies have reported that neutrophils and monocytes/macrophages contribute to secondary tissue loss after spinal cord injury (SCI), recent work has shown that depletion of Gr-1⁺ leukocytes compromised tissue healing and worsened functional recovery. Here, we demonstrate that astrocytes distributed throughout the spinal cord initially contribute to early neuroinflammation by rapidly synthesizing MCP-1, KC, and MIP-2, from 3 up to 12 h post-SCI. Chemokine expression by astrocytes was followed by the infiltration of blood-derived immune cells, such as type I “inflammatory” monocytes and neutrophils, into the lesion site and nearby damaged areas. Interestingly, astrocytes from mice deficient in MyD88 signaling produced significantly less MCP-1 and MIP-2 and were unable to synthesize KC. Analysis of the contribution of MyD88-dependent receptors revealed that the astrocytic expression of MCP-1, KC, and MIP-2 was mediated by the IL-1 receptor (IL-1R1), and not by TLR2 or TLR4. Flow cytometry analysis of cells recovered from the spinal cord of MyD88- and IL-1R1-knockout mice confirmed the presence of significantly fewer type I “inflammatory” monocytes and the almost complete absence of neutrophils at 12 h and 4 days post-SCI. Together, these results indicate that MyD88/IL-1R1 signals regulate the entry of neutrophils and, to a lesser extent, type I “inflammatory” monocytes at sites of SCI.     

Inflammatory cells, microglia and MHC class II antigen-positive cells in the spinal cord of Lewis rats with acute and chronic relapsing experimental autoimmune encephalomyelitis

Chronic relapsing experimental autoimmune encephalomyelitis (CR-EAE) was induced in Lewis rats by inoculation with guinea pig spinal cord and adjuvants and treatment with low dose cyclosporin A (CsA). Acute EAE was induced by the same method without CsA treatment. Immunocytochemistry and flow cytometry were used to assess inflammatory cells and MHC class II (Ia) antigen expression in the central nervous system of these rats. The inflammatory infiltrate was composed mainly of CD4⁺ T cells and macrophages, and αß T cells constituted about 65% of the CD2⁺ T cells. After recovery from acute EAE and during the first remission of CR-EAE, the number of T cells was significantly less than in the preceding episodes. The number of T cells was higher in the second episode of CR-EAE than in the first remission. Throughout the course of CR-EAE, the majority of the CD2⁺ T cells were CD45RC⁻. The ratio of IL-2R⁺ cells to CD2⁺ cells ranged from 10.5 to 24.0%. The ratio of CD4⁺ T cells to B cells was lower in the later episodes of CR-EAE than in the first episode. Ia antigen was expressed on filtrating round cells at all stages of CR-EAE and on microglial cells (identified by dendritic morphology) with increasing intensity throughout the course of CR-EAE. With flow cytometry, the number of Ia⁺ cells obtained from the spinal cord rose throughout the course of CR-EAE. The number of FSC^lowOX1^low cells, which we consider represent microglia, also increased during the course of CR-EAE.     

Temporal kinetics of CD8+CD28+ and CD8+CD28− T lymphocytes in the injured rat spinal cord

This study aims to explore the temporal changes of cytotoxic CD8⁺CD28⁺ and regulatory CD8⁺ CD28⁻ T‐cell subsets in the lesion microenvironment after spinal cord injury (SCI) in rats, by combination of immunohistochemistry (IHC) and flow cytometry (FCM). In the sham‐opened spinal cord, few CD8⁺ T cells were found. After SCI, the CD8⁺ T cells were detected at one day post‐injury (dpi), then markedly increased and were significantly higher at 3, 7, and 14 dpi compared with one dpi (p < 0.01), the highest being seven dpi. In CD8⁺ T cells, more than 90% were CD28⁺, and there were only small part of CD28⁻ ( < 10%). After 14 days, the infiltrated CD8⁺ T cells were significantly decreased, and few could be found in good condition at 21 and 28 dpi. Annexin V and propidium iodide (PI) staining showed that the percentages of apoptotic/necrotic CD8⁺ cells at 14 dpi and 21 dpi were significantly higher than those of the other early time‐points (p < 0.01). These results indicate that CD8⁺ T cells could rapidly infiltrate into the injured spinal cords and survive two weeks, however, cytotoxic CD8⁺ T cells were dominant. Therefore, two weeks after injury might be the “time window” for treating SCI by prolonging survival times and increasing the fraction of CD8⁺ regulatory T‐cells. © 2016 Wiley Periodicals, Inc.     

Leukocyte infiltration into spinal cord of EAE mice is attenuated by removal of endothelial leptin signaling

Leptin, a pleiotropic adipokine, crosses the blood-brain barrier (BBB) and blood–spinal cord barrier (BSCB) from the periphery and facilitates experimental autoimmune encephalomyelitis (EAE). EAE induces dynamic changes of leptin receptors in enriched brain and spinal cord microvessels, leading to further questions about the potential roles of endothelial leptin signaling in EAE progression. In endothelial leptin receptor specific knockout (ELKO) mice, there were lower EAE behavioral scores in the early phase of the disorder, better preserved BSCB function shown by reduced uptake of sodium fluorescein and leukocyte infiltration into the spinal cord. Flow cytometry showed that the ELKO mutation decreased the number of CD3 and CD45 cells in the spinal cord, although immune cell profiles in peripheral organs were unchanged. Not only were CD4⁺ and CD8⁺ T lymphocytes reduced, there were also lower numbers of CD11b⁺Gr1⁺ granulocytes in the spinal cord of ELKO mice. In enriched microvessels from the spinal cord of the ELKO mice, the decreased expression of mRNAs for a few tight junction proteins was less pronounced in ELKO than WT mice, as was the elevation of mRNA for CCL5, CXCL9, IFN-γ, and TNF-α. Altogether, ELKO mice show reduced inflammation at the level of the BSCB, less leukocyte infiltration, and better preserved tight junction protein expression and BBB function than WT mice after EAE. Although leptin concentrations were high in ELKO mice and microvascular leptin receptors show an initial elevation before inhibition during the course of EAE, removal of leptin signaling helped to reduce disease burden. We conclude that endothelial leptin signaling exacerbates BBB dysfunction to worsen EAE.     

Gintonin mitigates experimental autoimmune encephalomyelitis by stabilization of Nrf2 signaling via stimulation of lysophosphatidic acid receptors

Gintonin (GT), a glycolipoprotein fraction isolated from ginseng, exerts neuroprotective effects in models of neurodegenerative diseases such as Alzheimer’s disease. However, the in vivo role of GT in multiple sclerosis (MS) has not been clearly resolved. We investigated the effect of GT in myelin oligodendrocyte glycoprotein (MOG_35-55)-induced experimental autoimmune encephalomyelitis (EAE), an animal model of MS. GT alleviated behavioral symptoms of EAE associated with reduced demyelination, diminished infiltration and activation of immune cells (microglia and macrophage), and decreased expression of inflammatory mediators in the spinal cord of the EAE group compared to that of the sham group. GT reduced the percentages of CD4⁺/IFN-γ⁺ (Th1) and CD4⁺/IL-17⁺ (Th17) cells but increased the population of CD4⁺/CD25⁺/Foxp3⁺ (Treg) cells in the spinal cord, in agreement with altered mRNA expression of IFN-γ, IL-17, and TGF-ß in the spinal cord in concordance with mitigated blood–brain barrier disruption. The underlying mechanism is related to inhibition of the ERK and p38 mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) pathways and the stabilization of nuclear factor erythroid 2-related factor 2 (Nrf2) via increased expression of lysophosphatidic acid receptor (LPAR) 1–3. Impressively, these beneficial effects of GT were completely neutralized by inhibiting LPARs with Ki16425, a LPAR1/3 antagonist. Our results strongly suggest that GT may be able to alleviate EAE due to its anti-inflammatory and antioxidant activities through LPARs. Therefore, GT is a potential therapeutic option for treating autoimmune disorders including MS.     

Exosomes derived from bone marrow mesenchymal stem cells protect the injured spinal cord by inhibiting pericyte pyroptosis

Mesenchymal stem cell (MSC) transplantation is a promising treatment strategy for spinal cord injury, but immunological rejection and possible tumor formation limit its application. The therapeutic effects of MSCs mainly depend on their release of soluble paracrine factors. Exosomes are essential for the secretion of these paracrine effectors. Bone marrow mesenchymal stem cell-derived exosomes (BMSC-EXOs) can be substituted for BMSCs in cell transplantation. However, the underlying mechanisms remain unclear. In this study, a rat model of T10 spinal cord injury was established using the impact method. Then, 30 minutes and 1 day after spinal cord injury, the rats were administered 200 μL exosomes via the tail vein (200 μg/mL; approximately 1 × 10⁶ BMSCs). Treatment with BMSC-EXOs greatly reduced neuronal cell death, improved myelin arrangement and reduced myelin loss, increased pericyte/endothelial cell coverage on the vascular wall, decreased blood-spinal cord barrier leakage, reduced caspase 1 expression, inhibited interleukin-1β release, and accelerated locomotor functional recovery in rats with spinal cord injury. In the cell culture experiment, pericytes were treated with interferon-γ and tumor necrosis factor-α. Then, Lipofectamine 3000 was used to deliver lipopolysaccharide into the cells, and the cells were co-incubated with adenosine triphosphate to simulate injury in vitro. Pre-treatment with BMSC-EXOs for 8 hours greatly reduced pericyte pyroptosis and increased pericyte survival rate. These findings suggest that BMSC-EXOs may protect pericytes by inhibiting pyroptosis and by improving blood-spinal cord barrier integrity, thereby promoting the survival of neurons and the extension of nerve fibers, and ultimately improving motor function in rats with spinal cord injury. All protocols were conducted with the approval of the Animal Ethics Committee of Zhengzhou University on March 16, 2019.

Chinese Library Classification No. R456; R745.4; R363     

Therapeutic potential of experimental autoimmune encephalomyelitis by Fasudil,a Rho kinase inhibitor

The migration of aberrant inflammatory cells into the central nervous system plays an important role in the pathogenesis of demyelinating diseases potentially through the Rho/Rho‐kinase (Rock) pathway, but direct evidence from human and animal models remains inadequate. Here we further confirm that Fasudil, a selective Rock inhibitor, has therapeutic potential in a mouse model of myelin oligodendrocyte glycoprotein (MOG)‐induced experimental autoimmune encephalomyelitis (EAE). The results show that Fasudil decreased the development of EAE in C57BL/6 mice. Immunohistochemistry disclosed that expression of Rock‐II in the perivascular spaces and vascular endothelial cells of spleens, spinal cords, and brains was elevated in EAE and was inhibited in the Fasudil‐treated group. T‐cell proliferation specific to MOG_35–55 was markedly reduced, together with a significant down‐regulation of interleukin (IL)‐17, IL‐6, and MCP‐1. In contrast, secretion of IL‐4 was increased, and IL‐10 was slightly elevated. There were no differences in the percentages of CD4⁺CD25⁺, CD8⁺CD28^?, and CD8⁺CD122⁺ in mononuclear cells. Histological staining disclosed a marked decrease of inflammatory cells in spinal cord and brain of Fasudil‐treated mice. These results, together with previous studies showing the inhibitory effect of Fasudil on T‐cell migration, might expand its clinical application as a new therapy for multiple sclerosis by decreasing cell migration and regulating immune balance. © 2010 Wiley‐Liss, Inc.     

Glial and axonal responses in areas of Wallerian degeneration of the corticospinal and dorsal ascending tracts after spinal cord dorsal funiculotomy

Wallerian degeneration (WD), composed of the breakdown and phagocytosis of damaged axons and their myelin sheaths distal to the injury, is a major sequela of spinal cord injury (SCI). To understand the microenvironment within WD that may affect repair following SCI, we investigated the fate of major glial types and axons in this region following acute (1 h), subacute (10 days), and chronic (30 days) dorsal funiculotomy at the eighth thoracic (T8) level. This lesion induces a confined WD in two distinct functional pathways, that is, the corticospinal tract (CST) and dorsal ascending tract (DAT) in opposite directions. Here we report that astrocytes, reactive microglia and macrophages were all significantly increased in areas of WD in both the CST and DAT at subacute and chronic stages compared to the sham‐operated or acute stage. While the level of GFAP⁺ astrocytes remained stable after the subacute stage, the number of OX‐42⁺ microglia and ED‐1⁺ macrophages markedly decreased at the chronic stage. Interestingly, a mild but significant increase in ED‐1⁺ macrophages was also found in the intact fiber tracts 3 mm proximal to the injury at the chronic stage, coinciding with axonal dieback observed at that level. Axons distal to the injury experienced a continued and prolonged degeneration in both fiber tracts. Finally, although a significant decrease of Olig2⁺ oligodendrocyte lineage (OL) cells was found in areas of WD, the presence of these cells at the chronic stage indicates that they are available for endogenous repair. Taken together, our data have provided spatiotemporal evidence for the dynamic pathogenic changes of major cellular components in areas of WD remote to an SCI. Information obtained in this study should be useful for designing experiments aimed at modifying this region to accommodate endogenous or exogenous repair following SCI.