Restoration of spinal cord injury: From endogenous repairing process to cellular therapy

Inhibition of the RNA Regulator HuR Mitigates Spinal Cord Injury by Potently Suppressing Post-Injury Neuroinflammation

Neuroinflammation is a major driver of secondary tissue damage after spinal cord injury (SCI). Within minutes after SCI, activated microglia and astrocytes produce proinflammatory mediators such as TNF-α, IL-6, iNOS, and COX-2 which induce tissue injury through cytotoxicity, vascular hyperpermeability, and secondary ischemia. The inflammatory cascade is amplified by chemokines like CCL2 and CXCL1 which recruit immune cells to the injured site. HuR is an RNA regulator that promotes glial expression of many proinflammatory factors by binding to adenylate- and uridylate-rich elements in the 3' untranslated regions of their mRNAs. SRI-42127 is a small molecule which blocks HuR function by preventing its nucleocytoplasmic translocation. This study aimed to evaluate the potential of SRI-42127 to suppress neuroinflammation after SCI and improve functional outcome. Adult female mice underwent a T10 contusion injury and received SRI-42127 1 h post injury for up to 5 days. Locomotor function was assessed by open field testing, balance beam, and rotarod. Immunohistochemistry was used to assess lesion size, neuronal loss, myelin sparing, microglial/astroglial activation, and HuR localization. Inflammatory mediator expression was assessed by qPCR, immunohistochemistry, ELISA, or western blot. We found that SRI-42127 treatment significantly attenuated loss of locomotor function and post-SCI pain. There was a reduction in lesion size and neuronal loss with an increase in myelin sparing. Microglia and astrocytes showed reduced activation and reduced nucleocytoplasmic translocation of HuR. There was a striking suppression of proinflammatory mediators at the epicenter along with peripheral suppression of inflammatory responses in serum, liver, and spleen. In conclusion, HuR inhibition with SRI-42127 may be a viable therapeutic approach for suppressing neuroinflammatory responses after SCI and improving functional outcome.

Regulation of Neuroimmune Microenvironment by PLA/GO/Anti-TNF-α Composite to Enhance Neurological Repair After Spinal Cord Injury

Introduction

Spinal cord injury (SCI) is a severe neurological condition with limited treatment options. Polylactic acid (PLA)+graphene oxide (GO)+anti-TNF-α (Ab) composites have shown potential in regulating immune responses and promoting neural repair.

Methods

Electrospinning PLA+GO+Ab materials were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and X-ray diffraction (XRD). Their effects on neural stem cells (NSCs) and macrophage polarization were evaluated through in vitro assays, including proliferation, migration, differentiation, and flow cytometry. A rat SCI model was used to assess motor function recovery and histological changes.

Results

PLA+GO+Ab promoted NSC proliferation, migration, and differentiation while inducing macrophage polarization toward the M2 phenotype, reducing inflammation. In the SCI model, PLA+GO+Ab treatment enhanced motor function recovery, reduced spinal cord damage, and promoted axonal regeneration and oligodendrocyte maturation. RNA sequencing identified activation of the Rap1 signaling pathway, contributing to these effects.

Discussion

PLA+GO+Ab composites effectively modulate the neuroimmune microenvironment, supporting SCI recovery by promoting neural repair and immune regulation. These findings suggest its potential as a therapeutic biomaterial for SCI treatment.

Bioinformatics analysis reveals key mechanisms of oligodendrocytes and oligodendrocyte precursor cells regulation in spinal cord Injury

Despite extensive research, spinal cord injuries (SCI), which could cause severe sensory, motor and autonomic dysfunction, remain largely incurable. Oligodendrocytes and oligodendrocyte precursor cells (ODC/OPC) play a crucial role in neural morphological repair and functional recovery following SCI. We performed single-cell sequencing (scRNA-seq) on 59,558 cells from 39 mouse samples, combined with microarray data from 164 SCI samples and 3 uninjured samples. We further validated our findings using a large clinical cohort consisting of 38 SCI patients, 10 healthy controls, and 10 trauma controls, assessed with the American Spinal Cord Injury Association (ASIA) scale. We proposed a novel SCI classification model based on the expression of prognostic differentially expressed ODC/OPC differentiation-related genes (PDEODGs). This model includes three types: Low ODC/OPC Score Classification (LOSC), Median ODC/OPC Score Classification (MOSC), and High ODC/OPC Score Classification (HOSC). Considering the relationship between these subtypes and prognosis, we speculated that enhancing ODC/OPC differentiation and inhibiting inflammatory infiltration may improve outcomes. Additionally, we identified potential treatments for SCI that target key genes within these subtypes, offering promising implications for therapy.

Physiological Insights Into the Role of Pericytes in Spinal Cord Injury

Vascular regeneration plays a vital role in tissue repair yet is drastically impaired in those with a spinal cord injury (SCI). Pericytes are of great significance as they are entwined with vessel-specific endothelial cells and actively contribute to maintaining the spinal cord's vascular network. Within the neurovascular unit (NVU), subtypes of pericytes characterized by various markers such as PDGFR-β, Desmin, CD146, and NG-2 are involved in vascular regeneration in SCI repair. Various pericyte signaling, pericyte-derived exosomes, and endothelial-pericyte interplay were revealed to participate in SCI repair or fibrotic scars. Through further understanding pericyte biology, it is aimed to accurately generate subtypes of pericytes and develop their therapeutic potential. This review focuses on recent advanced research and development of pericytes as a potential treatment for SCI.

The role of astrocytes response triggered by hyperglycaemia during spinal cord injury

OBJECTIVE

This manuscript aimed to provide a comprehensive overview of the physiological, molecular, and cellular mechanisms triggered by reactive astrocytes (RA) in the context of spinal cord injury (SCI), with a particular focus on cases involving hyperglycaemia.

METHODS

The compilation of articles related to astrocyte responses in neuropathological conditions, with a specific emphasis on those related to SCI and hyperglycaemia, was conducted by searching through databases including Science Direct, Web of Science, and PubMed.

RESULTS AND CONCLUSIONS

This article explores the dual role of astrocytes in both neurophysiological and neurodegenerative conditions within the central nervous system (CNS). In the aftermath of SCI and hyperglycaemia, astrocytes undergo a transformation into RA, adopting a distinct phenotype. While there are currently no approved therapies for SCI, various therapeutic strategies have been proposed to alleviate the detrimental effects of RAs following SCI and hyperglycemia. These strategies show promising potential in the treatment of SCI and its likely comorbidities.

Lentivirus-mediated Knockdown of Ski Improves Neurological Function After Spinal Cord Injury in Rats

The glial scar that forms at the site of injury after spinal cord injury (SCI) is an important physical and biochemical barrier that prevents axonal regeneration and thus delays functional recovery. Ski is a multifunctional transcriptional co-regulator that is involved in a wide range of physiological and pathological processes in humans. Previous studies by our group found that Ski is significantly upregulated in the spinal cord after in vivo injury and in astrocytes after in vitro activation, suggesting that Ski may be a novel molecule regulating astrocyte activation after spinal cord injury. Further studies revealed that knockdown or overexpression intervention of Ski expression could significantly affect the proliferation and migration of activated astrocytes. To further verify the effect of knockdown of Ski expression in vivo on glial scar formation and neurological function after spinal cord injury, we prepared a rat spinal cord injury model using Allen's percussion method and used lentivirus as a vector to mediate the downregulation of Ski in the injured spinal cord. The results showed that knockdown of Ski expression after spinal cord injury significantly suppressed the expression of glial fibrillary acidic protein (Gfap) and vimentin, hallmark molecules of glial scarring, and increased the expression of neurofilament protein-200 (Nf-200) and growth-associated protein (Gap43), key molecules of axon regeneration, as well as Synaptophysin, a key molecule of synapse formation expression. In addition, knockdown of Ski after spinal cord injury also promoted the recovery of motor function. Taken together, these results suggest that Ski is able to inhibit the expression of key molecules of glial scar formation, and at the same time promotes the expression of molecules that are markers of axonal regeneration and synapse formation after spinal cord injury, making it a potential target for targeted therapy after spinal cord injury.

Biomaterials targeting the microenvironment for spinal cord injury repair: progression and perspectives

Spinal cord injury (SCI) disrupts nerve pathways and affects sensory, motor, and autonomic function. There is currently no effective treatment for SCI. SCI occurs within three temporal periods: acute, subacute, and chronic. In each period there are different alterations in the cells, inflammatory factors, and signaling pathways within the spinal cord. Many biomaterials have been investigated in the treatment of SCI, including hydrogels and fiber scaffolds, and some progress has been made in the treatment of SCI using multiple materials. However, there are limitations when using individual biomaterials in SCI treatment, and these limitations can be significantly improved by combining treatments with stem cells. In order to better understand SCI and to investigate new strategies for its treatment, several combination therapies that include materials combined with cells, drugs, cytokines, etc. are summarized in the current review.

Dual-layer conduit containing VEGF-A - Transfected Schwann cells promotes peripheral nerve regeneration via angiogenesis

Peripheral nerve injuries (PNIs) can cause neuropathies and significantly affect the patient's quality of life. Autograft transplantation is the gold standard for conventional treatment; however, its application is limited by nerve unavailability, size mismatch, and local tissue adhesion. Tissue engineering, such as nerve guidance conduits, is an alternative and promising strategy to guide nerve regeneration for peripheral nerve repair; however, only a few conduits could reach the high repair efficiency of autografts. The healing process of PNI is frequently accompanied by not only axonal and myelination regeneration but also angiogenesis, which initializes nerve regeneration through vascular endothelial growth factor A (VEGF-A). In this study, a composite nerve conduit with a poly (lactic-co-glycolic acid) (PLGA) hollow tube as the outer layer and gelatin methacryloyl (GelMA) encapsulated with VEGF-A transfected Schwann cells (SCs) as the inner layer was established to evaluate its promising ability for peripheral nerve repair. A rat model of peripheral nerve defect was used to examine the efficiency of PLGA/GelMA-SC (VA) conduits, whereas autograft, PLGA, PLGA/GelMA, and PLGA/GelMA-SC (NC) were used as controls. VEGF-A-transfected SCs can provide a stable source for VEGF-A secretion. Furthermore, encapsulation in GelMA cannot only promote proliferation and tube formation of human umbilical vein endothelial cells but also enhance dorsal root ganglia and neuronal cell extension. Previous animal studies have demonstrated that the regenerative effects of PLGA/GelMA-SC (VA) nerve conduit were similar to those of autografts and much better than those of other conduits. These findings indicate that combination of VEGF-A-overexpressing SCs and PLGA/GelMA conduit-guided peripheral nerve repair provides a promising method that enhances angiogenesis and regeneration during nerve repair. STATEMENT OF SIGNIFICANCE: Nerve guidance conduits shows promise for peripheral nerve repair, while achieving the repair efficiency of autografts remains a challenge. In this study, a composite nerve conduit with a PLGA hollow tube as the outer layer and gelatin methacryloyl (GelMA) encapsulated with vascular endothelial growth factor A (VEGF-A)-transfected Schwann cells (SCs) as the inner layer was established to evaluate its potential ability for peripheral nerve repair. This approach preserves growth factor bioactivity and enhances material properties. GelMA insertion promotes Schwann cell proliferation and morphology extension. Moreover, transfected SCs serve as a stable VEGF-A source and fostering angiogenesis. This study offers a method preserving growth factor efficacy and safeguarding SCs, providing a comprehensive solution for enhanced angiogenesis and nerve regeneration.

Caffeic acid phenethyl ester inhibits neuro-inflammation and oxidative stress following spinal cord injury by mitigating mitochondrial dysfunction via the SIRT1/PGC1α/DRP1 signaling pathway

BACKGROUND

The treatment of spinal cord injury (SCI) has always been a significant research focus of clinical neuroscience, with inhibition of microglia-mediated neuro-inflammation as well as oxidative stress key to successful SCI patient treatment. Caffeic acid phenethyl ester (CAPE), a compound extracted from propolis, has both anti-inflammatory and anti-oxidative effects, but its SCI therapeutic effects have rarely been reported.

METHODS

We constructed a mouse spinal cord contusion model and administered CAPE intraperitoneally for 7 consecutive days after injury, and methylprednisolone (MP) was used as a positive control. Hematoxylin-eosin, Nissl, and Luxol Fast Blue staining were used to assess the effect of CAPE on the structures of nervous tissue after SCI. Basso Mouse Scale scores and footprint analysis were used to explore the effect of CAPE on the recovery of motor function by SCI mice. Western blot analysis and immunofluorescence staining assessed levels of inflammatory mediators and oxidative stress-related proteins both in vivo and in vitro after CAPE treatment. Further, reactive oxygen species (ROS) within the cytoplasm were detected using an ROS kit. Changes in mitochondrial membrane potential after CAPE treatment were detected with 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide. Mechanistically, western blot analysis and immunofluorescence staining were used to examine the effect of CAPE on the SIRT1/PGC1α/DRP1 signaling pathway.

RESULTS

CAPE-treated SCI mice showed less neuronal tissue loss, more neuronal survival, and reduced demyelination. Interestingly, SCI mice treated with CAPE showed better recovery of motor function. CAPE treatment reduced the expression of inflammatory and oxidative mediators, including iNOS, COX-2, TNF-α, IL-1β, 1L-6, NOX-2, and NOX-4, as well as the positive control MP both in vitro and in vivo. In addition, molecular docking experiments showed that CAPE had a high affinity for SIRT1, and that CAPE treatment significantly activated SIRT1 and PGC1α, with down-regulation of DRP1. Further, CAPE treatment significantly reduced the level of ROS in cellular cytoplasm and increased the mitochondrial membrane potential, which improved normal mitochondrial function. After administering the SIRT1 inhibitor nicotinamide, the effect of CAPE on neuro-inflammation and oxidative stress was reversed.On the contrary, SIRT1 agonist SRT2183 further enhanced the anti-inflammatory and antioxidant effects of CAPE, indicating that the anti-inflammatory and anti-oxidative stress effects of CAPE after SCI were dependent on SIRT1.

CONCLUSION

CAPE inhibits microglia-mediated neuro-inflammation and oxidative stress and supports mitochondrial function by regulating the SIRT1/PGC1α/DRP1 signaling pathway after SCI. These effects demonstrate that CAPE reduces nerve tissue damage. Therefore, CAPE is a potential drug for the treatment of SCI through production of anti-inflammatory and anti-oxidative stress effects.

Activity based restorative therapy considerations for children: medical and therapeutic perspectives for the pediatric population

Well-established scientific evidence demonstrates that activity is essential for the development and repair of the central nervous system, yet traditional rehabilitation approaches target muscles only above the lesion as a means of compensation. Activity-Based Rehabilitation (ABR) represents an evolving paradigm shift in neurorehabilitation targeting activation of the neuromuscular system below the lesion. Based on activity-dependent plasticity, ABR offers high intensity activation of the nervous system to optimize the capacity for recovery, while working to offset the chronic complications that occur as a result of neurologic injury. Treatment focus shifts from compensatory training to promotion of restoration of function with special emphasis on normalizing sensory cues and movement kinematics. ABR in children carries special considerations for a developing nervous system and the focus is not just restoring functions but advancing functions in line with typical development. Application of activity-based interventions includes traditional rehabilitation strategies at higher intensity and frequency than in traditional models, including locomotor training, functional electrical stimulation, massed practice, and task specific training, applied across the continuum of care from early intervention to the chronic condition.