Experimental Spinal Cord Injury Research Articles

Virus-mediated neuron-specific retrograde gene delivery in spinal cord injury

Virus-mediated retrograde neuron-specific retrograde transport serves as an effective tool for determining the localization of neuronal somas, identifying interneuronal connections, and facilitating the retrograde delivery of therapeutic transgenes to support neuronal function and restoration. in the context of experimental spinal cord injury (SCI), retrograde transport of therapeutic transgenes offers several advantages over other more common delivery methods. these advantages include targeted transfer of genetic constructs to specific types of spinal neuron somas, low invasiveness, relatively low risk of inflammatory response, and the potential for repeated injections. research on retrograde transport has extensively focused on enhancing its efficiency through capsid modification and the application of novel promoters. this review provides a detailed examination of the outcomes of virus-mediated neuron-specific retrograde transduction of transgenes following intramuscular injection of genetic constructs. in retrograde delivery technology, the ability to choose between monosynaptic and polysynaptic transport, depending on the specific viral vector used, is a positive aspect. the review also separately addresses the effects of virus-mediated retrograde transduction on both spinal motoneurons and interneurons, which collectively form motor neuronal networks. by delivering transgenes through retrograde transport along axons from the periphery to the perikarya of spinal neurons, one can anticipate not only localized effects within the spinal cord but also in supraspinal structures, a crucial aspect for the restoration of extensive neural connections.

Neuroprotective Effects of Coenzyme Q10 and Ozone Therapy on Experimental Traumatic Spinal Cord Injuries in Rats

This study investigates the neuroprotective effects and functional recovery potential of Coenzyme Q10 (CoQ10) and ozone therapy in spinal cord injury (SCI). In this study, 40 female Sprague-Dawley rats were divided into five groups of eight. Surgical procedures induced spinal cord trauma in all groups, except the control group. The ozone group received 0.7 mg/kg rectal ozone daily for seven days, starting one hour post-spinal cord trauma. The CoQ10 group was administered 120 mg/kg CoQ10 orally once daily for seven days, beginning 24 hours prior to trauma. The CoQ10 + ozone group received both treatments. Examinations included a modified Tarlov scale and inclined plane test on days 1, 3, 5, and 7. Malondialdehyde (MDA) analysis was conducted on serum samples, and assessments of caspase-3, Bcl-2, and Bax levels were performed on tissue samples. Additionally, a comprehensive examination analyzed histopathological and ultrastructural changes. After SCI, there was a statistically significant increase in serum MDA, tissue caspase-3, and Bax levels (MDA p<0.001, caspase-3 p<0.001, Bax p=0.003). In the CoQ10 + ozone group, serum MDA (p=0.002), tissue caspase-3 (p=0.001), and Bax (p=0.030) levels were significantly lower compared to the trauma group. Tissue Bcl-2 levels were also significantly higher (p=0.019). The combined treatment group demonstrated improved histopathological, ultrastructural, and neurological outcomes. This study shows that CoQ10 + ozone therapy in traumatic SCI demonstrates neuroprotective effects via antioxidant and antiapoptotic mechanisms. The positive effects on functional recovery are supported by data from biochemical, histopathological, ultrastructural, and neurological examinations.

Evaluation of human mononuclear umbilical cord blood cells systemic administration efficiency in the acute period of experimental severe spinal cord injury

Aim. To evaluate the efficiency of systemic (intravenous) application of cryopreserved human umbilical cord blood mononuclear cells (HUCBCs) in animal models of acute contusion spinal cord injury for the restoration of hind limb motor function and formation of posttraumatic cysts using clinically significant examination methods.Materials and methods. Adult female Sprague–Dowley rats were used for the study. Severe acute contusion spinal cord injury model was performed using standard “weight‑drop” method. All samples of cryopreserved HUCBCs concentrate were prestored prior to infusion for 3 to 4 years at –196 °C. Hind limbs motor function was evaluated using open‑field technique and standard BBB testing system. Magnetic resonance scanning was performed using high‑field magnetic resonance CleanScan 7.0 T tomography (Bruker BioSpin, Germany).Results. Intravenous infusions of HUCBCs were performed on Day 1 following acute severe spinal cord injury. Motor function assessment demonstrated significant (p &lt;0.05) improvement of hind limbs motor function (up to 40–50 %) comparing to self‑healing outcomes. Moreover, by the Days 4 and 5 after severe spinal cord injury, the volume of posttraumatic cystic cavity decreases significantly (up to 40 %) (p &lt;0.05).Conclusion. The obtained results demonstrated that cryopreserved HUCBCs can be used as an effective source for cell therapy of acute contusion spinal cord injury.

Refinement of the motorised laminectomy-assisted rat spinal cord injury model by analgesic treatment.

Usage and reporting of analgesia in animal models of spinal cord injury (SCI) have been sparse and requires proper attention. The majority of experimental SCI research uses rats as an animal model. This study aimed to probe into the effects of some commonly used regimens with NSAIDs and opioids on well-being of the rats as well as on the functional outcome of the model. This eight-week study used forty-two female Wistar rats (Crl: WI), randomly and equally divided into 6 treatment groups, viz. I) tramadol (5mg/kg) and buprenorphine (0.05mg/kg); II) carprofen (5mg/kg) and buprenorphine (0.05mg/kg); III) carprofen (5mg/kg); IV) meloxicam (1mg/kg) and buprenorphine (0.05mg/kg); V) meloxicam (1mg/kg); and VI) no analgesia (0.5 ml sterile saline). Buprenorphine was administered twice daily whereas other treatments were given once daily for five days post-operatively. Injections were given subcutaneously. All animals underwent dental burr-assisted laminectomy at the T10-T11 vertebra level. A custom-built calibrated spring-loaded 200 kilodynes force deliverer was used to induce severe SCI. Weekly body weight scores, Rat Grimace Scale (RGS), and dark-phase home cage activity were used as markers for well-being. Weekly Basso Beattie and Bresnahan (BBB) scores served as markers for functionality together with Novel Object Recognition test (NOR) at week 8 and terminal histopathology using area of vacuolisation and live neuronal count from the ventral horns of spinal cord. It was concluded that the usage of analgesia improved animal wellbeing while having no effects on the functional aspects of the animal model in comparison to the animals that received no analgesics.

Glutathione effect on functional and histological recovery after spinal cord injury in rats

ObjectiveThe aim of this study was to evaluate the GSH effect on functional and histological recovery after experimental spinal cord injury in rats. MethodsForty Wistar rats were subjected to spinal cord injury through the Multicenter Animal Spinal Cord Injury Study (MASCIS) Impactor system. The rats were sorted and divided into four groups, as follows: Group 1 ‒ Laminectomy and spinal cord injury; Group 2 ‒ Laminectomy, spinal cord injury and Saline Solution (SS) 0.9%; Group 3 ‒ Laminectomy, spinal cord injury, and GSH; and Group 4 ‒ lLaminectomy without spinal cord injury. GSH and SS were administered intraperitoneally. Groups 1 and 4 received no intervention. ResultsThe rats were evaluated for locomotor function recovery at seven different times by the Basso, Beattie, and Bresnahan (BBB) scale on days 2, 7, 14, 21, 28, 35, and 42 after the spinal cord injury. On day 42, the rats were sacrificed to analyze the histological findings of the injured spinal cord. In the group submitted to GSH, our experimental study revealed better functional scores on the BBB scale, horizontal ladder scale, and cranial and caudal axon count. The differences found were statistically significant in BBB scores and axonal count analysis. ConclusionThis study demonstrated that using glutathione in experimental spinal trauma can lead to better functional recovery and improved axonal regeneration rate in Wistar rats submitted to experimental spinal cord injury.

Contribution of mechanoreceptors to spinal cord injury-induced mechanical allodynia.

Evidence from previous studies supports the concept that spinal cord injury (SCI)-induced neuropathic pain (NP) has its neural roots in the peripheral nervous system. There is uncertainty about how and to which degree mechanoreceptors contribute. Sensorimotor activation-based interventions (eg, treadmill training) have been shown to reduce NP after experimental SCI, suggesting transmission of pain-alleviating signals through mechanoreceptors. The aim of the present study was to understand the contribution of mechanoreceptors with respect to mechanical allodynia in a moderate mouse contusion SCI model. After genetic ablation of tropomyosin receptor kinase B expressing mechanoreceptors before SCI, mechanical allodynia was reduced. The identical genetic ablation after SCI did not yield any change in pain behavior. Peptidergic nociceptor sprouting into lamina III/IV below injury level as a consequence of SCI was not altered by either mechanoreceptor ablation. However, skin-nerve preparations of contusion SCI mice 7 days after injury yielded hyperexcitability in nociceptors, not in mechanoreceptors, which makes a substantial direct contribution of mechanoreceptors to NP maintenance unlikely. Complementing animal data, quantitative sensory testing in human SCI subjects indicated reduced mechanical pain thresholds, whereas the mechanical detection threshold was not altered. Taken together, early mechanoreceptor ablation modulates pain behavior, most likely through indirect mechanisms. Hyperexcitable nociceptors seem to be the main drivers of SCI-induced NP. Future studies need to focus on injury-derived factors triggering early-onset nociceptor hyperexcitability, which could serve as targets for more effective therapeutic interventions.

High resolution terahertz ATR frequency-domain spectroscopy for monitoring spinal cord injury in rats.

Traumatic spinal cord injury (SCI) can lead to permanent neurological impairment, underscoring the urgency of regular therapeutic intervention and monitoring. In this study, we propose a new strategy for monitoring spinal cord injury through serum based on high-resolution THz attenuated total reflection frequency domain spectroscopy (THz-ATR-FDS). We demonstrated serum spectral differences at different time points after experimental SCI in rats. We also studied the relationship between serum lipid concentration and the time of SCI, which revealed the potential of lipid molecules as biomarkers of SCI. In addition, based on the principal component analysis (PCA) and least squares regression (LSR) models, the quantitative relationship between the refractive index spectrum and lipid concentration in serum was automatically analyzed. This work highlights terahertz spectroscopy as a promising tool for label-free, periodic, and efficient monitoring of SCI.

Microglial TNFR2 signaling regulates the inflammatory response after CNS injury in a sex-specific fashion

Microglia, the resident immune cells of the central nervous system (CNS), play a major role in damage progression and tissue remodeling after acute CNS injury, including ischemic stroke (IS) and spinal cord injury (SCI). Understanding the molecular mechanisms regulating microglial responses to injury may thus reveal novel therapeutic targets to promote CNS repair. Here, we investigated the role of microglial tumor necrosis factor receptor 2 (TNFR2), a transmembrane receptor previously associated with pro-survival and neuroprotective responses, in shaping the neuroinflammatory environment after CNS injury. By inducing experimental IS and SCI in Cx3cr1CreER:Tnfrsf1bfl/fl mice, selectively lacking TNFR2 in microglia, and corresponding Tnfrsf1bfl/fl littermate controls, we found that ablation of microglial TNFR2 significantly reduces lesion size and pro-inflammatory cytokine levels, and favors infiltration of leukocytes after injury. Interestingly, these effects were paralleled by opposite sex-specific modifications of microglial reactivity, which was found to be limited in female TNFR2-ablated mice compared to controls, whereas it was enhanced in males. In addition, we show that TNFR2 protein levels in the cerebrospinal fluid (CSF) of human subjects affected by IS and SCI, as well as healthy donors, significantly correlate with disease stage and severity, representing a valuable tool to monitor the inflammatory response after acute CNS injury. Hence, these results advance our understanding of the mechanisms regulating microglia reactivity after acute CNS injury, aiding the development of sex- and microglia-specific, personalized neuroregenerative strategies.

Inhibition of the Nogo-pathway in experimental spinal cord injury: a meta-analysis of 76 experimental treatments

Recovery after spinal cord injury (SCI) may be propagated by plasticity-enhancing treatments. The myelin-associated nerve outgrowth inhibitor Nogo-A (Reticulon 4, RTN4) pathway has been shown to restrict neuroaxonal plasticity in experimental SCI models. Early randomized controlled trials are underway to investigate the effect of Nogo-A/Nogo-Receptor (NgR1) pathway blockers. This systematic review and meta-analysis of therapeutic approaches blocking the Nogo-A pathway interrogated the efficacy of functional locomotor recovery after experimental SCI according to a pre-registered study protocol. A total of 51 manuscripts reporting 76 experiments in 1572 animals were identified for meta-analysis. Overall, a neurobehavioral improvement by 18.9% (95% CI 14.5–23.2) was observed. Subgroup analysis (40 experiments, N = 890) revealed SCI-modelling factors associated with outcome variability. Lack of reported randomization and smaller group sizes were associated with larger effect sizes. Delayed treatment start was associated with lower effect sizes. Trim and Fill assessment as well as Egger regression suggested the presence of publication bias. Factoring in theoretically missing studies resulted in a reduced effect size [8.8% (95% CI 2.6–14.9)]. The available data indicates that inhibition of the Nogo-A/NgR1pathway alters functional recovery after SCI in animal studies although substantial differences appear for the applied injury mechanisms and other study details. Mirroring other SCI interventions assessed earlier we identify similar factors associated with outcome heterogeneity.

Lesion level-dependent systemic muscle wasting after spinal cord injury is mediated by glucocorticoid signaling in mice.

An incomplete mechanistic understanding of skeletal muscle wasting early after spinal cord injury (SCI) precludes targeted molecular interventions. Here, we demonstrated systemic wasting that also affected innervated nonparalyzed (supralesional) muscles and emerged within 1 week after experimental SCI in mice. Systemic muscle wasting caused muscle weakness, affected fast type 2 myofibers preferentially, and became exacerbated after high (T3) compared with low (T9) thoracic paraplegia, indicating lesion level-dependent ("neurogenic") mechanisms. The wasting of nonparalyzed muscle and its rapid onset and severity beyond what can be explained by disuse implied unknown systemic drivers. Muscle transcriptome and biochemical analysis revealed a glucocorticoid-mediated catabolic signature early after T3 SCI. SCI-induced systemic muscle wasting was mitigated by (i) endogenous glucocorticoid ablation (adrenalectomy) and (ii) pharmacological glucocorticoid receptor (GR) blockade and was (iii) completely prevented after T3 relative to T9 SCI by genetic muscle-specific GR deletion. These results suggest that neurogenic hypercortisolism contributes to a rapid systemic and functionally relevant muscle wasting syndrome early after paraplegic SCI in mice.

Comparative evaluation of contusion spinal cord injury models from ventral and dorsal approaches in rabbits in an experiment

BACKGROUND: Contemporary experimental models for spinal cord injury studies are mainly based on spinal cord injury in rats and mice. Modeling of experimental spinal cord injuries is generally performed from the dorsal approach, which excludes its injury as a result of compression by the fragments of the fractured vertebral body and significantly restricts the application of the results obtained from clinical practice.&#x0D; AIM: To develop and create contusional spinal cord injury model from the ventral approach with its subsequent comparison with the contusional spinal cord injury model from the dorsal approach.&#x0D; MATERIALS AND METHODS: The study examined 20 female Soviet Chinchilla rabbits weighing 3.5–4.5 kg. The rabbits were subjected to standardized spinal cord injuries from the ventral and dorsal approaches at the LII level. Somatosensory- and motor-evoked potentials, H-reflex, were recorded in all experimental animals before injury, immediately after, and 3 and 8 h after injury. Histological studies were also performed using qualitative and semiquantitative analyses of biopsy samples of damaged areas and assessing the number of dystrophic neurons over time. The results of neurophysiological and histological examinations of the spinal cord in cases of ventral and dorsal trauma were statistically processed.&#x0D; RESULTS: When modeling spinal cord injury from the ventral approach, in comparison with the model from the dorsal approach, more significant damage is detected. As a result of the injury factor, the dysfunction of both neurons at the traumatization level and peripheral neurons below the injury zone was revealed; however, as histological examinations have shown, in contrast to the dorsal approach, mild hemorrhage was observed in the ventral approach.&#x0D; CONCLUSIONS: The results obtained indicate a more significant and strict contusion mechanism of the spinal cord injury model from the ventral approach and the maximum proximity of the resulting model in a clinical situation. In the future, the experimental model of the contusional spinal cord injury in a laboratory animal can be used in chronic experiments.

Contrasting Experimental Rodent Aftercare With Human Clinical Treatment for Cervical Spinal Cord Injury: Bridging the Translational "Valley of Death".

More than half of all spinal cord injuries (SCIs) occur at the cervical level and often lead to life-threatening breathing motor dysfunction. The C2 hemisection (C2Hx) and high cervical contusion mouse and rat models of SCI are widely utilized both to understand the pathological effects of SCI and to develop potential therapies. Despite rigorous research effort, pre-clinical therapeutics studied in those animal models of SCI sometimes fail when evaluated in the clinical setting. Differences between standard-of-care treatment for acute SCI administered to clinical populations and experimental animal models of SCI could influence the heterogeneity of outcome between pre-clinical and clinical studies. In this review, we have summarized both the standard clinical interventions used to treat patients with cervical SCI and the various veterinary aftercare protocols used to care for rats and mice after experimentally induced C2Hx and high cervical contusion models of SCI. Through this analysis, we have identified areas of marked dissimilarity between clinical and veterinary protocols and suggest the modification of pre-clinical animal care particularly with respect to analgesia, anticoagulative measures, and stress ulcer prophylaxis. In our discussion, we intend to inspire consideration of potential changes to aftercare for animal subjects of experimental SCI that may help to bridge the translational "Valley of Death" and ultimately contribute more effectively to finding treatments capable of restoring independent breathing function to persons with cervical SCI.

Effects of isotretinoin and acitretin on neuroregeneration in experimental spinal cord injury.

This study aimed to determine whether isotretinoin and acitretin have beneficial effects on neural tissue damage following acute spinal cord injury. Thirty-six rats were randomly divided into 6 groups: control, sham spinal cord injury, spinal cord injury with isotretinoin 15 mg/kg for 14 days, spinal cord injury with isotretinoin 15 mg/kg for 28 days, spinal cord injury with acitretin 10 mg/kg for 14 days, and spinal cord injury with acitretin 10 mg/kg for 28 days. The damage to the spinal cord was formed by the clip compression technique. A neurological evaluation was conducted on days 1, 14, and 28. All rats were sacrificed following the treatment period, and samples of their spinal cords were collected for histopathological analysis. The inclined plane angle was significantly increased on the 14th and 28th days in the isotretinoin 15 mg and acitretin 10 mg groups, compared to the spinal injury group (P=.049 and P=.009, respectively). The Drummond-Moore criterion was significantly higher in the acitretin 10 mg group than in the injury group (P=.026). Cleaved Caspase-3 expression was similar in the isotretinoin 15 mg day 28 group and the control group (P > .05), but significantly decreased in the acitretin 10 mg 14th-day and acitretin 10 mg 28th-day groups compared to spinal injury isotretinoin 15 mg 14th-day and isotretinoin 15 mg 28th-day groups (P < .05). This was the first study elaborating that isotretinoin and acitretin reduced neuronal apoptosis and improved functional recovery after spinal cord injury. These neuroprotective effects might open a window of opportunity for patients.

Heimdall, an alternative protein issued from a ncRNA related to kappa light chain variable region of immunoglobulins from astrocytes: a new player in neural proteome

The dogma “One gene, one protein” is clearly obsolete since cells use alternative splicing and generate multiple transcripts which are translated into protein isoforms, but also use alternative translation initiation sites (TISs) and termination sites on a given transcript. Alternative open reading frames for individual transcripts give proteins originate from the 5′- and 3′-UTR mRNA regions, frameshifts of mRNA ORFs or from non-coding RNAs. Longtime considered as non-coding, recent in-silico translation prediction methods enriched the protein databases allowing the identification of new target structures that have not been identified previously. To gain insight into the role of these newly identified alternative proteins in the regulation of cellular functions, it is crucial to assess their dynamic modulation within a framework of altered physiological modifications such as experimental spinal cord injury (SCI). Here, we carried out a longitudinal proteomic study on rat SCI from 12 h to 10 days. Based on the alternative protein predictions, it was possible to identify a plethora of newly predicted protein hits. Among these proteins, some presented a special interest due to high homology with variable chain regions of immunoglobulins. We focus our interest on the one related to Kappa variable light chains which is similarly highly produced by B cells in the Bence jones disease, but here expressed in astrocytes. This protein, name Heimdall is an Intrinsically disordered protein which is secreted under inflammatory conditions. Immunoprecipitation experiments showed that the Heimdall interactome contained proteins related to astrocyte fate keepers such as “NOTCH1, EPHA3, IPO13” as well as membrane receptor protein including “CHRNA9; TGFBR, EPHB6, and TRAM”. However, when Heimdall protein was neutralized utilizing a specific antibody or its gene knocked out by CRISPR-Cas9, sprouting elongations were observed in the corresponding astrocytes. Interestingly, depolarization assays and intracellular calcium measurements in Heimdall KO, established a depolarization effect on astrocyte membranes KO cells were more likely that the one found in neuroprogenitors. Proteomic analyses performed under injury conditions or under lipopolysaccharides (LPS) stimulation, revealed the expression of neuronal factors, stem cell proteins, proliferation, and neurogenesis of astrocyte convertor factors such as EPHA4, NOTCH2, SLIT3, SEMA3F, suggesting a role of Heimdall could regulate astrocytic fate. Taken together, Heimdall could be a novel member of the gatekeeping astrocyte-to-neuroprogenitor conversion factors.

Plasticity of colonic enteric nervous system following spinal cord injury in male and female rats.

Neurogenic bowel is a dysmotility disorder following spinal cord injury (SCI) that negatively impacts quality of life, social integration, and physical health. Colonic transit is directly modulated by the enteric nervous system. Interstitial Cells of Cajal (ICC) distributed throughout the small intestine and colon serve as specialized pacemaker cells, generating rhythmic electrical slow waves within intestinal smooth muscle, or serve as an interface between smooth muscle cells and enteric motor neurons of the myenteric plexus. Interstitial Cells of Cajal loss has been reported for other preclinical models of dysmotility, and our previous experimental SCI study provided evidence of reduced excitatory and inhibitory enteric neuronal count and smooth muscle neural control. Immunohistochemistry for the ICC-specific marker c-Kit was utilized to examine neuromuscular remodeling of the distal colon in male and female rats with experimental SCI. Myenteric plexus ICC (ICC-MP) exhibited increased cell counts 3 days following SCI in male rats, but did not significantly increase in females until 3 weeks after SCI. On average, ICC-MP total primary arborization length increased significantly in male rats at 3-day, 3-week, and 6-week time points, whereas in females, this increase occurred most frequently at 6 weeks post-SCI. Conversely, circular muscle ICC (ICC-CM) did not demonstrate post-SCI changes. These data demonstrate resiliency of the ICC-MP in neurogenic bowel following SCI, unlike seen in other related disease states. This plasticity underscores the need to further understand neuromuscular changes driving colonic dysmotility after SCI in order to advance therapeutic targets for neurogenic bowel treatment.

Effects of Acute Ethanol Intoxication on Spinal Cord Injury Outcomes in Female Mice.

Abstract Approximately one in three traumatic spinal cord injuries (SCIs) occurs during or shortly after the consumption of alcohol. A small number of retrospective clinical studies report variable effects of alcohol intoxication on mortality, neurological recovery, and complications after SCI. Some of these studies demonstrate a protective effect of alcohol intoxication on SCI outcomes, whereas others show an increased complication risk. Pre-clinical studies in rat, ferret, and feline SCI models report a detrimental effect of ethanol intoxication on hemorrhage, motor recovery, and biochemical markers of tissue injury. However, no studies to date have investigated the neuropathological consequences of ethanol intoxication at the time of SCI or the reciprocal effect of SCI on ethanol metabolism. Therefore, we combined a pre-clinical mouse model of acute ethanol intoxication and experimental vertebral level T9 contusion SCI to investigate their interactive effects in female mice. We first investigated the effect of SCI on ethanol metabolism and found that T9 SCI does not alter ethanol metabolism. However, we did find that isoflurane anesthesia significantly slowed ethanol metabolism independent of SCI. We also determined how acute ethanol intoxication at the time of SCI alters locomotor recovery and lesion pathology. Using the Basso Mouse Scale (BMS) and CatWalk XT Gait Analysis System, we assessed locomotor recovery for 6 weeks after injury and observed that acute ethanol intoxication at the time of injury did not alter locomotor recovery. We also found no effect of ethanol intoxication on heat hyperalgesia development. There was, however, a detrimental effect of ethanol on tissue sparing after SCI. Therefore, we conclude that acute alcohol intoxication at the time of injury may contribute to the neuropathological consequences of SCI.

FGF23 alleviates neuronal apoptosis and inflammation, and promotes locomotion recovery via activation of PI3K/AKT signalling in spinal cord injury.

Fibroblast growth factor 23 (FGF23) regulates neuronal morphology, synaptic growth and inflammation; however, its involvement in spinal cord injury (SCI) remains unclear. Therefore, the present study aimed to investigate the effect of FGF23 on neuronal apoptosis, inflammation and locomotion recovery, as well as its underlying mechanism in experimental SCI models. Primary rat neurons were stimulated with H2O2 to establish an in vitro model of SCI and were then transfected with an FGF23 overexpression (oeFGF23) or short hairpin RNA (shFGF23) adenovirus-associated virus and treated with or without LY294002 (a PI3K/AKT inhibitor). Subsequently, an SCI rat model was constructed, followed by treatment with oeFGF23, LY294002 or a combination of the two. FGF23 overexpression (oeFGF23 vs. oeNC) decreased the cell apoptotic rate and cleaved-caspase3 expression, but increased Bcl-2 expression in H2O2-stimulated neurons, whereas shFGF23 transfection (shFGF23 vs. shNC) exhibited the opposite effect (all P<0.05). Furthermore, FGF23 overexpression (oeFGF23 vs. oeNC) could activate the PI3K/AKT signalling pathway, whereas treatment with the PI3K/AKT inhibitor (LY294002) (oeFGF23 + LY294002 vs. LY294002) attenuated these effects in H2O2-stimulated neurons (all P<0.05). In SCI model rats, FGF23 overexpression (oeFGF23 vs. oeNC) reduced the laceration and inflammatory cell infiltration in injured tissue, decreased TNF-α and IL-1β levels, and improved locomotion recovery (all P<0.05); these effects were attenuated by additional administration of LY294002 (oeFGF23 + LY294002 vs. LY294002) (all P<0.05). In conclusion, FGF23 alleviated neuronal apoptosis and inflammation, and promoted locomotion recovery via activation of the PI3K/AKT signalling pathway in SCI, indicating its potential as a treatment option for SCI; however, further studies are warranted for validation.

Human Adipose-Derived Stem Cells Reduce Cellular Damage after Experimental Spinal Cord Injury in Rats.

Traumatic spinal cord injury (SCI) is a devastating condition without an effective therapy. Cellular therapies are among the promising treatment strategies. Adult stem cells, such as mesenchymal stem cells, are often used clinical research for their immunomodulatory and regenerative potential. This study aimed to evaluate the effect of human adipose tissue-derived stem cells (ADSC) infusion through the cauda equina in rats with SCI. The human ADSC from bariatric surgery was isolated, expanded, and characterized. Wistar rats were subjected to blunt SCI and were divided into four groups. Two experimental groups (EG): EG1 received one ADSC infusion after SCI, and EG2 received two infusions, the first one after SCI and the second infusion seven days after the injury. Control groups (CG1 and CG2) received infusion with a culture medium. In vivo, cell tracking was performed 48 h and seven days after ADSC infusion. The animals were followed up for 40 days after SCI, and immunohistochemical quantification of myelin, neurons, and astrocytes was performed. Cellular tracking showed cell migration towards the injury site. ADSC infusion significantly reduced neuronal loss, although it did not prevent the myelin loss or enhance the area occupied by astrocytes compared to the control group. The results were similar when comparing one or two cell infusions. The injection of ADSC distal to the injured area was shown to be a safe and effective method for cellular administration in spinal cord injury.

Experimental high-thoracic spinal cord injury reduces splanchnic sympathetic nerve activity and is associated with persistent hypotension

Objective: High-thoracic spinal cord injury (SCI) is associated with blood pressure (BP) dysregulation that consists of persistent hypotension, orthostatic intolerance and autonomic dysreflexia. Whilst several mechanisms have been suggested to underlie blood pressure dysregulation post-SCI, the most common inference made is that the sub-lesional sympathetic circuitry is hypoactive due to a loss of medullary input to the sympathetic preganglionic neurons. Yet, a remarkable paucity of data exists from electrophysiological studies that have assessed sympathetic nerve activity (SNA) in the setting of SCI. Aim: Assess the changes in SNA and resting BP in rats with and without high-thoracic SCI. Methods: 24 male Wistar rats (10wks old) were randomized and counterbalanced to receive a severe contusion SCI at the T3 spinal level (n=12) or remain as naïve controls (CON). Two weeks post-SCI, rats underwent our neurovascular terminal preparation. Animals were ventilated, anesthetized with inhalant isoflurane, and underwent catheterization of the left-femoral artery (BP), as well as the right femoral artery and vein for arterial blood gas sampling and i.v. fluid/drugs, respectively. Rats were then transitioned to urethane anesthesia (~2.1g.kg-1 i.v). Next, the splanchnic nerve was isolated from a retroperitoneal approach, cut, and the proximal end was recorded using a suction electrode for the measurement of splanchnic sympathetic nerve activity (sSNA). Following 30 minutes of hemodynamic stabilization, SNA and cardiovascular hemodynamics were sampled for 10 minutes, from which a 1 min recording was selected for analyses. Animals were subsequently administered a hexamethonium bolus (30 mg.kg-1) to block ganglionic transmission and the euthanized with chloral hydrate. Results: SCI animals exhibited lower systolic, diastolic and mean arterial BP (all p&lt;0.007), but heart rate was not different between groups. SCI animals also exhibited lower total sSNA (1.9 ± 0.7 vs. 3.2 ± 1.9 mv.s-1, p=0.038) as well reduced burst height (2.2 ± 1.5 vs. 3.7 ± 0.8 v.s-1, p=0.033), but the number of sSNA spikes.s-1 was higher in SCI vs. CON (182 ± 65 vs. 155 ± 33, p=0.043). Blood gases were stable and similar between groups. Conclusions: Our findings show that persistent hypotension in SCI animals is associated with lower total sub-lesional sSNA. While SCI resulted in more spontaneous sSNA spikes, these spikes fail to coordinate into equally-sized sSNA bursts. International Spinal Research Trust and Natural Sciences and Engineering Research Council of Canada (NSERC). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Clinical Evaluation of the Effect of Methylprednisolone Sodium Succinate and Meloxicam in Experimental Acute Spinal Cord Injury

Background: Central nervous system (CNS) has limited repair capacity, and any spinal cord injury (SCI) can cause persistent disability in motor, sensory, and autonomic functions. The harmful reactions around the lesion must be stopped to prevent this consequence. Objectives: The present study compares the clinical effects of methylprednisolone sodium succinate (MPSS) and meloxicam in acute spinal cord injury in an animal model of rats. Methods: We randomly divided 24 male Wistar rats into 4 groups: 1) sham, 2) placebo, 3) SCI+MPSS (30 mg/kg, IV), and 4) SCI+meloxicam (1 mg/kg, SC). We used a Fogarty embolectomy catheter to induce a compression injury to the rats’ T8-T9 spinal cord segment. The drugs were injected one hour after surgery. Neurological evaluation was performed using BBB (Basso, Beattie, and Bresnahan) test immediately after recovery and then once a week for up to 6 weeks. Results: According to the BBB test results, single-dose administration of MPSS one hour after injury improved motor function significantly compared to placebo. But, there was no significant difference between MPSS and meloxicam groups and between meloxicam and placebo groups (P&gt;0.01). Conclusion: In clinical evaluation, single-dose administration of MPSS one hour after injury improved motor function compared to meloxicam.