Stem Cell Therapy for Spinal Cord Injury

Construction of a biomimetic chemokine reservoir stimulates rapid in situ wound repair and regeneration

Skin is the first protection of human body. It is always challenged by a range of external factors, resulting in the wounds of skin. Hydrogel, as a dressing with multiple advantages, causes increasing interests or the applications in wound treatment. However, the function and importance of micro-environment of wound region are frequently neglected. In this study, we successfully developed a chemokine loaded biomimetic hydrogel as a functional reservoir to stimulate the rapid in situ recruitment of BMSCs for fast wound repair and regeneration. The biomimetic hydrogel was fabricated by using the Polyvinyl alcohol (PVA) combined with chitosan (CS) as the hybrid materials. The fabricated hydrogel possesses many features such as the porous structure, high swelling rate and moisture retention property. More importantly, the incorporated chemokine could be released with a sustained manner from the hydrogel and recruited the bone marrow mesenchymal stem cells (BMSCs) significantly both in vitro & in vivo. Moreover, the hydrogel was demonstrated to be highly biocompatible to the skin tissue without any side effect or irritation observed. Topical delivery of chemokine by the biomimetic PVA/CS hybrid material based hydrogel is demonstrated as a promising carrier to accelerate wound repair and regeneration without inducing scar formation and any other negative complications. The PVA/CS/SDF-1 hydrogel was shown a novel therapeutic system for wound therapy.

Use of a combination strategy to improve neuroprotection and neuroregeneration in a rat model of acute spinal cord injury

Spinal cord injury is a very common pathological event that has devastating functional consequences in patients. In recent years, several research groups are trying to find an effective therapy that could be applied in clinical practice. In this study, we analyzed the combination of different strategies as a potential therapy for spinal cord injury. Immunization with neural derived peptides (INDP), inhibition of glial scar formation (dipyridyl: DPY), as well as the use of biocompatible matrix (fibrin glue: FG) impregnated with bone marrow mesenchymal stem cells (MSCs) were combined and then its beneficial effects were evaluated in the induction of neuroprotection and neuroregeneration after acute SCI. Sprague-Dawley female rats were subjected to a moderate spinal cord injury and then randomly allocated into five groups: 1) phosphate buffered saline; 2) DPY; 3) INDP + DPY; 4) DPY+ FG; 5) INDP + DPY + FG + MSCs. In all rats, intervention was performed 72 hours after spinal cord injury. Locomotor and sensibility recovery was assessed in all rats. At 60 days after treatment, histological examinations of the spinal cord (hematoxylin-eosin and Bielschowsky staining) were performed. Our results showed that the combination therapy (DPY+ INDP + FG + MSCs) was the best strategy to promote motor and sensibility recovery. In addition, significant increases in tissue preservation and axonal density were observed in the combination therapy group. Findings from this study suggest that the combination theapy (DPY+ INDP + FG + MSCs) exhibits potential effects on the protection and regeneration of neural tissue after acute spinal cord injury. All procedures were approved by the Animal Bioethics and Welfare Committee (approval No. 178544; CSNBTBIBAJ 090812960) on August 15, 2016.

Human UCB-MSCs treatment upon intraventricular hemorrhage contributes to attenuate hippocampal neuron loss and circuit damage through BDNF-CREB signaling

Background

Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) have been shown to prevent brain damage and improve neurocognition following intraventricular hemorrhage (IVH). However, the molecular mechanisms underlying the effects of hUCB-MSCs are still elusive. Thus, as the hippocampus is essential for learning, memory, and cognitive functions and is intimately involved in the ventricular system, making it a potential site of IVH-induced injury, we determined the molecular basis of the effects of hUCB-derived MSCs on hippocampal neurogenesis and the recovery of hippocampal neural circuits after IVH in a rodent model.

Methods

We inflicted severe IVH injury on postnatal day 4 (P4) in rats. After confirmation of successful induction of IVH using MRI (P5), intracerebroventricular administration of MSCs (ICV-MSC) was performed at 2 days post-injury (P6). For hippocampal synaptic determination, a rat entorhinal-hippocampus (EH) organotypic slice co-culture (OSC) was performed using day 3 post-IVH brains (P7) with or without ICV-MSCs. A similar strategy of experiments was applied to those rats receiving hUCB-MSC transfected with BDNF-Si-RNA for knockdown of BDNF or scrambled siRNA controls after IVH. The molecular mechanism of the MSCs effects on neurogenesis and the attenuation of neuron death was determined by evaluation of BDNF-TrkB-Akt-CREB signaling axis.

Results

We showed that treatment with hUCB-MSCs attenuated neuronal loss and promoted neurogenesis in the hippocampus, an area highly vulnerable to IVH-induced brain injury. hUCB-MSCs activate BDNF-TrkB receptor signaling, eliciting intracellular activation of Akt and/or Erk and subsequent phosphorylation of CREB, which is responsible for promoting rat BDNF transcription. In addition to the beneficial effects of neuroprotection and neurogenesis, hUCB-MSCs also contribute to the restoration of impaired synaptic circuits in the hippocampus and improve neurocognitive functions in IVH-injured neonatal rat through BDNF-TrkB-CREB signaling axis activation.

Conclusions

Our data suggest that hUCB-MSCs possess therapeutic potential for treating neuronal loss and neurocognitive dysfunction in IVH through the activation of intracellular TrkB-CREB signaling that is invoked by hUCB-MSC-secreted BDNF.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1052-5) contains supplementary material, which is available to authorized users.

A biodegradable hybrid inorganic nanoscaffold for advanced stem cell therapy

Stem cell transplantation, as a promising treatment for central nervous system (CNS) diseases, has been hampered by crucial issues such as a low cell survival rate, incomplete differentiation, and limited neurite outgrowth in vivo. Addressing these hurdles, scientists have designed bioscaffolds that mimic the natural tissue microenvironment to deliver physical and soluble cues. However, several significant obstacles including burst release of drugs, insufficient cellular adhesion support, and slow scaffold degradation rate remain to be overcome before the full potential of bioscaffold-based stem-cell therapies can be realized. To this end, we developed a biodegradable nanoscaffold-based method for enhanced stem cell transplantation, differentiation, and drug delivery. These findings collectively support the therapeutic potential of our biodegradable hybrid inorganic (BHI) nanoscaffolds for advanced stem cell transplantation and neural tissue engineering.

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.

Therapeutics targeting the inflammasome after central nervous system injury

Innate immunity is part of the early response of the body to deal with tissue damage and infections. Because of the early nature of the innate immune inflammatory response, this inflammatory reaction represents an attractive option as a therapeutic target. The inflammasome is a component of the innate immune response involved in the activation of caspase 1 and the processing of pro-interleukin 1β. In this article, we discuss the therapeutic potential of the inflammasome after central nervous system (CNS) injury and stroke, as well as the basic knowledge we have gained so far regarding inflammasome activation in the CNS. In addition, we discuss some of the therapies available or under investigation for the treatment of brain injury, spinal cord injury, and stroke.

Donor mesenchymal stem cell-derived neural-like cells transdifferentiate into myelin-forming cells and promote axon regeneration in rat spinal cord transection

Introduction

Severe spinal cord injury often causes temporary or permanent damages in strength, sensation, or autonomic functions below the site of the injury. So far, there is still no effective treatment for spinal cord injury. Mesenchymal stem cells (MSCs) have been used to repair injured spinal cord as an effective strategy. However, the low neural differentiation frequency of MSCs has limited its application. The present study attempted to explore whether the grafted MSC-derived neural-like cells in a gelatin sponge (GS) scaffold could maintain neural features or transdifferentiate into myelin-forming cells in the transected spinal cord.

Methods

We constructed an engineered tissue by co-seeding of MSCs with genetically enhanced expression of neurotrophin-3 (NT-3) and its high-affinity receptor tropomyosin receptor kinase C (TrkC) separately into a three-dimensional GS scaffold to promote the MSCs differentiating into neural-like cells and transplanted it into the gap of a completely transected rat spinal cord. The rats received extensive post-operation care, including cyclosporin A administrated once daily for 2 months.

Results

MSCs modified genetically could differentiate into neural-like cells in the MN + MT (NT-3-MSCs + TrKC-MSCs) group 14 days after culture in the GS scaffold. However, after the MSC-derived neural-like cells were transplanted into the injury site of spinal cord, some of them appeared to lose the neural phenotypes and instead transdifferentiated into myelin-forming cells at 8 weeks. In the latter, the MSC-derived myelin-forming cells established myelin sheaths associated with the host regenerating axons. And the injured host neurons were rescued, and axon regeneration was induced by grafted MSCs modified genetically. In addition, the cortical motor evoked potential and hindlimb locomotion were significantly ameliorated in the rat spinal cord transected in the MN + MT group compared with the GS and MSC groups.

Conclusion

Grafted MSC-derived neural-like cells in the GS scaffold can transdifferentiate into myelin-forming cells in the completely transected rat spinal cord.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0100-7) contains supplementary material, which is available to authorized users.

Intranasal delivery of hypoxia-preconditioned bone marrow-derived mesenchymal stem cells enhanced regenerative effects after intracerebral hemorrhagic stroke in mice

Intracerebral hemorrhagic stroke (ICH) causes high mortality and morbidity with very limited treatment options. Cell-based therapy has emerged as a novel approach to replace damaged brain tissues and promote regenerative processes. In this study we tested the hypothesis that intranasally delivered hypoxia-preconditioned BMSCs could reach the brain, promote tissue repair and improve functional recovery after ICH. Hemorrhagic stroke was induced in adult C57/B6 mice by injection of collagenase IV into the striatum. Animals were randomly divided into three groups: sham group, intranasal BMSC treatment group, and vehicle treatment group. BMSCs were pre-treated with hypoxic preconditioning (HP) and pre-labeled with Hoechst before transplantation. Behavior tests, including the mNSS score, rotarod test, adhesive removal test, and locomotor function evaluation were performed at varying days, up to 21days, after ICH to evaluate the therapeutic effects of BMSC transplantation. Western blots and immunohistochemistry were performed to analyze the neurotrophic effects. Intranasally delivered HP-BMSCs were identified in peri-injury regions. NeuN+/BrdU+ co-labeled cells were markedly increased around the hematoma region, and growth factors, including BDNF, GDNF, and VEGF were significantly upregulated in the ICH brain after BMSC treatment. The BMSC treatment group showed significant improvement in behavioral performance compared with the vehicle group. Our data also showed that intranasally delivered HP-BMSCs migrated to peri-injury regions and provided growth factors to increase neurogenesis after ICH. We conclude that intranasal administration of BMSC is an effective treatment for ICH, and that it enhanced neuroregenerative effects and promoted neurological functional recovery after ICH. Overall, the investigation supports the potential therapeutic strategy for BMSC transplantation therapy against hemorrhagic stroke.

Sema4D knockdown in oligodendrocytes promotes functional recovery after spinal cord injury

Semaphorin4D (Sema4D) belongs to Semaphorins family and is secreted and membrane-bound protein. Its function on angiogenesis and axon regeneration makes it an ideal therapeutic target for spinal cord injury (SCI). Here we examined Sema4D expression profile by real-time PCR and western blot and found Sema4D was upregulated after SCI. In vitro study showed Sema4D was not only expressed in oligodendrocytes but also in endothelial cells (ECs). Hypoxia can mimic Sema4D upregulation in both cell lines. Moreover, overexpression of Sema4D through lentivirus in ECs promoted tube formation. However, Sema4D overexpression in oligodendrocytes precursor cells (OPCs) inhibited neuron myelination in neuron-oligodendrocyte co-culture system. Therefore, Sema4D knockdown in OPCs was applied in SCI rats. The results indicated that Sema4D knockdown significantly promoted functional recovery with blood-brain barrier score. Taken together, our data suggest that specific Sema4D knockdown in oligodendrocytes without disturbing its angiogenesis effect can be a beneficial strategy for SCI treatment.

Stable transfection into rat bone marrow mesenchymal stem cells by lentivirus-mediated NT-3

Transplantation of bone marrow mesenchymal stem cells (BMSCs) is the most promising therapeutic strategy in the treatment of spinal cord injuries. BMSCs have a wide variety of sources and are characterized by being exempt from immune rejection, marked secretory functions and neuronal plasticity during differentiation. The lentiviral vector, namely PLV.Ex3d.P/neo-EF1A-NT3-internal ribosome entry site-enhanced green fluorescent protein, was constructed and subsequently transfected into Sprague Dawley (SD) rat BMSCs. The gene and protein expression levels of the nucleic acid neurotrophin-3 (NT-3) were then detected. The results demonstrated that the constructed NT-3 gene lentiviral expression vector matched the expected design and that the NT-3 gene was transfected into the BMSCs via the lentivirus‑mediated method at a transfection efficiency of 60‑70%. NT-3 gene expression was detected within the stably transfected positive cells at the nucleic acid and protein levels. The cell morphology and biological activity of BMSCs did not alter significantly following transfection with NT-3. NT-3-transfected SD BMSCs were successfully constructed and served as effective vector seed cells with stable expression. These results can be used as a reference for subsequent studies on the transplantation therapy of rat spinal cord injuries using lentivirus-mediated NT-3-transfected SD BMSCs.

Transplantation of neurotrophin-3-transfected bone marrow mesenchymal stem cells for the repair of spinal cord injury

Bone marrow mesenchymal stem cell transplantation has been shown to be therapeutic in the repair of spinal cord injury. However, the low survival rate of transplanted bone marrow mesenchymal stem cells in vivo remains a problem. Neurotrophin-3 promotes motor neuron survival and it is hypothesized that its transfection can enhance the therapeutic effect. We show that in vitro transfection of neurotrophin-3 gene increases the number of bone marrow mesenchymal stem cells in the region of spinal cord injury. These results indicate that neurotrophin-3 can promote the survival of bone marrow mesenchymal stem cells transplanted into the region of spinal cord injury and potentially enhance the therapeutic effect in the repair of spinal cord injury.

Transplantation of neurotrophin-3-expressing bone mesenchymal stem cells improves recovery in a rat model of spinal cord injury

BACKGROUND

This study aimed to investigate the therapeutic effects of transplanting neutrophin-3 (NT-3)-expressing bone marrow-derived mesenchymal stem cells (BMSCs) in a rat model of spinal cord injury (SCI).

METHODS

Forty-eight adult female Sprague-Dawley rats were randomly assigned to three groups: the control, BMSC, and NT-3-BMSC groups. BMSCs were infected with NT-3-DsRed or DsRed lentivirus and injected into the cerebrospinal fluid (CSF) via lumbar puncture (LP) 7 days after SCI in the NT-3-BMSC and BMSC groups, respectively. The hind-limb motor function of all rats was recorded using the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale on days 1, 3, 7, 14, 21, 28, and 35 after transplantation. Haematoxylin-eosin (HE) staining, immunofluorescence labelling, and western blotting were performed at the final time point.

RESULTS

Expressions of NT-3, brain-derived neurotrophic factor (BDNF), and vascular endothelial growth factor (VEGF) proteins increased significantly in the NT-3-BMSC group, and hind-limb locomotor functions improved significantly in the NT-3-BMSC group compared with the other two groups. The cystic cavity area was smallest in the NT-3-BMSC group. In the NT-3-BMSC group, neurofilament 200 (NF200) and glial fibrillary acidic protein (GFAP) expression levels around the lesions were significantly increased and decreased, respectively.

CONCLUSIONS

Our findings demonstrate that transplantation of NT-3 gene-modified BMSCs via LP can strengthen the therapeutic benefits of BMSC transplantation. We observed that these modified cells increased locomotor function recovery, promoted nerve regeneration, and improved the injured spinal cord microenvironment, suggesting that it could be a promising treatment for SCI.

The known-unknowns in spinal cord injury, with emphasis on cell-based therapies - a review with suggestive arenas for research

INTRODUCTION

In spite of extensive research, the progress toward a cure in spinal cord injury (SCI) is still elusive, which holds good for the cell- and stem cell-based therapies. We have critically analyzed seven known gray areas in SCI, indicating the specific arenas for research to improvise the outcome of cell-based therapies in SCI.

AREAS COVERED

The seven, specific known gray areas in SCI analyzed are: i) the gap between animal models and human victims; ii) uncertainty about the time, route and dosage of cells applied; iii) source of the most efficacious cells for therapy; iv) inability to address the vascular compromise during SCI; v) lack of non-invasive methodologies to track the transplanted cells; vi) need for scaffolds to retain the cells at the site of injury; and vii) physical and chemical stimuli that might be required for synapses formation yielding functional neurons.

EXPERT OPINION

Further research on scaffolds for retaining the transplanted cells at the lesion, chemical and physical stimuli that may help neurons become functional, a meta-analysis of timing of the cell therapy, mode of application and larger clinical studies are essential to improve the outcome.

Subventricular zone-derived neural stem cell grafts protect against hippocampal degeneration and restore cognitive function in the mouse following intrahippocampal kainic acid administration

Temporal lobe epilepsy (TLE) is a major neurological disease, often associated with cognitive decline. Since approximately 30% of patients are resistant to antiepileptic drugs, TLE is being considered as a possible clinical target for alternative stem cell-based therapies. Given that insulin-like growth factor I (IGF-I) is neuroprotective following a number of experimental insults to the nervous system, we investigated the therapeutic potential of neural stem/precursor cells (NSCs) transduced, or not, with a lentiviral vector for overexpression of IGF-I after transplantation in a mouse model of kainic acid (KA)-induced hippocampal degeneration, which represents an animal model of TLE. Exposure of mice to the Morris water maze task revealed that unilateral intrahippocampal NSC transplantation significantly prevented the KA-induced cognitive decline. Moreover, NSC grafting protected against neurodegeneration at the cellular level, reduced astrogliosis, and maintained endogenous granule cell proliferation at normal levels. In some cases, as in the reduction of hippocampal cell loss and the reversal of the characteristic KA-induced granule cell dispersal, the beneficial effects of transplanted NSCs were manifested earlier and were more pronounced when these were transduced to express IGF-I. However, differences became less pronounced by 2 months postgrafting, since similar amounts of IGF-I were detected in the hippocampi of both groups of mice that received cell transplants. Grafted NSCs survived, migrated, and differentiated into neurons-including glutamatergic cells-and not glia, in the host hippocampus. Our results demonstrate that transplantation of IGF-I producing NSCs is neuroprotective and restores cognitive function following KA-induced hippocampal degeneration.

Clinical application of olfactory ensheathing cells in the treatment of spinal cord injury

OBJECTIVES

To investigate the safety and therapeutic efficacy of autologous olfactory ensheathing cell (OEC) transplantation in cervical spinal cord injury (SCI).

METHODS

Patients with cervical SCI of >6 months' duration were treated with autologous OECs, injected into the area surrounding the SCI under magnetic resonance imaging guidance, twice a week for 4 weeks. Patients were evaluated before treatment and at 3, 6, 12 and 24 months post-treatment, using the American Spinal Injury Association (ASIA) Impairment Scale, the ASIA sensory and motor score and the Functional Independence Measure (FIM) score.

RESULTS

Eight patients were recruited to the study. Three months after treatment, ASIA and FIM scores had improved significantly compared with pretreatment, though by 1 year no further significant improvements in the ASIA score were seen. The return of substantial sensation and motor activity in various muscles below the injury level was observed in three patients during follow-up. In addition, bladder function was restored in two patients. There were no serious complications postoperatively or during the follow-up period.

CONCLUSIONS

This study provides preliminary evidence of the safety and possible efficacy of autologous OEC transplantation.

A role for interleukin-1β in determining the lineage fate of embryonic rat hippocampal neural precursor cells

Neurogenesis occurs in the hippocampus of the developing and adult brain due to the presence of multipotent stem cells and restricted precursor cells at different stages of differentiation. It has been proposed that they may be of potential benefit for use in cell transplantation approaches for neurodegenerative disorders and trauma. Prolonged release of interleukin-1β (IL-1β) from activated microglia has a deleterious effect on hippocampal neurons and is implicated in the impaired neurogenesis and cognitive dysfunction associated with aging, Alzheimer's disease and depression. This study assessed the effect of IL-1β on the proliferation and differentiation of embryonic rat hippocampal NPCs in vitro. We show that IL-1R1 is expressed on proliferating NPCs and that IL-1β treatment decreases cell proliferation and neurosphere growth. When NPCs were differentiated in the presence of IL-1β, a significant reduction in the percentages of newly-born neurons and post-mitotic neurons and a significant increase in the percentage of astrocytes was observed in these cultures. These effects were attenuated by IL-1 receptor antagonist. These data reveal that IL-1β exerts an anti-proliferative, anti-neurogenic and pro-gliogenic effect on embryonic hippocampal NPCs, which is mediated by IL-1R1. The present results emphasise the consequences of an inflammatory environment during NPC development, and indicate that strategies to inhibit IL-1β signalling may be necessary to facilitate effective cell transplantation approaches or in conditions where endogenous hippocampal neurogenesis is impaired.

Cell therapies for the central nervous system

PURPOSE OF REVIEW

Central to the obstacles to be overcome in moving promising cell-based therapies from the laboratory to the clinic is that of determining which of the many cell types being examined are optimal for repairing particular lesions.

RECENT FINDINGS

Our studies on astrocyte replacement therapies demonstrate clearly that some cells are far better than others at promoting recovery in spinal cord injury and that, at least in some cases, transplanting undifferentiated precursor cells is far less useful than transplanting specific astrocytes derived from those precursor cells. But further comparison between different approaches is hindered by the difficulties in replicating results between laboratories, even for well defined pharmacological agents and bioactive proteins. These difficulties in replication appear most likely to be due to unrecognized nuances in lesion characteristics and in the details of delivery of therapies.

SUMMARY

We propose that the challenge of reproducibility provides a critical opportunity for refining cell-based therapies. If the utility of a particular approach is so restricted that even small changes in lesions or treatment protocols eliminate benefit, then the variability inherent in clinical injuries will frustrate translation. In contrast, rising to this challenge may enable discovery of refinements needed to confer the robustness needed for successful clinical trials.

What is the potential of oligodendrocyte progenitor cells to successfully treat human spinal cord injury?

Background

Spinal cord injury is a serious and debilitating condition, affecting millions of people worldwide. Long seen as a permanent injury, recent advances in stem cell research have brought closer the possibility of repairing the spinal cord. One such approach involves injecting oligodendrocyte progenitor cells, derived from human embryonic stem cells, into the injured spinal cord in the hope that they will initiate repair. A phase I clinical trial of this therapy was started in mid 2010 and is currently underway.

Discussion

The theory underlying this approach is that these myelinating progenitors will phenotypically replace myelin lost during injury whilst helping to promote a repair environment in the lesion. However, the importance of demyelination in the pathogenesis of human spinal cord injury is a contentious issue and a body of literature suggests that it is only a minor factor in the overall injury process.

Summary

This review examines the validity of the theory underpinning the on-going clinical trial as well as analysing published data from animal models and finally discussing issues surrounding safety and purity in order to assess the potential of this approach to successfully treat acute human spinal cord injury.