Schwann Cell-Derived Exosomes Induced Axon Growth after Spinal Cord Injury by Decreasing PTP-σ Activation on CSPGs via the Rho/ROCK Pathway.

Spinal cord injury (SCI) is a severe neurological condition that involves a lengthy pathological process. This process leads to the upregulation of chondroitin sulfate proteoglycans (CSPGs) by reactive glia, which impedes repair and regeneration in the spinal cord. The role of the CSPG-specific receptor protein tyrosine phosphatase-sigma (PTP-σ) in post-SCI remains largely unexplored. Exosomes have great potential in the diagnosis, prognosis, and treatment of SCI due to their ability to easily cross the blood‒brain barrier. Schwann cell-derived exosomes (SCDEs) promote functional recovery in mice post-SCI by decreasing CSPG deposition. However, the mechanism by which SCDEs decrease CSPGs after SCI remains unknown. Herein, we observed elevated levels of PTP-σ and increased CSPG deposition during glial scar formation after SCI in vivo. After SCDEs were injected into SCI mice, CSPG deposition decreased in scar tissue at the injury site, the expression of PTP-σ increased during axonal growth around the injury site, and motor function subsequently recovered. Additionally, we demonstrated that the use of both Rho/ROCK inhibitors and SCDEs inhibited the reparative effects of SCDEs on scar tissue after SCI. In conclusion, our study revealed that treatment with SCDEs targeting the Rho/ROCK signaling pathway reduced PTP-σ activation in the CSPG post-SCI, which inhibited scar tissue formation.

miR-NPs-RVG promote spinal cord injury repair: implications from spinal cord-derived microvascular endothelial cells.

BACKGROUND: Spinal cord injury (SCI) often leads to a loss of motor and sensory function. Axon regeneration and outgrowth are key events for functional recovery after spinal cord injury. Endogenous growth of axons is associated with a variety of factors. Inspired by the relationship between developing nerves and blood vessels, we believe spinal cord-derived microvascular endothelial cells (SCMECs) play an important role in axon growth. RESULTS: We found SCMECs could promote axon growth when co-cultured with neurons in direct and indirect co-culture systems via downregulating the miR-323-5p expression of neurons. In rats with spinal cord injury, neuron-targeting nanoparticles were employed to regulate miR-323-5p expression in residual neurons and promote function recovery. CONCLUSIONS: Our study suggests that SCMEC can promote axon outgrowth by downregulating miR-323-5p expression within neurons, and miR-323-5p could be selected as a potential target for spinal cord injury repair.

Epidemiological age-based differences in traumatic spinal cord injury patients: A multicenter study based on 13,334 inpatients.

CONTEXT: Compared with younger traumatic spinal cord injury (TSCI) patients, the elderly had longer delays in admission to surgery, higher proportion of incomplete injury, and longer hospital stays. However, in China, the country with the largest number of TSCI patients, there have been no large-scale reports on their age differences. OBJECTIVES: To explore the age-based differences among TSCI inpatients, focusing on the demographic and clinical characteristics, treatment status, and economic burden. METHODS: We collected the medical records of 13,334 inpatients with TSCI in the 30 hospitals of China, from January 1, 2013 to December 31, 2018. Trends are expressed as annual percentage changes (APCs) and 95% confidence intervals (CIs). RESULTS: A total of 13,334 inpatients were included. Both the number and proportion of the elderly showed an increasing trend. The APC of the number and proportion in patients ≥85 years were 39.5% (95% CI, 14.3 to 70.3; P < 0.01) and 30.5% (95% CI, 8.6 to 56.9; P < 0.01), respectively. Younger patients were more likely to undergo decompression surgery, and older patients were more likely to receive high-dose methylprednisolone sodium succinate/methylprednisolone (MPSS/MP). Of the patients ≥85 years, none underwent decompression surgery within 8 h, and only 1.4% received a high dose of MPSS/MP within 8 h after injury. Elderly patients had lower hospitalization costs than younger. The total and daily medical costs during hospitalization of patients ≥85 years were 8.06 ± 18.80 (IQR: 5.79) and 0.61 ± 0.73 (IQR: 0.55) thousands dollars, respectively. CONCLUSIONS: As the first study to focus on age differences of TSCI patients in China, this study found many differences, in demographic and clinical characteristics, treatment status, and economic costs, between older and younger TSCI patients. The number and proportion of elderly patients increased, and the rate of early surgery for elderly patients is low.

Identification of Differentially Expressed Proteins in Rats with Early Subacute Spinal Cord Injury using an iTRAQ-based Quantitative Analysis.

BACKGROUND: Injuries to the central nervous system (CNS), such as spinal cord injury (SCI), may devastate families and society. Subacute SCI may majorly impact secondary damage during the transitional period between the acute and subacute phases. A range of CNS illnesses has been linked to changes in the level of protein expression. However, the importance of proteins during the early subacute stage of SCI remains unknown. The role of proteins in the early subacute phase of SCI has not been established yet. METHODS: SCI-induced damage in rats was studied using isobaric tagging for relative and absolute protein quantification (iTRAQ) to identify proteins that differed in expression 3 days after the injury, as well as proteins that did not alter in expression. Differentially expressed proteins (DEPs) were analyzed employing Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis to discover the biological processes, cell components, and molecular functions of the proteins. We also performed Gene Set Enrichment Analysis (GSEA) software BP pathway and KEGG analysis on all proteins to further identify their functions. In addition, the first 15 key nodes of a protein-protein interaction (PPI) system were found. RESULTS: During the early subacute stage of SCI, we identified 176 DEPs in total between the control and damage groups, with 114 (64.77%) being up-regulated and 62 (35.23%) being downregulated. As a result of this study, we discovered the most important cellular components and molecular activities, as well as biological processes and pathways, in the early subacute phase of SCI. The top 15 high-degree core nodes were Alb, Plg, F2, Serpina1, Fgg, Apoa1, Vim, Hpx, Apoe, Agt, Ambp, Pcna, Gc, F12, and Gfap. CONCLUSION: Our study could provide new views on regulating the pathogenesis of proteins in the early subacute phase after SCI, which provides a theoretical basis for exploring more effective therapeutic targets for SCI in the future.

N1-Methyladenosine modification of mRNA regulates neuronal gene expression and oxygen glucose deprivation/reoxygenation induction.

N1-Methyladenosine (m1A) is an abundant modification of transcripts, plays important roles in regulating mRNA structure and translation efficiency, and is dynamically regulated under stress. However, the characteristics and functions of mRNA m1A modification in primary neurons and oxygen glucose deprivation/reoxygenation (OGD/R) induced remain unclear. We first constructed a mouse cortical neuron OGD/R model and then used methylated RNA immunoprecipitation (MeRIP) and sequencing technology to demonstrate that m1A modification is abundant in neuron mRNAs and dynamically regulated during OGD/R induction. Our study suggests that Trmt10c, Alkbh3, and Ythdf3 may be m1A-regulating enzymes in neurons during OGD/R induction. The level and pattern of m1A modification change significantly during OGD/R induction, and differential methylation is closely associated with the nervous system. Our findings show that m1A peaks in cortical neurons aggregate at both the 5' and 3' untranslated regions. m1A modification can regulate gene expression, and peaks in different regions have different effects on gene expression. By analysing m1A-seq and RNA-seq data, we show a positive correlation between differentially methylated m1A peaks and gene expression. The correlation was verified by using qRT-PCR and MeRIP-RT-PCR. Moreover, we selected human tissue samples from Parkinson's disease (PD) and Alzheimer's disease (AD) patients from the Gene Expression Comprehensive (GEO) database to analyse the selected differentially expressed genes (DEGs) and differential methylation modification regulatory enzymes, respectively, and found similar differential expression results. We highlight the potential relationship between m1A modification and neuronal apoptosis following OGD/R induction. Furthermore, by mapping mouse cortical neurons and OGD/R-induced modification characteristics, we reveal the important role of m1A modification in OGD/R and gene expression regulation, providing new ideas for research on neurological damage.

The landscape of m1A modification and its posttranscriptional regulatory functions in primary neurons.

Cerebral ischaemia‒reperfusion injury (IRI), during which neurons undergo oxygen-glucose deprivation/reoxygenation (OGD/R), is a notable pathological process in many neurological diseases. N1-methyladenosine (m1A) is an RNA modification that can affect gene expression and RNA stability. The m1A landscape and potential functions of m1A modification in neurons remain poorly understood. We explored RNA (mRNA, lncRNA, and circRNA) m1A modification in normal and OGD/R-treated mouse neurons and the effect of m1A on diverse RNAs. We investigated the m1A landscape in primary neurons, identified m1A-modified RNAs, and found that OGD/R increased the number of m1A RNAs. m1A modification might also affect the regulatory mechanisms of noncoding RNAs, e.g., lncRNA-RNA binding proteins (RBPs) interactions and circRNA translation. We showed that m1A modification mediates the circRNA/lncRNA‒miRNA-mRNA competing endogenous RNA (ceRNA) mechanism and that 3' untranslated region (3'UTR) modification of mRNAs can hinder miRNA-mRNA binding. Three modification patterns were identified, and genes with different patterns had intrinsic mechanisms with potential m1A-regulatory specificity. Systematic analysis of the m1A landscape in normal and OGD/R neurons lays a critical foundation for understanding RNA modification and provides new perspectives and a theoretical basis for treating and developing drugs for OGD/R pathology-related diseases.

Sex-related Differences in Epidemiology, Treatment, and Economic Burden of Traumatic Spinal Cord Injury in China (2013-2018).

STUDY DESIGN: Retrospective epidemiological study. OBJECTIVE: To describe differences based on biological sex in the epidemiology and treatment of the economic burden of traumatic spinal cord injury (TSCI) in China (2013-2018). SUMMARY OF BACKGROUND DATA: Although there have been many regional single-center studies on TSCI in China, there are few reports involving multicenter data, especially those that report on discrepancies related to biological sex. MATERIALS AND METHODS: This study is a nationally representative hospital-based retrospective study. The treatment data of TSCI patients in 30 hospitals in 11 provinces/cities from January 2013 to December 2018 were analyzed. Sociodemographic characteristics, accident and related injury characteristics, treatment methods, and hospital costs were obtained. Regression models were used to evaluate differences in the outcomes of interest based on biological sex and other factors. RESULTS: There were 13,465 individuals with TSCI, with a mean age of 50.0 years, and females (52.2) older than males (49.3). Overall, the average ratio of males to females was 3.1:1, ranging from 3.0:1 in 2013 to 2.8:1 in 2018. The overall proportion of patients with TSCI increased from 2013 to 2018 [annual percentage change (APC)=6.8%, 95% CI, 3.3-10.4] ( P < 0.05). The percent increase in females (APC=8.2%, 95% CI, 5.6-10.8) was greater than that of males (APC=6.3%, 95% CI, 2.1-10.6). Overall, high-level falls mainly affected males (30.8%), and low-level falls mainly occurred in females (36.6%). Females demonstrated a higher frequency of thoracolumbar trauma and less severe neurological impairment. CONCLUSIONS: This study suggests that although the main population of TSCI is male, the average ratio of males to females is decreasing. The frequency of TSCI may be increasing faster in females than in males. Therefore, it is necessary to develop sex-specific public prevention measures. In addition, more medical resources should be devoted to improving the ability of hospitals to perform early surgery.

Identification and characterization of aging/senescence-induced genes in osteosarcoma and predicting clinical prognosis.

Background: Aging is an influential risk factor for progression of both degenerative and oncological diseases of the bone. Osteosarcoma, considered the most common primary mesenchymal tumor of the bone, is a worldwide disease with poor 5-year survival. This study investigated the role of aging-/senescence-induced genes (ASIGs) in contributing to osteosarcoma diagnosis, prognosis, and therapeutic agent prediction. Methods: Therapeutically Applicable Research to Generate Effective Treatments (TARGET), Gene Expression Omnibus (GEO), and The Cancer Genome Atlas (TCGA) were used to collect relevant gene expression and clinical data of osteosarcoma and paracancerous tissues. Patients were clustered by consensus using prognosis-related ASIGs. ssGSEA, ESTIMATE, and TIMER were used to determine the tumor immune microenvironment (TIME) of subgroups. Functional analysis of differentially expressed genes between subgroups, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set variation analyses (GSVAs), was performed to clarify functional status. Prognostic risk models were constructed by univariate Cox regression and least absolute shrinkage and selection operator (LASSO) regression. SCISSOR was used to identify relevant cells in osteosarcoma single-cell data for different risk groups. The effect of immunotherapy was predicted based on TIDE scores and chemotherapy drug sensitivity using CTRP and PRISM. Results: Three molecular subgroups were identified based on prognostic differentially expressed ASIGs. Immunological infiltration levels of the three groups differed significantly. Based on GO and KEGG analyses, differentially expressed genes between the three subgroups mainly relate to immune and aging regulation pathways; GSVA showed substantial variations in multiple Hallmark pathways among the subgroups. The ASIG risk score built based on differentially expressed genes can predict patient survival and immune status. We also developed a nomogram graph to accurately predict prognosis in combination with clinical characteristics. The correlation between the immune activation profile of patients and the risk score is discussed. Through single-cell analysis of the tumor microenvironment, we identified distinct risk-group-associated cells with significant differences in immune signaling pathways. Immunotherapeutic efficacy and chemotherapeutic agent screening were evaluated based on risk score. Conclusion: Aging-related prognostic genes can distinguish osteosarcoma molecular subgroups. Our novel aging-associated gene signature risk score can be used to predict the osteosarcoma immune landscape and prognosis. Moreover, the risk score correlates with the TIME and provides a reference for immunotherapy and chemotherapy in terms of osteosarcoma.

Clinical features and burden of osteoporotic fractures among the elderly in the USA from 2016 to 2018.

This study provides a national estimate of the incidence of hospitalizations and assesses the clinical features and outcomes during inpatient admission due to osteoporotic fractures diagnosed by ICD-10-CM/PCS among the elderly in the USA, using the US Nationwide Inpatient Sample, 2016-2018. PURPOSE: To provide a national estimate of the incidence of hospitalizations and assess the clinical features and outcomes during inpatient admission due to osteoporotic fractures (OFs) among the elderly in the USA. METHODS: The study included all inpatients aged 65 years and older who participated in the US Nationwide Inpatient Sample (NIS). We conducted a retrospective analysis of hospitalizations with OFs diagnosed by the International Classification of Diseases, Tenth Revision, Clinical Modification/Procedure Coding System (ICD-10-CM/PCS), using the US NIS, 2016-2018. Trends in epidemiological characteristics and outcomes were calculated by annual percentage change (APC). RESULTS: From 2016 to 2018, there were an estimated 0.16 million hospitalizations for OFs, and the estimated annual incidence rate changed from 995 cases per 1 million persons in 2016 to 1114 cases per 1 million persons in 2018 (APC, 5.8% [95% CI, 0.0 to 12.0]; P > 0.05). Over two-thirds of the patients (68.2%) were age-related osteoporosis with current pathological fracture, and OFs were more likely to occur in vertebra (51.7%) and femur (34.7%). During the hospitalization, the average length of stay (LOS) was 5.83 days, the average cost reached $60,901.04, and the overall mortality was 2.3%. All outcomes including LOS, average cost and mortality did not change significantly in 2016-2018 (all P values for trend were over 0.05). CONCLUSION: Between 2016 and 2018, the incidence rate of OFs remained relatively stable, but the total number of cases was huge. OFs was predominantly age-related, mostly in vertebrae and femurs, with relatively stable cost and mortality during hospitalization.

Regulating DNA methylation could reduce neuronal ischemia response and apoptosis after ischemia-reperfusion injury.

BACKGROUND: Ischemia-reperfusion injury (IRI) is an important pathophysiological condition that can cause cell injury and large-scale tissue injury in the nervous system. Previous studies have shown that epigenetic regulation may play a role in the pathogenesis of IRI. METHODS: In this study, we isolated mouse cortical neurons and constructed an oxygen-glucose deprivation/reoxygenation (OGD) model to explore the change in DNA methylation and its effect on the expression of corresponding genes. RESULTS: We found that DNA methylation in neurons increased with hypoxia duration and that hypermethylation of numerous promoters and 3'-untranslated regions increased. We performed Gene Ontology enrichment analysis to study gene function and Kyoto Encyclopedia of Genes and Genomes pathway analysis to identify the pathways associated with gene regulation. The results showed that hypermethylation-related genes expressed after OGD were related to physiological pathways such as neuronal projection, ion transport, growth and development, while hypomethylation-related genes were related to pathological pathways such as the external apoptosis signaling pathway, neuronal death regulation, and regulation of oxidative stress. However, the changes in DNA methylation were specific for certain genes and may have been related to OGD-induced neuronal damage. Importantly, we integrated transcription and DNA methylation data to identify several candidate target genes, including hypomethylated Apoe, Pax6, Bmp4, and Ptch1 and hypermethylated Adora2a, Crhr1, Stxbp1, and Tac1. This study further indicated the effect of DNA methylation on gene function in brain IRI from the perspective of epigenetics, and the identified genes may become new targets for achieving neuroprotection in the brain after IRI.

A novel, minimally invasive technique to establish the animal model of spinal cord injury.

BACKGROUND: Spinal cord injury (SCI) is a traumatic disease that is associated with high morbidity, disability, and mortality worldwide. The animal spinal cord contusion model is similar to clinical SCI; therefore, this model is often used to study the pathophysiological changes and treatment strategies for humans after SCI. The present study aimed to introduce a novel, minimally invasive technique to establish an SCI model, and to evaluate its advantages compared with conventional methods. METHODS: Incision length, blood loss, length of time, and model success rate during the operation were recorded. Postoperative hematuria, incision hematoma, scoliosis [detected by micro computed tomography (Micro-CT)] and mortality were analyzed to evaluate surgical complications. The visual observation of the tissue was used to compare the effect of laminectomy by 2 methods on the scar hyperplasia at the injured site. Basso-Beattie-Bresnahan (BBB) score and catwalk automated quantitative gait analysis were conducted to measure behavioral function recovery. To evaluate the nerve function recovery of rats postoperatively, somatosensory evoked potential (SEP) and motor evoked potential (MEP) were studied by electrophysiological analyses. RESULTS: The results of operation-related parameters of the two models (conventional surgery group vs. minimally invasive surgery group) were as follows: surgical incision length: 23.58±1.58 versus 12.67±1.50 mm (P<0.05), blood loss: 3.96±1.05 versus 1.34±0.87 mL (P<0.05), and total operative time: 12.67±1.78 versus 10.33±1.92 min (P<0.05). In addition, the success rate of the 2 models was 100%. Surgical complications (conventional surgery group vs. minimally invasive surgery group) were as follows: hematuria: 25% versus 8.3%, kyphosis: 25% versus 0%, incision hematoma: 30% versus 9%, and mortality: 25% versus 8.3%. Micro-CT indicated severe scoliosis in the conventional surgery group. Gross tissue results showed that the conventional surgery group had more severe fibrous scar hyperplasia. The results of the BBB scores, catwalk automated quantitative gait analysis, and electrophysiology showed that the difference between the two groups was statistically significant in terms of behavioral recovery and neuroelectrophysiology. CONCLUSIONS: The minimally invasive technique has the advantages of small incision and reduced tissue damage and surgical complications, and may be used as an alternative spinal cord contusion method.

Alteration of mRNA 5-Methylcytosine Modification in Neurons After OGD/R and Potential Roles in Cell Stress Response and Apoptosis.

Epigenetic modifications play an important role in central nervous system disorders. As a widespread posttranscriptional RNA modification, the role of the m5C modification in cerebral ischemia-reperfusion injury (IRI) remains poorly defined. Here, we successfully constructed a neuronal oxygen-glucose deprivation/reoxygenation (OGD/R) model and obtained an overview of the transcriptome-wide m5C profiles using RNA-BS-seq. We discovered that the distribution of neuronal m5C modifications was highly conserved, significantly enriched in CG-rich regions and concentrated in the mRNA translation initiation regions. After OGD/R, modification level of m5C increased, whereas the number of methylated mRNA genes decreased. The amount of overlap of m5C sites with the binding sites of most RNA-binding proteins increased significantly, except for that of the RBM3-binding protein. Moreover, hypermethylated genes in neurons were significantly enriched in pathological processes, and the hub hypermethylated genes RPL8 and RPS9 identified by the protein-protein interaction network were significantly related to cerebral injury. Furthermore, the upregulated transcripts with hypermethylated modification were enriched in the processes involved in response to stress and regulation of apoptosis, and these processes were not identified in hypomethylated transcripts. In final, we verified that OGD/R induced neuronal apoptosis in vitro using TUNEL and western blot assays. Our study identified novel m5C mRNAs associated with ischemia-reperfusion in neurons, providing valuable perspectives for future studies on the role of the RNA methylation in cerebral IRI.