Regular ArticleGraded Histological and Locomotor Outcomes after Spinal Cord Contusion Using the NYU Weight-Drop Device versus Transection
Abstract
Injury reproducibility is an important characteristic of experimental models of spinal cord injuries (SCI) because it limits the variability in locomotor and anatomical outcome measures. Recently, a more sensitive locomotor rating scale, the Basso, Beattie, and Bresnahan scale (BBB), was developed but had not been tested on rats with severe SCI complete transection. Rats had a 10-g rod dropped from heights of 6.25, 12.5, 25, and 50 mm onto the exposed cord at T10 using the NYU device. A subset of rats with 25 and 50 mm SCI had subsequent spinal cord transection (SCI + TX) and were compared to rats with transection only (TX) in order to ascertain the dependence of recovery on descending systems. After 7–9 weeks of locomotor testing, the percentage of white matter measured from myelin-stained cross sections through the lesion center was significantly different between all the groups with the exception of 12.5 vs 25 mm and 25 vs 50 mm groups. Locomotor recovery was greatest for the 6.25-mm group and least for the 50-mm group and was correlated positively to the amount of tissue sparing at the lesion center (p < 0.0001). BBB scale sensitivity was sufficient to discriminate significant locomotor differences between the most severe SCI (50 mm) and complete TX (p < 0.01). Transection following SCI resulted in a drop in locomotor scores and rats were unable to step or support weight with their hindlimbs (p < 0.01), suggesting that locomotor recovery depends on spared descending systems. The SCI + TX group had a significantly greater frequency of HL movements during open field testing than the TX group (p < 0.005). There was also a trend for the SCI + TX group to have higher locomotor scores than the TX group (p > 0.05). Thus, spared descending systems appear to modify segmental systems which produce greater behavioral improvements than isolated cord systems.
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Ferrostatin-1 improves neurological impairment induced by ischemia/reperfusion injury in the spinal cord through ERK1/2/SP1/GPX4
2024, Experimental NeurologySpinal cord ischemia/reperfusion injury (SCIRI) induced by artificial aortic occlusion for a while during aortic surgery is a serious complication, leading to paraplegia and even death. Ferroptosis in the nervous system has been confirmed to contribute to neuronal death induced by SCIRI. Therefore, we investigated the therapeutic benefits of ferrostatin-1 (Fer-1, a ferroptosis inhibitor) and explored the mechanism and target of Fer-1 in SCIRI. Our results demonstrate that intrathecal injection of Fer-1 had a strong anti-SCIRI effect, improved ferroptosis-related indices, increased neurological function scores and motor neuron counts, and reduced BSCB leakage and neuroinflammation levels in the anterior horn. We found that SCIRI significantly elevated the levels of several important proteins, including SP1, p-ERK1/2/ERK1/2, COX2, TFR1, SLC40A1, SLC7A11, cleaved Caspase 3, GFAP, and Iba1, while reducing FTH1 and GPX4 protein expression, with no effect on ACSL4 expression. Fer-1 effectively ameliorated the ferroptosis-related changes in these proteins induced by SCIRI. However, for p-ERK1/2 and SP1, Fer-1 not only failed to reduce their expression but also significantly enhanced it. Fer-1 was injected into sham operation rats, abnormal increases in p-ERK1/2/ERK1/2 and SP1 were observed, along with an increase in GPX4. Fluorescent double labeling revealed that SP1 and GPX4 were expressed in neurons and astrocytes. Inhibitors of the ERK pathway (SCH772984) and siRNA against SP1 (AV-sh-SP1) significantly decreased the increase in SP1 and GPX4 protein levels, fluorescent density of SP1 and GPX4 in neurons, and the number of SP1-positive and GPX4-positive neurons induced by Fer-1. SCH772984 but not AV-sh-SP1 significantly reversed the decrease in GFAP and Iba1 induced by Fer-1. In conclusion, our results indicate that Fer-1 inhibited ferroptosis in spinal cord anterior horn neurons, improving neurological impairment and BSCB damage after SCIRI through the ERK1/2/SP1/GPX4 signaling pathway in rats.
Microvascular endothelial cells derived from spinal cord promote spinal cord injury repair
2023, Bioactive MaterialsNeural regeneration after spinal cord injury (SCI) closely relates to the microvascular endothelial cell (MEC)-mediated neurovascular unit formation. However, the effects of central nerve system-derived MECs on neovascularization and neurogenesis, and potential signaling involved therein, are unclear. Here, we established a primary spinal cord-derived MECs (SCMECs) isolation with high cell yield and purity to describe the differences with brain-derived MECs (BMECs) and their therapeutic effects on SCI. Transcriptomics and proteomics revealed differentially expressed genes and proteins in SCMECs were involved in angiogenesis, immunity, metabolism, and cell adhesion molecular signaling was the only signaling pathway enriched of top 10 in differentially expressed genes and proteins KEGG analysis. SCMECs and BMECs could be induced angiogenesis by different stiffness stimulation of PEG hydrogels with elastic modulus 50-1650 Pa for SCMECs and 50-300 Pa for BMECs, respectively. Moreover, SCMECs and BMECs promoted spinal cord or brain-derived NSC (SNSC/BNSC) proliferation, migration, and differentiation at different levels. At certain dose, SCMECs in combination with the NeuroRegen scaffold, showed higher effectiveness in the promotion of vascular reconstruction. The potential underlying mechanism of this phenomenon may through VEGF/AKT/eNOS- signaling pathway, and consequently accelerated neuronal regeneration and functional recovery of SCI rats compared to BMECs. Our findings suggested a promising role of SCMECs in restoring vascularization and neural regeneration.
Hyperbaric oxygen therapy and coenzyme Q10 synergistically attenuates damage progression in spinal cord injury in a rat model
2023, Journal of Chemical NeuroanatomyIdentifying effective spinal cord injury (SCI) treatments remains a major challenge, and current approaches are still unable to effectively improve its. Currently, we investigated the combined effects of hyperbaric oxygen (HBO) along with coenzyme Q10 (CoQ10) in the recovery of SCI in rats.
Ninety female mature Sprague-Dawley rats were allocated into five equal groups, including; sham group, SCI group, HBO group (underwent SCI and received HBO), CoQ10 group (underwent SCI and received CoQ10), and HBO+CoQ10 group (underwent SCI and received HBO plus CoQ10). Tissue samples at the lesion site were obtained for evaluation of stereological, immunohistochemical, biochemical, molecular. Also, functional tests were performed to evaluate of behavioral properties.
We found that a significant increase in stereological parameters, biochemical factors (GSH, SOD and CAT), IL-10 gene expression and behavioral functions (BBB and EMG Latency) in the treatment groups, especially HBO+CoQ10 group, compared to SCI group. In addition, MDA levels, the density of apoptotic cells, as well as expression of inflammatory genes (TNF-α and IL-1β) were considerably reduced in the treatment groups, especially HBO+CoQ10 group, compared to SCI group.
We conclude that co-administration of HBO and HBO+CoQ10 has a synergistic neuroprotective effects in animals undergoing SCI.
Elevation of NAD<sup>+</sup> by nicotinamide riboside spares spinal cord tissue from injury and promotes locomotor recovery
2023, Experimental NeurologySpinal cord injury (SCI)-induced tissue damage spreads to neighboring spared cells in the hours, days, and weeks following injury, leading to exacerbation of tissue damage and functional deficits. Among the biochemical changes is the rapid reduction of cellular nicotinamide adenine dinucleotide (NAD+), an essential coenzyme for energy metabolism and an essential cofactor for non-redox NAD+-dependent enzymes with critical functions in sensing and repairing damaged tissue. NAD+ depletion propagates tissue damage. Augmenting NAD+ by exogenous application of NAD+, its synthesizing enzymes, or its cellular precursors mitigates tissue damage. Nicotinamide riboside (NR) is considered to be one of the most promising NAD+ precursors for clinical application due to its ability to safely and effectively boost cellular NAD+ synthesis in rats and humans. Moreover, various preclinical studies have demonstrated that NR can provide tissue protection. Despite these promising findings, little is known about the potential benefits of NR in the context of SCI. In the current study, we tested whether NR administration could effectively increase NAD+ levels in the injured spinal cord and whether this augmentation of NAD+ would promote spinal cord tissue protection and ultimately lead to improvements in locomotor function. Our findings indicate that administering NR (500 mg/kg) intraperitoneally from four days before to two weeks after a mid-thoracic contusion-SCI injury, effectively doubles NAD+ levels in the spinal cord of Long-Evans rats. Moreover, NR administration plays a protective role in preserving spinal cord tissue post-injury, particularly in neurons and axons, as evident from the observed gray and white matter sparing. Additionally, it enhances motor function, as evaluated through the BBB subscore and missteps on the horizontal ladderwalk. Collectively, these findings demonstrate that administering NR, a precursor of NAD+, increases NAD+ within the injured spinal cord and effectively mitigates the tissue damage and functional decline that occurs following SCI.
Black phosphorus nanosheets enhance differentiation of neural progenitor cells for improved treatment in spinal cord injury
2023, Chemical Engineering JournalStem cell transplantation holds great potential as a treatment option for nerve damage diseases. However, the therapeutic effects are significantly impeded by low survival rate and uncontrolled differentiation of stem cells. In this study, black phosphorus nanosheets (BPNs), which are biodegradable inorganic nanomaterials, are first revealed with remarkable abilities to regulate cellular redox homeostasis, enhance transplant survival rate of stem cells, and facilitate neural differentiation of neural progenitor cells (NPCs). These effects of BPNs are proved to be associated with the activation of nuclear factor erythroid 2-like 2 (Nrf2) pathways in NPCs. In vivo, BPNs-treated NPCs could effectively inhibit inflammatory response and neuronal apoptosis in the mice with spinal cord injury (SCI). In addition, BPNs-treated NPCs more effectively reduce glial scar formation and promote axon regeneration compared with natural NPCs in SCI site. These findings collectively support the therapeutic potentials of BPNs for advanced stem cell transplantation and neural tissue engineering in the future.
Inhibition of T-Type Calcium Channels With TTA-P2 Reduces Chronic Neuropathic Pain Following Spinal Cord Injury in Rats
2023, Journal of PainSpinal cord injury (SCI)-induced neuropathic pain (SCI-NP) develops in up to 60 to 70% of people affected by traumatic SCI, leading to a major decline in quality of life and increased risk for depression, anxiety, and addiction. Gabapentin and pregabalin, together with antidepressant drugs, are commonly prescribed to treat SCI-NP, but their efficacy is unsatisfactory. The limited efficacy of current pharmacological treatments for SCI-NP likely reflects our limited knowledge of the underlying mechanism(s) responsible for driving the maintenance of SCI-NP. The leading hypothesis in the field supports a major role for spontaneously active injured nociceptors in driving the maintenance of SCI-NP. Recent data from our laboratory provided additional support for this hypothesis and identified the T-type calcium channels as key players in driving the spontaneous activity of SCI-nociceptors, thus providing a rational pharmacological target to treat SCI-NP. To test whether T-type calcium channels contribute to the maintenance of SCI-NP, male and female SCI and sham rats were treated with TTA-P2 (a blocker of T-type calcium channels) to determine its effects on mechanical hypersensitivity (as measured with the von Frey filaments) and spontaneous ongoing pain (as measured with the conditioned place preference paradigm), and compared them to the effects of gabapentin, a blocker of high voltage–activated calcium channels. We found that both TTA-P2 and gabapentin reduced mechanical hypersensitivity in male and females SCI rats, but surprisingly only TTA-P2 reduced spontaneous ongoing pain in male SCI rats.
SCI-induced neuropathic pain, and in particular the spontaneous ongoing pain component, is notoriously very difficult to treat. Our data provide evidence that inhibition of T-type calcium channels reduces spontaneous ongoing pain in SCI rats, supporting a clinically relevant role for T-type channels in the maintenance of SCI-induced neuropathic pain.