Spinal Cord Injury and Related Clinical Trials

mTOR pathway: A potential therapeutic target for spinal cord injury

Spinal cord injury (SCI) is the most common disabling spinal injury, and the complex pathological process can eventually lead to severe neurological dysfunction. Many studies have reported that the mammalian target of rapamycin (mTOR) signaling pathway plays an important role in synaptogenesis, neuron growth, differentiation, and survival after central nervous system injury. It is also involved in various traumatic and central nervous system diseases, including traumatic brain injury, neonatal hypoxic-ischemic brain injury, Alzheimer's disease, Parkinson's disease, and cerebral apoplexy. mTOR has also been reported to play an important regulatory role in various pathophysiological processes following SCI. Activation of mTOR signals after SCI can regulate physiological and pathological processes, such as proliferation and differentiation of neural stem cells, regeneration of nerve axons, neuroinflammation, and glial scar formation, through various pathways. Inhibition of mTOR activity has been confirmed to promote repair in SCI. At present, many studies have reported that Chinese herbal medicine can inhibit the SCI-activated mTOR pathway to improve the microenvironment and promote nerve repair after SCI. Due to the role of the mTOR pathway in SCI, it may be a potential therapeutic target for SCI. This review is focused on the pathophysiological process of SCI, characteristics of the mTOR pathway, role of the mTOR pathway in SCI, role of inhibition of mTOR on SCI, and role and significance of inhibition of mTOR by related Chinese herbal medicine inhibitors in SCI. In addition, the review discusses the deficiencies and solutions to mTOR and SCI research shortcomings. This study hopes to provide reference for mTOR and SCI research and a theoretical basis for SCI biotherapy.

Anti-inflammatory and antioxidant effects of astaxanthin following spinal cord injury in a rat animal model

Spinal cord injury (SCI) is a severely debilitating problem leading to substantial decrease in the quality of life. After spinal cord injury, inflammation and oxidative stress plays a key role in initiating the secondary injury cascades leading to progressive tissue degradation and extreme functional deficits. Given that the primary mechanical injuries to spinal cord are rarely repaired, the pharmacological interventions may improve the neurological outcomes caused by secondary injury. Astaxanthin (AST) is considered as a xanthophyll carotenoid with potent antioxidant and anti-inflammatory properties, which has various pharmacological activities. In the present study, we aimed to firstly assess the protective effect of AST, and then to define the AST mechanism of action on a rat model of SCI. Based on the results of von Frey test, AST treatment significantly alleviated the SCI-induced neuropathic pain compared with the control groups (P < 0.05). The expression analysis by western blot shows reduced expression levels of COX-2, TNF-α, IL-1β, and IL-6 following AST treatment (P < 0.05). The activity of antioxidant enzymes was evaluated using ELISA. Therefore, ELISA experiments showed a significant reduction in the level of oxidative stress in SCI rat following AST treatment (P < 0.05). Furthermore, histopathological evaluations revealed that myelinated white matter and motor neuron number were significantly preserved after treatment with AST (P < 0.05). In conclusion, our study shows that AST could improve SCI through anti-inflammatory and antioxidant effects which leads to decreased tissue damage and mechanical pain after SCI.

Time-to-enrollment in clinical trials investigating neurological recovery in chronic spinal cord injury: observations from a systematic review and ClinicalTrials.gov database

Currently, large numbers of clinical trials are performed to investigate different forms of experimental therapy for patients suffering from chronic spinal cord injury (SCI). However, for the enrollment process, there are different views on how the time period between injury and interventions should be determined. Herein, we sought to evaluate the impact of time-to-enrollment in chronic SCI clinical trials. A data set comprising 957 clinical studies from clinicalTrials.gov was downloaded and analyzed focusing on the eligibility criteria for post-injury time-to-enrollment. We also aggregated individual patient data from nine clinical trials of regenerative interventions for chronic SCI selected by a systematic literature search from 1990 to 2018. Characteristics of the studies were assessed and compared by dividing into three groups based on time-to-enrollment (group 1 ≤ 12 months, group 2 = 12–23 months and group 3 ≥ 24 months). In ClinicalTrials.gov registry, 445 trials were identified for chronic SCI where 87% (385) were unrestricted in the maximum post-injury time for trial eligibility. From systematic literature search, nine studies and 156 patients (group 1 = 30, group 2 = 55 and group 3 = 71) were included. The range of time-to-enrollment was 0.5 to 321 months in those studies. We also observed various degrees of motor and sensory improvement in between three time-to-enrollment groups. Our results indicate that enrolling wide ranges of time-to-enrollment in a group may present imprecise outcomes. Clinical trial designs should consider appropriate post-injury time frames to evaluate therapeutic benefit.

Dexmedetomidine alleviates traumatic spinal cord injury in rats via inhibiting apoptosis induced by endoplasmic reticulum stress

OBJECTIVE

To investigate the protective effect of dexmedetomidine (Dex) on traumatic spinal cord injury (TSCI) and to evaluate the involvement of inhibition of endoplasmic reticulum (ER) stress response in the potential mechanism.

METHOD

Sprague-Dawley rats were randomly divided into five groups. The hind limb locomotor function of rats was evaluated at 1, 3 and 7 days after the operation. At 7 days after the operation, spinal cord specimens were obtained for hematoxylin and eosin (H&E), Nissl and TUNEL staining, as well as immunofluorescence and Western blot analyses to detect the level of apoptosis and the levels of proteins related to ER stress.

RESULTS

7 days after the operation, Dex treatment promoted the recovery and also inhibited apoptosis of neurons in the spinal cord. Additionally, Dexinhibited the expression of proteins related to ER stress response after spinal cord injury.

CONCLUSIONS

Dex improves the neurological function of rats with TSCI and reduces apoptosis of spinal cord neurons. The potential mechanism is related to the inhibition of the ER stress response.

Bioinformatic Analysis of the Proteome in Exosomes Derived From Plasma: Exosomes Involved in Cholesterol Metabolism Process of Patients With Spinal Cord Injury in the Acute Phase

Spinal cord injury (SCI) is a common but severe disease caused by traffic accidents. Coronary atherosclerotic heart disease (CHD) caused by dyslipidemia is known as the leading cause of death in patients with SCI. However, the quantitative analysis showed that the cholesterol and lipoprotein concentrations in peripheral blood (PB) did not change significantly within 48 h after SCI. Due to the presence of the Blood spinal cord barrier (BSCB), there are only few studies concerning the plasma cholesterol metabolism in the acute phase of SCI. Exosomes have a smaller particle size, which enables them relatively less limitation of BSCB. This study uses exosomes derived from the plasma of 43 patients in the acute phase of SCI and 71 patients in the control group as samples. MS proteomics and bioinformatics analysis found 590 quantifiable proteins, in which 75 proteins were upregulated and 153 proteins were downregulated, and the top 10 differentially expressed proteins are those including downregulating proteins: HIST1H4A, HIST2H3A, HIST2H2BE, HCLS1, S100A9, HIST1H2BM, S100A8, CALM3, YWHAH, and SFN, and upregulating proteins: SERPIND1, C1QB, SPTLC3, IGHV4-28, C4A, IGHV4-38-2, IGHV4-30-2, SLC15A1, C4B, and ACTG2. Enrichment analysis showed that the largest part of proteins was related to cholesterol metabolism among the downregulated proteins. The main components of cholesterol [ApoB-48 and ApoB-100 increased, ApoA-I, ApoA-II, ApoA-IV, ApoC, ApoE, and Apo(a) decreased] were changed in exosomes derived from plasma of patients. ELISA analysis showed that some components were disordered in the acute phase of SCI. These results suggested that the exosomes might be involved in cholesterol metabolism regulation in the acute phase of SCI.

Acute spinal cord injury: Pathophysiology and pharmacological intervention (Review)

Spinal cord injury (SCI) is one of the most debilitating of all the traumatic conditions that afflict individuals. For a number of years, extensive studies have been conducted to clarify the molecular mechanisms of SCI. Experimental and clinical studies have indicated that two phases, primary damage and secondary damage, are involved in SCI. The initial mechanical damage is caused by local impairment of the spinal cord. In addition, the fundamental mechanisms are associated with hyperflexion, hyperextension, axial loading and rotation. By contrast, secondary injury mechanisms are led by systemic and cellular factors, which may also be initiated by the primary injury. Although significant advances in supportive care have improved clinical outcomes in recent years, a number of studies continue to explore specific pharmacological therapies to minimize SCI. The present review summarized some important pathophysiologic mechanisms that are involved in SCI and focused on several pharmacological and non‑pharmacological therapies, which have either been previously investigated or have a potential in the management of this debilitating injury in the near future.

Pharmacological management of secondary spinal cord injury

Introduction: Secondary spinal cord injury (SCI) sets on immediately after trauma and, despite prompt treatment, may become chronic. SCI is a complex condition and presents numerous challenges to patients and physicians alike, also considering the lack of an approved pharmacological therapy.Areas covered: This review describes the pathophysiological mechanisms leading to secondary SCI to highlight possible targets for pharmacological therapy. Furthermore, an extensive search of the literature on different databases (PubMed, Google scholar, Embase, and Scopus) and of the current clinical trials (clinicaltrials.gov) was performed to investigate the current outlook for the pharmacological management of SCI. Only drugs with performed or ongoing clinical trials were considered.Expert opinion: Pharmacological therapy aims to improve motor and sensory function in patients. Overall, drugs are divided into neuroprotective compounds, which aim to limit the damage induced by the pro-inflammatory and pro-apoptotic milieu of SCI, and neuroregenerative drugs, which induce neuronal and axonal regrowth. While many compounds have been trialed with promising results, none has yet completed a stage III trial and has been approved for the pharmacological management of SCI.

Association of intravenous administration of human Muse cells with deficit amelioration in a rat model of spinal cord injury

OBJECTIVE

Multilineage-differentiating stress-enduring (Muse) cells are pluripotent stem cells, which can be harvested from the bone marrow. After transplantation, Muse cells can migrate to an injured site of the body and exert repair effects. However, it remains unknown whether Muse cell transplantation can be an effective treatment in spinal cord injury (SCI).

METHODS

The authors used a rat model of thoracic spinal cord contusion injury. For Muse cell transplantation, the clinical product CL2020 containing 300,000 Muse cells was administered intravenously 1 day after midthoracic SCI. Animals were divided into CL2020 (n = 11) and vehicle-treated (n = 15) groups. Behavioral and histological evaluations were conducted over a period of 8 weeks to see whether intravenous CL2020 administration provided therapeutic effects for SCI. The effects of human-selective diphtheria toxin on reversion of the therapeutic effects of CL2020 were also investigated.

RESULTS

Hindlimb motor function significantly improved after CL2020 transplantations. Importantly, the effects were reverted by the human-selective diphtheria toxin. In immunohistochemical analyses, the cystic cavity formed after the injury was smaller in the CL2020 group. Furthermore, higher numbers of descending 5-hydroxytryptamine (5-HT) fibers were preserved distal to the injury site after CL2020 administration. Eight weeks after the injury, Muse cells in CL2020 were confirmed to differentiate most predominantly into neuronal cells in the injured spinal cord.

CONCLUSIONS

Following SCI, Muse cells in CL2020 can reach the injured spinal cord after intravenous administration and differentiate into neuronal cells. Muse cells in CL2020 facilitated nerve fiber preservation and exerted therapeutic potential for severe SCI.

Effects of combination treatment with transcranial magnetic stimulation and bone marrow mesenchymal stem cell transplantation or Raf inhibition on spinal cord injury in rats

Spinal cord injury (SCI) remains a global challenge due to limited treatment strategies. Transcranial magnetic stimulation (TMS), bone marrow mesenchymal stem cell (BMSC) transplantation and downregulation of Raf/MEK/ERK signaling effectively improve SCI. The combination of BMSCs and TMS displays synergistic effects on vascular dementia. However, whether TMS displays a synergistic effect when combined with BMSC transplantation or Raf inhibitor (RafI) therapy for the treatment of SCI is not completely understood. The present study aimed to compare the therapeutic effect of monotherapy and combination therapy on SCI. In the present study, 8‑week‑old female Sprague Dawley rats were used to establish a model of SCI using the weight‑drop method followed by treatment with monotherapy (TMS, BMSCs or RafI) or combination therapy (TMS+BMSCs or TMS+RafI). The effect of monotherapy and combination therapy on locomotor function, pathological alterations, neuronal apoptosis and expression of axonal regeneration‑associated factors and Raf/MEK/ERK signaling‑associated proteins in the spinal cord was analyzed by Basso, Beattie and Bresnahan (BBB) scoring, hematoxylin and eosin staining, TUNEL‑neuronal nuclei (NeuN) staining and immunofluorescence or western blotting, respectively. The results demonstrated that compared with untreated SCI model rats, monotherapy significantly enhanced locomotor functional recovery, as evidenced by higher BBB scores, and slightly alleviated histopathological lesions of the spinal cord in SCI model rats. Furthermore, monotherapy markedly suppressed neuronal apoptosis and promoted axonal regeneration, as well as inhibiting astroglial activation in SCI model rats. The aforementioned results were demonstrated by significantly decreased numbers of apoptotic neurons, markedly decreased expression levels of glial fibrillary acidic protein (GFAP), significantly increased numbers of NeuN+ cells, markedly increased expression levels of growth‑associated protein 43 (GAP‑43) and significantly upregulated nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) expression levels in monotherapy groups (excluding the RafI monotherapy group) compared with untreated SCI model rats. In addition, monotherapy markedly suppressed activation of the Raf/MEK/ERK signaling pathway, as evidenced by significantly reduced p‑Raf/Raf, p‑MEK/MEK and p‑ERK/ERK protein expression levels in monotherapy groups (excluding the BMSC monotherapy group) compared with untreated SCI model rats. Notably, combination therapy further alleviated SCI‑induced spinal cord lesions and neuronal apoptosis, increased GAP‑43, NGF and BDNF expression levels, downregulated GFAP expression levels and inhibited activation of the Raf/MEK/ERK signaling pathway in SCI model rats compared with the corresponding monotherapy groups. Therefore, it was hypothesized that compared with monotherapy, combination therapy displayed an improved therapeutic effect on SCI by further suppressing Raf/MEK/ERK signaling. The results of the present study provided an important basis for the clinical application of combination therapy.

The effect of the therapy of "combination 3 methods progression" in patients with neurogenic bowel dysfunction (constipated type): Study protocol for a randomized controlled trial

BACKGROUND

As one of the important manifestations of neurogenic bowel dysfunction, constipation is characterized by high incidence and harmful effects. It has a negative impact on both physical and psychological health of patients. And there are no effective treatment options for this type of disease clinically. Therefore, this study is designed to examine the effect of the therapy of "combination 3 methods progression" in patients with neurogenic bowel dysfunction (constipated type).

METHODS

This is a randomized, controlled, parallel-design clinical trial. A total of 60 patients with neurogenic bowel dysfunction (constipated type) will be randomly assigned to intervention group and control group. The control group will receive 4 weeks of usual rehabilitation care, the intervention group will receive 4 weeks of the therapy of "combination 3 methods progression" in addition to usual rehabilitation care. The primary outcome is the number of spontaneous bowel movement per week. Secondary outcomes are stool characteristics, degree of difficulty in defecation, level of anxiety, level of depression, and level of self-efficacy.

DISCUSSION

The interventions of this protocol have been programmed to alleviate constipation in patients with neurogenic bowel dysfunction. Findings may provide preliminary evidence for clinical efficacy of the therapy of "combination 3 methods progression."

TRIAL REGISTRATION

Chinese Clinical Trial Registry, IDF: ChiCTR2000041463. Registered on December 26, 2020.

Engineered liposomes targeting the gut-CNS Axis for comprehensive therapy of spinal cord injury

Effective curative therapies for spinal cord injury (SCI), which is often accompanied by intestinal complications, are lacking. Potential therapeutic targets include astrocytes and their enteric nervous system counterpart, enteric glial cells (EGCs). Based on shared biomarkers and similar functions of both cell types, we designed an orally administered targeted delivery system in which the neuropeptide apamin, stabilized by sulfur replacement with selenium, was adopted as a targeting moiety, and the liposome surface was protected with a non-covalent cross-linked chitosan oligosaccharide lactate layer. The system effectively permeated through oral absorption barriers, targeted local EGCs and astrocytes after systemic circulation, allowing for comprehensive SCI therapy. Given the involvement of the gut-organ axis in a growing number of diseases, our research may shed light on new aspects of the oral administration route as a bypass for multiple interventions and targeted therapy.

Uric acid released from poly(ε-caprolactone) fibers as a treatment platform for spinal cord injury

Spinal cord injury (SCI) is characterized by a primary mechanical phase of injury, resulting in physical tissue damage, and a secondary pathological phase, characterized by biochemical processes contributing to inflammation, neuronal death, and axonal demyelination. Glutamate-induced excitotoxicity (GIE), in which excess glutamate is released into synapses and overstimulates glutamate receptors, is a major event in secondary SCI. GIE leads to mitochondrial damage and dysfunction, release of reactive oxygen species (ROS), DNA damage, and cell death. There is no clinical treatment that targets GIE after SCI, and there is a need for therapeutic targets for secondary damage in patients. Uric acid (UA) acts as an antioxidant and scavenges free radicals, upregulates glutamate transporters on astrocytes, and preserves neuronal viability in in vitro and in vivo SCI models, making it a promising therapeutic candidate. However, development of a drug release platform that delivers UA locally to the injured region in a controlled manner is crucial, as high systemic UA concentrations can be detrimental. Here, we used the electrospinning technique to synthesize UA-containing poly(ɛ-caprolactone) fiber mats that are biodegradable, biocompatible, and have a tunable degradation rate. We optimized delivery of UA as a burst within 20 min from uncoated fibers and sustained release over 2 h with poly(ethylene glycol) diacrylate coating. We found that both of these fibers protected neurons and decreased ROS generation from GIE in organotypic spinal cord slice culture. Thus, fiber mats represent a promising therapeutic for UA release to treat patients who have suffered a SCI.

Adaptive trial designs for spinal cord injury clinical trials directed to the central nervous system

STUDY DESIGN

Narrative review.

PURPOSE

To provide an overview of adaptive trial designs, and describe how adaptive methods can address persistent challenges encountered by randomized controlled trials of people with spinal cord injury (SCI).

RESULTS

With few exceptions, adaptive methodologies have not been incorporated into clinical trial designs of people with SCI. Adaptive methods provide an opportunity to address high study costs, slow recruitment, and excessive amount of time needed to carry out the trial. The availability of existing SCI registries are well poised to support modeling and simulation, both of which are used extensively in adaptive trial designs. Eight initiatives for immediate advancement of adaptive methods in SCI were identified.

CONCLUSION

Although successfully applied in other fields, adaptive clinical trial designs in SCI clinical trial programs have been narrow in scope and few in number. Immediate application of several adaptive methods offers opportunity to improve efficiency of SCI trials. Concerted effort is needed by all stakeholders to advance adaptive clinical trial design methodology in SCI.

Mesenchymal Stem Cell-Derived Exosomes: Hope for Spinal Cord Injury Repair

Spinal cord injury (SCI) is a devastating medical condition with profound social and economic impacts. Although research is ongoing, current treatment options are limited and do little to restore functionality. However, recent studies suggest that mesenchymal stem cell-derived exosomes (MSC-exosomes) may hold the key to exciting new treatment options for SCI patients. MSCs are self-renewing multipotent stem cells with multi-directional differentiation and can secrete a large number of exosomes (vesicles secreted into the extracellular environment through endocytosis, called MSC-exosomes). These MSC-exosomes play a critical role in repairing SCI through promoting angiogenesis and axonal growth, regulating inflammation and the immune response, inhibiting apoptosis, and maintaining the integrity of the blood-spinal cord barrier. Furthermore, they can be utilized to transport genetic material or drugs to target cells, and their relatively small size makes them able to permeate the blood-brain barrier. In this review, we summarize recent advances in MSC-exosome themed SCI treatments and cell-free therapies to better understand this newly emerging methodology.

Collateral Circulation in Spinal Cord Injury: A Comprehensive Review

Surgery is the most common cause of spinal cord ischemia; it is also caused by hemodynamic changes, which disrupt the blood flow. Direct ligation of the spinal arteries, especially the Adamkiewicz artery is involved as well. Other causes of spinal cord ischemia include arteriography procedures, thoracic surgery, epidural and rachianesthesia, foraminal infiltration, arterial dissection, systemic hypotension, emboligenic heart disease, thoracic disc herniation, and compression. Understanding the vascular anatomy of the spinal cord is essential to develop optimal strategies for preventing ischemic injuries to the spinal cord. During ischemia, a rich network of intra and paraspinal collaterals allow enough blood flow to compensate the intensity of spinal cord ischemia. In case of interruption of flow of a main artery, the collateral artery increases its flow to maintain perfusion to the tissues. Avoiding spinal cord ischemia by using collateral circulation is necessary to prevent the establishment of hypovolemia, hyperthermia and elevations in venous pressures. The objective of this narrative review is to present the current concepts of spinal collateral circulation and its role in the setting of ischemic events, affecting the vascular supply of the spinal cord.

Revealing the Therapeutic Potential of Botulinum Neurotoxin Type A in Counteracting Paralysis and Neuropathic Pain in Spinally Injured Mice

Botulinum neurotoxin type A (BoNT/A) is a major therapeutic agent that has been proven to be a successful treatment for different neurological disorders, with emerging novel therapeutic indications each year. BoNT/A exerts its action by blocking SNARE complex formation and vesicle release through the specific cleavage of SNAP-25 protein; the toxin is able to block the release of pro-inflammatory molecules for months after its administration. Here we demonstrate the extraordinary capacity of BoNT/A to neutralize the complete paralysis and pain insensitivity induced in a murine model of severe spinal cord injury (SCI). We show that the toxin, spinally administered within one hour from spinal trauma, exerts a long-lasting proteolytic action, up to 60 days after its administration, and induces a complete recovery of muscle and motor function. BoNT/A modulates SCI-induced neuroglia hyperreactivity, facilitating axonal restoration, and preventing secondary cells death and damage. Moreover, we demonstrate that BoNT/A affects SCI-induced neuropathic pain after moderate spinal contusion, confirming its anti-nociceptive action in this kind of pain, as well. Our results provide the intriguing and real possibility to identify in BoNT/A a therapeutic tool in counteracting SCI-induced detrimental effects. Because of the well-documented BoNT/A pharmacology, safety, and toxicity, these findings strongly encourage clinical translation.

Advances in the Signaling Pathways Downstream of Glial-Scar Axon Growth Inhibitors

Axon growth inhibitors generated by reactive glial scars play an important role in failure of axon regeneration after CNS injury in mature mammals. Among the inhibitory factors, chondroitin sulfate proteoglycans (CSPGs) are potent suppressors of axon regeneration and are important molecular targets for designing effective therapies for traumatic brain injury or spinal cord injury (SCI). CSPGs bind with high affinity to several transmembrane receptors, including two members of the leukocyte common antigen related (LAR) subfamily of receptor protein tyrosine phosphatases (RPTPs). Recent studies demonstrate that multiple intracellular signaling pathways downstream of these two RPTPs mediate the growth-inhibitory actions of CSPGs. A better understanding of these signaling pathways may facilitate development of new and effective therapies for CNS disorders characterized by axonal disconnections. This review will focus on recent advances in the downstream signaling pathways of scar-mediated inhibition and their potential as the molecular targets for CNS repair.

Botulinum Toxin and Neuronal Regeneration after Traumatic Injury of Central and Peripheral Nervous System

Botulinum neurotoxins (BoNTs) are toxins produced by the bacteria Clostridiumbotulinum, the causing agent for botulism, in different serotypes, seven of which (A-G) are well characterized, while others, such as H or FA, are still debated. BoNTs exert their action by blocking SNARE (soluble N-ethylmale-imide-sensitive factor-attachment protein receptors) complex formation and vesicle release from the neuronal terminal through the specific cleavage of SNARE proteins. The action of BoNTs at the neuromuscular junction has been extensively investigated and knowledge gained in this field has set the foundation for the use of these toxins in a variety of human pathologies characterized by excessive muscle contractions. In parallel, BoNTs became a cosmetic drug due to its power to ward off facial wrinkles following the activity of the mimic muscles. Successively, BoNTs became therapeutic agents that have proven to be successful in the treatment of different neurological disorders, with new indications emerging or being approved each year. In particular, BoNT/A became the treatment of excellence not only for muscle hyperactivity conditions, such as dystonia and spasticity, but also to reduce pain in a series of painful states, such as neuropathic pain, lumbar and myofascial pain, and to treat various dysfunctions of the urinary bladder. This review summarizes recent experimental findings on the potential efficacy of BoNTs in favoring nerve regeneration after traumatic injury in the peripheral nervous system, such as the injury of peripheral nerves, like sciatic nerve, and in the central nervous system, such as spinal cord injury.

Heparin-hyaluronic acid nanofibers for growth factor sequestration in spinal cord repair

Growth factor (GF) delivery is a common strategy for spinal cord injury repair, however, GF degradation can impede long-term therapies. GF sequestration via heparin is known to protect bioactivity after delivery. We tested two heparin modifications, methacrylated heparin and thiolated heparin, and electrospun these with methacrylated hyaluronic acid (MeHA) to form HepMAHA and HepSHHA nanofibers. For loaded conditions, MeHA, HepMAHA, and HepSHHA fibers were incubated with soluble basic fibroblast growth factor (bFGF) or nerve growth factor (NGF) and rinsed with PBS. Control groups were hydrated in PBS. L929 fibroblast proliferation was analyzed after 24 hr of culture in either growth media or bFGF-supplemented media. Dissociated chick dorsal root ganglia neurites were measured after 3 days of cell culture in serum free media (SFM) or NGF-supplemented SFM (SFM + NGF). In growth media, fibroblast proliferation was significantly increased in loaded HepMAHA (α < .05) compared to other groups. In SFM, loaded HepMAHA had the longest average neurite length compared to all other groups. In SFM + NGF, HepMAHA and HepSHHA had increased neurite lengths compared to MeHA, regardless of loading (α < .01), suggesting active sequestration of soluble NGF. HepMAHA is a promising biomaterial for sequestering released GFs in a spinal cord injury environment and will be combined with GF filled microspheres for future studies.

The R-line: A New Imaging Index for Decision Making Regarding C2 Lamina Decompression in Cervical Ossification of the Posterior Longitudinal Ligament

Objective

The optimal treatment modality for cervical ossification of the posterior longitudinal ligament (OPLL) including the C2 level remains controversial. Cervical laminoplasty is a widely accepted considering of advantages such as development of few postoperative complications, including kyphosis or neck pain. We encountered seven patients with postoperative disabilities resulting from incomplete decompression after undercutting of the C2 lamina. Based on this experience, we developed a new index to determine the degree of decompression in cervical OPLL—the rostral line (R-line).

Methods

Total of 79 consecutive patients who underwent posterior decompression of cervical OPLL were included in this study. Mean age at the time of operation, the C2-C7 cervical lordotic angle and OPLL thickness at the most stenotic level of the spinal canal, and preoperative/postoperative Japanese Orthopedic Association score was checked in these group. We compared the correspondence between the degree of C2 lamina decompression using the R-line and actual degree of decompression.

Results

In all patients, the R-line touched the upper half of the C2 lamina on preoperative magnetic resonance imaging (MRI). The C2-C3 local segment lordotic angle and maximal degree of spinal cord compression by OPLL were independently correlated to postoperative C2 cord shifting. This result indicates that the R-line is a valid indicator to determine the degree of C2 lamina decompression in OPLL extending to the C2 level.

Conclusion

The results showed that undercutting the C2 lamina can result in incomplete spinal cord decompression and poor clinical outcome if the R-line touches the upper half of the C2 lamina on preoperative MRI.

RNA-seq analysis and compound screening highlight multiple signalling pathways regulating secondary cell death after acute CNS injury in vivo

Understanding the molecular mechanisms that regulate secondary cell death after acute central nervous system (CNS) injury is critical for the development of effective neuroprotective drugs. Previous research has shown that neurotoxic processes including excitotoxicity, oxidative stress and neuroinflammation can cause secondary cell death. Nevertheless, clinical trials targeting these processes have been largely unsuccessful, suggesting that the signalling pathways underlying secondary cell death remain incompletely understood. Due to their suitability for live imaging and their amenability to genetic and pharmacological manipulation, larval zebrafish provide an ideal platform for studying the regulation of secondary cell death in vivo Here, we use RNA-seq gene expression profiling and compound screening to identify signalling pathways that regulate secondary cell death after acute neural injury in larval zebrafish. RNA-seq analysis of genes upregulated in cephalic mpeg1⁺ macrophage-lineage cells isolated from mpeg1:GFP transgenic larvae after neural injury suggested an involvement of cytokine and polyamine signalling in secondary cell death. Furthermore, screening a library of FDA approved compounds indicated roles for GABA, serotonin and dopamine signalling. Overall, our results highlight multiple signalling pathways that regulate secondary cell death in vivo, and thus provide a starting point for the development of novel neuroprotective treatments for patients with CNS injury.This article has an associated First Person interview with the two first authors of the paper.

Applying univariate vs. multivariate statistics to investigate therapeutic efficacy in (pre)clinical trials: A Monte Carlo simulation study on the example of a controlled preclinical neurotrauma trial

BACKGROUND

Small sample sizes combined with multiple correlated endpoints pose a major challenge in the statistical analysis of preclinical neurotrauma studies. The standard approach of applying univariate tests on individual response variables has the advantage of simplicity of interpretation, but it fails to account for the covariance/correlation in the data. In contrast, multivariate statistical techniques might more adequately capture the multi-dimensional pathophysiological pattern of neurotrauma and therefore provide increased sensitivity to detect treatment effects.

RESULTS

We systematically evaluated the performance of univariate ANOVA, Welch's ANOVA and linear mixed effects models versus the multivariate techniques, ANOVA on principal component scores and MANOVA tests by manipulating factors such as sample and effect size, normality and homogeneity of variance in computer simulations. Linear mixed effects models demonstrated the highest power when variance between groups was equal or variance ratio was 1:2. In contrast, Welch's ANOVA outperformed the remaining methods with extreme variance heterogeneity. However, power only reached acceptable levels of 80% in the case of large simulated effect sizes and at least 20 measurements per group or moderate effects with at least 40 replicates per group. In addition, we evaluated the capacity of the ordination techniques, principal component analysis (PCA), redundancy analysis (RDA), linear discriminant analysis (LDA), and partial least squares discriminant analysis (PLS-DA) to capture patterns of treatment effects without formal hypothesis testing. While LDA suffered from a high false positive rate due to multicollinearity, PCA, RDA, and PLS-DA were robust and PLS-DA outperformed PCA and RDA in capturing a true treatment effect pattern.

CONCLUSIONS

Multivariate tests do not provide an appreciable increase in power compared to univariate techniques to detect group differences in preclinical studies. However, PLS-DA seems to be a useful ordination technique to explore treatment effect patterns without formal hypothesis testing.

Therapeutic repair for spinal cord injury: combinatory approaches to address a multifaceted problem

The recent years saw the advent of promising preclinical strategies that combat the devastating effects of a spinal cord injury (SCI) that are progressing towards clinical trials. However, individually, these treatments produce only modest levels of recovery in animal models of SCI that could hamper their implementation into therapeutic strategies in spinal cord injured humans. Combinational strategies have demonstrated greater beneficial outcomes than their individual components alone by addressing multiple aspects of SCI pathology. Clinical trial designs in the future will eventually also need to align with this notion. The scenario will become increasingly complex as this happens and conversations between basic researchers and clinicians are required to ensure accurate study designs and functional readouts.

Expression of long non-coding RNAs in complete transection spinal cord injury: a transcriptomic analysis

Long non-coding RNAs (lncRNAs) are abundantly expressed in the central nervous system and exert a critical role in gene regulation via multiple biological processes. To uncover the functional significance and molecular mechanisms of lncRNAs in spinal cord injury (SCI), the expression signatures of lncRNAs were profiled using RNA sequencing (RNA-seq) technology in a Sprague-Dawley rat model of the 10^th thoracic vertebra complete transection SCI. Results showed that 116 of 14,802 detected lncRNAs were differentially expressed, among which 16—including eight up-regulated (H19, Vof16, Hmox2-ps1, LOC100910973, Ybx1-ps3, Nnat, Gcgr, LOC680254) and eight down-regulated (Rmrp, Terc, Ngrn, Ppp2r2b, Cox6a2, Rpl37a-ps1, LOC360231, Rpph1)—demonstrated fold changes > 2 in response to transection SCI. A subset of these RNA-seq results was validated by quantitative real-time PCR. The levels of 821 mRNAs were also significantly altered post-SCI; 592 mRNAs were up-regulated and 229 mRNAs were down-regulated by more than 2-fold. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that differentially expressed mRNAs were related to GO biological processes and molecular functions such as injury and inflammation response, wound repair, and apoptosis, and were significantly enriched in 15 KEGG pathways, including cell phagocytosis, tumor necrosis factor alpha pathway, and leukocyte migration. Our results reveal the expression profiles of lncRNAs and mRNAs in the rat spinal cord of a complete transection model, and these differentially expressed lncRNAs and mRNAs represent potential novel targets for SCI treatment. We suggest that lncRNAs may play an important role in the early immuno-inflammatory response after spinal cord injury. This study was approved by the Administration Committee of Experimental Animals, Guangdong Province, China.

Efficacy of human HC016 cell transplants on neuroprotection and functional recovery in a rat model of acute spinal cord injury

Spinal cord injury (SCI) is a devastating event with huge personal and social costs, for which there is no effective treatment. Cell therapy constitutes a promising therapeutic approach for SCI; however, its clinical potential is seriously limited by their low survival in the hostile conditions encompassing the acute phase of SCI. Human HC016 (hHC016) cells, generated from expanded human adipose mesenchymal stem cells (hAMSCs) and pulsed with a patented protocol with hydrogen peroxide (H₂ O₂ ), are expected to acquire improved resistance to oxidative environments which appears as a major limiting factor hampering the engrafting success. Our specific aim was to assess whether H₂ O₂ -pulsed hHC016 cells had an improved survival and thus therapeutic efficacy in a rat contusion model of acute SCI when grafted 48 hr after injury. Functional recovery was evaluated up to 56 days post-injury (dpi) by locomotor (open field test and CatWalk) and sensory (Von Frey and Hargreaves) tests. Besides, histological evaluation of transplanted cell survival and tissue protection/regeneration was also performed. Functional results showed a statistically significant improvement on locomotor recovery outcomes with hHC016 cells. Accordingly, superior cell survival in correlation with long-term neuroprotection, higher axonal regeneration, and reduced astroglial and microglial reactivity was also observed with hHC016 cells. These results demonstrate an enhanced survival capacity of hHC016 cells resulting in improved functional and histological outcomes as compared with hAMSCs, indicating that hHC016 cell transplants may constitute a promising cell therapy for acute SCI.

Protective Effects of MiR-129-5p on Acute Spinal Cord Injury Rats

BACKGROUND Spinal cord injury (SCI) is a severe devastating condition associated with serious disability and neurologic deficits. Aberrant micro RNA (miRNA) expression has been related to a variety of central nervous system diseases including SCI. In the present study, we aimed to discover the role of miR-129-5p on SCI. MATERIAL AND METHODS An acute SCI rat model was induced, following the modified Allen method. A total of 36 rats were randomly assigned into 4 groups (n=9 in every group): Sham group; Model group (SCI+saline); SCI+NC group; and SCI+miR-129-5p group (100 nm solution, every 2 days). Basso-Beattie-Bresnahan (BBB) locomotor rating score was carried out to determine functional recovery. TUNEL (terminal dUTP nick-end labeling) staining was used to evaluate cell apoptosis. Hematoxylin and eosin staining was performed to assess the pathological state of spinal cord. Furthermore, western blot assay was conducted to measure the calpain1 and calpain2 expression. RESULTS Our data suggested that the expression level of miR-129-5p was markedly reduced in rats after SCI. Then miR-129-5p mimic was injected into the vertebral canal. We found that the SCI+miR-129-5p group had a high score in the BBB test compared with the SCI+NC group and the Model group. The overexpression of miR-129-5p obviously reduced tissue loss, damaged cells, and the number of TUNEL positive cells. Moreover, western blot assay exhibited that overexpression of miR-129-5p decreased calpain1, calpain2, and cleaved caspase-3 expression. CONCLUSIONS Our findings suggested that overexpression of miR-129-5p improved neurological function by promoting functional recovery, reducing tissue loss and cell apoptosis in rats in an SCI model, possibly through downregulation of calpain1 and calpain2.

Tissue-Engineered Neural Network Graft Relays Excitatory Signal in the Completely Transected Canine Spinal Cord

Tissue engineering produces constructs with defined functions for the targeted treatment of damaged tissue. A complete spinal cord injury (SCI) model is generated in canines to test whether in vitro constructed neural network (NN) tissues can relay the excitatory signal across the lesion gap to the caudal spinal cord. Established protocols are used to construct neural stem cell (NSC)-derived NN tissue characterized by a predominantly neuronal population with robust trans-synaptic activities and myelination. The NN tissue is implanted into the gap immediately following complete transection SCI of canines at the T10 spinal cord segment. The data show significant motor recovery of paralyzed pelvic limbs, as evaluated by Olby scoring and cortical motor evoked potential (CMEP) detection. The NN tissue survives in the lesion area with neuronal phenotype maintenance, improves descending and ascending nerve fiber regeneration, and synaptic integration with host neural circuits that allow it to serve as a neuronal relay to transmit excitatory electrical signal across the injured area to the caudal spinal cord. These results suggest that tissue-engineered NN grafts can relay the excitatory signal in the completely transected canine spinal cord, providing a promising strategy for SCI treatment in large animals, including humans.

Stretch growth of motor axons in custom mechanobioreactors to generate long-projecting axonal constructs

The central feature of peripheral motor axons is their remarkable lengths as they project from a motor neuron residing in the spinal cord to distant target muscle. However, current in vitro models have not replicated this feature owing to challenges in generating motor axon tracts beyond a few millimeters in length. To address this, we have developed a novel combination of microtissue engineering and mechanically assisted growth techniques to create long-projecting centimeter-scale motor axon tracts. Here, primary motor neurons were isolated from rat spinal cords and induced to form engineered microspheres via forced aggregation in custom microwells. This technique yielded healthy motor neurons projecting dense, fasciculated axonal tracts. Within our custom-built mechanobioreactors, motor neuron culture conditions, neuronal/axonal architecture, and mechanical growth conditions were optimized to generate parameters for robust and efficient stretch growth of motor axons. We found that axons projecting from motor neuron aggregates were able to tolerate displacement rates at least 10 times greater than those by axons projecting from dissociated motor neurons. The growth and structural characteristics of these stretch-grown motor axons were compared with that of benchmark stretch-grown sensory axons, revealing increased motor axon fasciculation. Finally, motor axons were integrated with myocytes and stretch grown to create novel long-projecting axonal-myocyte constructs that recreate characteristic dimensions of native nerve-muscle anatomy. This is the first demonstration of mechanical elongation of spinal motor axons and may have applications as anatomically inspired in vitro testbeds or as tissue-engineered living scaffolds for targeted axon tract reconstruction following nervous system injury or disease.

Emerging molecular therapeutic targets for spinal cord injury

Introduction: Spinal cord injury (SCI) is a complicated and devastating neurological disorder. Patients with SCI usually have dramatically reduced quality of life. In recent years, numerous studies have reported advances in understanding the pathophysiology of SCI and developing preclinical therapeutic strategies for SCI, including various molecular therapies, and yet there is still no cure. Areas covered: After SCI, tissue damage, responses and repair involve interactions among many cellular components, including neurons, axons, glia, leukocytes, and other cells. Accordingly, numerous cellular genes and molecules have become therapeutic targets for neural tissue repair, circuit reconstruction, and behavioral restoration. Here, we review the major recent advances in biological and molecular strategies to enhance neuroprotection, axon regeneration, remyelination, neuroplasticity and functional recovery in preclinical studies of SCI. Expert opinion: Researchers have made tremendous progress in identifying individual and combined molecular therapies in animal studies. It is very important to identify additional highly effective treatments for early neuroprotective intervention and for functionally meaningful axon regeneration and neuronal reconnections. Because multiple mechanisms contribute to the functional loss after SCI, combining the most promising approaches that target different pathophysiological and molecular mechanisms should exhibit synergistic actions for maximal functional restoration. [Databases searched: PubMed; inclusive dates: 6/27/2019].

Efficacy of low molecular weight heparin in spinal trauma patients after part concentrated screw surgery and its influence on blood parameters and the incidence of deep venous thrombosis

This study was to investigate the efficacy of low molecular weight heparin (LMWH) therapy in patients with spinal trauma after part concentrated screw (PCS) pedicle screw surgery (PSS) and its influence on blood parameters and the incidence of deep venous thrombosis. Prospectively, 36 patients with spinal trauma who underwent PSS were randomly divided into an experimental group (n = 18) and a control group (n = 18). The experimental group was treated with LMWH after the operation. Changes in the vascular endothelial function, inflammatory factors and other blood indexes, and the incidence of deep venous thrombosis in lower extremities were compared between the two groups before and after the surgery. Compared to pre-surgery, the levels of endothelin (ET) and tissue plasminogen activator (tPA) in the experimental group decreased significantly after surgery (all P < 0.001), while the levels of ET increased and tPA decreased significantly in the control group (all P < 0.001). In addition, compared with pre-surgical levels, interleukin-8 (IL-8), IL-6 and procalcitonin (PCT) decreased significantly in the experimental group after surgery while there was a significant increase in these cytokines in the control group (all P < 0.001), with a significant difference in the cytokine levels between the two groups post-surgery (P < 0.01). After the surgery, plasma viscosity, erythrocyte electrophoresis time and platelet aggregation rate in the control group were significantly increased from pre-surgery levels (all P < 0.001), and these levels were also significantly higher than in the experimental group (P < 0.01). The D-dimer (D-D) level in both groups also increased significantly after surgery (all P < 0.001), and the level post-surgery was significantly higher in the experimental group as compared to the control group (P < 0.01). Finally, the incidence of deep venous thrombosis in the experimental group was significantly lower than in the control group (P < 0.05). LMWH is beneficial in reducing the degree of hypercoagulability, hyperviscosity and inflammatory reaction in patients with spinal trauma who underwent PSS. It also effectively reduced the occurrence of deep vein thrombosis in lower limbs after surgery. Thus, it is a candidate for further clinical development.

Molecular Pathophysiology of Ossification of the Posterior Longitudinal Ligament (OPLL)

Ossification of the posterior longitudinal ligament (OPLL) can be defined as an ectopic ossification in the tissues of spinal ligament showing a hyperostotic condition. OPLL is developed mostly in the cervical spine and clinical presentations of OPLL are majorly myelopathy and/or radiculopathy, with serious neurological pathology resulting in paralysis of extremities and disturbances of motility lowering the quality of life. OPLL is known to be an idiopathic and multifactorial disease, which genetic factors and non-genetic factors including diet, obesity, physical strain on the posterior longitudinal ligament, age, and diabetes mellitus, are involved into the pathogenesis. Up to now, surgical management by decompressing the spinal cord is regarded as standard treatment for OPLL, although there might be the risk of development of reprogression of ossification. The molecular pathogenesis and efficient therapeutic strategy, especially pharmacotherapy and/or preventive intervention, of OPLL has not been clearly elucidated and suggested. Therefore, in this review, we tried to give an overview to the present research results on OPLL, in order to shed light on the potential pharmacotherapy based on molecular pathophysiologic aspect of OPLL, especially on the genetic/genomic factors involved into the etiology of OPLL.

Spinal cord injury: pathophysiology, treatment strategies, associated challenges, and future implications

Axonal regeneration and formation of tripartite (axo-glial) junctions at damaged sites is a prerequisite for early repair of injured spinal cord. Transplantation of stem cells at such sites of damage which can generate both neuronal and glial population has gained impact in terms of recuperation upon infliction with spinal cord injury. In spite of the fact that a copious number of pre-clinical studies using different stem/progenitor cells have shown promising results at acute and subacute stages, at the chronic stages of injury their recovery rates have shown a drastic decline. Therefore, developing novel therapeutic strategies are the need of the hour in order to assuage secondary morbidity and effectuate improvement of the spinal cord injury (SCI)-afflicted patients' quality of life. The present review aims at providing an overview of the current treatment strategies and also gives an insight into the potential cell-based therapies for the treatment of SCI.

Neurological recovery following traumatic spinal cord injury: a systematic review and meta-analysis

OBJECTIVE

Predicting neurological recovery following traumatic spinal cord injury (TSCI) is a complex task considering the heterogeneous nature of injury and the inconsistency of individual studies. This study aims to summarize the current evidence on neurological recovery following TSCI by use of a meta-analytical approach, and to identify injury, treatment, and study variables with prognostic significance.

METHODS

A literature search in MEDLINE and EMBASE was performed, and studies reporting follow-up changes in American Spinal Injury Association (ASIA) Impairment Scale (AIS) or Frankel or ASIA motor score (AMS) scales were included in the meta-analysis. The proportion of patients with at least 1 grade of AIS/Frankel improvement, and point changes in AMS were calculated using random pooled effect analysis. The potential effect of severity, level and mechanism of injury, type of treatment, time and country of study, and follow-up duration were evaluated using meta-regression analysis.

RESULTS

A total of 114 studies were included, reporting AIS/Frankel changes in 19,913 patients and AMS changes in 6920 patients. Overall, the quality of evidence was poor. The AIS/Frankel conversion rate was 19.3% (95% CI 16.2-22.6) for patients with grade A, 73.8% (95% CI 69.0-78.4) for those with grade B, 87.3% (95% CI 77.9-94.8) for those with grade C, and 46.5% (95% CI 38.2-54.9) for those with grade D. Neurological recovery was significantly different between all grades of SCI severity in the following order: C > B > D > A. Level of injury was a significant predictor of recovery; recovery rates followed this pattern: lumbar > cervical and thoracolumbar > thoracic. Thoracic SCI and penetrating SCI were significantly more likely to result in complete injury. Penetrating TSCI had a significantly lower recovery rate compared to blunt injury (OR 0.76, 95% CI 0.62-0.92; p = 0.006). Recovery rate was positively correlated with longer follow-up duration (p = 0.001). Studies with follow-up durations of approximately 6 months or less reported significantly lower recovery rates for incomplete SCI compared to studies with long-term (3-5 years) follow-ups.

CONCLUSIONS

The authors' meta-analysis provides an overall quantitative description of neurological outcomes associated with TSCI. Moreover, they demonstrated how neurological recovery after TSCI is significantly dependent on injury factors (i.e., severity, level, and mechanism of injury), but is not associated with type of treatment or country of origin. Based on these results, a minimum follow-up of 12 months is recommended for TSCI studies that include patients with neurologically incomplete injury.

Filling the Gap: Neural Stem Cells as A Promising Therapy for Spinal Cord Injury

Spinal cord injury (SCI) can lead to severe motor, sensory and social impairments having a huge impact on patients’ lives. The complex and time-dependent SCI pathophysiology has been hampering the development of novel and effective therapies. Current treatment options include surgical interventions, to stabilize and decompress the spinal cord, and rehabilitative care, without providing a cure for these patients. Novel therapies have been developed targeting different stages during trauma. Among them, cell-based therapies hold great potential for tissue regeneration after injury. Neural stem cells (NSCs), which are multipotent cells with inherent differentiation capabilities committed to the neuronal lineage, are especially relevant to promote and reestablish the damaged neuronal spinal tracts. Several studies demonstrate the regenerative effects of NSCs in SCI after transplantation by providing neurotrophic support and restoring synaptic connectivity. Therefore, human clinical trials have already been launched to assess safety in SCI patients. Here, we review NSC-based experimental studies in a SCI context and how are they currently being translated into human clinical trials.

Extrusion of Biocompatible Osteoconductive Polymer (BOP) Causing Cervical Myelopathy

BACKGROUND

As the prevalence of spinal fusion surgery has increased, reliable and safe bone graft substitutes have been developed in response. Biocompatible osteoconductive polymer (BOP) has been used as a bone graft alternative for spine surgery. We present a case of cervical myelopathy due to extrusion of BOP 23 years after surgery and discuss the pathophysiology in terms of spinal fusion.

CASE DESCRIPTION

A 65-year-old man presented with a 3-month history of cervical myelopathic symptoms. Twenty-three years earlier, the patient had undergone cervical surgery for a C6-7 herniated disc with the use of BOP. Imaging studies of the cervical spine showed cord compression due to extruded BOP at C6-7. He underwent corpectomy of the C7 vertebral body and removal of the BOP for the neural decompression, combined with interbody fusion by use of an iliac bone graft and plate fixation. During the operation, crumbly fibers of the BOP were easily removed. His myelopathic symptoms improved immediately after surgery. Postoperative magnetic resonance imaging also showed successful decompression of the spinal cord. Histologically, a foreign body reaction and bony degeneration were found around the synthetic fibers of the BOP.

CONCLUSIONS

Spine surgeons should recognize the pathophysiology of the BOP used for spine fusion surgery. Although BOP is not currently used for spinal surgery, patients undergoing previous surgery with the BOP can present with related complications. Revision surgery is recommended to remove the unincorporated BOP and achieve solid spine fusion.

Application of Hepatocyte Growth Factor for Acute Spinal Cord Injury: The Road from Basic Studies to Human Treatment

Hepatocyte growth factor (HGF) was first identified as a potent mitogen for mature hepatocytes, and has also gained attention as a strong neurotrophic factor in the central nervous system. We found that during the acute phase of spinal cord injury (SCI) in rats, c-Met, the specific receptor for HGF, increases sharply, while the endogenous HGF up-regulation is relatively weak. Introducing exogenous HGF into the spinal cord by injecting an HGF-expressing viral vector significantly increased the neuron and oligodendrocyte survival, angiogenesis, and axonal regeneration, to reduce the area of damage and to promote functional recovery in rats after SCI. Other recent studies in rodents have shown that exogenously administered HGF during the acute phase of SCI reduces astrocyte activation to decrease glial scar formation, and exerts anti-inflammatory effects to reduce leukocyte infiltration. We also reported that the intrathecal infusion of recombinant human HGF (intrathecal rhHGF) improves neurological hand function after cervical contusive SCI in the common marmoset, a non-human primate. Based on these collective results, we conducted a phase I/II clinical trial of intrathecal rhHGF for patients with acute cervical SCI who showed a modified Frankel grade of A/B1/B2 72 h after injury onset, from June 2014 to May 2018.

The cell repair research of spinal cord injury: a review of cell transplantation to treat spinal cord injury

Through retrospective analysis of the literature on the cell repair of spinal cord injury worldwide, it is found that the mechanism of cell transplantation repairing spinal cord injury is mainly to replace damaged neurons, protect host neurons, prevent apoptosis, promote axonal regeneration and synapse formation, promote myelination, and secrete trophic factors or growth factors to improve microenvironment. A variety of cells are used to repair spinal cord injury. Stem cells include multipotent stem cells, embryonic stem cells, and induced pluripotent stem cells. The multipotent stem cells are mainly various types of mesenchymal stem cells and neural stem cells. Non-stem cells include olfactory ensheathing cells and Schwann cells. Transplantation of inhibitory interneurons to alleviate neuropathic pain in patients is receiving widespread attention. Different types of cell transplantation have their own advantages and disadvantages, and multiple cell transplantation may be more helpful to the patient’s functional recovery. These cells have certain effects on the recovery of neurological function and the improvement of complications, but further exploration is needed in clinical application. The application of a variety of cell transplantation, gene technology, bioengineering and other technologies has made the prospect of cell transplantation more extensive. There is a need to find a safe and effective comprehensive treatment to maximize and restore the patient’s performance.

The Importance of Early Surgical Decompression for Acute Traumatic Spinal Cord Injury

Background

Traumatic spinal cord injury (SCI) is a tragic event that has a major impact on individuals and society as well as the healthcare system. The purpose of this study was to investigate the strength of association between surgical treatment timing and neurological improvement.

Methods

Fifty-six patients with neurological impairment due to traumatic SCI were included in this study. From January 2013 to June 2017, all their medical records were reviewed. Initially, to identify the factors affecting the recovery of neurological deficit after an acute SCI, we performed univariate logistic regression analyses for various variables. Then, we performed a multivariate logistic regression analysis for variables that showed a p-value of < 0.2 in the univariate analyses. The Hosmer-Lemeshow test was used to determine the goodness of fit for the multivariate logistic regression model.

Results

In the univariate analysis on the strength of associations between various factors and neurological improvement, the following factors had a p-value of < 0.2: surgical timing (early, < 8 hours; late, 8–24 hours; p = 0.033), completeness of SCI (complete/incomplete; p = 0.033), and smoking (p = 0.095). In the multivariate analysis, only two variables were significant: surgical timing (odds ratio [OR], 0.128; p = 0.004) and completeness of SCI (OR, 9.611; p = 0.009).

Conclusions

Early surgical decompression within 8 hours after traumatic SCI appeared to improve neurological recovery. Furthermore, incomplete SCI was more closely related to favorable neurological improvement than complete SCI. Therefore, we recommend early decompression as an effective treatment for traumatic SCI.

Survival and Migration of Rat Olfactory Ensheathing Cells after Transplantation into Posttraumatic Cysts in the Spinal Cord

We studied survival of rat ensheathing cells after transplantation into experimental posttraumatic cysts. These cells were prepared according to our original protocol, labeled with intravital membrane dye PKH26, and transplanted into posttraumatic cysts of the spinal cord. The presence of cysts was verified by magnetic resonance imaging. Olfactory ensheathing cells were detected in the spinal cord by the immunofluorescence method. It was shown that rat olfactory ensheathing cells survived in the spinal cord over 4 weeks and their migration was observed. High survival rate and the possibility of obtaining olfactory ensheathing cells from the olfactory mucosa of patients for creation of an autologous preparation allow considering them as very promising material for the treatment of patients with posttraumatic cysts of the spinal cord.

A speed-adaptive intraspinal microstimulation controller to restore weight-bearing stepping in a spinal cord hemisection model

OBJECTIVE

The goal of this study was to develop control strategies to produce alternating, weight-bearing stepping in a cat model of hemisection spinal cord injury (SCI) using intraspinal microstimulation (ISMS).

APPROACH

Six cats were anesthetized and the functional consequences of a hemisection SCI were simulated by manually moving one hind-limb through the gait cycle over a moving treadmill belt. ISMS activated the muscles in the other leg by stimulating motor networks in the lumbosacral enlargement using low levels of current (<110 µA). The control strategy used signals from ground reaction forces and angular velocity from the manually-moved limb to anticipate states of the gait cycle, and controlled ISMS to move the other hind-limb into the opposite state. Adaptive control strategies were developed to ensure weight-bearing at different stepping speeds. The step period was predicted using generalizations obtained through four supervised machine learning algorithms and used to adapt the control strategy for faster steps.

MAIN RESULTS

At a single speed, 100% of the steps had sufficient weight-bearing; at faster speeds without adaptation, 97.6% of steps were weight-bearing (significantly less than that for single speed; p  =  0.002). By adapting the control strategy for faster steps using the predicted step period, weight-bearing was achieved in more than 99% of the steps in three of four methods (significantly more than without adaptation p  <  0.04). Overall, a multivariate model tree increased the number of weight-bearing steps, restored step symmetry, and maintained alternation at faster stepping speeds.

SIGNIFICANCE

Through the adaptive control strategies guided by supervised machine learning, we were able to restore weight-bearing and maintain alternation and step symmetry at varying stepping speeds.

Clinical Trials in Traumatic Spinal Cord Injury

Traumatic spinal cord injury (SCI) results in impaired neurologic function that for many individuals is permanent and significantly impacts health, function, quality of life, and life expectancy. Many efforts have been taken to develop effective treatments for SCI; nevertheless, proven therapies targeting neurologic regeneration and functional recovery have been limited. Existing therapeutic approaches, including early surgery, strict blood pressure control, and consideration of treatment with steroids, remain debated and largely focus on mitigating secondary injury after the primary trauma has occurred. Today, there is more research being performed in SCI than ever before. Current clinical trials are exploring pharmacologic, cell-based, physiologic, and rehabilitation approaches to reduce secondary injury and also overcome barriers to neurorecovery. In the future, it is likely that tailored treatments combining many of these strategies will offer significant benefits for persons with SCI. This article aims to review key past, current and emerging neurologic and rehabilitation therapeutic approaches for adults with traumatic SCI.

The Prognostic Value of Serum Neuron Specific Enolase (NSE) and S100B Level in Patients of Acute Spinal Cord Injury

Background

The correlation between serum concentration of neuron specific enolase (NSE), S100B, and the prognosis of patients with acute spinal cord injury (ASCI) remains controversial.

Material/Methods

Sixty patients with confirmed diagnosis of ASCI were recruited for this study from February 2015 to January 2017. The serum level of NSE and S100B were dynamically measured: on the day of injury and for 2 weeks. The 60 cases were divided into Group A (1 or more than 1 ASIA grade improved at 6 months after the injury) and Group B (ASIA grades changed <1 at 6 months after the injury). The serum level of the 2 groups were compared at different time points. And the prognostic value of serum NSE and S100B as biomarkers in patients with ASCI were calculated by Bayes theorem.

Results

The serum levels of NSE in Groups A and B on the 2^nd day of injury reached a peak at 66.80±13.76 g/L and 98.87±20.12 μg/L, respectively, and then declined gradually. On the 14^th day of injury, the serum levels of NSE in both groups were 21.23±8.45 and 39.32±16.31 μg/L, respectively, which were much lower than those on the 2^nd day (P<0.05). The serum levels of S100B in Groups A and B rose after the injury and reached a peak on the 4^th day of injury. Then, the levels declined gradually to 1.14±0.64 and 1.97±0.98 μg/L, respectively, 2 weeks after the injury. Serum levels of NSE and S100B were good biomarkers for predicting the prognosis of ASCI patients with the sensitivity of 74.35% and 71.79%, the specificity of 71.43% and 66.67%. The cutoff value for serum NSE and S100B were 29.07 μg/L and 1.67 μg/L respectively. The AUCs were 0.78 (95% CI: 0.66–0.89) and 0.76 (95% CI: 0.63–0.89) respectively for serum NSE and S100B.

Conclusions

Serum levels of NSE and S100B protein can reflect the degree of spinal cord injury and could be potential biomarkers for the prognosis of acute spinal cord injury.

Bioinformatics analysis of the molecular mechanisms underlying traumatic spinal cord injury

Spinal cord injury (SCI) is a cause of disability. The present study aimed to investigate the molecular mechanisms involved in traumatic SCI. Transcriptome data under accession no. GSE5296, including 96 chips, were downloaded from the Gene Expression Omnibus database. The raw data were normalized and differentially expressed genes (DEGs) were identified. Furthermore, Kyoto Encyclopedia of Genes and Genomes pathway and Gene Ontology enrichment analysis of up‑ and downregulated DEGs was performed. Additionally, a protein‑protein interaction network was constructed and the expression patterns of different genes were determined. Compared with sham samples, there were 374, 707, 1,322, 1,475, 1,724 and 1,342 DEGs identified at 0.5, 4, 24 and 72 h, and 7 and 28 days post‑injury, respectively. At 24 and 72 h, and 7 days following injury, the upregulated DEGs were markedly enriched in 'inflammatory response' and 'immune process'. Downregulated DEGs were predominantly enriched in neuronal function‑associated pathways and 'steroid biosynthesis' process. Protein‑protein interaction network analysis demonstrated similar results. Trend charts further demonstrated that the inflammatory and neuronal functions were altered in a temporal and site‑specific manner. The present study provided an insight into the molecular mechanisms underlying traumatic SCI, which may benefit future SCI research and aid in therapy development.

Concomitant use of mesenchymal stem cells and neural stem cells for treatment of spinal cord injury: A combo cell therapy approach

with neural stem cells (NSCs) provides a hope to recover the neural damage and compensate for the lost neural structures for restoration of interrupted neural communications above and below the site of injury. However, cell-based therapy approach suffers from many biological barriers and technical caveats which severely hamper the prognosis. The biochemically-rich microenvironment at the site of spinal cord injury (SCI), the continuing neuro-degenerative process and infiltrating immune cells offer a serious barrier to the donor cells. We hypothesized that mesenchymal stem cells (MSCs) concomitantly delivered with NSCs would significantly enhance the effectiveness of cell-based therapy for SCI. In a rodent model of SCI (n = 15 animals/group), MSCs labeled with PKH67 (green fluorescence dye) were delivered on day1 after SCI whereas the same animals were treated with NSCs during the subacute phase on day3 (group-5). In comparison with untreated control (group-1), sham group (without cell treatment; group-2), MSCs alone (group-3) and NSCs alone treated animals (group-4), the combined cell treated animals (group-5) showed significantly higher homing of cells at the site of injury during in vivo imaging. Caspase-3 activity was lower in group-5 (P < 0.05 vs all groups) with concomitant reduction in the pro-inflammatory cytokines IL-1β and IL-6 (P < 0.05 vs all groups). All cell therapy groups showed significant improvement in neurological function as compared to group-2, however, it was highest in group-5 (P < 0.05 vs all groups). In conclusion, combined treatment with (NSCs + MSCs) enhances NSCs survival and functional recovery in SCI and is superior to the treatment with either of NSCs or MSCs alone.

Effect of Graphene Nanoribbons (TexasPEG) on locomotor function recovery in a rat model of lumbar spinal cord transection

A sharply transected spinal cord has been shown to be fused under the accelerating influence of membrane fusogens such as polyethylene glycol (PEG) (GEMINI protocol). Previous work provided evidence that this is in fact possible. Other fusogens might improve current results. In this study, we aimed to assess the effects of PEGylated graphene nanoribons (PEG-GNR, and called “TexasPEG” when prepared as 1wt% dispersion in PEG600) versus placebo (saline) on locomotor function recovery and cellular level in a rat model of spinal cord transection at lumbar segment 1 (L₁) level. In vivo and in vitro experiments (n = 10 per experiment) were designed. In the in vivo experiment, all rats were submitted to full spinal cord transection at L₁ level. Five weeks later, behavioral assessment was performed using the Basso Beattie Bresnahan (BBB) locomotor rating scale. Immunohistochemical staining with neuron marker neurofilament 200 (NF200) antibody and astrocytic scar marker glial fibrillary acidic protein (GFAP) was also performed in the injured spinal cord. In the in vitro experiment, the effects of TexasPEG application for 72 hours on the neurite outgrowth of SH-SY5Y cells were observed under the inverted microscope. Results of both in vivo and in vitro experiments suggest that TexasPEG reduces the formation of glial scars, promotes the regeneration of neurites, and thereby contributes to the recovery of locomotor function of a rat model of spinal cord transfection.

Lysophospholipid-Related Diseases and PPARγ Signaling Pathway

The nuclear receptor superfamily includes ligand-inducible transcription factors that play diverse roles in cell metabolism and are associated with pathologies such as cardiovascular diseases. Lysophosphatidic acid (LPA) belongs to a family of lipid mediators. LPA and its naturally occurring analogues interact with G protein-coupled receptors on the cell surface and an intracellular nuclear hormone receptor. In addition, several enzymes that utilize LPA as a substrate or generate it as a product are under its regulatory control. Recent studies have demonstrated that the endogenously produced peroxisome proliferator-activated receptor gamma (PPARγ) antagonist cyclic phosphatidic acid (cPA), which is structurally similar to LPA, inhibits cancer cell invasion and metastasis in vitro and in vivo. We recently observed that cPA negatively regulates PPARγ function by stabilizing the binding of the co-repressor protein, a silencing mediator of retinoic acid, and the thyroid hormone receptor. We also showed that cPA prevents neointima formation, adipocyte differentiation, lipid accumulation, and upregulation of PPARγ target gene transcription. The present review discusses the arbitrary aspects of the physiological and pathophysiological actions of lysophospholipids in vascular and nervous system biology.