Dorsal column sensory axons degenerate due to impaired microvascular perfusion after spinal cord injury in rats

Applications of Stem Cell-Derived Extracellular Vesicles in Nerve Regeneration

Extracellular vesicles (EVs), including exosomes, microvesicles, and other lipid vesicles derived from cells, play a pivotal role in intercellular communication by transferring information between cells. EVs secreted by progenitor and stem cells have been associated with the therapeutic effects observed in cell-based therapies, and they also contribute to tissue regeneration following injury, such as in orthopaedic surgery cases. This review explores the involvement of EVs in nerve regeneration, their potential as drug carriers, and their significance in stem cell research and cell-free therapies. It underscores the importance of bioengineers comprehending and manipulating EV activity to optimize the efficacy of tissue engineering and regenerative therapies.

Emerging trends in the blood spinal-cord barrier: A bibliometric analysis

BACKGROUND

The blood-spinal cord barrier (BSCB) is a unique protective barrier located between the circulatory system and the central nervous system. BSCB plays a vital role in various diseases. However, there is little systematic research and recording in this field by bibliometrics analysis. We aim to visualize this field through bibliometrics to analyze the hotspots and trends of BSCB and in order to facilitate an understanding of future developments in basic and clinical research.

METHODS

To conduct a bibliometric study of original publications and their references, the keywords Blood Spinal-Cord Barrier and BSCB are searched and filtered from the Web of Science database (2000-2022), focusing on citations, authors, journals, and countries/regions. Additionally, clustering of the references and co-citation analysis was completed, including a total of 1926 articles and comments.

RESULTS

From the results, 193 authors were identified, among which Sharma Hs played a key role. As far as the analysis result of the clustering of the references is concerned, the most common type in cluster analysis is spinal cord injury (SCI) which is a current and developing research field. The keywords are also the specific content under these clusters. The most influential organization is Univ Calif San Francisco, and "Proceedings of The National Academy of Sciences of The United States of America" magazine is the most cited magazine.

CONCLUSION SUBSECTIONS

The research on BSCB is booming focusing mainly on "BSCB in SCI" including "activation," "pathway," and "drug delivery" which is also the trend of future research.

Neuron-Derived Exosomes Promote the Recovery of Spinal Cord Injury by Modulating Nerve Cells in the Cellular Microenvironment of the Lesion Area

During spinal cord injury (SCI), the homeostasis of the cellular microenvironment in the injured area is seriously disrupted, which makes it extremely difficult for injured neurons with regenerative ability to repair, emphasizing the importance of restoring the cellular microenvironment at the injury site. Neurons interact closely with other nerve cells in the central nervous system (CNS) and regulate these cells. However, the specific mechanisms by which neurons modulate the cellular microenvironment remain unclear. Exosomes were isolated from the primary neurons, and their effects on astrocytes, microglia, oligodendrocyte progenitor cells (OPCs), neurons, and neural stem cells were investigated by quantifying the expression of related proteins and mRNA. A mouse SCI model was established, and neuron-derived exosomes were injected into the mice by the caudal vein to observe the recovery of motor function in mice and the changes in the nerve cells in the lesion area. Neuron-derived exosomes could reverse the activation of microglia and astrocytes and promote the maturation of OPCs in vivo and in vitro. In addition, neuron-derived exosomes promoted neurite outgrowth of neurons and the differentiation of neural stem cells into neurons. Moreover, our experiments showed that neuron-derived exosomes enhanced motor function recovery and nerve regeneration in mice with SCI. Our findings highlight that neuron-derived exosomes could promote the repair of the injured spinal cord by regulating the cellular microenvironment of neurons and could be a promising treatment for spinal cord injury.

Surgical Decompression of Traumatic Cervical Spinal Cord Injury: A Pilot Study Comparing Real-Time Intraoperative Ultrasound After Laminectomy With Postoperative MRI and CT Myelography

BACKGROUND

Decompression of the injured spinal cord confers neuroprotection. Compared with timing of surgery, verification of surgical decompression is understudied.

OBJECTIVE

To compare the judgment of cervical spinal cord decompression using real-time intraoperative ultrasound (IOUS) following laminectomy with postoperative MRI and CT myelography.

METHODS

Fifty-one patients were retrospectively reviewed. Completeness of decompression was evaluated by real-time IOUS and compared with postoperative MRI (47 cases) and CT myelography (4 cases).

RESULTS

Five cases (9.8%) underwent additional laminectomy after initial IOUS evaluation to yield a final judgment of adequate decompression using IOUS in all 51 cases (100%). Postoperative MRI/CT myelography showed adequate decompression in 43 cases (84.31%). Six cases had insufficient bony decompression, of which 3 (50%) had cerebrospinal fluid effacement at >1 level. Two cases had severe circumferential intradural swelling despite adequate bony decompression. Between groups with and without adequate decompression on postoperative MRI/CT myelography, there were significant differences for American Spinal Injury Association motor score, American Spinal Injury Association Impairment Scale grade, AO Spine injury morphology, and intramedullary lesion length (IMLL). Multivariate analysis using stepwise variable selection and logistic regression showed that preoperative IMLL was the most significant predictor of inadequate decompression on postoperative imaging (P = .024).

CONCLUSION

Patients with severe clinical injury and large IMLL were more likely to have inadequate decompression on postoperative MRI/CT myelography. IOUS can serve as a supplement to postoperative MRI/CT myelography for the assessment of spinal cord decompression. However, further investigation, additional surgeon experience, and anticipation of prolonged swelling after surgery are required.

Effects of fluids vs. vasopressors on spinal cord microperfusion in hemorrhagic shock induced ischemia/reperfusion

OBJECTIVE

Spinal cord injury induced by ischemia/reperfusion is a devastating complication of aortic repair. Despite developments for prevention and treatment of spinal cord injury, incidence is still considerably high majorly impacting patient outcome. Microcirculation is paramount for tissue perfusion and oxygen supply and often dissociated from macrohemodynamic parameters used to guide resuscitation. Effects of fluids vs. vasopressors in the setting of hemodynamic resuscitation on spinal cord microperfusion are unknown. Aim of this study was to compare the effects of vasopressor and fluid resuscitation on spinal cord microperfusion in a translational acute pig model of hemorrhagic shock induced ischemia/reperfusion injury.

METHODS

We designed this study as prospective randomized explorative large animal study. We induced hemorrhagic shock in 20 pigs as a model of global ischemia/reperfusion injury. We randomized animals to receive either fluid or vasopressor resuscitation. We measured spinal cord microperfusion using fluorescent microspheres as well as laser-Doppler probes. We monitored and analyzed macrohemodynamic parameters and cerebrospinal fluid pressure.

RESULTS

Spinal cord microperfusion decreased following hemorrhagic shock induced ischemia/reperfusion injury. Both fluids and vasopressors sufficiently restored spinal cord microperfusion. There were no important changes between groups (percentage changes compared to baseline: fluids 14.0 (0.31-27.6) vs. vasopressors 24.3 (8.12-40.4), p = .340). However, cerebrospinal fluid pressure was higher in animals receiving fluid resuscitation (percentage changes compared to baseline: fluids 27.7 (12.6-42.8) vs. vasopressors -5.56 ((-19.8)-8.72), p = .003). Microcirculatory resuscitation was in line with improvements of macrohemodynamic parameters.

CONCLUSIONS

Both, fluids and vasopressors, equally restored spinal cord microperfusion in a porcine acute model of hemorrhagic shock induced ischemia/reperfusion injury. However, significant differences in cerebrospinal fluid pressure following resuscitation were present. Future studies should evaluate these effects in perfusion disruption induced ischemia/reperfusion conditions of microcirculatory deterioration.

Mitochondrial function in spinal cord injury and regeneration

Many people around the world suffer from some form of paralysis caused by spinal cord injury (SCI), which has an impact on quality and life expectancy. The spinal cord is part of the central nervous system (CNS), which in mammals is unable to regenerate, and to date, there is a lack of full functional recovery therapies for SCI. These injuries start with a rapid and mechanical insult, followed by a secondary phase leading progressively to greater damage. This secondary phase can be potentially modifiable through targeted therapies. The growing literature, derived from mammalian and regenerative model studies, supports a leading role for mitochondria in every cellular response after SCI: mitochondrial dysfunction is the common event of different triggers leading to cell death, cellular metabolism regulates the immune response, mitochondrial number and localization correlate with axon regenerative capacity, while mitochondrial abundance and substrate utilization regulate neural stem progenitor cells self-renewal and differentiation. Herein, we present a comprehensive review of the cellular responses during the secondary phase of SCI, the mitochondrial contribution to each of them, as well as evidence of mitochondrial involvement in spinal cord regeneration, suggesting that a more in-depth study of mitochondrial function and regulation is needed to identify potential targets for SCI therapeutic intervention.

Clemastine Enhances Myelination, Delays Axonal Loss and Promotes Functional Recovery in Spinal Cord Injury

Recent evidence has shown that demyelination occurs along with axonal degeneration in spinal cord injury (SCI) during the secondary injury phase. Oligodendrocyte precursor cells (OPC) are present in the lesions but fail to differentiate into mature oligodendrocytes and form new myelin. Given the limited recovery of neuronal functions after SCI in adults without effective treatment available so far, it remains unknown whether enhancing OPC differentiation and myelination could benefit the recovery of SCI. To show the significance of myelin regeneration after SCI, the injury was treated with clemastine in the rat model. Clemastine is an FDA-approved drug that is potent in promoting oligodendrocyte differentiation and myelination in vivo, for four weeks following SCI. Motor function was assessed using sloping boards and grid walking tests and scored according to the Basso, Beattie, and Bresnahan protocol. The myelin integrity and protein expression were evaluated using transmission electron microscopy and immunofluorescence, respectively. The results indicated that clemastine treatment preserves myelin integrity, decreases loss of axons and improves functional recovery in the rat SCI model. The presented data suggest that myelination-enhancing strategies may serve as a potential therapeutic approach for the functional recovery in SCI.

M2 Macrophages Promote PDGFRβ+ Pericytes Migration After Spinal Cord Injury in Mice via PDGFB/PDGFRβ Pathway

Platelet derived growth factor receptor β positive (PDGFRβ⁺) pericytes form fibrotic scar, which prevents axonal regeneration after spinal cord injury (SCI). However, the mechanism by which PDGFRβ⁺ pericytes migrate to the injury core is unclear. Here, we investigated the effect and mechanism of macrophages polarization on PDGFRβ⁺ pericytes migration after SCI. Macrophages were closely related to the spatiotemporal distribution of PDGFRβ⁺ pericytes in the injury core at 3, 7, and 14 days postinjury (dpi). Macrophages appeared M2 polarization at 3 and 7 dpi while M1 polarization at 14 dpi. The expression of platelet derived growth factor B (PDGFB) was significantly increased after SCI and after macrophages M2 polarization. The promoting effect of exogenous PDGFB and M2 macrophages conditioned medium on PDGFRβ⁺ pericytes migration could be blocked by SU16f, a PDGFRβ specific inhibitor. These findings indicate that M2 macrophages can secrete PDGFB acting on PDGFRβ to promote PDGFRβ⁺ pericytes migration, which can be blocked by a PDGFRβ specific inhibitor SU16f. The PDGFB/PDGFRβ pathway is a promising new target for the treatment of SCI.

Microtubule Stabilization Promotes Microcirculation Reconstruction After Spinal Cord Injury

Spinal cord microcirculation plays an important role in maintaining the function of spinal cord neurons and other cells. Previous studies have largely focused on the ability of microtubule stabilization to inhibit the fibroblast migration and promote axon regeneration after spinal cord injury (SCI). However, the effect of microtubule stabilization treatment on microcirculation reconstruction after SCI remains unclear. By using immunofluorescence, we found that microtubule stabilization treatment improved microcirculation reconstruction via increasing the number of microvessels, pericytes, and the perfused microvessels after SCI. To clarify the underlying mechanisms, rat brain microvascular endothelial cells and pericytes were subjected to glucose oxygen deprivation. By using flow cytometry and western blotting, we found that microtubule stabilization treatment inhibited apoptosis and migration of endothelial cells and pericytes but promoted proliferation and survival of endothelial cells and pericytes through upregulated expression of vascular endothelial growth factor A (VEGFA), VEGF receptor 2, platelet-derived growth factor-B (PDGFB), PDGF receptor β, and angiopoietin-1 after SCI. Taken together, this study provides evidence for the mechanisms underlying the promotion of microcirculation reconstruction after SCI by microtubule stabilization treatment. Importantly, this study suggests the potential of microtubule stabilization as a therapeutic target to reduce microcirculation dysfunction after SCI in the clinic.

Retracted Article: Melatonin protects spinal cord injury by up-regulating IGFBP3 through the improvement of microcirculation in a rat model

The present study was aimed at the investigation of the effects of melatonin on spinal cord injury (SCI) and the role of IGFBP3 in SCI both in vivo and in vitro. The rats received treatment with 100 mg kg-1 melatonin or both melatonin and pGenesil-1-si-IGFBP3 (50 µg per g bw) after SCI surgery. The motor function in rats was measured using the Basso-Beattie-Bresnahan (BBB) scale score; perfusion vessel area was determined by injecting FITC-conjugated lycopersicon esculentum agglutinin lectin (FITC-LEA), whereas the blood-spinal cord barrier permeability was measured using Evans blue. The pericytes were isolated, and the cells were cultured under hypoxia, treated with melatonin or transfected with si-IGFBP3. RT-qPCR and western blotting were conducted for the determination of IGFBP3, VEGF, MMP-2, ICAM-1 and Ang1. The expression of IGFBP3 was significantly down-regulated in the SCI rats, and melatonin significantly enhanced the IGFBP3 level. Melatonin improved the motor function, reduced the neuron injury, and improved the microcirculation in rats. However, the down-regulation of IGFBP3 significantly reversed these effects. Moreover, in both the SCI rat spinal cord tissues and the in vitro pericytes under hypoxia, the expressions of IGFBP3 and Ang1 were significantly down-regulated, whereas those of the proteins MMP-2, VEGF and ICAM-1 were significantly up-regulated, and melatonin dramatically inhibited these changes. Melatonin could protect the rats from SCI by improving the microcirculation through the up-regulation of IGFBP3.

Axonal degeneration and demyelination following traumatic spinal cord injury: A systematic review and meta-analysis

The pathophysiology of spinal cord injury (SCI) related processes of axonal degeneration and demyelination are poorly understood. The present systematic review and meta-analysis were performed such to establish quantitative results of animal studies regarding the role of injury severity, SCI models and level of injury on the pathophysiology of axon and myelin sheath degeneration. 39 related articles were included in the analysis. The compiled data showed that the total number of axons, number of myelinated axons, myelin sheath thickness, axonal conduction velocity, and internode length steadily decreased as time elapsed from the injury (P_{for trend}<0.0001). The rate of axonal retrograde degeneration was affected by SCI model and severity of the injury. Axonal degeneration was higher in injuries of the thoracic region. The SCI model and the site of the injury also affected axonal retrograde degeneration. The number of myelinated axons in the caudal region of the injury was significantly higher than the lesion site and the rostral region. The findings of the present meta-analysis show that the pathophysiology of axons and myelin sheath differ in various phases of SCI and are affected by multiple factors related to the injury.

The Biology of Regeneration Failure and Success After Spinal Cord Injury

Since no approved therapies to restore mobility and sensation following spinal cord injury (SCI) currently exist, a better understanding of the cellular and molecular mechanisms following SCI that compromise regeneration or neuroplasticity is needed to develop new strategies to promote axonal regrowth and restore function. Physical trauma to the spinal cord results in vascular disruption that, in turn, causes blood-spinal cord barrier rupture leading to hemorrhage and ischemia, followed by rampant local cell death. As subsequent edema and inflammation occur, neuronal and glial necrosis and apoptosis spread well beyond the initial site of impact, ultimately resolving into a cavity surrounded by glial/fibrotic scarring. The glial scar, which stabilizes the spread of secondary injury, also acts as a chronic, physical, and chemo-entrapping barrier that prevents axonal regeneration. Understanding the formative events in glial scarring helps guide strategies towards the development of potential therapies to enhance axon regeneration and functional recovery at both acute and chronic stages following SCI. This review will also discuss the perineuronal net and how chondroitin sulfate proteoglycans (CSPGs) deposited in both the glial scar and net impede axonal outgrowth at the level of the growth cone. We will end the review with a summary of current CSPG-targeting strategies that help to foster axonal regeneration, neuroplasticity/sprouting, and functional recovery following SCI.

Ethyl pyruvate modulates delayed paralysis following thoracic aortic ischemia reperfusion in mice

OBJECTIVE

Delayed paralysis is an unpredictable problem for patients undergoing complex repair of the thoracic/thoracoabdominal aorta. These experiments were designed to determine whether ethyl pyruvate (EP), a potent anti-inflammatory and antioxidant agent, might ameliorate delayed paralysis following thoracic aortic ischemia reperfusion (TAR).

METHODS

C57BL6 mice were subjected to 5 minutes of thoracic aortic ischemia followed by reperfusion for up to 48 hours. Mice received either 300 mg/kg EP or lactated ringers (LR) at 30 minutes before ischemia and 3 hours after reperfusion. Neurologic function was assessed using an established rodent scale. Spinal cord tissue was analyzed for markers of inflammation (keratinocyte chemoattractant [KC], interleukin-6 [IL-6]), microglial activation (ionized calcium-binding adapter molecule-1 [Iba-1]), and apoptosis (Bcl-2, Bax, and terminal deoxynucleotidyl transferase dUTP nick end labeling [TUNEL] staining) at 24 and 48 hours after TAR. Nissl body stained motor neurons were counted in the anterior horns sections from L1-L5 segments.

RESULTS

Ninety-three percent of the LR mice developed dense delayed paralysis between 40 and 48 hours after TAR, whereas only 39% of EP mice developed delayed paralysis (P < .01). Bcl-2 expression was higher (P < .05) and Iba-1 expression was lower (P < .05) in the EP group only at 24 hours reperfusion. At 48 hours, the number of motor neurons was higher (P < .01) and the number and TUNEL-positive cells was lower (P < .001) in the EP-treated mice. EP decreased the expression of KC (P < .01) and IL-6 (P < .001) at 48 hours after TAR.

CONCLUSIONS

The protection provided by EP against delayed paralysis correlated with preservation of motor neurons, higher expression of antiapoptotic molecules, decreased microglial cell activation, and decreased spinal cord inflammation. EP may be a treatment for humans at risk for delayed paralysis.

Reduced FAK-STAT3 signaling contributes to ER stress-induced mitochondrial dysfunction and death in endothelial cells

Excessive endoplasmic reticulum (ER) stress leads to cell loss in many diseases, e.g., contributing to endothelial cell loss after spinal cord injury. Here, we determined whether ER stress-induced mitochondrial dysfunction could be explained by interruption of the focal adhesion kinase (FAK)-mitochondrial STAT3 pathway we recently discovered. ER stress was induced in brain-derived mouse bEnd5 endothelial cells by thapsigargin or tunicamycin and caused apoptotic cell death over a 72h period. In concert, ER stress caused mitochondrial dysfunction as shown by reduced bioenergetic function, loss of mitochondrial membrane potential and increased mitophagy. ER stress caused a reduction in mitochondrial phosphorylated S727-STAT3, known to be important for maintaining mitochondrial function. Normal activation or phosphorylation of the upstream cytoplasmic FAK was also reduced, through mechanisms that involve tyrosine phosphatases and calcium signaling, as shown by pharmacological inhibitors, bisperoxovanadium (bpV) and 2-aminoethoxydiphenylborane (APB), respectively. APB mitigated the reduction in FAK and STAT3 phosphorylation, and improved endothelial cell survival caused by ER stress. Transfection of cells rendered null for STAT3 using CRISPR technology with STAT3 mutants confirmed the specific involvement of S727-STAT3 inhibition in ER stress-mediated cell loss. These data suggest that loss of FAK signaling during ER stress causes mitochondrial dysfunction by reducing the protective effects of mitochondrial STAT3, leading to endothelial cell death. We propose that stimulation of the FAK-STAT3 pathway is a novel therapeutic approach against pathological ER stress.

Melatonin prevents blood vessel loss and neurological impairment induced by spinal cord injury in rats

BACKGROUND

Melatonin can be neuroprotective in models of neurological injury, but its effects on blood vessel loss and neurological impairment following spinal cord injury (SCI) are unclear. Our goal herein was to evaluate the possible protective action of melatonin on the above SCI-induced damage in rats.

MATERIALS AND METHODS

Sixty-three female Sprague-Dawley rats were randomly divided into three equal groups: sham, SCI and melatonin groups. Melatonin (10 mg/kg) was injected intraperitoneally and further administered twice a day at indicated time after a moderate injury at T10 in melatonin group. Blood vessel was assessed by CD31staining and FITC-LEA, the permeability of blood-spinal cord barrier (BSCB) was detected by Evan's Blue. Neuron was assessed by NeuN staining and the expression of Nissl bodies in the neurons was assessed by Nissl staining. The expressions of brain-derived neurotrophic factor (BDNF), synapsin I, or growth associated protein-43 (GAP-43) in the spinal cord and hippocampus were evaluated by Western blotting.

RESULTS

At 7 days post-injury, melatonin treatment rescued blood vessels, increased CD31 levels, ameliorated BSCB permeability. Additionally, melatonin significantly increased the number of neurons and the expression of Nissl bodies in neurons at the injury epicenter. Furthermore, our data showed that SCI reduced levels of the molecular substrates of neurological plasticity, including BDNF, synapsin I, or GAP-43 in the spinal cord and hippocampus. Melatonin treatment partially prevented these reductions.

CONCLUSION

The neuroprotective effect of melatonin was associated with melioration of the microcirculation in the spinal cord and reduction of neurological impairment in the spinal cord and brain.

Does being female provide a neuroprotective advantage following spinal cord injury?

It has been controversial whether gender has any effect on recovery following spinal cord injury (SCI). Past experimental and clinical research aimed at addressing this subject has led to constrasting findings on whether females hold any advantage in locomotor recovery. Additionally, for studies supporting the notion of a female gender related advantage, a definite cause has not been explained. In a recent study, using large sample sizes for comparative male and female spinal cord injury cohorts, we reported that a significant gender advantage favoring females existed in both tissue preservation and functional recovery after taking into consideration discrepancies in age and weight of the animals across sexes. Prior animal research frequently used sample sizes that were too small to determine significance with certainty and also did not account for two other factors that influence locomotor performance: age and weight. Our finding is important in light of controversy surrounding the effect of gender on outcome and the fact that SCI affects more than ten thousand new individuals annually, a population that is disproportionately male. By deepening our understanding of why a gender advantage exists, potential new therapeutics can be designed to improve recovery for the male population following the initial trauma or putatively augment the neuroprotective privilege in females for enhanced outcomes.

Intrathecal Acetyl-L-Carnitine Protects Tissue and Improves Function after a Mild Contusive Spinal Cord Injury in Rats

Primary and secondary ischemia after spinal cord injury (SCI) contributes to tissue and axon degeneration, which may result from decreased energy substrate availability for cellular and axonal mitochondrial adenosine triphosphate (ATP) production. Therefore, providing spinal tissue with an alternative energy substrate during ischemia may be neuroprotective after SCI. To assess this, rats received a mild contusive SCI (120 kdyn, Infinite Horizons impactor) at thoracic level 9 (T9), which causes loss of ∼ 80% of the ascending sensory dorsal column axonal projections to the gracile nucleus. Immediately afterwards, the energy substrate acetyl-L-carnitine (ALC; 1 mg/day) or phosphate-buffered saline (PBS) was infused intrathecally (sub-arachnoid) for 6 days via an L5/6 catheter attached to a subcutaneous Alzet pump. ALC treatment improved overground locomotor function (Basso-Beattie-Breshnahan [BBB] score 18 vs. 13) at 6 days, total spared epicenter (71% vs. 57%) and penumbra white matter (90% vs. 85%), ventral penumbra microvessels (108% vs. 79%), and penumbra motor neurons (42% vs. 15%) at 15 days post-SCI, compared with PBS treatment. However, the ascending sensory projections (anterogradely traced with cholera toxin B from the sciatic nerves) and dorsal column white matter and perfused blood vessels were not protected. Furthermore, grid walking, a task we have shown to be dependent on dorsal column function, was not improved. Thus, mitochondrial substrate replacement may only be efficacious in areas of lesser or temporary ischemia, such as the ventral spinal cord and injury penumbra in this study. The current data also support our previous evidence that microvessel loss is central to secondary tissue degeneration.

Recent advances in the pharmacologic treatment of spinal cord injury

A need exists for the effective treatment of individuals suffering from spinal cord injury (SCI). Recent advances in the understanding of the pathophysiological mechanisms occurring in SCI have resulted in an expansion of new therapeutic targets. This review summarizes both preclinical and clinical findings investigating the mechanisms and cognate pharmacologic therapeutics targeted to modulate hypoxia, ischemia, excitotoxicity, inflammation, apoptosis, epigenetic alterations, myelin regeneration and scar remodeling. Successful modulation of these targets has been demonstrated in both preclinical and clinical studies with agents such as Oxycyte, Minocycline, Riluzole, Premarin, Cethrin, and ATI-355. The translation of these agents into clinical studies highlights the progress the field has made in the past decade. SCI proves to be a complex condition; the numerous pathophysiological mechanisms occurring at varying time points suggests that a single agent approach to the treatment of SCI may not be optimal. As the field continues to mature, the hope is that the knowledge gained from these studies will be applied to the development of an effective multi-pronged treatment strategy for SCI.

Beneficial effects of thymosin β4 on spinal cord injury in the rat

Thymosin β4 (Tβ4) has many physiological functions that are highly relevant to spinal cord injury (SCI), including neuronal survival, anti-inflammation, wound repair promotion, and angiogenesis. The present study investigated the therapeutic value of Tβ4 in SCI, with a focus on its neuroprotective, anti-inflammatory, and vasculoprotective properties. Tβ4 or a saline control was administered by intraperitoneal injection 30 min, 3 days, or 5 days after SCI with mild compression in rat. Locomotor recovery was tested with the Basso-Beattie-Bresnahan scale and a footprint analysis. All behavioral assessments were markedly improved with Tβ4 treatment. Histological examination at 7 days post injury showed that the numbers of surviving neurons and oligodendrocytes were significantly increased in Tβ4-treated animals compared to saline-treated controls. Levels of myelin basic protein, a marker of mature oligodendrocytes, in Tβ4-treated rats were 57.8% greater than those in saline-treated controls. The expression of ED1, a marker of activated microglia/macrophages, was reduced by 36.9% in the Tβ4-treated group compared to that of the saline-treated group. Tβ4 treatment after SCI was also associated with a significant decrease in pro-inflammatory cytokine gene expression and a significant increase in the mRNA levels of IL-10 compared to the control. Moreover, the size of lesion cavity delineated by astrocyte scar in the injured spinal cord was markedly reduced in Tβ4-treated animals compared to saline-treated controls. Given the known safety of Tβ4 in clinical trials and its beneficial effects on SCI recovery, the results of this study suggested that Tβ4 is a good candidate for SCI treatment in humans.