LncRNA Neat1 Promotes Regeneration after Spinal Cord Injury by Targeting miR-29b

Long non-coding RNAs plasmacytoma variant translocation 1 regulates bone marrow mesenchymal stem cell transplantation to promote the repair of spinal cord injury

This study investigated the therapeutic potential of long non-coding RNAs plasmacytoma variant translocation 1 (lncRNA PVT1) in regulating the function of bone marrow mesenchymal stem cells (BMSCs) following experimental spinal cord injury (SCI). Rat BMSCs were isolated and characterized. Loss-of and gain-of-function experiments were performed to assess the effects of lncRNA PVT1 on BMSCs and Schwann cells (SCs). Fusion PCR mutation, dual-luciferase reporter, and RNA immunoprecipitation assays were employed to explore the binding region between lncRNA PVT1 and polypyrimidine tract binding protein 1 (PTBP1). LncRNA PVT1 increased the proliferation, migration, and apoptosis of BMSCs; lncRNA PVT1 knockdown had the opposite effects. LncRNA PVT1 inhibited PTBP1 expression. The promoting effect of lncRNA PVT1 on the proliferation and migration of BMSCs was suppressed by overexpression of PTBP1. LncRNA PVT1 also induced SC-like differentiation of BMSCs. LncRNA PVT1-modified BMSCs promoted the proliferation and migration of SCs and upregulated levels of neurotrophic factors and SC biomarkers. Transplantation of lncRNA PVT1-modified BMSCs also improved functional recovery of rats with SCI. Altogether, lncRNA PVT1 promoted the proliferation, migration, and differentiation of BMSCs by inhibiting PTBP1. LncRNA PVT1-modified BMSCs also influenced the function of SCs and promoted recovery in rats following SCI.

Long non-coding RNA GAS5 promotes neuronal apoptosis in spinal cord injury via the miR-21/PTEN axis

BACKGROUND

Spinal cord injury (SCI) is a severe and permanent trauma that often leads to significant motor, sensory, and autonomic dysfunction. Neuronal apoptosis is a major pathomechanism underlying secondary injury in SCI. Long non-coding RNAs (lncRNAs) have emerged as key regulators of gene expression and cellular processes, including apoptosis. However, the role of lncRNA growth arrest-specific transcript 5 (GAS5) in SCI-induced neuronal apoptosis remains unclear.

AIM

To investigate the role of lncRNA GAS5 in SCI-induced neuronal apoptosis via its interaction with microRNA (miR)-21 and the phosphatase and tensin homolog (PTEN)/AKT pathway.

METHODS

SCI rat models and hypoxic neuronal cell models were established. Motor function was assessed using the Basso-Beattie-Bresnahan score. Expression levels of GAS5, miR-21, PTEN, caspase 3, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), and AKT were measured using quantitative PCR or Western blot analysis. Neuronal apoptosis was determined by TUNEL staining. Dual-luciferase reporter assays validated GAS5-miR-21 binding. Knockdown and overexpression experiments explored the functional effects of the GAS5/miR-21 axis.

RESULTS

GAS5 was significantly upregulated in the spinal cord following SCI, coinciding with increased neuronal apoptosis and decreased AKT activation. In vitro experiments demonstrated that GAS5 acted as a molecular sponge for miR-21, leading to increased PTEN expression and inhibition of the AKT signaling pathway, thereby promoting apoptosis. In vivo, GAS5 knockdown attenuated neuronal apoptosis, enhanced AKT activation, and improved motor function recovery in SCI rats.

CONCLUSION

GAS5 promotes neuronal apoptosis in SCI by binding to miR-21 and upregulating PTEN expression, inhibiting the AKT pathway. Targeting GAS5 may represent a novel therapeutic strategy for SCI.

Identification and validation of biomarkers associated with mitochondrial dysfunction and ferroptosis in rat spinal cord injury

Introduction

Mitochondrial dysfunction and ferroptosis have been implicated in the pathophysiological processes following spinal cord injury (SCI), with evidence suggesting their interplay influences neuronal cell survival and repair mechanisms. This study seeks to identify mitochondria- and ferroptosis-related biomarkers through comprehensive bioinformatics analysis.

Methods

Mitochondria- and ferroptosis-associated differentially expressed genes (DEGs) were identified through the integration of differential expression analysis and weighted gene co-expression network analysis. Two machine learning algorithms, least absolute shrinkage and selection operator (LASSO) and Boruta, were employed to isolate SCI-associated feature genes. Biomarkers were subsequently identified by analyzing their expression levels. An artificial neural network (ANN) diagnostic model was constructed to predict SCI likelihood based on these biomarkers. Further evaluations were performed using enrichment analysis, immune infiltration profiling, molecular modulation assessment, and drug prediction. The biomarkers' expression levels were validated using RT-qPCR.

Results

In this study, two biomarkers, Hcrt and Cdca2, linked to mitochondrial function and ferroptosis in SCI, were found to be highly expressed in SCI samples. Tissue-specific analysis from the GTEx database revealed expression of these biomarkers in brain and spinal cord tissues. The ANN model, constructed using these biomarkers, accurately discriminated between SCI and control samples. Enrichment analysis highlighted several co-enriched pathways for Hcrt and Cdca2, including "ubiquitin-mediated proteolysis," "endocytosis," and the "neurotrophin signaling pathway." Immune infiltration analysis, based on the Wilcoxon test, demonstrated significant differences in T follicular helper cell levels, which were lower in SCI samples compared to controls. Notably, T follicular helper cells exhibited a positive correlation with Hcrt and a negative correlation with Cdca2. Furthermore, seven transcription factors, including CEBPB, FOXC1, and GATA2, were identified as potential co-regulators of Hcrt and Cdca2. Drug prediction analysis revealed stable interactions of Cdca2 with pinosylvin, zinc acetate dihydrate, hydroquinone, lucanthone, and dasatinib. RT-qPCR validation confirmed the expression patterns of Hcrt and Cdca2 in alignment with the dataset, showing statistically significant differences.

Discussion

This study identifies Hcrt and Cdca2 as biomarkers related to mitochondrial function and ferroptosis in SCI, providing new insights for the diagnosis and mechanistic understanding of SCI.

LncRNAs Orchestrating Neuroinflammation: A Comprehensive Review

CNS diseases account for a major part of the comorbidity and mortality of the human population; moreover, neuroinflammation has become an indication for different CNS diseases, for instance, Parkinson's and Alzheimer's disease. Microglia and astrocytes are the two main glial cells that can be found in the CNS. Each of these plays an important role in mediating immune responses like inflammation. There are many studies suggesting the role of LncRNAs in mediating neuroinflammation. Indeed, LncRNAs orchestrate neuroinflammation through various mechanisms, namely miRNA sponge, and transcriptional activation/inhibition. In addition, LncRNAs regulate different downstream pathways like NF-κB, and PI3K/AKT. In this study, we gathered the existing studies regarding the mechanisms of action of LncRNAs in the pathogenesis of different CNS diseases like neurodegenerative diseases and traumatic injuries through regulating neuroinflammation. We aim to elaborate on the regulatory roles of LncRNAs in neuroinflammation and bring a more profound understanding of the etiology of CNS diseases in terms of neuroinflammation.

Exosomal lncRNA RMRP-shuttled by Olfactory Mucosa-Mesenchymal Stem Cells Suppresses Microglial Pyroptosis to Improve Spinal Cord Injury via EIF4A3/SIRT1

Microglial pyroptosis significantly influences the pathological process and functional recovery after spinal cord injury (SCI). Olfactory mucosal mesenchymal stem cells (OM-MSCs) have shown remarkable therapeutic effects in SCI due to their neural substitution potential and paracrine mechanism. Therefore, the purpose of this study was to investigate the function and mechanism of OM-MSCs-derived exosomes (Exo) in regulating microglial pyroptosis after SCI. OM-MSCs and their secreted Exo were extracted and identified correspondingly. Microglia cells (HMC3) were stimulated by lipopolysaccharide (LPS) and co-cultured with Exo; the cell viability and pyroptosis of HMC3 cells were validated by CCK-8 and flow cytometry analysis. The inflammatory cytokines and pyroptosis-related proteins were measured by ELISA and western blot. Molecular interactions were verified by RNA immunoprecipitation and RNA pull-down. The SCI mouse model was constructed and administered with Exo, and then the histopathological features were detected using H&E, Nissl staining, and BMS score. lncRNA RMRP was enriched in OM-MSCs-Exo and downregulated in LPS-induced HMC3 cells. OM-MSCs-Exo administration markedly elevated lncRNA RMRP expression and repressed microglial pyroptosis in LPS-induced HMC3 cells, while these effects were diminished when lncRNA RMRP was depleted in OM-MSCs-Exo. Mechanistically, lncRNA RMRP maintained SIRT1 mRNA stability by recruiting EIF4A3. Overexpression of SIRT1 could rescue lncRNA RMRP knockdown-mediated microglia pyroptosis. In vivo data further supported that OM-MSCs-Exo administration relieves pyroptosis and nerve damage after SCI by carrying lncRNA RMRP. Our data suggested that exosomal lncRNA RMRP mitigated microglia pyroptosis and promoted motor function recovery after SCI by regulating the EIF4A3/SIRT1 axis.

Stem Cell-Derived Extracellular Vesicle-Mediated Therapeutic Signaling in Spinal Cord Injury

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have emerged as a promising therapeutic strategy for spinal cord injury (SCI). These nanosized vesicles possess unique properties such as low immunogenicity and the ability to cross biological barriers, making them ideal carriers for delivering bioactive molecules to injured tissues. MSC-EVs have been demonstrated to exert multiple beneficial effects in SCI, including reducing inflammation, promoting neuroprotection, and enhancing axonal regeneration. Recent studies have delved into the molecular mechanisms underlying MSC-EV-mediated therapeutic effects. Exosomal microRNAs (miRNAs) have been identified as key regulators of various cellular processes involved in SCI pathogenesis and repair. These miRNAs can influence inflammation, oxidative stress, and apoptosis by modulating gene expression. This review summarized the current state of MSC-EV-based therapies for SCI, highlighting the underlying mechanisms and potential clinical applications. We discussed the challenges and limitations of translating these therapies into clinical practice, such as inconsistent EV production, complex cargo composition, and the need for targeted delivery strategies. Future research should focus on optimizing EV production and characterization, identifying key therapeutic miRNAs, and developing innovative delivery systems to maximize the therapeutic potential of MSC-EVs in SCI.

The potential of long non-coding RNAs for motor function recovery after spinal cord injury in rodents: A systematic review and meta-analysis

OBJECTIVE

Long non-coding RNAs (LncRNAs) have garnered significant attention in preclinical studies for their potential in treating spinal cord injury (SCI). This meta-analysis aimed to assess the overall efficacy of lncRNA treatments in improving motor function in rodent models of SCI.

METHODS

The Embase, PubMed, Web of Science, and Scopus databases were searched. Meta-analysis was performed using STATA 14.0. The standardized mean difference (SMD) was employed to combine various motor function scores.

RESULTS

A total of 33 studies were included in this review. Key findings indicated that lncRNA treatments could markedly enhance locomotor function in rodents with SCI compared to control groups (SMD = 4.20, 95% CI: 3.35 to 5.05, I2 = 80.0%, P < 0.0001). Furthermore, in male rats with contusion/compression injuries, targeting specific cytosol-enriched lncRNAs to downregulate their expression may significantly improve motor function recovery. Specifically, intrathecal injection of non-viral vectors for lncRNA delivery proved to be the most effective method in this study.

CONCLUSIONS

LncRNA treatments have demonstrated the potential to improve motor function in rodent models with SCI. However, the therapeutic efficacy may be overestimated. Future research should rigorously assess the clinical translational efficacy and safety of lncRNA treatments.

Role of Long Non-coding RNA in Nerve Regeneration

Nerve injury can be caused by a variety of factors. It often takes a long time to repair a nerve injury and severe nerve injury is even difficult to heal. Therefore, increasing attention has focused on nerve injury and repair. Long non-coding RNA (lncRNA) is a newly discovered non-coding RNA with a wide range of biological activities. Numerous studies have shown that a variety of lncRNAs undergo changes in expression after nerve injury, indicating that lncRNAs may be involved in various biological processes of nerve repair and regeneration. Herein, we summarize the biological roles of lncRNAs in neurons, glial cells and other cells during nerve injury and regeneration, which will help lncRNAs to be better applied in nerve injury and regeneration in the future.

Bone marrow mesenchymal stem cells-derived exosomes promote spinal cord injury repair through the miR-497-5p/TXNIP/NLRP3 axis

Bone marrow mesenchymal stem cells (BMSCs) indicate a repairing prospect to treat spinal cord injury, a major traumatic disease. This study investigated the repair effect of bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) on spinal cord injury. BMSCs were collected to extract BMSC-Exos which were identified by different means. The SCI model of rats was established, the motor behavior was scored by BBB field test, and the spinal cord tissues were separated and stained by HE, Nissl, and Tunel, respectively, as well as analyzed to measure inflammatory and oxidative stress responses. PC12 cells were co-cultured with Exos and analyzed by CCK-8 and flow cytometry to measure cell proliferation and apoptosis. BMSC-Exos improved SCI in rats with the recovery of motor function, alleviation of pathological conditions, and reduction of apoptosis, inflammatory responses, and oxidative stress. BMSC-Exos increased miR-497-5p expression, and miR-497-5p overexpression strengthened the protective effect of BMSC-Exos on SCI. miR-497-5p targeted inactivation of TXNIP/NLRP3 pathway. TXNIP saved the repair effect of miR-497-5p-carrying BMSC-Exos on SCI rats. miR-497-5p-carrying BMSC-Exos alleviated apoptosis and induced proliferation of H2O2-treated PC12 cells. BMSC-Exos promote SCI repair via the miR-497-5p/TXNIP/NLRP3 axis, which may be a target for alleviating SCI-associated nerve damage.

Effects of ADSC-Derived Exosome LRRC75A-AS1 on Anti-inflammatory Function After SCI

Spinal cord injury (SCI) is a highly debilitating disorder of the central nervous system that can severely impact an affected patient's quality of life. This study aimed to examine how adipose-derived mesenchymal stem cell exosomes (ADSC-exos) can be used to treat spinal cord injury. We analysed differentially expressed mRNAs in SCI using bioinformatics data, gene expression profiles in inflammatory cell models, RT-qPCR and WB. Apoptosis was detected with flow cytometry. Starbase provides the control mechanism for FDFT1. Target interactions were detected with dual-luciferase reporter and RIP assays. Exosomes were isolated from adipose tissue-derived mesenchymal stem cells and subsequently characterized with western blot analysis, transmission electron microscopy and nanoparticle tracking analysis. By analysing the GSE102964 database, we found that FDFT1 was significantly downregulated as SCI progressed. Overexpression of FDFT1 can significantly reverse the inflammatory response and apoptosis of BV2 cells induced by hemin. Mechanically, ADSC-exos can affect the expression of FDFT1 through the ceRNA mechanism mediated by LRRC75A-AS1 and in an RBP-dependent manner mediated by IGF2BP2. The overexpression of LRRC75A-AS1 significantly enhances BV2 apoptosis and can be reversed by FDFT1 knockdown. ADSC-exos LRRC75A-AS1 inhibits inflammation and reduces SCI by increasing the expression and stability of FDFT1 mRNA in a ceRNA and RBP-dependent manner.

Spinal Cord Injury: From MicroRNAs to Exosomal MicroRNAs

Spinal cord injury (SCI) is an unfortunate experience that may generate extensive sensory and motor disabilities due to the destruction and passing of nerve cells. MicroRNAs are small RNA molecules that do not code for proteins but instead serve to regulate protein synthesis by targeting messenger RNA's expression. After SCI, secondary damage like apoptosis, oxidative stress, inflammation, and autophagy occurs, and differentially expressed microRNAs show a function in these procedures. Almost all animal and plant cells release exosomes, which are sophisticated formations of lipid membranes. These exosomes have the capacity to deliver significant materials, such as proteins, RNAs and lipids, to cells in need, regulating their functions and serving as a way of communication. This new method offers a fresh approach to treating spinal cord injury. Obviously, the exosome has the benefit of conveying the transported material across performing regulatory activities and the blood-brain barrier. Among the exosome cargoes, microRNAs, which modulate their mRNA targets, show considerable promise in the pathogenic diagnosis, process, and therapy of SCI. Herein, we describe the roles of microRNAs in SCI. Furthermore, we emphasize the importance of exosomal microRNAs in this disease.

The role of apoptosis in spinal cord injury: a bibliometric analysis from 1994 to 2023

Background

Apoptosis after spinal cord injury (SCI) plays a pivotal role in the secondary injury mechanisms, which cause the ultimate neurologic insults. A better understanding of the molecular and cellular basis of apoptosis in SCI allows for improved glial and neuronal survival via the administrations of anti-apoptotic biomarkers. The knowledge structure, development trends, and research hotspots of apoptosis and SCI have not yet been systematically investigated.

Methods

Articles and reviews on apoptosis and SCI, published from 1st January 1994 to 1st Oct 2023, were retrieved from the Web of Science™. Bibliometrix in R was used to evaluate annual publications, countries, affiliations, authors, sources, documents, key words, and hot topics.

Results

A total of 3,359 publications in accordance with the criterions were obtained, which exhibited an ascending trend in annual publications. The most productive countries were the USA and China. Journal of Neurotrauma was the most impactive journal; Wenzhou Medical University was the most prolific affiliation; Cuzzocrea S was the most productive and influential author. "Apoptosis," "spinal-cord-injury," "expression," "activation," and "functional recovery" were the most frequent key words. Additionally, "transplantation," "mesenchymal stemness-cells," "therapies," "activation," "regeneration," "repair," "autophagy," "exosomes," "nlrp3 inflammasome," "neuroinflammation," and "knockdown" were the latest emerging key words, which may inform the hottest themes.

Conclusions

Apoptosis after SCI may cause the ultimate neurological damages. Development of novel treatments for secondary SCI mainly depends on a better understanding of apoptosis-related mechanisms in molecular and cellular levels. Such therapeutic interventions involve the application of anti-apoptotic agents, free radical scavengers, as well as anti-inflammatory drugs, which can be targeted to inhibit core events in cellular and molecular injury cascades pathway.

A future blood test for acute traumatic spinal cord injury

Acute spinal cord injury (SCI) requires prompt diagnosis and intervention to minimize the risk of permanent neurologic deficit. Presently, SCI diagnosis and interventional planning rely on magnetic resonance imaging (MRI), which is not always available or feasible for severely injured patients. Detection of disease-specific biomarkers in biofluids via liquid biopsy may provide a more accessible and objective means of evaluating patients with suspected SCI. Cell-free DNA, which has been used for diagnosing and monitoring oncologic disease, may detect damage to spinal cord neurons via tissue-specific methylation patterns. Other types of biomarkers, including proteins and RNA species, have also been found to reflect neuronal injury and may be included as part of a multi-analyte assay to improve liquid biopsy performance. The feasibility of implementing liquid biopsy into current practices of SCI management is supported by the relative ease of blood sample collection as well as recent advancements in droplet digital polymerase chain reaction technology. In this review, we detail the current landscape of biofluid biomarkers for acute SCI and propose a framework for the incorporation of a putative blood test into the clinical management of SCI.

Tanshinone IIA protects motor neuron-like NSC-34 cells against lipopolysaccharide-induced cell injury by the regulation of the lncRNA TCTN2/miR-125a-5p/DUSP1 axis

Background

Tanshinone IIA (TSIIA) exerts a protective role in spinal cord injury (SCI). However, the mechanism of TSIIA activity in SCI remains to be elucidated.

Methods

Cell viability and apoptosis were gauged by CCK-8 assay and flow cytometry, respectively. The expression levels of lncRNA TCTN2, miR-125a-5p and DUSP1 were detected by qRT-PCR and western blot. Direct relationship between miR-125a-5p and TCTN2 or DUSP1 was verified by dual-luciferase reporter assay.

Results

In mouse NSC-34 cells, LPS reduced the expression of TCTN2. TSIIA alleviated cell injury induced by LPS and increased TCTN2 expression in LPS-exposed NSC-34 cells. TCTN2 was a downstream mediator of TSIIA activity. TCTN2 targeted miR-125a-5p, and TCTN2 over-expression attenuated LPS-induced cell damage in NSC-34 cells by down-regulating miR-125a-5p. TCTN2 functioned as a post-transcriptional regulator of DUSP1 expression through miR-125a-5p. DUSP1 was a functional target of miR-125a-5p in controlling NSC-34 cell injury induced by LPS. TSIIA inhibited miR-125a-5p expression and increased the level of DUSP1 protein in LPS-exposed NSC-34 cells.

Conclusion

Our study establishes a novel mechanism, the TCTN2/miR-125a-5p/DUSP1 axis, at least in part, for the protective activity of TSIIA in cell injury induced by LPS.

Tetramethylpyrazine promotes angiogenesis and nerve regeneration and nerve defect repair in rats with spinal cord injury

Objective

This study evaluated the regulatory effect of Tetramethylpyrazine (TMP) on the spinal cord injury (SCI) rat model and clarified the neuroprotective mechanism of TMP on SCI.

Methods

An SCI rat model was generated and treated with TMP injections for two weeks. miR-497-5p and EGFL7 expression changes were evaluated, motor function recovery after SCI was assessed by BBB score test and footprint analysis, lesions of rat spinal cord were assessed by HE staining and TUNEL staining; angiogenesis was assessed by immunoblotting for CD31; inflammatory factor levels were detected by ELISA. EGFL7 was verified as a target of miR-497-5p by bioinformatics website analysis and luciferase reporter gene assay. H2O2-injured neurons were cultured in vitro to explore the effect of TMP.

Results

After SCI, miR-497-5p was upregulated while EGFL7 was downregulated in rats. TMP inhibited apoptosis and promoted angiogenesis, nerve regeneration, and repair of nerve defects by reducing miR-497-5p and increasing EGFL7 expression. miR-497-5p targeted EGFL7. In addition, TMP hindered neuronal inflammation and apoptosis induced by H2O2in vitro.

Conclusion

TMP promotes angiogenesis by downregulating miR-497-5p to target EGFL7, and promotes nerve regeneration and repair of nerve defects in rats with SCI.

The circ_006573/miR-376b-3p Axis Advances Spinal Cord Functional Recovery after Injury by Modulating Vascular Regeneration

Abnormal expression of non-coding RNAs after spinal cord injury (SCI) is associated with pathophysiological outcomes. We bioinformatically predicted a circRNA-miRNA-mRNA axis in SCI. A total of 4690 mRNAs, 17 miRNAs, and 3928 circRNAs were differentially expressed, with co-expressed RNAs predicted to regulate pathways related to wound healing. Among the most highly differentially expressed circRNAs, circ_006573, but not circ_016395, weakened the viability and migration of rat aortic endothelial cells, and its biological effects were rescued with miR-376b-3p mimics. Furthermore, circ_006573 overexpression induced changes in Cebpb, IL-18, and Plscr1 expression that were reversed by miR-376b-3p. In a rat model, circ_006573 shRNA administration improved the pathological manifestations of SCI and ameliorated motor function. Moreover, the expression of CD31, CD34, and VEGF-A in spinal cord tissues was significantly elevated after circ_006573 shRNA treatment, indicating that circ_006573 may be involved in vascular regeneration and functional recovery after SCI. Thus, the circ_006573-miR-376b-3p axis offers a foundation for understanding pathophysiological mechanisms and predicting strategies for treating SCI.

lncRNA XIST inhibition promotes M2 polarization of microglial and aggravates the spinal cord injury via regulating miR-124-3p / IRF1 axis

Spinal cord injury (SCI) has a high disability rate and mortality rate. Recently, LncRNA XIST has been found to be involved in the regulation of inflammatory responses. Therefore, we aimed to investigate the role of XIST in the occurrence and development of SCI and the specific regulation mechanism. Methods: 100 ng/mL lipopolysaccharide (LPS) was used to treat mouse microglia BV2 cells. Hitting spinal cord was performed to C57BL/6 mice for establishing SCI model. Real-time reverse transcriptase-polymerase chain reaction (RT-qPCR), Western blot, Immunofluorescence (IF) and Enzyme linked immunosorbent assay (ELISA) experiments were used to explore the function of XIST, miR-124-3p and IRF1 in LPS-induced BV2 cells. RT-qPCR, Nissl staining, IF, Western blot and ELISA experiment were performed to study the function of XIST in SCI mice. Dual-luciferase reporter assay, RNA immunoprecipitation (RIP), RT-qPCR and Western blot assays were utilized to identify the interaction among XIST, miR-124-3p and IRF1. Results: XIST was upregulated in LPS-induced BV2 cells and spinal cord tissues of SCI mice. Overexpression of XIST promoted the M1 microphages polarization and cytokines concentration in LPS-stimulated BV2 cells, aggravated SCI of mice. Downregulated XIST promoted M1-to-M2 conversion of microglial and relieved the injury of SCI mice. Mechanism verification indicated that XIST acted as a molecular sponge of miR-124-3p and regulated IRF1 expression. Increased miR-124-3p or reduced IRF1 inhibited M1 polarization of microglial and decreased the production of inflammatory cytokines in LPS-induced BV2 cells. Increased XIST or decreased miR-124-3p had an opposite of on LPS-induced BV2 cells. Conclusion: Overexpression of XIST enhanced M1 polarization of microglia and promoted the level of inflammatory cytokines through sponging miR-124-3p and regulating IRF1 expression.

MicroRNAs in spinal cord injury: A narrative review

Spinal cord injury (SCI) is a global medical problem with high disability and mortality rates. At present, the diagnosis and treatment of SCI are still lacking. Spinal cord injury has a complex etiology, lack of diagnostic methods, poor treatment effect and other problems, which lead to the difficulty of spinal cord regeneration and repair, and poor functional recovery. Recent studies have shown that gene expression plays an important role in the regulation of SCI repair. MicroRNAs (miRNAs) are non-coding RNA molecules that target mRNA expression in order to silence, translate, or interfere with protein synthesis. Secondary damage, such as oxidative stress, apoptosis, autophagy, and inflammation, occurs after SCI, and differentially expressed miRNAs contribute to these events. This article reviews the pathophysiological mechanism of miRNAs in secondary injury after SCI, focusing on the mechanism of miRNAs in secondary neuroinflammation after SCI, so as to provide new ideas and basis for the clinical diagnosis and treatment of miRNAs in SCI. The mechanisms of miRNAs in neurological diseases may also make them potential biomarkers and therapeutic targets for spinal cord injuries.

Inhibition of TERC inhibits neural apoptosis and inflammation in spinal cord injury through Akt activation and p-38 inhibition via the miR-34a-5p/XBP-1 axis

This study investigated the function of telomerase RNA component (TERC) in spinal cord injury (SCI). SCI models were established in rats via laminectomy and PC-12 cells were treated with lipopolysaccharide (LPS). TERC and miR-34a-5p expressions in cells and rat spinal cords were detected by quantitative reverse transcription polymerase chain reaction, followed by overexpression/knockdown of TERC/miR-34a-5p. Spinal cord histopathological changes were examined via hematoxylin-eosin staining. miR-34a-5p' relation with TERC and XBP-1 was predicted by TargetScan and checked by dual-luciferase reporter/RNA immunoprecipitation assays. Cell biological behaviors were assessed by Cell counting kit-8, wound healing, Transwell, and flow cytometry assays. XBP-1 and inflammation/apoptosis-related protein expressions were analyzed by western blot. TERC was upregulated and miR-34a-5p was low-expressed in SCI tissues and LPS-induced PC-12 cells. TERC-knockdown alleviated histopathological abnormalities yet upregulated miR-34a-5p in SCI tissues. In LPS-induced PC-12 cells, TERC knockdown promoted cell viability, migration, invasion, and inhibited apoptosis, while TERC overexpression ran oppositely. TERC knockdown downregulated the XBP-1, IL-6, TNF-α, Bax, p-p38/t-p38, and cleaved caspase-9/-3, but upregulated Bcl-2 and p-Akt/t-Akt. TERC targeted miR-34a-5p, which further targeted XBP-1. miR-34a-5p downregulation exerted effects opposite to and offset TERC knockdown-induced effects. TERC knockdown facilitated the regeneration of neuron tissues yet inhibited inflammation in SCI through Akt activation and p-38 inhibition via the miR-34a-5p/XBP-1 axis.

Research Progress of Long Non-coding RNAs in Spinal Cord Injury

Spinal cord injury (SCI) can result in a partial or complete loss of motor and sensory function below the injured segment, which has a significant impact on patients' quality of life and places a significant social burden on them. Long non-coding RNA (LncRNA) is a 200-1000 bp non-coding RNA that has been shown to have a key regulatory role in the progression of a variety of neurological illnesses. Many studies have demonstrated that differentially expressed LncRNAs following spinal cord injury can participate in inflammatory damage, apoptosis, and nerve healing by functioning as competitive endogenous RNA (ceRNA); at the same time, it has a significant regulatory effect on sequelae such neuropathic pain. As a result, we believe that LncRNAs could be useful as a molecular regulatory target in the diagnosis, treatment, and prognosis of spinal cord injury.

Overexpression of long non-coding RNA LINC00158 inhibits neuronal apoptosis by promoting autophagy in spinal cord injury

Spinal cord injury (SCI) is a common central nervous system disease. It is reported that long non-coding RNA LINC00158 is involved in the process of SCI. The purpose of this study was to explore the biological role of LINC00158 in the SCI. First, we established a rat SCI model by surgical method and evaluated the motor function of rats by the Basso-Beattie-Bresnahan locomotor rating scale. The results showed that the expression of LINC00158 decreased and apoptotic cells increased in the SCI model rats. Meanwhile, we found the upregulated LC3-II/LC3-I, Beclin-1, and p62 in the SCI rats. Then, primary rat spinal cord neurons were exposed to oxygen/glucose deprivation (OGD) as an in vitro cell model of SCI. After OGD treatment, the expression of LINC00158 decreased significantly and the apoptosis of spinal cord neurons increased. OGD treatment resulted in upregulation of LC3-II/LC3-I and Beclin-1 and downregulation of p62 in primary spinal cord neurons, which could be eliminated by overexpression of LINC00158. 3-Methyladenine and chloroquine (autophagy inhibitor) reversed the inhibitory effect of LINC00158 overexpression on apoptosis of primary spinal cord neurons. In conclusion, this study demonstrated that LINC00158 overexpression repressed neuronal apoptosis by promoting autophagy, suggesting that LINC00158 may be a potential therapeutic target in the SCI.

Extracellular vesicles from human umbilical cord mesenchymal stem cells reduce lipopolysaccharide-induced spinal cord injury neuronal apoptosis by mediating miR-29b-3p/PTEN

OBJECTIVE

This study investigated the molecular mechanism of whether hUC-MSCs-EVs repressed PTEN expression and activated the PI3K/AKT pathway through miR-29b-3p, thus inhibiting LPS-induced neuronal injury.

METHODS

hUC-MSCs were cultured and then identified. Cell morphology was observed. Alizarin red, oil red O, and alcian blue staining were used for inducing osteogenesis, adipogenesis, and chondrogenesis. EVs were extracted from hUC-MSCs and identified by transmission electron microscope observation and Western blot. SCI neuron model was established by 24h lipopolysaccharide (LPS) induction. After the cells were cultured with EVs without any treatment, uptake of EVs by SCI neurons, miR-29b-3p expression, cell viability, apoptosis, caspase-3, cleaved caspase-3, caspase 9, Bcl-2, PTEN, PI3K, AKT, and p-Akt protein levels, caspase 3 and caspase 9 activities, and inflammatory factors IL-6 and IL-1β levels were detected by immunofluorescence labeling, RT-qPCR, MTT, flow cytometry, Western blot, caspase 3 and caspase 9 activity detection kits, and ELISA. The binding sites between PTEN and miR-29b-3p were predicted by the database and verified by dual-luciferase assay.

RESULTS

LPS-induced SCI cell model was successfully established, and hUC-MSCs-EVs inhibited LPS-induced apoptosis of injured spinal cord neurons. EVs transferred miR-29b-3p into LPS-induced injured neurons. miR-29b-3p silencing reversed EV effects on reducing LPS-induced neuronal apoptosis. miR-29b-3p reduced LPS-induced neuronal apoptosis by targeting PTEN. After EVs-miR-inhi and si-PTEN treatment, inhibition of the PI3K/AKT pathway reversed hUC-MSCs-EVs effects on reducing LPS-induced neuronal apoptosis.

CONCLUSION

hUC-MSCs-EVs activated the PI3K/AKT pathway by carrying miR-29b-3p into SCI neurons and silencing PTEN, thus reducing neuronal apoptosis.

MiRNAs as Promising Translational Strategies for Neuronal Repair and Regeneration in Spinal Cord Injury

Spinal cord injury (SCI) represents a devastating injury to the central nervous system (CNS) that is responsible for impaired mobility and sensory function in SCI patients. The hallmarks of SCI include neuroinflammation, axonal degeneration, neuronal loss, and reactive gliosis. Current strategies, including stem cell transplantation, have not led to successful clinical therapy. MiRNAs are crucial for the differentiation of neural cell types during CNS development, as well as for pathological processes after neural injury including SCI. This makes them ideal candidates for therapy in this condition. Indeed, several studies have demonstrated the involvement of miRNAs that are expressed differently in CNS injury. In this context, the purpose of the review is to provide an overview of the pre-clinical evidence evaluating the use of miRNA therapy in SCI. Specifically, we have focused our attention on miRNAs that are widely associated with neuronal and axon regeneration. “MiRNA replacement therapy” aims to transfer miRNAs to diseased cells and improve targeting efficacy in the cells, and this new therapeutic tool could provide a promising technique to promote SCI repair and reduce functional deficits.

Long Non-Coding RNA X-Inactive Specific Transcript (LncRNA Xist) Improves the Repair of Nerve Function in Spinal Cord Injury Models via Targeting CXC Motif Chemokine Receptor 4 (CXCR4) in Bone Mesenchymal Stem Cells (BMSCs)

This study assessed the effect of lncRNA Xist on the repair of neural function in spinal cord injury (SCI) model. Rat SCI model was established and assigned into blank group, Mock siRNA group and Xist siRNA group followed by analysis of the differentiation of BMSCs and rats’ neural functional recovery. The volume of mineralized nodule and quantity of LD in Xist siRNA group was significantly higher than control group and Mock siRNA group (P < 0.05). The expression of RUNX2, ALP, OCN, lncRNA Xist, and CXCR4 in Xist siRNA group was also significantly increased compared to other two groups (P < 0.05) along with elevated cell proliferation rate in Xist siRNA group. However, no differences of above parameters were found between control group and Mock siRNA group (P > 0.05). In conclusion, lncRNA Xist promotes the repair of rats’ neurological function and the adilpogenesis and osteogenesis differentiation of BMSCs via targeting CXCR4 in SCI model, indicating that it might be a novel target for treating SCI.

miR-338-5p Levels and Cigarette Smoking are Associated With Neuropathic Pain Severity in Individuals With Spinal Cord Injury: Preliminary Findings From a Genome-Wide microRNA Expression Profiling Screen

OBJECTIVE

To identify microRNA biomarkers and clinical factors associated with neuropathic pain after spinal cord injury.

DESIGN

Cross-sectional, secondary analysis of baseline data collected from ongoing clinical studies. Using a genome-wide microRNA screening approach, we studied differential microRNA expression in serum from 43 adults with spinal cord injury enrolled in ongoing clinical studies. Least squares regression was used to identify associations between microRNA expression, clinical factors, and neuropathic pain severity.

SETTING

Community-dwelling individuals with spinal cord injury.

PARTICIPANTS

Participants (N=43) were at least 18 years old with spinal cord injury, with 28 reporting neuropathic pain and 15 reporting no neuropathic pain.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Pain presence, type, and intensity were assessed with the International Spinal Cord Injury Pain Basic Data Set. Serum microRNA normalized deep sequencing counts were quantified from blood samples. Participant demographic factors, injury characteristics, medication use, and health habits were collected via questionnaire.

RESULTS

miR-338-5p expression and history of cigarette smoking were associated with and explained 37% of the variance in neuropathic pain severity (R2=0.37, F2,18=5.31, P=.02) independent of other clinical factors. No association was identified between miR-338-5p levels and nociceptive pain severity.

CONCLUSIONS

Our findings suggest that miR-338-5p and cigarette smoking may both play a role in the development or maintenance of neuropathic pain after spinal cord injury. While additional work is needed to confirm these findings, validated target analysis suggests a neuroprotective role of miR-338-5p in modulating neuroinflammation and neuronal apoptosis and that its downregulation may result in maladaptive neuroplastic mechanisms contributing to neuropathic pain after spinal cord injury.

Repair of Spinal Cord Injury by Inhibition of PLK4 Expression Through Local Delivery of siRNA-Loaded Nanoparticles

Polo-like kinase 4 (PLK4) is one of the key regulators of centrosomal replication. However, its role and mechanism in spinal cord injury (SCI) are still unclear. The SCI model on rats was constructed and the expression and localization of PLK4 in the spinal cord are analyzed with Western blot and immunofluorescence, respectively. Then the specific siRNAs were encapsulated in nanoparticles for the inhibition of PLK4 expression. Afterward, the role of PLK4 on astrocytes was investigated by knocking down its expression in the primary astrocytes. Moreover, siRNA-loaded nanoparticles were injected into the injured spinal cord of rats, and the motor function recovery of rats after SCI was assessed using the Basso, Beattie, and Bresnahan (BBB) locomotor scale method. Notably, the siRNA-loaded nanoparticles effectively transfect primary astrocytes and significantly inhibit PLK4 expression, together with the expression of PCNA with significance. After treatment, restoration of the motor function following SCI was significantly improved in the PLK4 knockdown group compared with the control group. Therefore, we speculate that inhibition of Plk4 may inhibit the proliferation of astrocytes and decrease the inflammatory response mediated by astrocytes, so as to promote the functional recovery of SCI. In conclusion, inhibition of PLK4 expression via siRNA-loaded nanoparticles may be a potential treatment for SCI.

Exosomes Derived from lncRNA TCTN2-Modified Mesenchymal Stem Cells Improve Spinal Cord Injury by miR-329-3p/IGF1R Axis

Mesenchymal stem cells (MSCs)-derived exosomes play significant roles in alleviating spinal cord injury (SCI). Previous study showed that long non-coding RNA tectonic family member 2 (TCTN2) was able to relieve SCI. Herein, whether TCTN2 exerted its roles in functional recovery after SCI via exosomes derived from MSCs was explored. The SCI model was established in rats, and the neurological function was evaluated using the Basso, Beattie, and Bresnahan (BBB) scoring. Lipopolysaccharide (LPS)-induced differentiated PC12 cells were used as an in vitro model for neurotoxicity research. The expression of genes and proteins was detected by qRT-PCR and Western blot. Exosomes were isolated by ultracentrifugation and qualified by TEM and Western blot. In vitro assays were performed using CCK-8 assay, EdU assay, and flow cytometry, respectively. Dual-luciferase reporter assay and RIP assay were used to confirm the target relationship between miR-329-3p and TCTN2 or insulin-like growth factor1 receptor (IGF1R). TCTN2 expression was down-regulated in SCI model rat and lipopolysaccharide (LPS)-stimulated PC12 cells. MSCs produced exosomes and could package TCTN2 into secreted exosomes. Tail vein injection of TCTN2 exosomes into rats significantly improved functional recovery of SCI. Meanwhile, TCTN2 exosomes treatment alleviated LPS-induced neuronal apoptosis, inflammation, and oxidative stress in vitro. Additionally, TCTN2 targeted miR-329-3p and subsequently regulated the expression of its target IGF1R. Rescue assays suggested that miR-329-3p/IGF1R axis mediated the beneficial effects of TCTN2 exosomes on LPS-treated PC12 cells. In all, exosomes derived from TCTN2-modified MSCs could improve functional recovery of SCI in vivo and attenuate LPS-induced neuronal apoptosis, inflammation, and oxidative stress in vitro via miR-329-3p/IGF1R axis, suggesting a novel insight into the development of MSC-exosomes-based therapy for SCI.

Human umbilical cord mesenchymal stem cells-derived extracellular vesicles facilitate the repair of spinal cord injury via the miR-29b-3p/PTEN/Akt/mTOR axis

Spinal cord injury (SCI) is a salient traumatic disease that often leads to permanent disability, and motor and sensory impairments. Human umbilical cord mesenchymal stem cells (HucMSCs) have a wide application prospect in the treatment of SCI. This study explored the repair effect of HucMSCs-derived extracellular vesicles (HucMSCs-EVs) on SCI. HucMSCs and HucMSCs-EVs were cultured and identified. The rat model of SCI was established, and SCI rats were treated with HucMSCs-EVs. The motor function of SCI rats and morphology of spinal cord tissues were evaluated. Levels of NeuN, GFAP, and NF200 in spinal cord tissues were detected and cell apoptosis was measured. SCI rats were treated with EVs extracted from miR-29b-3p inhibitor-transfected HucMSCs. The downstream gene and pathway of miR-29b-3p were examined. HucMSCs-EVs-treated rats showed obvious motor function recovery and reduced necrosis, nuclear pyknosis, and cavity. HucMSCs-EVs alleviated spinal cord neuronal injury. miR-29b-3p was poorly expressed in SCI tissues, but highly expressed in EVs and SCI rats treated with EVs. miR-29b-3p targeted PTEN. Inhibition of miR-29b-3p or overexpression of PTEN reversed the repair effect of EVs on SCI. EVs activated the AKT/mTOR pathway via the miR-29b-3p/PTEN. In conclusion, HucMSCs-EVs reduced pathological changes, improved motor function, and promoted nerve function repair in SCI rats via the miR-29b-3p/PTEN/Akt/mTOR axis.