Inhibition of MSK1 Promotes Inflammation and Apoptosis and Inhibits Functional Recovery After Spinal Cord Injury

Inhibiting SHP2 reduces glycolysis, promotes microglial M1 polarization, and alleviates secondary inflammation following spinal cord injury in a mouse model

JOURNAL/nrgr/04.03/01300535-202503000-00030/figure1/v/2024-06-17T092413Z/r/image-tiff Reducing the secondary inflammatory response, which is partly mediated by microglia, is a key focus in the treatment of spinal cord injury. Src homology 2-containing protein tyrosine phosphatase 2 (SHP2), encoded by PTPN11, is widely expressed in the human body and plays a role in inflammation through various mechanisms. Therefore, SHP2 is considered a potential target for the treatment of inflammation-related diseases. However, its role in secondary inflammation after spinal cord injury remains unclear. In this study, SHP2 was found to be abundantly expressed in microglia at the site of spinal cord injury. Inhibition of SHP2 expression using siRNA and SHP2 inhibitors attenuated the microglial inflammatory response in an in vitro lipopolysaccharide-induced model of inflammation. Notably, after treatment with SHP2 inhibitors, mice with spinal cord injury exhibited significantly improved hind limb locomotor function and reduced residual urine volume in the bladder. Subsequent in vitro experiments showed that, in microglia stimulated with lipopolysaccharide, inhibiting SHP2 expression promoted M2 polarization and inhibited M1 polarization. Finally, a co-culture experiment was conducted to assess the effect of microglia treated with SHP2 inhibitors on neuronal cells. The results demonstrated that inflammatory factors produced by microglia promoted neuronal apoptosis, while inhibiting SHP2 expression mitigated these effects. Collectively, our findings suggest that SHP2 enhances secondary inflammation and neuronal damage subsequent to spinal cord injury by modulating microglial phenotype. Therefore, inhibiting SHP2 alleviates the inflammatory response in mice with spinal cord injury and promotes functional recovery postinjury.

Biochanin A attenuates spinal cord injury in rats during early stages by inhibiting oxidative stress and inflammasome activation

JOURNAL/nrgr/04.03/01300535-202409000-00038/figure1/v/2024-01-16T170235Z/r/image-tiff Previous studies have shown that Biochanin A, a flavonoid compound with estrogenic effects, can serve as a neuroprotective agent in the context of cerebral ischemia/reperfusion injury; however, its effect on spinal cord injury is still unclear. In this study, a rat model of spinal cord injury was established using the heavy object impact method, and the rats were then treated with Biochanin A (40 mg/kg) via intraperitoneal injection for 14 consecutive days. The results showed that Biochanin A effectively alleviated spinal cord neuronal injury and spinal cord tissue injury, reduced inflammation and oxidative stress in spinal cord neurons, and reduced apoptosis and pyroptosis. In addition, Biochanin A inhibited the expression of inflammasome-related proteins (ASC, NLRP3, and GSDMD) and the Toll-like receptor 4/nuclear factor-κB pathway, activated the Nrf2/heme oxygenase 1 signaling pathway, and increased the expression of the autophagy markers LC3 II, Beclin-1, and P62. Moreover, the therapeutic effects of Biochanin A on early post-spinal cord injury were similar to those of methylprednisolone. These findings suggest that Biochanin A protected neurons in the injured spinal cord through the Toll-like receptor 4/nuclear factor κB and Nrf2/heme oxygenase 1 signaling pathways. These findings suggest that Biochanin A can alleviate post-spinal cord injury at an early stage.

Upregulated miR-125b mitigates inflammation, astrocyte activation, and dysfunction of spinal cord injury by inactivating the MAPK pathway

BACKGROUND

Since the abnormal expression of miR-125b in spinal cord injury (SCI) and the regulatory effect of miR-125b on the MAPK pathway have been expounded, we attempt to investigate whether miR-125b exerts a regulatory effect on SCI by modulating the MAPK pathway.

METHOD

A SCI rat model was established. The rats were treated with miR-125b antagomir or agomir, and their motor function affected by miR-125b was further detected by Basso-Beattie-Bresnahan (BBB) scoring. The histopathological changes and neuronal loss in the spinal cord were evaluated using hematoxylin-eosin and Nissl staining. Microglia-conditioned medium (MCM) was prepared and further used to treat the astrocytes, the activation of which was evaluated via immunofluorescence staining. The expressions of miR-125b, inflammation-related factors (IL-6, IL-1β, TNF-α, and IL-10), and MAPK pathway-related proteins (p38, ERK1/2, and JNK1/2 as well as their phosphorylated (p) forms) in the spinal cord, serum, and MCM-treated astrocytes of rats were determined by reverse-transcription quantitative polymerase chain reaction (RT-qPCR), enzyme-linked immunosorbent assay, and Western blot.

RESULT

MiR-125b was lowly expressed in SCI-modeled rats. MiR-125b downregulation aggravated the impaired motor function, the disorder within the tissue, astrocyte activation, and neuron loss in the spinal cord tissues of SCI-modeled rats, while miR-125b upregulation did oppositely. MiR-125b downregulation enhanced the levels of IL-6, IL-1β, TNF-α, p38, p-p38, p-ERK1/2, and p-JNK1/2, whilst reducing that of IL-10. Contrarily, miR-125b upregulation exerted the opposite effects in SCI-modeled rats and MCM-treated astrocytes.

CONCLUSION

Up-regulation of miR-125b mitigates inflammation, astrocyte activation, and dysfunction in SCI by inactivating the MAPK pathway.

Engineered Multifunctional Zinc-Organic Framework-Based Aggregation-Induced Emission Nanozyme for Accelerating Spinal Cord Injury Recovery

Functional recovery following a spinal cord injury (SCI) is challenging. Traditional drug therapies focus on the suppression of immune responses; however, strategies for alleviating oxidative stress are lacking. Herein, we developed the zinc-organic framework (Zn@MOF)-based aggregation-induced emission-active nanozymes for accelerating recovery following SCI. A multifunctional Zn@MOF was modified with the aggregation-induced emission-active molecule 2-(4-azidobutyl)-6-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)-1H-phenalene-1,3-dione via a bioorthogonal reaction, and the resulting nanozymes were denoted as Zn@MOF-TPD. These nanozymes gradually released gallic acid and zinc ions (Zn2+) at the SCI site. The released gallic acid, a scavenger of reactive oxygen species (ROS), promoted antioxidation and alleviated inflammation, re-establishing the balance between ROS production and the antioxidant defense system. The released Zn2+ ions inhibited the activity of matrix metalloproteinase 9 (MMP-9) to facilitate the regeneration of neurons via the ROS-mediated NF-κB pathway following secondary SCI. In addition, Zn@MOF-TPD protected neurons and myelin sheaths against trauma, inhibited glial scar formation, and promoted the proliferation and differentiation of neural stem cells, thereby facilitating the repair of neurons and injured spinal cord tissue and promoting functional recovery in rats with contusive SCI. Altogether, this study suggests that Zn@MOF-TPD nanozymes possess a potential for alleviating oxidative stress-mediated pathophysiological damage and promoting motor recovery following 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.

Mitogen- and stress-activated protein kinase (MSK1/2) regulated gene expression in normal and disease states

The mitogen- and stress-activated protein kinases (MSK) are epigenetic modifiers that regulate gene expression in normal and disease cell states. MSK1 and 2 are involved in a chain of signal transduction events bringing signals from the external environment of a cell to specific sites in the genome. MSK1/2 phosphorylate histone H3 at multiple sites, resulting in chromatin remodeling at regulatory elements of target genes and the induction of gene expression. Several transcription factors (RELA of NF-κB and CREB) are also phosphorylated by MSK1/2 and contribute to induction of gene expression. In response to signal transduction pathways, MSK1/2 can stimulate genes involved in cell proliferation, inflammation, innate immunity, neuronal function, and neoplastic transformation. Abrogation of the MSK-involved signaling pathway is among the mechanisms by which pathogenic bacteria subdue the host's innate immunity. Depending on the signal transduction pathways in play and the MSK-targeted genes, MSK may promote or hinder metastasis. Thus, depending on the type of cancer and genes involved, MSK overexpression may be a good or poor prognostic factor. In this review, we focus on mechanisms by which MSK1/2 regulate gene expression, and recent studies on their roles in normal and diseased cells.

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.

Depleted histone deacetylase 3 or restored microRNA-19b-1-5p facilitates recovery of spinal cord injury via inactivating JAK2/STAT3 signaling pathway

We intended to discuss the influence of histone deacetylase 3 (HDAC3) on spinal cord injury (SCI) by regulating microRNA-19b-1-5p (miR-19b-1-5p) and janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway. In a rat model, the role of HDAC3 and miR-19b-1-5p in SCI was identified through detecting motor function, serum inflammation, pathological damage, cell apoptosis and GFAP expression. Also, by measuring GFAP expression and migration of spinal cord astrocytes, the effects of HDAC3 and miR-19b-1-5p in SCI were identified in vitro. Restoration of miR-19b-1-5p or depletion of HDAC3 attenuated motor function, inflammation, pathological damage and apoptosis, and reduced GFAP expression in the spinal cord tissue of SCI rats. Up-regulating miR-19b-1-5p or down-regulating HDAC3 decreased migration and GFAP expression of injured astrocytes. Our study presents that down-regulated HDAC3 can facilitate the recovery of SCI via inhibiting the activation of JAK2/STAT3 pathway by up-regulating miR-19b-1-5p.

Resveratrol promotes axonal regeneration after spinal cord injury through activating Wnt/β-catenin signaling pathway

Background: Spinal cord injury (SCI) is characterized by autonomic dysreflexia, chronic pain, sensory and motor deficits. Resveratrol has shown potential neuroprotective function in several neurodegenerative diseases’ models. However, if resveratrol could improve the function recovery after SCI and the further mechanism have not been investigated.

Methods: SCI rat model was established through laminectomy at lamina T9-10 aseptically. Basso, beattie and bresnahan (BBB) and inclined plane score, sensory recovery, spinal cord content, and inflammatory factors were measured. The levels of GAP43, NF421, GFAP, Bax, Bcl-2 and caspase-3 were measured using immunohistochemical staining. Tunel staining was applied to detect apoptosis level.

Results: Resveratrol significantly improved the function recovery, promoted axonal regeneration, suppressed apoptosis after SCI. The activation of Wnt/β-catenin signaling pathway was achieved by resveratrol. XAV939 significantly reversed the influence of resveratrol on function recovery, axonal regeneration, apoptosis after SCI.

Conclusions: Resveratrol could promote the function recovery and axonal regeneration, improve histological damage, inhibit apoptosis level after SCI through regulating Wnt/β-catenin signaling pathway. This research expanded the regulatory mechanism of resveratrol in SCI injury.

Upregulation of miR‑128 inhibits neuronal cell apoptosis following spinal cord injury via FasL downregulation by repressing ULK1

Spinal cord injury (SCI) is characterized by permanent motor deficits followed by inflammation and oxidative stress, causing neuronal cell death. The present study aimed to investigate the role of microRNA (miR)‑128 in neuronal cell apoptosis and its underlying mechanism. Targeting relationships among miR‑128 and Unc‑51 like autophagy activating kinase 1 (ULK1) and Fas ligand (FasL) were verified using dual‑luciferase reporter assay and ChIP assays. Loss‑ and gain‑of‑function assays were conducted in rat models of SCI to determine the roles of miR‑128 and ULK1 in neuronal cell apoptosis, inflammation, and motor function. Apoptosis, motor function and expression of inflammatory factors were respectively determined by Terminal deoxynucleotidyl transferase‑mediated dUTp nick end‑labeling, Basso, Beattie and Bresnahan (BBB) score and enzyme‑linked immunosorbent assay. Hematoxylin and eosin staining, Nissl staining and immunofluorescence were respectively performed to observe morphological changes and number of neurons and nestin‑positive cells. The neuronal cells were isolated from neuron injury models and cultured in vitro. MTT and flow cytometry was conducted to determine the neuronal cell viability and apoptosis respectively. miR‑128 was downregulated whereas ULK1 was upregulated in rats with SCI. Overexpression of miR‑128 or downregulation of ULK1 inhibited neuronal cell apoptosis and inflammation as evidenced by an increased BBB score and more neurons and nestin‑positive cells, but reduced expression of inflammatory and apoptosis‑related factors. ULK1 was negatively regulated by miR‑128, whereas FasL was positively regulated by ULK1. In vitro experiments validated the roles of miR‑128 and ULK1 in neuronal cell differentiation and apoptosis. In conclusion, the upregulation of miR‑128 depresses neuronal cell apoptosis by downregulating ULK1, thereby attenuating SCI via the downregulation of FasL.

Protective Effects of SIRT6 Against Inflammation, Oxidative Stress, and Cell Apoptosis in Spinal Cord Injury

Accumulating evidence supports that Sirtuin 6 (SIRT6) may play a vital role in the pathogenesis of spinal cord injury. The current study was designed to investigate the specific effects of SIRT6 on spinal cord injury (SCI). HE and Nissl staining were performed for pathological analysis in SCI rats. SIRT6 expression was detected by RT-qPCR. CCK8 assay was applied for the detection of cell viability of LPS-injured PC12 cells. TNF-a, IL-1β, IL-6, MCP-1 levels and ROS, MPO, SOD levels were assessed to evaluate inflammation and oxidative stress in spinal cord injury. Cell apoptosis were evaluated by morphological examination using AO/EB fluorescent staining methods and key proteins related to apoptosis were explored via western blot. HE staining revealed increased cavity involving the dorsal white matter and central gray matter, and Nissl staining discovered the loss of motor neurons in the ventral horn in SCI rats. SIRT6 had lower expression in SCI rats. Lipopolysaccharide (LPS) exposure induced cell apoptosis and reduced the expression of SIRT6. Mechanistically, we revealed that up-regulation of SIRT6 alleviated inflammation and oxidative stress and inhibited cell apoptosis in spinal cord injury. Together, our findings indicated that SIRT6 attenuated spinal cord injury by suppressing inflammation, oxidative stress, and cell apoptosis. This study demonstrates that SIRT6 may represent a protective effect against spinal cord injury.

Mettl14-mediated m6A modification modulates neuron apoptosis during the repair of spinal cord injury by regulating the transformation from pri-mir-375 to miR-375

BACKGROUND

Spinal cord injury (SCI) is a disabling disorder, resulting in neurological impairments. This study investigated the mechanism of methyltransferase-like 14 (Mettl14) on apoptosis of spinal cord neurons during SCI repair by mediating pri-microRNA (miR) dependent N6-methyladenosine (m6A) methylation.

METHODS

The m6A content in total RNA and Mettl14 levels in spinal cord tissues of SCI rats were detected. Mettl14 expression was intervened in SCI rats to examine motor function, neuron apoptosis, and recovery of neurites. The cell model of SCI was established and intervened with Mettl14. miR-375, related to SCI and positively related to Mettl14, was screened out. The expression of miR-375 and pri-miR-375 after Mettl14 intervention was detected. The expression of pri-miR-375 combined with DiGeorge critical region 8 (DGCR8) and that modified by m6A was detected. Furthermore, the possible downstream gene and pathway of miR-375 were analysed. SCI cell model with Mettl14 intervention was combined with Ras-related dexamethasone-induced 1 (RASD1)/miR-375 intervention to observe the apoptosis.

RESULTS

Mettl14 level and m6A content in spinal cord tissue were significantly increased. After Mettl14 knockdown, the injured motor function was restored and neuron apoptosis was reduced. In vitro, Mettl14 silencing reduced the apoptosis of SCI cells; miR-375 was reduced and pri-miR-375 was increased; miR-375 targeted RASD1. Silencing Mettl14 inactivated the mTOR pathway. The apoptosis in cells treated with silencing Mettl14 + RASD1/miR-375 was inhibited.

CONCLUSIONS

Mettl14-mediated m6A modification inhibited RASD1 and induced the apoptosis of spinal cord neurons in SCI by promoting the transformation of pri-miR-375 to mature miR-375.

The protective mechanism of action of plantamajoside on a rat model of acute spinal cord injury

Acute spinal cord injury (ASCI) is a severe traumatic disease of the central nervous system, characterized by a high incidence and high morbidity, for which there are no effective drug therapies in the clinic. A rat model of ASCI was established to study the effects of plantamajoside (PMS) treatment on the expression of apoptotic factors, including caspase-3, caspase-9, poly (ADP-ribose) polymerase (PARP), Bax and Bcl-2. The Allen's weight hit rat ASCI model was used for the present study, and the rats were treated with various concentrations of PMS. The behavior of rats was assessed using the Basso-Beattle-Bresnahan locomotor rating scale (BBB), the histopathologic changes of spinal cord tissue were observed by hematoxylin and eosin staining, the survival of neurons was assessed by TUNEL staining and the expression levels of apoptotic proteins such as caspase-3, caspase-9, PARP, Bcl-2 and Bax was measured using western blot assays and RT-qPCR. It was observed that PMS could reverse the decrease in the BBB score after ASCI, improve the morphological characteristics of the spinal cord, reduce the degree apoptosis and affect the expression of caspase-3, caspase-9, PARP, Bax and Bcl-2 in a concentration dependent manner. In conclusion, PMS protected ASCI rats by inhibiting apoptosis; therefore PMS may be a potential candidate for ASCI therapy.

Inflammatory response and oxidative stress attenuated by sulfiredoxin‑1 in neuron‑like cells depends on nuclear factor erythroid‑2‑related factor 2

Sulfiredoxin‑1 (SRX1) is a conserved endogenous antioxidative protein, which is involved in the response to cellular damage caused by oxidative stress. Oxidative stress and inflammation are the primary pathological changes in spinal cord injuries (SCI). The aim of present study was to explore the roles of SRX1 in SCI. Using reverse transcription‑quantitative PCR and western blotting, the present study discovered that the expression levels of SRX1 were downregulated in the spinal cord tissues of SCI model rats. Massive irregular cavities and decreased Nissl bodies were observed in the model group compared with the sham group. Thus, to determine the underlying mechanisms, neuron‑like PC12 cells were cultured in vitro. Western blotting analysis indicated that SRX1 expression levels were downregulated following the exposure of cells to lipopolysaccharide (LPS). Following the transfection with the SRX1 overexpression plasmid and stimulation with LPS, the results of the Cell Counting Kit‑8 assay indicated that the cell viability was increased compared with LPS stimulation alone. Furthermore, the expression levels of proinflammatory cytokines secreted by LPS‑treated PC12 cells were downregulated following SRX1 overexpression. Increased malondialdehyde content, decreased superoxide dismutase activity and reactive oxygen species production were also identified in PC12 cells treated with LPS using commercial detection kits, whereas the overexpression of SRX1 partially reversed the effects caused by LPS stimulation. The aforementioned results were further verified by determining the expression levels of antioxidative proteins using western blotting analysis. In addition, nuclear factor erythroid‑2‑related factor 2 (NRF2), a transcription factor known to regulate SRX1, was indicated to participate in the protective effect of SRX1 against oxidative stress. Inhibition of NRF2 further downregulated the expression levels of SRX1, NAD(P)H dehydrogenase quinone 1 and heme oxygenase‑1 in the presence of LPS, while activation of NRF2 reversed the effects of LPS on the expression levels of these proteins. In conclusion, the results of the present study indicated that the anti‑inflammatory and antioxidative effects of SRX1 may depend on NRF2, providing evidence that SRX1 may serve as a novel molecular target to exert a neuroprotective effect in SCI.

The role of cigarette smoke-induced epigenetic alterations in inflammation

Background

Exposure to cigarette smoke (CS) is a major threat to human health worldwide. It is well established that smoking increases the risk of respiratory diseases, cardiovascular diseases and different forms of cancer, including lung, liver, and colon. CS-triggered inflammation is considered to play a central role in various pathologies by a mechanism that stimulates the release of pro-inflammatory cytokines. During this process, epigenetic alterations are known to play important roles in the specificity and duration of gene transcription.

Main text

Epigenetic alterations include three major modifications: DNA modifications via methylation; various posttranslational modifications of histones, namely, methylation, acetylation, phosphorylation, and ubiquitination; and non-coding RNA sequences. These modifications work in concert to regulate gene transcription in a heritable fashion. The enzymes that regulate these epigenetic modifications can be activated by smoking, which further mediates the expression of multiple inflammatory genes. In this review, we summarize the current knowledge on the epigenetic alterations triggered by CS and assess how such alterations may affect smoking-mediated inflammatory responses.

Conclusion

The recognition of the molecular mechanisms of the epigenetic changes in abnormal inflammation is expected to contribute to the understanding of the pathophysiology of CS-related diseases such that novel epigenetic therapies may be identified in the near future.

Prospects of siRNA cocktails as tools for modifying multiple gene targets in the injured spinal cord

Gene silencing through RNA interference (RNAi) has been touted as a boon for identifying potential therapies for difficult-to-treat pathologies. In this regard, siRNA-mediated gene silencing for tackling the multifaceted pathophysiology of spinal cord injury seemed promising. The genes caspase 3 and sarm1 were targeted in the present study, using siRNAs in a rodent model of spinal cord injury, as the feasibility of concomitant silencing of more than one gene had not been previously attempted. The results indicated meager benefits in terms of functional recovery and tissue preservation. Interestingly, differential transfection efficiencies due to the heterogeneous nature of cells in the spinal cord along with variability in efficacy based on time of intervention affected the reproducibility of this approach. Complex gene interactions and inadequacies in molecular evaluation strategies further complicated the interpretation of the outcome. If these glitches are resolved through further research, gene therapy in general and RNAi, in particular, may become a mainstay approach for treating contusion spinal cord injury.

Impact statement

Gene therapy has reached the level of clinical trials. However, safety and efficacy are yet to be confirmed. The present study tested the prospects of gene silencing using siRNAs in a rat model of spinal cord injury. Some noteworthy observations include the effective and long-lasting silencing effects of siRNAs, inhibition of one gene's expression resulting in silencing of multiple genes in associated pathways, possibility of targeting more than one gene through siRNA cocktails, and differential gene silencing effects based on temporal changes in their expression patterns. It is argued that differential uptake of siRNAs by cells as observed and limitations in the analysis methods available can skew interpretations. Thus, this study may serve as a cautionary tale indicating that gene silencing using siRNAs for spinal cord injury can be a potential therapy, but practical issues are to be addressed in order to ensure consistency and safety.