Recent progress and challenges in the treatment of spinal cord injury

Natural polymer based drug-loaded hydrogel platform for comprehensive care of acute spinal cord injury

Traumatic spinal cord injury typically occurs at significant depths and triggers rapid and severe physiological responses. It is commonly accompanied by oxidative stress disorders, lipid peroxidation, accumulation of toxic aldehydes, and edema among other symptoms. The management of this condition requires intricate surgical procedures and vigilance against postoperative complications. Slow wound healing is a major clinical challenge. In this study, we developed an injectable hydrogel-based smart drug delivery platform (OPDL gel) for the treatment of cord injuries and integrated postoperative wound care. The hydrogel encapsulates the glucocorticoid dexamethasone (Dex) through a borate ester bond and can respond to degradation caused by reactive oxygen species (ROS) and pH changes in the microenvironment of spinal cord injuries. The OPDL gel was injected into the lesion with a degradation period of 60 h, enabling a controlled and intelligent release of Dex. Additionally, poly-ε-lysine macromolecules within the gel can absorb toxic aldehydes present in the microenvironment via Schiff base reactions, thereby mitigating secondary progression of spinal cord injury. When locally applied to spinal cord injuries, the gel demonstrated good biocompatibility and had a protective effect on damaged neural structures. In addition, OPDL gel also exhibited excellent bactericidal properties, achieving a 100 % kill rate against microorganisms within 80 min and providing wound healing care comparable to a commercial product, Tegaderm™. Therefore, this multifunctional hydrogel drug-loading platform represents a novel approach for integrated treatment strategies in the clinical setting to address spinal cord injuries.

DOCK2 deficiency alleviates neuroinflammation and affords neuroprotection after spinal cord injury

Neuroinflammation-caused secondary injury is a key event after spinal cord injury (SCI). Dedicator of cytokinesis 2 (DOCK2) belonging to DOCK-A subfamily has a vital role in microglia polarization and neuroinflammation via mediating Rac activation. However, the role of DOCK2 in SCI is unclear. In the present study, SCI model in mice was established by an impactor at thoracic T10 level. DOCK2 expression was significantly increased in the spinal cord after SCI. After knocking down DOCK2 using a lentivirus-mediated method, SCI mice exhibited improved motor function recovery, as revealed by increased Basso Mouse Scale (BMS) score, angle of incline, and relatively coordinated footprint, and decreased damaged area in the spinal cord. DOCK2 deficiency reduced neuronal apoptosis in the spinal cord after injury. Besides, deficiency of DOCK2 suppressed neuroinflammation after SCI, demonstrated by the reduction in pro-inflammatory mediators including IFN-γ, IL-1β and IL-6 and the increase in IL-4, IL-10 and IL-13, anti-inflammatory factors. The CD86, iNOS and COX-2 were down-regulated in the spinal cord, whereas CD206, Arg-1 and TGF-β were up-regulated by DOCK2 deficiency. Rac activation was prevented by DOCK2 deficiency following SCI. In vitro experiments were conducted for further verification. Treatment of BV-2 microglia with lentivirus-mediated DOCK2 inhibited IFN-γ/LPS-induced pro-inflammatory microglia polarization but increased IL-4-induced anti-inflammatory microglia, through inhibiting Rac activation. In brief, our data reveal that DOCK2 deficiency improves functional recovery in mice after SCI, which is related to Rac activation.

Microglial C/EBPβ-Fcgr1 regulatory axis blocking inhibits microglial pyroptosis and improves neurological recovery

CAAT/Enhancer Binding Protein β (C/EBPβ) is associated with inflammatory responses in neurodegenerative pathologies, particularly in the brain. However, the regulatory role of C/EBPβ in spinal cord injury and its impact on neurological recovery remain unknown. In this study, we observed significant upregulation of C/EBPβ in microglia after spinal cord injury in mice and was associated with neuroinflammation. Knocking down C/EBPβ in the spinal cord attenuated microglia pyroptosis, reduced the production of proinflammatory cytokines, and inhibited neuronal apoptosis. Mechanistically, C/EBPβ promoted the transcription of Fcgr1, which was involved in activating microglia pyroptosis. In both in-vivo and in-vitro experiments, knocking down Cebpb or Fcgr1, or the pyroptosis inhibitor VX765 inhibited neuronal apoptosis and improved neurological recovery in mice. These findings indicate that C/EBPβ functions as a key regulator that participates in the microglia pyroptosis-mediated neuroinflammation by activating Fcgr1 transcription.

Stem cell-derived exosome treatment for acute spinal cord injury: a systematic review and meta-analysis based on preclinical evidence

Background

The study aims were to systematically review and analyze preclinical research on the efficacy of exosomes derived from various mesenchymal stem cell sources (MSC-exos) for the treatment of spinal cord contusion injury (SCI) in small animal models.

Methods

We conducted a systematic search of PubMed, Embase and Google Scholar databases from their inception through February 29, 2024, to identify eligible English-language studies based on predefined inclusion and exclusion criteria. Two independent investigators performed literature screening, data extraction and bias assessment.

Results

A total of 235 rats were used to assess locomotor recovery at the initial assessment, and exhibited significant improvement in hind limb movement in those treated with exosomes, as indicated by a statistically significant increase in Basso-Beattie-Bresnahan (BBB) scores (MD: 1.26, 95% CI: 1.14-1.38, p < 0.01) compared to the controls. This trend persisted in final assessment data across 21 studies, with pooled analysis confirming similar results (MD: 1.56, 95% CI: 1.43-1.68, p < 0.01). Funnel plot analysis indicated asymmetry in the pooled BBB scores at both baseline and endpoint assessments, suggesting potential publication bias. Exosomes were derived from bone marrow, adipose tissue, umbilical cord or human placental MSCs. Meta-analysis results showed no statistically significant differences in therapeutic efficacy among these MSC-exos sources at various treatment time points.

Conclusion

MSC-exos demonstrated considerable promise in improving motor function in SCI-affected rats, with bone marrow MSC-derived exosomes having particularly notable effectiveness.

Nitric Oxide-Releasing Mesoporous Hollow Cerium Oxide Nanozyme-Based Hydrogel Synergizes with Neural Stem Cell for Spinal Cord Injury Repair

Neural stem cell (NSCs) transplantation is a promising therapeutic strategy for spinal cord injury (SCI), but its efficacy is greatly limited by the local inhibitory microenvironment. In this study, based on l-arginine (l-Arg)-loaded mesoporous hollow cerium oxide (AhCeO2) nanospheres, we constructed an injectable composite hydrogel (AhCeO2-Gel) with microenvironment modulation capability. AhCeO2-Gel protected NSCs from oxidative damage by eliminating excess reactive oxygen species while continuously delivering Nitric Oxide to the lesion of SCI in a pathological microenvironment, the latter of which effectively promoted the neural differentiation of NSCs. The process was confirmed to be closely related to the up-regulation of the cAMP-PKA pathway after NO-induced calcium ion influx. In addition, AhCeO2-Gel significantly promoted the polarization of microglia toward the M2 subtype as well as enhanced the regeneration of spinal nerves and myelinated axons. The prepared bioactive hydrogel system also efficiently facilitated the integration of transplanted NSCs with host neural circuits, replenished damaged neurons, alleviated neuroinflammation, and inhibited glial scar formation, thus significantly accelerating the recovery of motor function in SCI rats. Therefore, AhCeO2-Gel synergized with NSCs transplantation has great potential as an integrated therapeutic strategy to treat SCI by comprehensively reversing the inhibitory microenvironment.

Trends and disparities in the surgical management of spinal fractures in Sweden during 2008-2023

BACKGROUND

Spinal fractures are a group of complex injuries whose management varies according to a number of factors. The aim of this study was to analyze trends in the management of spinal fracture surgery in Sweden from 2008 to 2023 with a focus on disparities based on gender, surgery method, age and geographical location. A secondary aim was to predict future incidence of spinal fracture surgeries.

METHODS

Comprehensive open source data was obtained from the Swedish National Board of Health and Welfare. The data was stratified based on gender, surgery method, age and geographical location per year and analyzed for trends. Future trends were projected using regression modeling. The student's T-test was used to compare means.

RESULTS

The incidence of spinal fracture surgery decreased overall from 2008 to 2023 while maintaining an increased incidence for males compared to females. The highest incidence for osteosynthesis was 2.7 per 100 000 inhabitants in 2008 and 1 in 2023. This trend is projected to be reversed in 2030. Several surgery methods have decreased in usage and are projected to reach close to 0 in 2030. The patient group that underwent spinal fracture surgery had a higher mean age in 2023 compared to 2008. The incidence of spinal fracture surgery varied significantly across Sweden where region Östergötland performed 6.3 surgeries per 100 000 inhabitants and region Örebro performed 1.4.

CONCLUSIONS

We found several trends where males may undergo spinal fractures surgery more commonly than females. Probable influencing factors may be increased life-spans and osteoporosis. This may also explain the observed shift towards older age groups in spinal fracture surgery. The decreased use of several surgery methods may reflect changes in operational techniques, demographics, and more standardized care. Geographical disparities may indicate different local health care protocols and uneven healthcare utilization and access.

TRIAL REGISTRATION

Not applicable.

Combining therapeutic strategies with rehabilitation improves motor recovery in animal models of spinal cord injury: A systematic review and meta-analysis

BACKGROUND

Despite the lack of clinically validated strategies for treating spinal cord injury (SCI), combining therapeutic strategies with rehabilitation is believed to promote recovery of motor function; however, current research findings are inconsistent.

OBJECTIVES

To explore whether combination therapy involving therapy and rehabilitative training (CIRT) has a synergistic effect on motor function recovery in animal models of SCI.

METHODS

We conducted a systematic review and meta-analysis of studies identified in a keyword search of 6 databases and extracted open-field motor scores from the Basso Mouse Scale (BMS) and the Basso, Beattie, and Bresnahan Locomotor Rating Scale (BBB) for meta-analysis using a weighted mean difference (WMD) and 95 % CI. We also performed qualitative synthesis and analysis of secondary outcome measures related to histological improvements and adverse effects.

RESULTS

Eighty-seven preclinical studies were included. Combination treatment with treadmill training resulted in a significant improvement in motor function (1.40, 95 % CI 0.82 to 1.98, P < 0.01, I2 = 49 %), especially when initiated 1-2 weeks post-injury (1.77, 95 % CI 1.10 to 2.45, P < 0.01, I2 = 33 %) in rats. In mice, CIRT lasting <6 weeks may enhance recovery (0.95, 95 % CI 0.49 to 1.40, P < 0.01, I2 = 33 %). Although there is a trend toward better outcomes in the chronic phase, insufficient sample sizes prevent definitive conclusions from being drawn. Combined therapy also enhances the reorganization of inhibitory synaptic structures and functions, without aggravating allodynia or spasticity.

CONCLUSIONS

This systematic review and meta-analysis suggest that CIRT can lead to superior motor function recovery compared to single-modality therapy (SMT) in animal models of SCI, with no significant adverse effects on allodynia or spasticity. However, the efficacy of CIRT depends on various factors, and further research is needed to establish optimal treatment strategies and understand the underlying mechanisms of recovery.

Single-Cell Multi-omics Assessment of Spinal Cord Injury Blocking via Cerium-doped Upconversion Antioxidant Nanoenzymes

Spinal cord injury (SCI) impairs the central nervous system and induces the myelin-sheath-deterioration because of reactive oxygen species (ROS), further hindering the recovery of function. Herein, the simultaneously emergency treatment and dynamic luminescence severity assessment (SETLSA) strategy is designed for SCI based on cerium (Ce)-doped upconversion antioxidant nanoenzymes (Ce@UCNP-BCH). Ce@UCNP-BCH can not only efficiently eliminate the SCI localized ROS, but dynamically monitor the oxidative state in the SCI repair process using a ratiometric luminescence signal. Moreover, the classic basso mouse scale score and immunofluorescence analysis together exhibit that Ce@UCNP-BCH effectively facilitates the regeneration of spinal cord including myelin sheath, and promotes the functional recovery of SCI mice. Particularly, the study combines snATAC-eq and snRNA-seq to reveal the heterogeneity of spinal cord tissue following Ce@UCNP-BCH treatment. The findings reveal a significant increase in myelinating oligodendrocytes, as well as higher expression of myelination-related genes, and the study also reveals the gene regulatory dynamics of remyelination after treatment. Besides, the ETLSA strategy synergistically boosts ROS consumption through the superoxide dismutase (SOD)-related pathways after SOD-siRNA treatment. In conclusion, this SETLSA strategy with simultaneously blocking and dynamic monitoring oxidative stress has enriched the toolkit for promoting SCI repair.

The role of H3K27 acetylation in oxygen-glucose deprivation-induced spinal cord injury and potential for neuroprotective therapies

OBJECTIVE

Spinal cord injury (SCI) is a debilitating condition that often results in paralysis and lifelong medical challenges. Research has shown that epigenetic modifications, particularly histone acetylation, play a role in neuroprotection following hypoxic-ischemic events in SCI. The objective of this study was to explore the effects of histone H3K27 acetylation, along with its underlying mechanisms, on the tolerance to hypoxia and ischemia in SCI.

METHODS

This study employed an organotypic spinal cord slice culture model subjected to oxygen-glucose deprivation (OGD). We assessed cell apoptosis and changes in cellular type patterns under these conditions. Following hypoxia and ischemia, we analyzed the expression and distribution of H3K27ac across various nerve cell types. To identify key downstream genes, we integrated ChIP-seq and RNA-seq analyses, investigating molecular mechanisms driving the response to OGD in this model.

RESULTS

OGD stimulation increased cell apoptosis and induced time-dependent changes in the expression patterns of neurons, astrocytes, microglia, and oligodendrocytes in organotypic spinal cord slices, accompanied by a significant reduction in H3K27ac levels. Integrated ChIP-seq and RNA-seq analyses revealed that H3K27ac downregulation under hypoxic and ischemic conditions contributes to spinal cord damage by promoting neuroinflammation and disrupting gene regulation. Furthermore, we identified key downstream targets, including Apoc1, Spp1, Aff1, Brd4, KCNN3, and Rgma, which may represent promising therapeutic targets for SCI.

CONCLUSION

Our data underscore the pivotal role of H3K27ac in the organotypic spinal cord slice culture model following OGD exposure, offering promising avenues for neuroprotective therapies via epigenetic-immune regulation.

Heme Oxygenase-1 Overexpression Activates the IRF1/DRP1 Signaling Pathway to Promote M2-Type Polarization of Spinal Cord Microglia

Microglia-mediated neuroinflammatory responses have a critical function in the spinal cord injury (SCI) mechanism, and targeted modulation of microglia activity has emerged as a new therapeutic strategy for SCI. Heme oxygenase 1(HO-1) regulates the close dynamic crosstalk between oxidative stress and inflammatory responses. This investigation aimed to study the molecular pathways by which HO-1 regulates the inflammatory response of microglia. We cultivated primary rat spinal cord microglia and BV2 cell lines and used lipopolysaccharide (LPS) to stimulate microglia to establish an in vitro model. The adeno-associated virus (AAV) was used to induce HO-1 overexpression to observe the effects of HO-1 overexpression on microglia survival, morphological changes, microglia activation, inflammatory cytokines secretion, mitochondrial dynamics, and nucleotide-binding oligomerization domain-like receptor protein (NLRP3) inflammatory complex and nuclear factor-κB (NF-κB) signaling pathways. It was found that HO-1 overexpression was successfully induced using an AAV on microglia in vitro. HO-1 overexpression increased microglia survival and reduced microglia apoptosis in the inflammatory microenvironment. Overexpressed HO-1 inhibited microglia M1-type polarization, downregulated the NF-κB signaling pathway, inhibited NLRP3 inflammatory complex activation, and reduced the secretion of inflammatory factors. Overexpressed HO-1 maintained the stability of mitochondrial dynamics and inhibited excessive mitochondrial cleavage. Further experiments showed that overexpression of HO-1 activated the interferon regulatory factor 1 (IRF1)/dynamin-related protein 1 (DRP1) signaling pathway, thereby promoting microglia M2-type polarization and improving neuronal survival. This study demonstrates that HO-1 activates the IRF1/DRP1 axis, promoting M2 polarization in microglia and attenuating neuroinflammation by suppressing the NF-κB signaling pathway. These outcomes offer new visions and important clues for effectively managing SCI in the clinic.

The Role of Psychological Variables in Predicting Rehabilitation Outcomes After Spinal Cord Injury: An Artificial Neural Networks Study

Background: Accurate prediction of neurorehabilitation outcomes following Spinal Cord Injury (SCI) is crucial for optimizing healthcare resource allocation and improving rehabilitation strategies. Artificial Neural Networks (ANNs) may identify complex prognostic factors in patients with SCI. However, the influence of psychological variables on rehabilitation outcomes remains underexplored despite their potential impact on recovery success. Methods: A cohort of 303 patients with SCI was analyzed with an ANN model that employed 17 input variables, structured into two hidden layers and a single output node. Clinical and psychological data were integrated to predict functional outcomes, which were measured by the Spinal Cord Independence Measure (SCIM) at discharge. Paired Wilcoxon tests were used to evaluate pre-post differences and linear regression was used to assess correlations, with Pearson's coefficient and the Root Mean Square Error calculated. Results: Significant improvements in SCIM scores were observed (21.8 ± 15.8 at admission vs. 57.4 ± 22.5 at discharge, p < 0.001). The model assigned the highest predictive weight to SCIM at admission (10.3%), while psychological factors accounted for 36.3%, increasing to 40.9% in traumatic SCI cases. Anxiety and depression were the most influential psychological predictors. The correlation between the predicted and actual SCIM scores was R = 0.794 for the entire sample and R = 0.940 for traumatic cases. Conclusions: The ANN model demonstrated the strong impact, especially for traumatic SCI, of psychological factors on functional outcomes. Anxiety and depression emerged as dominant negative predictors. Conversely, self-esteem and emotional regulation functioned as protective factors increasing functional outcomes. These findings support the integration of psychological assessments into predictive models to enhance accuracy in SCI rehabilitation outcomes.

Endothelial Foxo1 Phosphorylation Inhibition via Aptamer-Liposome Alleviates OPN-Induced Pathological Vascular Remodeling Following Spinal Cord Injury

Reconstruction of the neurovascular unit is essential for the repair of spinal cord injury (SCI). Nonetheless, detailed documentation of specific vascular changes following SCI and targeted interventions for vascular treatment remains limited. This study demonstrates that traumatic pathological vascular remodeling occurs during the chronic phase of injury, characterized by enlarged vessel diameter, disruption of blood-spinal cord barrier, endothelial-to-mesenchymal transition (EndoMT), and heightened extracellular matrix deposition. After SCI, osteopontin (OPN), a critical factor secreted by immune cells, is indispensable for early vascular regeneration but also contributes to traumatic pathological vascular remodeling. This work further elucidates the mechanism by which OPN influences spinal cord microvascular endothelial cells, involving Akt-mediated Foxo1 phosphorylation. This process facilitates the extranuclear transport of Foxo1 and decreases Smad7 expression, leading to excessive activation of the TGF-β signaling pathway, which ultimately results in EndoMT and fibrosis. Targeted inhibition of Foxo1 phosphorylation through an endothelium-specific aptamer-liposome small molecule delivery system significantly mitigates vascular remodeling, thereby enhancing axon regeneration and neurological function recovery following SCI. The findings offer a novel perspective for drug therapies aimed at specifically targeting pathological vasculature after SCI.

Biomaterial-mediated delivery of traditional Chinese medicine ingredients for spinal cord injury: a systematic review

Objective

Biomaterials loaded with ingredients derived from traditional Chinese medicine (TCM) are viewed as a promising strategy for treating spinal cord injury (SCI). However, a comprehensive analysis of the existing literature on this topic has not yet been conducted. Therefore, this paper systematically reviews researches related to this approach, aiming to identify gaps and shortcomings in the field.

Methods

PubMed, EMBASE, Web of Science, Chinese Biomedical Literature, Wanfang, and China National Knowledge Infrastructure (CNKI) were searched for retrieving studies on biomaterials loaded with TCM ingredients published from their inception to October 2024. Two reviewers performed screening of search results, information extraction, and literature quality assessment independently.

Results

For this systematic review, 41 publications were included. Six TCM ingredients-paclitaxel, curcumin, tetramethylpyrazine, resveratrol, berberine, and tanshinone IIA were combined with biomaterials for treatment of SCI. Biomaterials were categorized into hydrogels, biodegradable scaffolds, nanoparticles, and microspheres according to the type of scaffold. These drug delivery systems exhibit commendable biocompatibility, drug-loading capacity, and drug-release capabilities, and in combination with TCM ingredients, synergistically contribute to anti-oxidative stress, anti-inflammatory, neuroprotective, and anti-apoptotic effects.

Conclusion

These studies demonstrated the efficacy of biomaterials loaded with TCM ingredients in facilitating motor function recovery and neuroprotection in SCI rats, providing evidence for future research. However, in the complex microenvironment of SCI, achieving the maximum drug loading capacity of TCM ingredients within biomaterials, along with sustained and controlled release to fully exert their pharmacological effects, remains a major challenge for future research.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/ identifier CRD42024505000.

Bu Shen Huo Xue Formula Provides Neuroprotection Against Spinal Cord Injury by Inhibiting Oxidative Stress by Activating the Nrf2 Signaling Pathway

Purpose

Spinal cord injury (SCI) is an irreversible neurological disease that can result in severe neurological dysfunction. The Bu Shen Huo Xue Formula (BSHXF) has been clinically shown to assist in the recovery of limb function in patients with SCI. However, the underlying mechanisms of BSHXF's therapeutic effects remain unclear. This study aimed to evaluate the effects of BSHXF in a mouse model of SCI and to identify potential therapeutic targets.

Methods

The composition of BSHXF was analyzed using high-performance liquid chromatography (HPLC). In vivo, SCI was induced in mice following established protocols, followed by administration of BSHXF. Motor function was assessed using the Basso-Beattie-Bresnahan (BBB) and footprint tests. Levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were quantified with specific assay kits. Protein expression analysis was performed using Western blot and immunofluorescence. Additionally, reactive oxygen species (ROS) levels and apoptosis rates were evaluated with dedicated staining kits. In vitro, neurons were exposed to lipopolysaccharide (LPS) to investigate the effects of BSHXF on neuronal oxidative stress. The protective effects of BSHXF against LPS-induced neuronal injury were examined through RT-PCR, Western blot, and immunofluorescence.

Results

The eight primary bioactive constituents of BSHXF were identified using HPLC. BSHXF significantly reduced tissue damage and enhanced functional recovery following SCI. Meanwhile, BSHXF treatment led to significant reductions in oxidative stress and apoptosis rates. It also reversed neuronal loss and reduced glial scarring after SCI. LPS exposure induced neuronal apoptosis and axonal degeneration; however, after intervention with BSHXF, neuronal damage was reduced, and the protective effects of BSHXF were mediated by the activation of the Nrf2 pathway.

Conclusion

BSHXF decreased tissue damage and enhanced functional recovery after SCI by protecting neurons against oxidative stress and apoptosis. The effects of BSHXF on SCI may be related to the activation of the Nrf2 pathway.

Impact of commonly administered drugs on the progression of spinal cord injury: a systematic review

BACKGROUND

Complications arising from acute traumatic spinal cord injury (SCI) are routinely managed by various pharmacological interventions. Despite decades of clinical application, the potential impact on neurological recovery has been largely overlooked. This study aims to highlight commonly administered drugs with potential disease-modifying effects.

METHODS

This systematic literature review included studies referenced in PubMed, Scopus and Web of Science from inception to March 31st, 2021, which assess disease-modifying properties on neurological and/or functional recovery of drugs routinely administered following spinal cord injury. Drug effects were classified as positive, negative, mixed, no effect, or not (statistically) reported. Risk of bias was assessed separately for animal, randomized clinical trials, and observational human studies.

RESULTS

We analyzed 394 studies conducting 486 experiments that evaluated 144 unique or combinations of drugs. 195 of the 464 experiments conducted on animals (42%) and one study in humans demonstrate positive disease-modifying properties on neurological and/or functional outcomes. Methylprednisolone, melatonin, estradiol, and atorvastatin are the most common drugs associated with positive effects. Two studies on morphine and ethanol report negative effects on recovery.

CONCLUSION

Despite a large heterogeneity observed in study protocols, research from bed to bench and back to bedside provides an alternative approach to identify new candidate drugs in the context of SCI. Future research in human populations is warranted to determine if introducing drugs like melatonin, estradiol, or atorvastatin would contribute to enhancing neurological outcomes after acute SCI.

Astrocyte-derived lipocalin 2 promotes inflammation and scarring after spinal cord injury by activating SMAD in mice

BACKGROUND

The inflammatory response and scar formation after spinal cord injury (SCI) limit nerve regeneration and functional recovery. Our research group has previously shown that the expression of astrocyte-derived lipocalin 2 (Lcn2) is upregulated after SCI, which correlates with neuronal apoptosis and functional recovery. Therefore, we speculate that astrocyte-specific knockdown of Lcn2 after SCI may lead to a better prognosis.

METHODS

Tissue RNA sequencing, Western blotting, PCR, and immunofluorescence assays were conducted to assess the expression of Lcn2 following SCI in mice. Adeno-associated virus 9 (AAV9) transfection was employed to specifically reduce the expression of Lcn2 in astrocytes, and subsequent evaluations of scarring and inflammation were conducted. In vitro experiments involved treating primary astrocytes with TGF-β or an A1-induced mixture (C1q, TNF-α and IL-1α) following Lcn2 knockdown. Finally, the intrathecal injection of recombinant Lcn2 (ReLcn2) protein was conducted post-injury to further confirm the role of Lcn2 and its underlying mechanism in SCI.

RESULTS

Lcn2 expression was elevated in astrocytes after SCI at 7 dpi (days post injury). Lcn2 knockdown in astrocytes is beneficial for neuronal survival and functional recovery after SCI, and is accompanied by a reduced inflammatory response and inhibited scar formation. The inhibition of SMAD-associated signaling activation was identified as a possible mechanism, and in vitro experiments further confirmed this finding. ReLcn2 further activated SMAD-associated signaling and aggravated motor function after SCI.

CONCLUSION

The upregulation of Lcn2 expression in astrocytes is involved in neuroinflammation and scar formation after SCI, and the activation of SMAD-associated signaling is one of the underlying mechanisms.

Current multi-scale biomaterials for tissue regeneration following spinal cord injury

Spinal cord injury (SCI) may cause loss of motor and sensory function, autonomic dysfunction, and thus disrupt the quality of life of patients, leading to severe disability and significant psychological, social, and economic burden. At present, existing therapy for SCI have limited ability to promote neural function recovery, and there is an urgent need to develop innovative regenerative approaches to repair SCI. Biomaterials have become a promising strategy to promote the regeneration and repair of damaged nerve tissue after SCI. Biomaterials can provide support for nerve tissue by filling cavities, and improve local inflammatory responses and reshape extracellular matrix structures through unique biochemical properties to create the optimal microenvironment at the SCI site, thereby promoting neurogenesis and reconnecting damaged spinal cord tissue. Considering the importance of biomaterials in repairing SCI, this article reviews the latest progress of multi-scale biomaterials in SCI treatment and tissue regeneration, and evaluates the relevant technologies for manufacturing biomaterials.

Effects of mindfulness-based stress reduction therapy for sleep quality and perceived stress in patients with spinal cord injury

OBJECTIVE

To explore the effect of the mindfulness-based stress reduction (MBSR) practice on sleep quality and perceived stress in patients with spinal cord injury (SCI).

METHOD

A total of 104 patients with SCI (diagnosed via imaging and clinical symptoms) admitted to our hospital between January 2020 and December 2022 were selected as the study participants. The patients were randomly divided into two groups: the MBSR (observation) group and the control group. The observation group received MBSR therapy and routine nursing, and the control group received music training therapy and routine nursing. The Pittsburgh Sleep Quality Index (PSQI) was used to evaluate sleep quality, and the perceived stress score was used to evaluate stress experienced by the patients at three timepoints: before intervention, 4 weeks and 8weeks after intervention.

RESULTS

Compared with before intervention, the PSQI scores of both the control group and intervention group participants significantly decreased after intervention(P < 0.01). Compared with the 4 weeks after intervention, the PSQI scores of both groups of participants decreased in the 8 weeks after intervention(P < 0.01). There was a significant difference in PSQI scores between the two groups of participants at 4 and 8 weeks after intervention(P < 0.01). Compared with before intervention, the average perceived stress score of both the control group and intervention group participants significantly decreased after intervention(P < 0.05). Compared with the 4 weeks after intervention, the average perceived stress score of both groups of participants decreased in the 8 weeks after intervention(P < 0.01). There was a significant difference in average perceived stress score between the two groups of participants at 4(P < 0.05) and 8 weeks(P < 0.01) after intervention(P < 0.01).

CONCLUSION

The use of MBSR therapy could effectively improve patient sleep quality and reduce perceived stress.

Extracorporeal Shock Wave Therapy (eSWT) in Spinal Cord Injury-A Narrative Review

BACKGROUND

Injury of the spinal cord causes motor and sensory dysfunction as well as pathological reflexes, leading to paraplegia or tetraplegia. The sequelae of traumatic spinal cord injury (SCI) are a significant burden and impact on healthcare systems. Despite constant progress in medicine, traumatic SCI still remains irreversible. To date, no satisfying treatment that can enable neuronal regeneration and recovery of function at the damaged level has been found. Hundreds of experiments have been conducted on various possibilities of influencing spinal regeneration; some of them have yielded promising results, but unfortunately, the successes obtained in experimental animals have not translated into humans.

METHODS

This narrative review article presents the application of extracorporeal shock wave therapy (eSWT) in patients with SCI. The article has been divided into parts: 1) use of extracorporeal shock wave therapy for regeneration of the spinal cord after traumatic spinal cord injury; 2) application of extracorporeal shock wave therapy in spasticity after spinal cord injury. In both cases, the hypotheses of possible mechanisms of action will be described.

RESULTS AND CONCLUSIONS

A small number of clinical trials have demonstrated the potential of eSWT to influence the regeneration of the spine, as an innovative, safe, and cost-effective treatment option for patients with SCI. Some reports have shown that eSWT can improve spasticity, walking ability, urological function, quality of life, and independence in daily life.

Enhancing mitophagy by ligustilide through BNIP3-LC3 interaction attenuates oxidative stress-induced neuronal apoptosis in spinal cord injury

Mitophagy selectively eliminates damaged or dysfunctional mitochondria, playing a crucial role in maintaining mitochondrial quality control. However, it remains unclear whether mitophagy can be fully activated and how it evolves after SCI. Our RNA-seq analysis of animal samples from sham and 1, 3, 5, and 7 days post-SCI indicated that mitophagy was indeed inhibited during the acute and subacute early stages. In vitro experiments showed that this inhibition was closely related to excessive production of reactive oxygen species (ROS) and the downregulation of BNIP3. Excessive ROS led to the blockage of mitophagy flux, accompanied by further mitochondrial dysfunction and increased neuronal apoptosis. Fortunately, ligustilide (LIG) was found to have the ability to reverse the oxidative stress-induced downregulation of BNIP3 and enhance mitophagy through BNIP3-LC3 interaction, alleviating mitochondrial dysfunction and ultimately reducing neuronal apoptosis. Further animal experiments demonstrated that LIG alleviated oxidative stress and mitophagy inhibition, rescued neuronal apoptosis, and promoted tissue repair, ultimately leading to improved motor function. In summary, this study elucidated the state of mitophagy inhibition following SCI and its potential mechanisms, and confirmed the effects of LIG-enhanced mitophagy through BNIP3-LC3, providing new therapeutic targets and strategies for repairing SCI.

Advances and Challenges in Spinal Cord Injury Treatments

Spinal cord injury (SCI) is a debilitating condition that is associated with long-term physical and functional disability. Our understanding of the pathogenesis of SCI has evolved significantly over the past three decades. In parallel, significant advances have been made in optimizing the management of patients with SCI. Early surgical decompression, adequate bony decompression and expansile duraplasty are surgical strategies that may improve neurological and functional outcomes in patients with SCI. Furthermore, advances in the non-surgical management of SCI have been made, including optimization of hemodynamic management in the critical care setting. Several promising therapies have also been investigated in pre-clinical studies, with some being translated into clinical trials. Given the recent interest in advancing precision medicine, several investigations have been performed to delineate the role of imaging, cerebral spinal fluid (CSF) and serum biomarkers in predicting outcomes and curating individualized treatment plans for SCI patients. Finally, technological advancements in biomechanics and bioengineering have also found a role in SCI management in the form of neuromodulation and brain-computer interfaces.

Global incidence and characteristics of spinal cord injury since 2000-2021: a systematic review and meta-analysis

BACKGROUND

This study employs systematic review and meta-analysis to explore the incidence and characteristics of spinal cord injury (SCI) between 2000 and 2021, aiming to provide the most recent and comprehensive data support for the prevention, diagnosis, treatment, and care of SCI.

METHODS

Systematic searches were conducted on epidemiological studies of SCI published between January 1, 2000, and March 29, 2024. Meta-analysis, subgroup analysis, meta-regression, publication bias detection, and literature quality assessment were extensively utilized.

RESULTS

The pooled results from 229 studies indicated that the overall incidence rate of SCI was 23.77 (95% CI, 21.50-26.15) per million people, with traumatic spinal cord injuries (TSCI) at a rate of 26.48 (95% CI, 24.15-28.93) per million people, and non-traumatic spinal cord injuries (NTSCI) at a rate of 17.93 (95% CI, 13.30-23.26) per million people. The incidence of TSCI exhibited a marked age-related increase and was significantly higher in community settings compared to hospital and database sources. Males experienced TSCI at a rate 3.2 times higher than females. Between 2000 and 2021, the incidence of TSCI remained consistently high, between 20 and 45 per million people, whereas NTSCI incidence has seen a steady rise since 2007, stabilizing at a high rate of 25-35 per million people. Additionally, the incidence of TSCI in developing countries was notably higher than that in developed countries. There were significant differences in the causes of injury, severity, injury segments, gender, and age distribution among the TSCI and NTSCI populations, but the proportion of male patients was much higher than that of female patients. Moreover, study quality, country type, and SCI type contributed to the heterogeneity in the meta-analysis.

CONCLUSIONS

The incidence rates of different types of SCI remain high, and the demographic distribution of SCI patients is changing, indicating a serious disease burden on healthcare systems and affected populations. These findings underscore the necessity of adopting targeted preventive, therapeutic, and rehabilitative measures based on the incidence and characteristics of SCI.

Regeneration of Propriospinal Axons in Rat Transected Spinal Cord Injury through a Growth-Promoting Pathway Constructed by Schwann Cells Overexpressing GDNF

Unsuccessful axonal regeneration in transected spinal cord injury (SCI) is mainly attributed to shortage of growth factors, inhibitory glial scar, and low intrinsic regenerating capacity of severely injured neurons. Previously, we constructed an axonal growth permissive pathway in a thoracic hemisected injury by transplantation of Schwann cells overexpressing glial-cell-derived neurotrophic factor (SCs-GDNF) into the lesion gap as well as the caudal cord and proved that this novel permissive bridge promoted the regeneration of descending propriospinal tract (dPST) axons across and beyond the lesion. In the current study, we subjected rats to complete thoracic (T11) spinal cord transections and examined whether these combinatorial treatments can support dPST axons' regeneration beyond the transected injury. The results indicated that GDNF significantly improved graft-host interface by promoting integration between SCs and astrocytes, especially the migration of reactive astrocyte into SCs-GDNF territory. The glial response in the caudal graft area has been significantly attenuated. The astrocytes inside the grafted area were morphologically characterized by elongated and slim process and bipolar orientation accompanied by dramatically reduced expression of glial fibrillary acidic protein. Tremendous dPST axons have been found to regenerate across the lesion and back to the caudal spinal cord which were otherwise difficult to see in control groups. The caudal synaptic connections were formed, and regenerated axons were remyelinated. The hindlimb locomotor function has been improved.

Repetitive transcranial magnetic stimulation promotes motor function recovery in mice after spinal cord injury via regulation of the Cx43-autophagy loop

Spinal cord injury (SCI) is a severe condition with an extremely high disability rate. It is mainly manifested as the loss of motor, sensory and autonomic nerve functions below the injury site. High-frequency transcranial magnetic stimulation, a recently developed neuromodulation method, can increase motor function in mice with spinal cord injury. This study aimed to explore the possible mechanism by which transcranial magnetic stimulation (TMS) restores motor function after SCI. A complete T8 transection model of the spinal cord was established in mice, and the mice were treated daily with 15 Hz high-frequency transcranial magnetic stimulation. The BMS was used to evaluate the motor function of the mice after SCI. Western blotting and immunofluorescence were used to detect the expression of Connexin43 (CX43) and autophagy-related proteins in vivo and in vitro, and correlation analysis was performed to study the relationships among autophagy, CX43 and motor function recovery after SCI in mice. Western blotting was used to observe the effect of magnetic stimulation on the expression of mTOR pathway members. In the control group, the expression of CX43 was significantly decreased, and the expression of microtubule-associated protein 1 A/1b light chain 3 (LC3II) and P62 was significantly increased after 4 weeks of spinal cord transection. After high-frequency magnetic stimulation, the level of CX43 decreased, and the levels of LC3II and P62 increased in primary astrocytes. The BMS of the magnetic stimulation group was greater than that of the control group. High-frequency magnetic stimulation can inhibit the expression of CX43, which negatively regulates autophagic flux. HF-rTMS increased the expression levels of mTOR, p-mTOR and p-S6. Our experiments showed that rTMS can restore hindlimb motor function in mice after spinal cord injury via regulation of the Cx43-autophagy loop and activation of the mTOR signalling pathway.

Genetically engineered electrospinning contributes to spinal cord injury repair by regulating the immune microenvironment

Introduction: Spinal cord injury (SCI) is associated with microenvironment imbalance, thereby resulting in poor regeneration and recovery of the spinal cord. Gene therapy can be used to balance the inflammatory response, however target genes cannot exist in localized injured areas. Methods: A genetically engineered electrospun scaffold (GEES) to achieve long-term immunoregulation and nerve repair was constructed. By combining the microfluidic and electrospinning techniques, interleukin-10 plasmid (pIL10) was loaded into lipid nanoparticles (LNPs) (pIL10-LNP), which was encapsulated to the nerve growth factor (NGF). Immunofluorescence staining, qRT-PCR, ELISA, flow cytometry, and other tests were employed to comprehensively assess the role of GEES in modulating macrophage polarization and facilitating neural repair. Results: The results showed that the scaffold released >70% of the pIL10-LNP within 10 d and continued slow release within 30 d. In vitro cell experiments have demonstrated that GEES effectively stimulates macrophages to secrete anti-inflammatory cytokines and facilitates the differentiation of neural stem cells into neuronal cells. In rat T9 SCI model, the GEES significantly inhibited the inflammatory response in the acute and chronic phases of SCI by transfecting local tissues with slow-release pIL10-LNP to promote the release of the anti-inflammatory factor IL10, thereby creating a favorable microenvironment. With the addition of NGF, the repair and regeneration of nerve tissues was effectively promoted, and the post-SCI motor function of rats improved. Discussion: GEES can regulate post-SCI immune responses through continuous and effective gene delivery, providing a new strategy for the construction of electrospun scaffolds for nerve repair in gene therapy.

Multifunctional Hierarchical Nanoplatform with Anisotropic Bimodal Mesopores for Effective Neural Circuit Reconstruction after Spinal Cord Injury

A persistent inflammatory response, intrinsic limitations in axonal regenerative capacity, and widespread presence of extrinsic axonal inhibitors impede the restoration of motor function after a spinal cord injury (SCI). A versatile treatment platform is urgently needed to address diverse clinical manifestations of SCI. Herein, we present a multifunctional nanoplatform with anisotropic bimodal mesopores for effective neural circuit reconstruction after SCI. The hierarchical nanoplatform features of a Janus structure consist of dual compartments of hydrophilic mesoporous silica (mSiO2) and hydrophobic periodic mesoporous organosilica (PMO), each possessing distinct pore sizes of 12 and 3 nm, respectively. Unlike traditional hierarchical mesoporous nanomaterials with dual-mesopores interlaced with each other, the two sets of mesopores in this Janus nanoplatform are spatially independent and possess completely distinct chemical properties. The Janus mesopores facilitate controllable codelivery of dual drugs with distinct properties: the hydrophilic macromolecular enoxaparin (ENO) and the hydrophobic small molecular paclitaxel (PTX). Anchoring with CeO2, the resulting mSiO2&PMO-CeO2-PTX&ENO nanoformulation not only effectively alleviates ROS-induced neuronal apoptosis but also enhances microtubule stability to promote intrinsic axonal regeneration and facilitates axonal extension by diminishing the inhibitory effect of extracellular chondroitin sulfate proteoglycans. We believe that this functional dual-mesoporous nanoplatform holds significant potential for combination therapy in treating severe multifaceted diseases.

Spinal Cord Injury Management Based on Microglia-Targeting Therapies

Spinal cord injury is a complicated medical condition both from the clinician's point of view in terms of management and from the patient's perspective in terms of unsatisfactory recovery. Depending on the severity, this disorder can be devastating despite the rapid and appropriate use of modern imaging techniques and convenient surgical spinal cord decompression and stabilization. In this context, there is a mandatory need for novel adjunctive therapeutic approaches to classical treatments to improve rehabilitation chances and clinical outcomes. This review offers a new and original perspective on therapies targeting the microglia, one of the most relevant immune cells implicated in spinal cord disorders. The first part of the manuscript reviews the anatomical and pathophysiological importance of the blood-spinal cord barrier components, including the role of microglia in post-acute neuroinflammation. Subsequently, the authors present the emerging therapies based on microglia modulation, such as cytokines modulators, stem cell, microRNA, and nanoparticle-based treatments that could positively impact spinal cord injury management. Finally, future perspectives and challenges are also highlighted based on the ongoing clinical trials related to medications targeting microglia.

Kdm6a-CNN1 axis orchestrates epigenetic control of trauma-induced spinal cord microvascular endothelial cell senescence to balance neuroinflammation for improved neurological repair

Cellular senescence assumes pivotal roles in various diseases through the secretion of proinflammatory factors. Despite extensive investigations into vascular senescence associated with aging and degenerative diseases, the molecular mechanisms governing microvascular endothelial cell senescence induced by traumatic stress, particularly its involvement in senescence-induced inflammation, remain insufficiently elucidated. In this study, we present a comprehensive demonstration and characterization of microvascular endothelial cell senescence induced by spinal cord injury (SCI). Lysine demethylase 6A (Kdm6a), commonly known as UTX, emerges as a crucial regulator of cell senescence in injured spinal cord microvascular endothelial cells (SCMECs). Upregulation of UTX induces senescence in SCMECs, leading to an amplified release of proinflammatory factors, specifically the senescence-associated secretory phenotype (SASP) components, thereby modulating the inflammatory microenvironment. Conversely, the deletion of UTX in endothelial cells shields SCMECs against senescence, mitigates the release of proinflammatory SASP factors, and promotes neurological functional recovery after SCI. UTX forms an epigenetic regulatory axis by binding to calponin 1 (CNN1), orchestrating trauma-induced SCMECs senescence and SASP secretion, thereby influencing neuroinflammation and neurological functional repair. Furthermore, local delivery of a senolytic drug reduces senescent SCMECs and suppresses proinflammatory SASP secretion, reinstating a local regenerative microenvironment and enhancing functional repair after SCI. In conclusion, targeting the UTX-CNN1 epigenetic axis to prevent trauma-induced SCMECs senescence holds the potential to inhibit SASP secretion, alleviate neuroinflammation, and provide a novel treatment strategy for SCI repair.

Robust and Multifunctional Nanoparticles Assembled from Natural Polyphenols and Metformin for Efficient Spinal Cord Regeneration

The treatment of spinal cord injury (SCI) remains unsatisfactory owing to the complex pathophysiological microenvironments at the injury site and the limited regenerative potential of the central nervous system. Metformin has been proven in clinical and animal experiments to repair damaged structures and functions by promoting endogenous neurogenesis. However, in the early stage of acute SCI, the adverse pathophysiological microenvironment of the injury sites, such as reactive oxygen species and inflammatory factor storm, can prevent the activation of endogenous neural stem cells (NSCs) and the differentiation of NSCs into neurons, decreasing the whole repair effect. To address those issues, a series of robust and multifunctional natural polyphenol-metformin nanoparticles (polyphenol-Met NPs) were fabricated with pH-responsiveness and excellent antioxidative capacities. The resulting NPs possessed several favorable advantages: First, the NPs were composed of active ingredients with different biological properties, without the need for carriers; second, the pH-responsiveness feature could allow targeted drug delivery at the injured site; more importantly, NPs enabled drugs with different performances to exhibit strong synergistic effects. The results demonstrated that the improved microenvironment by natural polyphenols boosted the differentiation of activated NSCs into neurons and oligodendrocytes, which could efficiently repair the injured nerve structures and enhance the functional recovery of the SCI rats. This work highlighted the design and fabrication of robust and multifunctional NPs for SCI treatment via efficient microenvironmental regulation and targeted NSCs activation.