Cell transplantation for spinal cord injury: a systematic review

How can clinical safety and efficacy concerns in stem cell therapy for spinal cord injury be overcome?

INTRODUCTION

Spinal cord injury (SCI) can lead to severe neurological dysfunction. Despite scientific and medical advances, clinically effective regenerative therapies including stem cells are lacking for SCI.

AREAS COVERED

This paper discusses translational challenges related to the safe, effective use of stem cells for SCI, with a focus on mesenchymal stem cells (MSCs), neural stem cells (NSCs), Schwann cells (SCs), olfactory ensheathing cells (OECs), oligodendrocyte precursor cells (OPCs), embryonic stem cells (ESCs), and induced pluripotent stem cells (iPSCs). We discuss approaches to enhance the efficacy of cell-based strategies by i) addressing patient heterogeneity and enhancing patient selection; ii) selecting cell type, cell source, cell developmental stage, and delivery technique; iii) enhancing graft integration and mitigating immune-mediated graft rejection; and iv) ensuring availability of cells. Additionally, we review strategies to optimize outcomes including combinatorial use of rehabilitation and discuss ways to mitigate potential risks of tumor formation associated with stem cell-based strategies.

EXPERT OPINION

Basic science research will drive translational advances to develop stem cell-based therapies for SCI. Genetic, serological, and imaging biomarkers may enable individualization of cell-based treatments. Moreover, combinatorial strategies will be required to enhance graft survival, migration and functional integration, to enable precision-based intervention.

In vivo neural tissue engineering using adipose-derived mesenchymal stem cells and fibrin matrix

BACKGROUND

The multipotency of adipose-derived mesenchymal stem cells (ADMSC) could be an advantage to regenerate tissues with multiple cell types. However, due to the hostile nature, trauma sites like spinal cord injury can augment the ADMSC differentiation into undesirable lineages. Immersing pre-differentiated neural progenitors in a biomimetic niche during delivery could guard them against any undesired differentiation or death.

OBJECTIVE

The study proposes using an insoluble cell-specific fibrin niche for in vitro differentiation of rat ADMSCs to neural progenitor cells (NPCs) and oligodendrocyte progenitor cells (OPCs). Further, the study explores fibrin hydrogel for in vivo progenitor cell delivery, and that can aid post-transplant survival/differentiation.

DESIGN

The in vitro experiments analyzed for differentiation-specific markers to establish derivation of rADMSCs to rNPCs and rOPCs. The derived progenitors, tagged with fluorescent tracker dye were delivered in rat T10 contusion SCI using fibrin hydrogel. After 28 days, imaged the experiment site to determine cell survival, immunostained the tissues to identify differentiation of transplanted cells, and evaluated the effect of fibrin and cells on regulating the injury-associated immune response.

RESULTS

The study demonstrated fibrin niche aided stable differentiation of rat ADMSCs into neural progenitors. Fibrin matrix holds up the delivered progenitor cells in the SCI site. The H&E stained tissues revealed regulated cavitation, astrogliosis, and inflammation in test tissues. Progression of transplanted cells into oligodendrocytes upon delivering a mixture of rNPCs, rOPCs, and fibrin is evident.

CONCLUSION

Fibrin niche-based derivation of neural progenitors from ADMSC seems valuable for transplantation using fibrin hydrogel. It is a promising strategy for extensive study towards further development of translational stem cell-based neural replacement therapy.

Pain Alleviating Effect of Adipose-Derived Stem Cells Transplantation on the Injured Spinal Cord: A Behavioral and Electrophysiological Evaluation

Few studies are conducted on the efficacy of human adipose-derived stem cells (ADSCs) in spinal cord injury (SCI) management and electrophysiological changes in the spinal cord. Therefore, the present study aimed to determine the effect of ADSCs on neuropathic pain, motor function recovery, and electrophysiology assessment. For the purpose of this study, adult male Wistar rats (weight: 140-160 gr, n = 42) were randomly allocated into five groups namely intact animals, sham-operated, SCI non-treated animals, vehicle-treated (culture media), and ADSCs treated groups. One week after clips compression SCI induction, about 1×10⁶ cells were transplanted into the spinal cord. As well, both neuropathic pain (allodynia and hyperalgesia) and motor function were measured weekly. Cavity size, ADSCs survival, and electrophysiology assessments were measured at the end of the eighth week. The transplantation of ADSCs resulted in a significant improvement in the locomotion of SCI animals (p<0.0001), mechanical allodynia (p<0.0001), cold allodynia (p<0.0001), mechanical hyperalgesia (p<0.0001), and thermal hyperalgesia (p<0.0001). The cavity size was significantly smaller among the ADSCs-treated animals (p <0.0001). The single-unit recording showed that the transplantation of ADSCs decreased wide dynamic range (WDR) in neurons and it evoked potential in response to receiving signals from Aβ (p<0.0001) and Aδ (p=0.003) C-fiber (p<0.0001) neurons. Post-discharge recorded from WDR neurons decreased after the transplantation of ADSCs (p<0.0001) and wind up in the ADSCs-treated group was lower than that of the SCI group (p=0.003). Our results showed that the transplantation of ADSCs could significantly alleviate neuropathic pain, enhance motor function recovery, and improve electrophysiology findings after SCI.

Multimodal Repair of Spinal Cord Injury With Mesenchymal Stem Cells

Spinal cord injury (SCI) is a result of a devastating injury to the central nervous system. Currently, there is no effective treatment available for these patients. The possible use of mesenchymal stem cell (MSC)-based treatment for SCI has been the focus of extensive investigations and is increasingly moving from the bench to bedside. Both experimental observations and clinical studies have shown the safety and efficacy of MSCs in managing SCI. However, the exact mechanism by which MSCs contribute to the repair of the injured spinal cord remains to be elucidated. In this review, we aim to summarize current research findings about the role of MSCs in improving complex pathology after SCI. MSCs exert a multimodal repair mechanism targeting multiple events in the secondary injury cascade. Our recent results showing the perineurium-like differentiation of surviving MSCs in the injured spinal cord may further the understanding of the fate of transplanted MSCs. These findings provide fundamental support for the clinical use of MSCs in SCI patients. Under experimental conditions, combining novel physical, chemical, and biological approaches led to significant improvements in the therapeutic efficacy of MSCs. These findings hold promise for the future of cell-based clinical treatment of SCI.

Macrophages Treated with VEGF and PDGF Exert Paracrine Effects on Olfactory Ensheathing Cell Function

Glial cell transplantation using olfactory ensheathing cells (OECs) holds a promising approach for treating spinal cord injury (SCI). However, integration of OECs into the hostile acute secondary injury site requires interaction and response to macrophages. Immunomodulation of macrophages to reduce their impact on OECs may improve the functionality of OECs. Vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF), known for their immunomodulatory and neuroprotective functions, have provided improved outcomes in SCI animal models. Thus, VEGF and PDGF modulation of the SCI microenvironment may be beneficial for OEC transplantation. In this in vitro study, the effect of VEGF and PDGF on macrophages in an inflammatory condition was tested. Combined VEGF + PDGF reduced translocation nuclear factor kappa B p65 in macrophages without altering pro-inflammatory cytokines. Further, the ability of OECs to phagocytose myelin debris was assessed using macrophage-conditioned medium. Conditioned medium from macrophages incubated with PDGF and combined VEGF + PDGF in inflammatory conditions promoted phagocytosis by OECs. The growth factor treated conditioned media also modulated the expression of genes associated with nerve repair and myelin expression in OECs. Overall, these results suggest that the use of growth factors together with OEC transplantation may be beneficial in SCI therapy.

Biomaterial-Based Schwann Cell Transplantation and Schwann Cell-Derived Biomaterials for Nerve Regeneration

Schwann cells (SCs) dominate the regenerative behaviors after peripheral nerve injury by supporting axonal regrowth and remyelination. Previous reports also demonstrated that the existence of SCs is beneficial for nerve regeneration after traumatic injuries in central nervous system. Therefore, the transplantation of SCs/SC-like cells serves as a feasible cell therapy to reconstruct the microenvironment and promote nerve functional recovery for both peripheral and central nerve injury repair. However, direct cell transplantation often leads to low efficacy, due to injection induced cell damage and rapid loss in the circulatory system. In recent years, biomaterials have received great attention as functional carriers for effective cell transplantation. To better mimic the extracellular matrix (ECM), many biodegradable materials have been engineered with compositional and/or topological cues to maintain the biological properties of the SCs/SCs-like cells. In addition, ECM components or factors secreted by SCs also actively contribute to nerve regeneration. Such cell-free transplantation approaches may provide great promise in clinical translation. In this review, we first present the current bio-scaffolds engineered for SC transplantation and their achievement in animal models and clinical applications. To this end, we focus on the physical and biological properties of different biomaterials and highlight how these properties affect the biological behaviors of the SCs/SC-like cells. Second, the SC-derived biomaterials are also reviewed and discussed. Finally, the relationship between SCs and functional biomaterials is summarized, and the trends of their future development are predicted toward clinical applications.

Cell–Cell Contact Mediates Gene Expression and Fate Choice of Human Neural Stem/Progenitor Cells

Transplantation of Neural Stem/Progenitor Cells (NPCs) is a promising regenerative strategy to promote neural repair following injury and degeneration because of the ability of these cells to proliferate, migrate, and integrate with the host tissue. Precise in vitro control of NPC proliferation without compromising multipotency and differentiation ability is critical in stem cell maintenance. This idea was highlighted in recent clinical trials, where discrepancies in NPC culturing protocols produced inconsistent therapeutic benefits. Of note, cell density plays an important role in regulating the survival, proliferation, differentiation, and fate choice of stem cells. To determine the extent of variability produced by inconsistent culturing densities, the present study cultured human-induced pluripotent NPCs (hiPSC-NPCs) at either a low or high plating density. hiPSC-NPCs were then isolated for transcriptomic analysis or differentiation in vitro. Following sequencing analysis, genes involved in cell–cell contact-mediated pathways, including Hippo-signaling, NOTCH, and WNT were differentially expressed. Modulation of these pathways was highly associated with the regulation of pro-neuronal transcription factors, which were also upregulated in response to higher-density hiPSC-NPC culture. Moreover, higher plating density translated into a greater neuronal and less astrocytic differentiation in vitro. This study highlights the importance of precisely controlling culture conditions during the development of NPC transplantation therapies.

Progression in translational research on spinal cord injury based on microenvironment imbalance

Spinal cord injury (SCI) leads to loss of motor and sensory function below the injury level and imposes a considerable burden on patients, families, and society. Repair of the injured spinal cord has been recognized as a global medical challenge for many years. Significant progress has been made in research on the pathological mechanism of spinal cord injury. In particular, with the development of gene regulation, cell sequencing, and cell tracing technologies, in-depth explorations of the SCI microenvironment have become more feasible. However, translational studies related to repair of the injured spinal cord have not yielded significant results. This review summarizes the latest research progress on two aspects of SCI pathology: intraneuronal microenvironment imbalance and regenerative microenvironment imbalance. We also review repair strategies for the injured spinal cord based on microenvironment imbalance, including medications, cell transplantation, exosomes, tissue engineering, cell reprogramming, and rehabilitation. The current state of translational research on SCI and future directions are also discussed. The development of a combined, precise, and multitemporal strategy for repairing the injured spinal cord is a potential future direction.

Application of a New Gene-Cell Construct Based on the Olfactory Mucosa Escheating Cells Transduced with an Adenoviral Vector Encoding Mature BDNF in the Therapy of Spinal Cord Cysts

A gene-cell construct based on rat olfactory mucosa ensheathing cells transduced with an adenoviral vector encoding a mature form of brain neurotrophic factor (mBDNF) was transplanted into post-traumatic cysts of rat spinal cord. Transplantation of the gene-cell construct improved motor activity of the hind limbs and reduced the size of cysts in some animals. However, comparison of the effects of transduced and non-transduced ensheathing cells revealed no significant differences. In parallel in vitro experiments, a decrease in the proliferation of transduced cells compared to non-transduced cells was observed. It is likely that mBDNF reduces proliferation of transduced cells, which can affect their efficiency. The therapeutic efficacy of the new gene-cell construct is most likely provided by the cellular component.

Pluripotent Stem Cells for Spinal Cord Injury Repair

Spinal cord injury (SCI) is a devastating condition of the central nervous system that strongly reduces the patient’s quality of life and has large financial costs for the healthcare system. Cell therapy has shown considerable therapeutic potential for SCI treatment in different animal models. Although many different cell types have been investigated with the goal of promoting repair and recovery from injury, stem cells appear to be the most promising. Here, we review the experimental approaches that have been carried out with pluripotent stem cells, a cell type that, due to its inherent plasticity, self-renewal, and differentiation potential, represents an attractive source for the development of new cell therapies for SCI. We will focus on several key observations that illustrate the potential of cell therapy for SCI, and we will attempt to draw some conclusions from the studies performed to date.

Clinical application of stem cell therapy in neurogenic bladder: a systematic review and meta-analysis

INTRODUCTION AND HYPOTHESIS

This review aims to investigate the effect of stem cell (SC) therapy on the management of neurogenic bladder (NGB) in four neurological diseases, including spinal cord injury (SCI), Parkinson's disease (PD), multiple sclerosis (MS), and stroke, in the clinical setting.

METHODS

An electronic database search was conducted in the Cochrane Library, EMBASE, Proquest, Clinicaltrial.gov , WHO, Google Scholar, MEDLINE via PubMed, Ovid, Web of Science, Scopus, ongoing trial registers, and conference proceedings in June 2019 and updated by hand searching on 1 February 2021. All randomized controlled trials (RCTs), quasi RCTs, phase I/II clinical trials, case-control, retrospective cohorts, and comprehensive case series that evaluated the regenerative potential of SCs on the management of NGB were included. Cochrane appraisal risk of bias checklist and the standardized critical appraisal instrument from the JBI Meta-Analysis of Statistics, Assessment, and Review Instrument (JBI-MAStARI) were used to appraise the studies.

RESULTS

Twenty-six studies among 1282 relevant publications met our inclusion criteria. Only SC therapy was applied for SCI or MS patients. Phase I/II clinical trials (without control arm) were the most conducted studies, and only four were RCTs. Four studies with 153 participants were included in the meta-analysis. The main route of transplantation was via lumbar puncture. There were no serious adverse events. Only nine studies in SCI and one in MS have used urodynamics, and the others have reported improvement based on patient satisfaction. SC therapy did not significantly improve residual urine volume, detrusor pressure, and maximum bladder capacity. Also, the quality of these publications was low or unclear.

CONCLUSION

Although most clinical trials provide evidence of the safety and effectiveness of MSCs on the management of NGB, the meta-analysis results did not show a significant improvement; however, the interpretation of study results is difficult because of the lack of placebo controls.

microRNA-125b and its downstream Smurf1/KLF2/ATF2 axis as important promoters on neurological function recovery in rats with spinal cord injury

The purpose of this study is to investigate the role of microRNA-125b (miR-125b) and its mechanism in spinal cord injury (SCI) by targeting Smurf1. After loss- and gain-function approaches were conducted in SCI rat models and neural stem cells (NSCs) isolated from foetal rats, the Basso-Beattie-Bresnahan (BBB) score was calculated, and related protein expression was determined by Western blot analysis and cell apoptosis by TUNEL staining. NSC viability was detected by CCK-8, migration abilities by Transwell assay and apoptosis by flow cytometry. The relationship between miR-125b, Smurf1 and KLF2 was evaluated by dual-luciferase reporter gene experiments, Co-IP and in vivo ubiquitin modification assays. Inhibition of miR-125b and KLF2 and the up-regulation of Smurf1 and ATF2 were observed in SCI rats. BBB scores were elevated, the expression of Nestin, NeuN, GFAP, NF-200 and Bcl-2 protein was enhanced but that of Bax protein was reduced, and cell apoptosis was inhibited in SCI rats after up-regulating miR-125b or silencing ATF2. Smurf1 was a target gene of miR-125b, which promoted KLF2 degradation through its E3 ubiquitin ligase function, and KLF2 repressed the expression of ATF2 in NSCs. The results in vivo were replicated in vitro. miR-125b overexpression promotes neurological function recovery after SCI.

Boosting Magnetoelectric Effect in Polymer-Based Nanocomposites

Polymer-based magnetoelectric composite materials have attracted a lot of attention due to their high potential in various types of applications as magnetic field sensors, energy harvesting, and biomedical devices. Current researches are focused on the increase in the efficiency of magnetoelectric transformation. In this work, a new strategy of arrangement of clusters of magnetic nanoparticles by an external magnetic field in PVDF and PFVD-TrFE matrixes is proposed to increase the voltage coefficient (αME) of the magnetoelectric effect. Another strategy is the use of 3-component composites through the inclusion of piezoelectric BaTiO3 particles. Developed strategies allow us to increase the αME value from ~5 mV/cm·Oe for the composite of randomly distributed CoFe2O4 nanoparticles in PVDF matrix to ~18.5 mV/cm·Oe for a composite of magnetic particles in PVDF-TrFE matrix with 5%wt of piezoelectric particles. The applicability of such materials as bioactive surface is demonstrated on neural crest stem cell cultures.

Neurod4 converts endogenous neural stem cells to neurons with synaptic formation after spinal cord injury

The transcriptome analysis of injured Xenopus laevis tadpole and mice suggested that Neurod4L.S., a basic-helix-loop-helix transcription factor, was the most promising transcription factor to exert neuroregeneration after spinal cord injury (SCI) in mammals. We generated a pseudotyped retroviral vector with the neurotropic lymphocytic choriomeningitis virus (LCMV) envelope to deliver murine Neurod4 to mice undergoing SCI. SCI induced ependymal cells to neural stem cells (NSCs) in the central canal. The LCMV envelope-based pseudotypedvector preferentially introduced Neurod4 into activated NSCs, which converted to neurons with axonal regrowth and suppressed the scar-forming glial lineage. Neurod4-induced inhibitory neurons predominantly projected to the subsynaptic domains of motor neurons at the epicenter, and Neurod4-induced excitatory neurons predominantly projected to subsynaptic domains of motor neurons caudal to the injury site suggesting the formation of functional synapses. Thus, Neurod4 is a potential therapeutic factor that can improve anatomical and functional recovery after SCI.

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Neurod4 is predominantly expressed in injured Xenopus laevis tadpole

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An LCMV-based pseudotyped retroviral vector has tropism to neural stem cells

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Neurod4 converts endogenous neural stem cells to neurons after spinal cord injury

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The new excitatory and inhibitory synaptic formation leads to functional recovery

Iron depletion with deferoxamine protects bone marrow-derived mesenchymal stem cells against oxidative stress-induced apoptosis

Bone marrow mesenchymal stem cells (BM-MSCs) are multipotent cells with self-renewal properties, making them an ideal candidate for regenerative medicine. Recently, numerous studies show that about more than 99% of transplanted cells are destroyed because of the stressful microenvironment. Meanwhile, in the target organs, iron overload can produce oxidative stress introducing it as the most important stress factor. The present study was aimed at increasing BM-MSCs' viability against oxidative stress microenvironment using iron depletion by deferoxamine (DFO). Mesenchymal stem cells are isolated and characterized from rat bone marrow. Then, the sensitivity of BM-MSCs against H2O2-induced oxidative stress was evaluated through half of the inhibitory concentration (IC50) estimation by using MTT assay. The maximum non-inhibitory concentration of DFO on BM-MSCs was determined. The next step was the comparison between DFO pre-treated BM-MSCs and untreated cells against H2O2-induced apoptosis. BM-MSCs were identified with morphologic and flow cytometry analysis. IC50 of H2O2 was determined as 0.55 mM at 4 h. Also, the maximum non-inhibitory concentration of DFO was ascertained as 5 μM at 48 h. Our results demonstrated that pretreatment with DFO significantly potentiates BM-MSCs against H2O2-induced oxidative stress which was confirmed by MTT assay, AO/EB double staining, DAPI staining, and activated caspase 3 quantification as well as western blot test. Expression of cleaved caspase 3 and pAKT/AKT ratio obviously demonstrated DFO can resist the cells against cytotoxicity. These findings may help to develop better stem cell culture medium for MSC-based cell therapy. Moreover, regulation of cell stress can be used in practical subjects.

A Novel function of Nebivolol: Stimulation of Adipose-derived Stem Cell Proliferation and Inhibition of Differentiation

Tissue engineering is limited by the time of culture expansion of cells needed for scaffold seeding. Thus, a simple means of accelerated stem cell proliferation could represent a significant advance. Here, Nebivolol was investigated for its effect on the replicative capacity of adipose-derived stem cells (ASCs). This study indicates that the number of ASCs with Nebivolol treatment showed a significant population increase of 51.5% compared to untreated cells (p<0.01). Cell cycle analysis showed a significant decrease in the percentage of ASCs in G1 phase with Nebivolol treatment compared to untreated cells (p<0.01), suggesting that Nebivolol shortens the G1 phase of ASCs, resulting in a faster proliferative rate. Furthermore, our results showed that Nebivolol significantly increased colony-forming units of ASCs (p<0.01). Despite increasing ASC proliferative potential, we showed that Nebivolol has an inhibitory effect on adipogenic and osteogenic differentiation potential as indicated by significantly reduced expression of CCAAT Enhancer Binding Protein alpha (P<0.01) and lipoprotein lipase (P<0.01) and inhibited activity of alkaline phosphatase (P<0.01), respectively. Taken together, these results showed that Nebivolol accelerated ASC proliferation through shortening G1 phase, while inhibiting both adipogenic and osteogenic potentials of ASCs. These data identify a novel and simple approach to accelerate stem cell expansion in vitro before cell differentiation.

Mesenchymal Stem Cell-Laden Hydrogel Microfibers for Promoting Nerve Fiber Regeneration in Long-Distance Spinal Cord Transection Injury

Mesenchymal stem cell (MSC)-based regenerative medicine is widely considered as a promising approach for repairing tissue and re-establishing function in spinal cord injury (SCI). However, low survival rate, uncontrollable migration, and differentiation of stem cells after implantation represent major challenges toward the clinical deployment of this approach. In this study, we fabricated three-dimensional MSC-laden microfibers via electrospinning in a rotating cell culture to mimic nerve tissue, control stem cell behavior, and promote integration with the host tissue. The hierarchically aligned fibrin hydrogel was used as the MSC carrier though a rotating method and the aligned fiber structure induced the MSC-aligned adhesion on the surface of the hydrogel to form microscale cell fibers. The MSC-laden microfiber implantation enhanced the donor MSC neural differentiation, encouraged the migration of host neurons into the injury gap and significantly promoted nerve fiber regeneration across the injury site. Abundant GAP-43- and NF-positive nerve fibers were observed to regenerate in the caudal, rostral, and middle sites of the injury position 8 weeks after the surgery. The NF fiber density reached to 29 ± 6 per 0.25 mm² at the middle site, 82 ± 13 per 0.25 mm² at the adjacent caudal site, and 70 ± 23 at the adjacent rostral site. Similarly, motor axons labeled with 5-hydroxytryptamine were significantly regenerated in the injury gap, which was 122 ± 22 at the middle injury site that was beneficial for motor function recovery. Most remarkably, the transplantation of MSC-laden microfibers significantly improved electrophysiological expression and re-established limb motor function. These findings highlight the combination of MSCs with microhydrogel fibers, the use of which may become a promising method for MSC implantation and SCI repair.

Comparison of the Efficiency of Transplantation of Rat and Human Olfactory Ensheathing Cells in Posttraumatic Cysts of the Spinal Cord

Olfactory ensheathing cells showed significant effects on the regeneration of the spinal cord in experimental models and in clinical trials. However, the use of these cells in the therapy of posttraumatic cysts of the spinal cord has not been studied. Cultures of human and rat olfactory mucosa were obtained according to the protocols developed by us. Passage 3-4 cultures are most enriched with olfactory ensheathing cells and are preferable for transplantation. We performed transplantation of 750,000 olfactory ensheathing cells into the region of modeled cysts. The therapeutic effect of human cells was more pronounced. The positive dynamics of recovery of motor activity in the hind limbs of rats can reflect regenerative processes in the spinal cord after transplantation of olfactory ensheathing cells into the region of posttraumatic cysts.

In Vitro Targeting and Imaging of Neurogenic Differentiation in Mouse Bone-Marrow Derived Mesenchymal Stem Cells with Superparamagnetic Iron Oxide Nanoparticles

Spinal cord injuries (SCI) are well thought to be a crucial issue that roots various side effects for a patient during their entire lifetime. Although therapeutical methods to resolve the SCI are limited, stem cell therapy is determined to be a resolving factor since it possesses the ability to induce the neurogenic differentiation and the paracrine effect. However, stem cells are difficult to inject directly into the lesion, so they must be carefully guided through the spinal canal. Therefore, superparamagnetic iron oxide nanoparticles (SPIONs) are introduced as an instigator that makes the cells respond to the applied magnetic field. This study intends to report the synthesis strategy to develop SPIONs that could be used to treat the injury site by an applied magnetic field. SPION-internalized D1 Mesenchymal stem cells (MSCs) are observed consistently using a confocal fluorescence microscope to analyze the toxicity, maintenance, and monitoring points of intracellular SPIONs. The prepared SPIONs are much anticipated to increase the migration efficiency using magnetism, which was not cytotoxic. Hence, the prepared SPIONs can adeptly target the damaged neural tissue to promote tissue regeneration and treat nervous system disorders. This primary study stands as a focal point to solve SCI by stem cell migration effectively.

Stem cell/cellular interventions in human spinal cord injury: Is it time to move from guidelines to regulations and legislations? Literature review and Spinal Cord Society position statement

PURPOSE

In preclinical studies, many stem cell/cellular interventions demonstrated robust regeneration and/or repair in case of SCI and were considered a promising therapeutic candidate. However, data from clinical studies are not robust. Despite lack of substantial evidence for the efficacy of these interventions in spinal cord injury (SCI), many clinics around the world offer them as "therapy." These "clinics" claim efficacy through patient testimonials and self-advertisement without any scientific evidence to validate their claims. Thus, SCS established a panel of experts to review published preclinical studies, clinical studies and current global guidelines/regulations on usage of cellular transplants and make recommendations for their clinical use.

METHODS

The literature review and draft position statement was compiled and circulated among the panel and relevant suggestions incorporated to reach consensus. This was discussed and finalized in an open forum during the SCS Annual Meeting, ISSICON.

RESULTS

Preclinical evidence suggests safety and clinical potency of cellular interventions after SCI. However, evidence from clinical studies consisted of mostly case reports or uncontrolled case series/studies. Data from animal studies cannot be generalized to human SCI with regard to toxicity prediction after auto/allograft transplantation.

CONCLUSIONS

Currently, cellular/stem cell transplantation for human SCI is experimental and needs to be tested through a valid clinical trial program. It is not ethical to provide unproven transplantation as therapy with commercial implications. To stop the malpractice of marketing such "unproven therapies" to a vulnerable population, it is crucial that all countries unite to form common, well-defined regulations/legislation on their use in SCI. These slides can be retrieved from Electronic Supplementary Material.

Biomimetic 3D-printed scaffolds for spinal cord injury repair

Current methods for bioprinting functional tissue lack appropriate biofabrication techniques to build complex 3D microarchitectures essential for guiding cell growth and promoting tissue maturation¹. 3D printing of central nervous system (CNS) structures has not been accomplished, possibly owing to the complexity of CNS architecture. Here, we report the use of a microscale continuous projection printing method (μCPP) to create a complex CNS structure for regenerative medicine applications in the spinal cord. μCPP can print 3D biomimetic hydrogel scaffolds tailored to the dimensions of the rodent spinal cord in 1.6 s and is scalable to human spinal cord sizes and lesion geometries. We tested the ability of µCPP 3D-printed scaffolds loaded with neural progenitor cells (NPCs) to support axon regeneration and form new 'neural relays' across sites of complete spinal cord injury in vivo in rodents^1,2. We find that injured host axons regenerate into 3D biomimetic scaffolds and synapse onto NPCs implanted into the device and that implanted NPCs in turn extend axons out of the scaffold and into the host spinal cord below the injury to restore synaptic transmission and significantly improve functional outcomes. Thus, 3D biomimetic scaffolds offer a means of enhancing CNS regeneration through precision medicine.

Combinatorial lentiviral gene delivery of pro-oligodendrogenic factors for improving myelination of regenerating axons after spinal cord injury

Spinal cord injury (SCI) results in paralysis below the injury and strategies are being developed that support axonal regrowth, yet recovery lags, in part, because many axons are not remyelinated. Herein, we investigated strategies to increase myelination of regenerating axons by overexpression of platelet-derived growth factor (PDGF)-AA and noggin either alone or in combination in a mouse SCI model. Noggin and PDGF-AA have been identified as factors that enhance recruitment and differentiation of endogenous progenitors to promote myelination. Lentivirus encoding for these factors was delivered from a multichannel bridge, which we have previously shown creates a permissive environment and supports robust axonal growth through channels. The combination of noggin+PDGF enhanced total myelination of regenerating axons relative to either factor alone, and importantly, enhanced functional recovery relative to the control condition. The increase in myelination was consistent with an increase in oligodendrocyte-derived myelin, which was also associated with a greater density of cells of an oligodendroglial lineage relative to each factor individually and control conditions. These results suggest enhanced myelination of regenerating axons by noggin+PDGF that act on oligodendrocyte-lineage cells post-SCI, which ultimately led to improved functional outcomes.

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.

BMSCs promote the differentiation of NSCs into oligodendrocytes via mediating Id2 and Olig expression through BMP/Smad signaling pathway

Neural stem cells (NSCs) have emerged as a promising treatment for spinal cord injuries. However, the increasing expression of bone morphogenetic proteins (BMPs) in spinal cord injury lesion sites seems to have contributed to the limited oligodendroglial differentiation and the majority of the astroglial differentiation of NSCs. In the present study, we demonstrate that BMPs promote NSCs differentiation toward astrocytes and prevent them from differentiating into oligodendrocytes. This effect is accompanied by the increasing expression of Id2 and the reduction in Oilg1/2 expression. Treatment with bone marrow stromal cells (BMSCs) can enhance the development of oligodendrocytes in the presence of BMPs. The analysis of Id2, as well as Olig1 and Olig2 gene expression, reveals that the effect of BMPs on these gene expressions is reversed with the addition of BMSCs. In sum, these data strongly suggest that BMSCs can promote the differentiation of NSCs into oligodendrocytes through mediating Id2 and Olig1/2 expression by blocking the BMP/Smad signaling pathway.

Comparison of Mesenchymal Stromal Cells Isolated from Murine Adipose Tissue and Bone Marrow in the Treatment of Spinal Cord Injury

The use of mesenchymal stromal cell (MSC) transplantation to repair the injured spinal cord has shown consistent benefits in preclinical models. However, the low survival rate of grafted MSC is one of the most important problems. In the injured spinal cord, transplanted cells are exposed to hypoxic conditions and exposed to nutritional deficiency caused by poor vascular supply. Also, the transplanted MSCs face cytotoxic stressors that cause cell death. The aim of this study was to compare adipose-derived MSCs (AD-MSCs) and bone marrow-derived MSCs (BM-MSCs) isolated from individual C57BL6/J mice in relation to: (i) cellular characteristics, (ii) tolerance to hypoxia, oxidative stress and serum-free conditions, and (iii) cellular survival rates after transplantation. AD-MSCs and BM-MSCs exhibited a similar cell surface marker profile, but expressed different levels of growth factors and cytokines. To research their relative stress tolerance, both types of stromal cells were incubated at 20.5% O₂ or 1.0% O₂ for 7 days. Results showed that AD-MSCs were more proliferative with greater culture viability under these hypoxic conditions than BM-MSCs. The MSCs were also incubated under H₂O₂-induced oxidative stress and in serum-free culture medium to induce stress. AD-MSCs were better able to tolerate these stress conditions than BM-MSCs; similarly when transplanted into the spinal cord injury region in vivo, AD-MSCs demonstrated a higher survival rate post transplantation Furthermore, this increased AD-MSC survival post transplantation was associated with preservation of axons and enhanced vascularization, as delineated by increases in anti-gamma isotype of protein kinase C and CD31 immunoreactivity, compared with the BM-MSC transplanted group. Hence, our results indicate that AD-MSCs are an attractive alternative to BM-MSCs for the treatment of severe spinal cord injury. However, it should be noted that the motor function was equally improved following moderate spinal cord injury in both groups, but with no significant improvement seen unfortunately following severe spinal cord injury in either group.

Preparation of Human Olfactory Ensheathing Cells for the Therapy of Spinal Cord Injuries

We developed an optimal protocol for preparing and culturing of olfactory ensheathing cells from human olfactory mucosa. Using this protocol, we obtained a culture enriched with human olfactory ensheathing cells. Immunofluorescence analysis by simultaneous expression of GFAP and p75NTR markers showed that the content of ensheathing cells was maximum in passage 3 and 4 cultures (94 and 89.5%, respectively). The developed protocol can be recommended for obtaining autologous preparations of human ensheathing cells for cell therapy of spinal cord injuries.

Isolation, Culture, and Cryopreservation of Adult Rodent Schwann Cells Derived from Immediately Dissociated Teased Fibers

Adult Schwann cell (SC) cultures are usually derived from nerves subjected to a lengthy step of pre-degeneration to facilitate enzymatic digestion and recovery of viable cells. To overcome the need for pre-degeneration, we developed a method that allows the isolation of adult rat sciatic nerve SCs immediately after tissue harvesting. This method combines the advantages of implementing a rapid enzymatic dissociation of the nerve fibers and a straightforward separation of cells versus myelin that improves both cell yield and viability. Essentially, the method consists of (1) acute dissociation with collagenase and dispase immediately after removal of the epineurium layer and extensive teasing of the nerve fibers, (2) removal of myelin debris by selective attachment of the cells to a highly adhesive poly-L-lysine/laminin substrate, (3) expansion of the initial SC population in medium containing chemical mitogens, and (4) preparation of cryogenic stocks for transfer or delayed experimentation. This protocol allows for the procurement of homogeneous SC cultures deprived of myelin and fibroblast growth as soon as 3-4 days after nerve tissue dissection. SC cultures can be used as such for experimentation or subjected to consecutive rounds of expansion prior to use, purification, or cryopreservation.

Curcumin Increase the Expression of Neural Stem/Progenitor Cells and Improves Functional Recovery after Spinal Cord Injury

Objective

To investigates the effect of curcumin on proliferation of spinal cord neural stem/progenitor cells (SC-NSPCs) and functional outcome in a rat spinal cord injury (SCI) model.

Methods

Sixty adult male Sprague-Dawley rats were randomly and blindly allocated into three groups (sham control group; curcumin treated group after SCI; vehicle treated group after SCI). Functional recovery was evaluated by the Basso, Beattie, and Bresnahan (BBB) scale during 6 weeks after SCI. The expression of SC-NSPC proliferation and astrogliosis were analyzed by nestin/Bromodeoxyuridine (BrdU) and Glial fibrillary acidic protein (GFAP) staining. The injured spinal cord was then examined histologically, including quantification of cavitation.

Results

The BBB score of the SCI-curcumin group was better than that of SCI-vehicle group up to 14 days (p<0.05). The co-immunoreactivity of nestin/BrdU in the SCI-curcumin group was much higher than that of the SCI-vehicle group 1 week after surgery (p<0.05). The GFAP immunoreactivity of the SCI-curcumin group was remarkably lower than that of the SCI-vehicle group 4 weeks after surgery (p<0.05). The lesion cavity was significantly reduced in the curcumin group as compared to the control group (p<0.05).

Conclusion

These results indicate that curcumin could increase the expression of SC-NSPCs, and reduce the activity of reactive astrogliosis and lesion cavity. Consequently curcumin could improve the functional recovery after SCI via SC-NSPC properties.

Spinal Cord Cells from Pre-metamorphic Stages Differentiate into Neurons and Promote Axon Growth and Regeneration after Transplantation into the Injured Spinal Cord of Non-regenerative Xenopus laevis Froglets

Mammals are unable to regenerate its spinal cord after a lesion, meanwhile, anuran amphibians are capable of spinal cord regeneration only as larvae, and during metamorphosis, this capability is lost. Sox2/3⁺ cells present in the spinal cord of regenerative larvae are required for spinal cord regeneration. Here we evaluate the effect of the transplantation of spinal cord cells from regenerative larvae into the resected spinal cord of non-regenerative stages (NR-stage). Donor cells were able to survive up to 60 days after transplantation in the injury zone. During the first 3-weeks, transplanted cells organize in neural tube-like structures formed by Sox2/3⁺ cells. This was not observed when donor cells come from non-regenerative froglets. Mature neurons expressing NeuN and Neurofilament-H were detected in the grafted tissue 4 weeks after transplantation concomitantly with the appearance of axons derived from the donor cells growing into the host spinal cord, suggesting that Sox2/3⁺ cells behave as neural stem progenitor cells. We also found that cells from regenerative animals provide a permissive environment that promotes growth and regeneration of axons coming from the host. These results suggest that Sox2/3 cells present in the spinal cord of regenerative stage (R-stage) larvae are most probably neural stem progenitor cells that are able to survive, proliferate, self-organize and differentiate into neurons in the environment of the non-regenerative host. In addition, we have established an experimental paradigm to study the biology of neural stem progenitor cells in spinal cord regeneration.

Effects of Bone-Marrow-Derived MSC Transplantation on Functional Recovery in a Rat Model of Spinal Cord Injury: Comparisons of Transplant Locations and Cell Concentrations

Spinal cord injury (SCI) is a widely disabling condition, constraining those affected by it to wheelchairs and requiring intense daily care and assistance. Cell replacement therapies, targeting regeneration of cells in the injured cord, are currently gaining momentum in the field of SCI research. Previous studies indicate that mesenchymal stem cells (MSCs) can reduce functional deficits through immunomodulation and production of trophic factors in a variety of neurological disorders. The present study assessed the efficacy of transplanted bone marrow-derived MSCs at different concentrations and locations for promoting functional recovery following SCI. Although effects were modest, MSCs facilitated an increase in the base of support, as measured by increased distance between the plantar surface of the hind paws, following incomplete contusive SCI, and reduced the density of astroglial scarring. Varying the concentrations or locations of transplanted cells did not provide additional benefits on these measures. These findings indicate that MSC transplants are safe at relatively high concentrations and confer therapeutic benefits that, when used as an adjunctive treatment, could significantly enhance functional recovery following SCI.

Clinical Study of NeuroRegen Scaffold Combined With Human Mesenchymal Stem Cells for the Repair of Chronic Complete Spinal Cord Injury

Regeneration of damaged neurons and recovery of sensation and motor function after complete spinal cord injury (SCI) are challenging. We previously developed a collagen scaffold, NeuroRegen, to promote axonal growth along collagen fibers and inhibit glial scar formation after SCI. When functionalized with multiple biomolecules, this scaffold promoted neurological regeneration and functional recovery in animals with SCI. In this study, eight patients with chronic complete SCI were enrolled to examine the safety and efficacy of implanting NeuroRegen scaffold with human umbilical cord mesenchymal stem cells (hUCB-MSCs). Using intraoperative neurophysiological monitoring, we identified and surgically resected scar tissues to eliminate the inhibitory effect of glial scarring on nerve regeneration. We then implanted NeuroRegen scaffold loaded with hUCB-MSCs into the resection sites. No adverse events (infection, fever, headache, allergic reaction, shock, perioperative complications, aggravation of neurological status, or cancer) were observed during 1 year of follow-up. Primary efficacy outcomes, including expansion of sensation level and motor-evoked potential (MEP)-responsive area, increased finger activity, enhanced trunk stability, defecation sensation, and autonomic neural function recovery, were observed in some patients. Our findings suggest that combined application of NeuroRegen scaffold and hUCB-MSCs is safe and feasible for clinical therapy in patients with chronic SCI. Our study suggests that construction of a regenerative microenvironment using a scaffold-based strategy may be a possible future approach to SCI repair.

Gene Expression Profiling in the Injured Spinal Cord of Trachemys scripta elegans: An Amniote with Self-Repair Capabilities

Slider turtles are the only known amniotes with self-repair mechanisms of the spinal cord that lead to substantial functional recovery. Their strategic phylogenetic position makes them a relevant model to investigate the peculiar genetic programs that allow anatomical reconnection in some vertebrate groups but are absent in others. Here, we analyze the gene expression profile of the response to spinal cord injury (SCI) in the turtle Trachemys scripta elegans. We found that this response comprises more than 1000 genes affecting diverse functions: reaction to ischemic insult, extracellular matrix re-organization, cell proliferation and death, immune response, and inflammation. Genes related to synapses and cholesterol biosynthesis are down-regulated. The analysis of the evolutionary distribution of these genes shows that almost all are present in most vertebrates. Additionally, we failed to find genes that were exclusive of regenerating taxa. The comparison of expression patterns among species shows that the response to SCI in the turtle is more similar to that of mice and non-regenerative Xenopus than to Xenopus during its regenerative stage. This observation, along with the lack of conserved “regeneration genes” and the current accepted phylogenetic placement of turtles (sister group of crocodilians and birds), indicates that the ability of spinal cord self-repair of turtles does not represent the retention of an ancestral vertebrate character. Instead, our results suggest that turtles developed this capability from a non-regenerative ancestor (i.e., a lineage specific innovation) that was achieved by re-organizing gene expression patterns on an essentially non-regenerative genetic background. Among the genes activated by SCI exclusively in turtles, those related to anoxia tolerance, extracellular matrix remodeling, and axonal regrowth are good candidates to underlie functional recovery.

Globose basal cells for spinal cord regeneration

Spinal cord injury (SCI) is a devastating condition with loss of motor and sensory functions below the injury level. Cell based therapies are experimented in pre-clinical studies around the world. Neural stem cells are located intra-cranially in subventricular zone and hippocampus which are highly invasive sources. The olfactory epithelium is a neurogenic tissue where neurogenesis takes place throughout the adult life by a population of stem/progenitor cells. Easily accessible olfactory neuroepithelial stem/progenitor cells are an attractive cell source for transplantation in SCI. Globose basal cells (GBCs) were isolated from rat olfactory epithelium, characterized by flow cytometry and immunohistochemically. These cells were further studied for neurosphere formation and neuronal induction. T10 laminectomy was done to create drop-weight SCI in rats. On the 9^th day following SCI, 5 × 10⁵ cells were transplanted into injured rat spinal cord. The outcome of transplantation was assessed by the Basso, Beattie and Bresnahan (BBB) locomotor rating scale, motor evoked potential and histological observation. GBCs expressed neural stem cell markers nestin, SOX2, NCAM and also mesenchymal stem cell markers (CD29, CD54, CD90, CD73, CD105). These cells formed neurosphere, a culture characteristics of NSCs and on induction, differentiated cells expressed neuronal markers βIII tubulin, microtubule-associated protein 2, neuronal nuclei, and neurofilament. GBCs transplanted rats exhibited hindlimb motor recovery as confirmed by BBB score and gastrocnemius muscle electromyography amplitude was increased compared to controls. Green fluorescent protein labelled GBCs survived around the injury epicenter and differentiated into βIII tubulin-immunoreactive neuron-like cells. GBCs could be an alternative to NSCs from an accessible source for autologous neurotransplantation after SCI without ethical issues.

Stem Cells and Labeling for Spinal Cord Injury

Spinal cord injury (SCI) is a devastating condition that usually results in sudden and long-lasting locomotor and sensory neuron degeneration below the lesion site. During the last two decades, the search for new therapies has been revolutionized with the improved knowledge of stem cell (SC) biology. SCs therapy offers several attractive strategies for spinal cord repair. The transplantation of SCs promotes remyelination, neurite outgrowth and axonal elongation, and activates resident or transplanted progenitor cells across the lesion cavity. However, optimized growth and differentiation protocols along with reliable safety assays should be established prior to the clinical application of SCs. Additionally, the ideal method of SCs labeling for efficient cell tracking after SCI remains a challenging issue that requires further investigation. This review summarizes the current findings on the SCs-based therapeutic strategies, and compares different SCs labeling approaches for SCI.

Assessment of Neuroprotective Properties of Melissa officinalis in Combination With Human Umbilical Cord Blood Stem Cells After Spinal Cord Injury

INTRODUCTION

The pathophysiology of spinal cord injury (SCI) has a classically bad prognosis. It has been demonstrated that human umbilical cord blood stem cells (hUCBSCs) and Melissa officinalis (MO) are useful for the prevention of neurological disease.

METHODS

Thirty-six adult male rats were randomly divided into intact, sham, control (SCI), MO, hUCBSC, and MO-hUCBSC groups. Intraperitoneal injection of MO (150 mg/kg) was commenced 24 hr post-SCI and continued once a day for 14 days. Intraspinal grafting of hUCBSCs was commenced immediately in the next day. The motor and sensory functions of all animals were evaluated once a week after the commencement of SCI. Electromyography (EMG) was performed in the last day in order to measure the recruitment index. Immunohistochemistry, reverse transcription-polymerase chain reaction, and transmission electron microscopy evaluations were performed to determine the level of astrogliosis and myelination.

RESULTS

The results revealed that motor function (MO-hUCBSC: 15 ± 0.3, SCI: 8.2 ± 0.37, p < .001), sensory function (MO-hUCBSC: 3.57 ± 0.19, SCI: 6.38 ± 0.23, p < .001), and EMG recruitment index (MO-hUCBSC: 3.71 ± 0.18, SCI: 1.6 ± 0.1, p < .001) were significantly improved in the MO-hUCBSC group compared with SCI group. Mean cavity area (MO-hUCBSC: 0.03 ± 0.03, SCI: 0.07 ± 0.004, p < .001) was reduced and loss of lower motor neurons (MO-hUCBSC: 7.6 ± 0.43, SCI: 3 ± 0.12, p < .001) and astrogliosis density (MO-hUCBSC: 3.1 ± 0.15, SCI: 6.25 ± 1.42, p < 0.001) in the ventral horn of spinal cord were prevented in MO-hUCBSC group compared with SCI group.

CONCLUSION

The results revealed that the combination of MO and hUCBSCs in comparison with the control group has neuroprotective effects in SCI.

Neural Growth Factor Stimulates Proliferation of Spinal Cord Derived-Neural Precursor/Stem Cells

Objective

Recently, regenerative therapies have been used in clinical trials (heart, cartilage, skeletal). We don't make use of these treatments to spinal cord injury (SCI) patients yet, but regenerative therapies are rising interest in recent study about SCI. Neural precursor/stem cell (NPSC) proliferation is a significant event in functional recovery of the central nervous system (CNS). However, brain NPSCs and spinal cord NPSCs (SC-NPSCs) have many differences including gene expression and proliferation. The purpose of this study was to investigate the influence of neural growth factor (NGF) on the proliferation of SC-NPSCs.

Methods

NPSCs (2×10⁴) were suspended in 100 µL of neurobasal medium containing NGF-7S (Sigma-Aldrich) and cultured in a 96-well plate for 12 days. NPSC proliferation was analyzed five times for either concentration of NGF (0.02 and 2 ng/mL). Sixteen rats after SCI were randomly allocated into two groups. In group 1 (SCI-vehicle group, n=8), animals received 1.0 mL of the saline vehicle solution. In group 2 (SCI-NGF group, n=8), the animals received single doses of NGF (Sigma-Aldrich). A dose of 0.02 ng/mL of NGF or normal saline as a vehicle control was intra-thecally injected daily at 24 hour intervals for 7 days. For Immunohistochemistry analysis, rats were sacrificed after one week and the spinal cords were obtained.

Results

The elevation of cell proliferation with 0.02 ng/mL NGF was significant (p<0.05) but was not significant for 2 ng/mL NGF. The optical density was increased in the NGF 0.02 ng/mL group compared to the control group and NGF 2 ng/mL groups. The density of nestin in the SCI-NGF group was significantly increased over the SCI-vehicle group (p<0.05). High power microscopy revealed that the density of nestin in the SCI-NGF group was significantly increased over the SCI-vehicle group.

Conclusion

SC-NPSC proliferation is an important pathway in the functional recovery of SCI. NGF enhances SC-NPSC proliferation in vitro and in vivo. NGF may be a useful option for treatment of SCI patients pending further studies to verify the clinical applicability.

A rapid and versatile method for the isolation, purification and cryogenic storage of Schwann cells from adult rodent nerves

We herein developed a protocol for the rapid procurement of adult nerve-derived Schwann cells (SCs) that was optimized to implement an immediate enzymatic dissociation of fresh nerve tissue while maintaining high cell viability, improving yields and minimizing fibroblast and myelin contamination. This protocol introduces: (1) an efficient method for enzymatic cell release immediately after removal of the epineurium and extensive teasing of the nerve fibers; (2) an adaptable drop-plating method for selective cell attachment, removal of myelin debris, and expansion of the initial SC population in chemically defined medium; (3) a magnetic-activated cell sorting purification protocol for rapid and effective fibroblast elimination; and (4) an optional step of cryopreservation for the storage of the excess of cells. Highly proliferative SC cultures devoid of myelin and fibroblast growth were obtained within three days of nerve processing. Characterization of the initial, expanded, and cryopreserved cell products confirmed maintenance of SC identity, viability and growth rates throughout the process. Most importantly, SCs retained their sensitivity to mitogens and potential for differentiation even after cryopreservation. To conclude, this easy-to-implement and clinically relevant protocol allows for the preparation of expandable homogeneous SC cultures while minimizing time, manipulation of the cells, and exposure to culture variables.

Selected suitable seed cell, scaffold and growth factor could maximize the repair effect using tissue engineering method in spinal cord injury

Spinal cord injury usually leads to permanent disability, which could cause a huge financial problem to the patient. Up to now there is no effective method to treat this disease. The key of the treatment is to enable the damage zone axonal regeneration and luckily it could go through the damage zone; last a connection can be established with the target neurons. This study attempts to combine stem cell, material science and genetic modification technology together, by preparing two genes modified adipose-derived stem cells and inducing them into neuron direction; then by compositing them on the silk fibroin/chitosan scaffold and implanting them into the spinal cord injury model, seed cells can have features of neuron cells. At the same time, it could stably express the brain-derived neurotrophic factor and neurotrophin-3, both of which could produce synergistic effects, which have a positive effect on the recovery of spinal cord. The spinal cord scaffold bridges the broken end of the spinal cord and isolates with the surrounding environment, which could avoid a scar effect on the nerve regeneration and provide three-dimensional space for the seed cell growth, and at last we hope to provide a new treatment for spinal cord injury with the tissue engineering technique.

Harnessing the power of cell transplantation to target respiratory dysfunction following spinal cord injury

The therapeutic benefit of cell transplantation has been assessed in a host of central nervous system (CNS) diseases, including disorders of the spinal cord such as traumatic spinal cord injury (SCI). The promise of cell transplantation to preserve and/or restore normal function can be aimed at a variety of therapeutic mechanisms, including replacement of lost or damaged CNS cell types, promotion of axonal regeneration or sprouting, neuroprotection, immune response modulation, and delivery of gene products such as neurotrophic factors, amongst other possibilities. Despite significant work in the field of transplantation in models of SCI, limited attention has been directed at harnessing the therapeutic potential of cell grafting for preserving respiratory function after SCI, despite the critical role pulmonary compromise plays in patient outcome in this devastating disease. Here, we will review the limited number of studies that have demonstrated the therapeutic potential of intraspinal transplantation of a variety of cell types for addressing respiratory dysfunction in SCI.

Neural stem/progenitor cell transplantation for spinal cord injury treatment; A systematic review and meta-analysis

Despite the vast improvements of cell therapy in spinal cord injury treatment, no optimum protocol has been developed for application of neural stem/progenitor cells. In this regard, the present meta-analysis showed that the efficacy of the neural stem/progenitor cell (NSPC) transplantation depends mainly on injury model, intervention phase, transplanted cell count, immunosuppressive use, and probably stem cell source. Improved functional recovery post NSPC transplantation was found to be higher in transection and contusion models. Moreover, NSPC transplantation in acute phase of spinal injury was found to have better functional recovery. Higher doses (>3×10(6)cell/kg) were also shown to be optimum for transplantation, but immunosuppressive agent administration negatively affected the motor function recovery. Scaffold use in NSPC transplantation could also effectively raise functional recovery.

PSA-NCAM positive neural progenitors stably expressing BDNF promote functional recovery in a mouse model of spinal cord injury

Background

Neural stem cells for the treatment of spinal cord injury (SCI) are of particular interest for future therapeutic use. However, until now, stem cell therapies are often limited due to the inhibitory environment following the injury. Therefore, in this study, we aimed at testing a combinatorial approach with BDNF (brain-derived neurotrophic factor) overexpressing early neural progenitors derived from mouse embryonic stem cells. BDNF is a neurotrophin, which both facilitates neural differentiation of stem cells and favors regeneration of damaged axons.

Methods

Mouse embryonic stem cells, modified to stably express BDNF-GFP, were differentiated into PSA-NCAM positive progenitors, which were enriched, and SSEA1 depleted by a sequential procedure of magnetic-activated and fluorescence-activated cell sorting. Purified cells were injected into the lesion core seven days after contusion injury of the spinal cord in mice, and the Basso mouse scale (BMS) test to evaluate motor function was performed for 5 weeks after transplantation. To analyze axonal regeneration the anterograde tracer biotinylated dextran amine was injected into the sensorimotor cortex two weeks prior to tissue analysis. Cellular differentiation was analyzed by immunohistochemistry of spinal cord sections.

Results

Motor function was significantly improved in animals obtaining transplanted BDNF-GFP-overexpressing cells as compared to GFP-expressing cells and vehicle controls. Stem cell differentiation in vivo revealed an increase of neuronal and oligodendrocytic lineage differentiation by BDNF as evaluated by immunohistochemistry of the neuronal marker MAP2 (microtubule associated protein 2) and the oligodendrocytic markers ASPA (aspartoacylase) and Olig2 (oligodendrocyte transcription factor 2). Furthermore, axonal tracing showed a significant increase of biotin dextran amine positive corticospinal tract fibers in BDNF-GFP-cell transplanted animals caudally to the lesion site.

Conclusions

The combinatorial therapy approach by transplanting BDNF-overexpressing neural progenitors improved motor function in a mouse contusion model of SCI. Histologically, we observed enhanced neuronal and oligodendrocytic differentiation of progenitors as well as enhanced axonal regeneration.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0268-x) contains supplementary material, which is available to authorized users.

Collagen Promotes Higher Adhesion, Survival and Proliferation of Mesenchymal Stem Cells

Mesenchymal stem cells (MSC) can differentiate into several cell types and are desirable candidates for cell therapy and tissue engineering. However, due to poor cell survival, proliferation and differentiation in the patient, the therapy outcomes have not been satisfactory. Although several studies have been done to understand the conditions that promote proliferation, differentiation and migration of MSC in vitro and in vivo, still there is no clear understanding on the effect of non-cellular bio molecules. Of the many factors that influence the cell behavior, the immediate cell microenvironment plays a major role. In this context, we studied the effect of extracellular matrix (ECM) proteins in controlling cell survival, proliferation, migration and directed MSC differentiation. We found that collagen promoted cell proliferation, cell survival under stress and promoted high cell adhesion to the cell culture surface. Increased osteogenic differentiation accompanied by high active RHOA (Ras homology gene family member A) levels was exhibited by MSC cultured on collagen. In conclusion, our study shows that collagen will be a suitable matrix for large scale production of MSC with high survival rate and to obtain high osteogenic differentiation for therapy.

Stem cells in canine spinal cord injury--promise for regenerative therapy in a large animal model of human disease

The use of cell transplantation for spinal cord injury is a rapidly evolving field in regenerative medicine. Numerous animal models are currently being used. However, translation to human patients is still a challenging step. Dogs are of increasing importance as a translational model for human disease since there is a greater awareness of the need to increase the quality of preclinical data. The use of dogs ultimately brings benefit to both human and veterinary medicine. In this review we analyze experimental and clinical studies using cell transplantation for canine spinal cord injury. Overall, in experimental studies, transplantation groups showed improvement over control groups. Improvements were measured at the functional, electrophysiological, histological, RNA and protein levels. Most clinical studies support beneficial effects of cell transplantation despite the fact that methodological limitations preclude definitive conclusions. However, the mechanisms of action and underlying the behavior of transplanted cells in the injured spinal cord remain unclear. Overall, we conclude here that stem cell interventions are a promising avenue for the treatment of spinal cord injury. Canines are a promising model that may help bridge the gap between translational research and human clinical trials.

Substance P stimulates proliferation of spinal neural stem cells in spinal cord injury via the mitogen-activated protein kinase signaling pathway

BACKGROUND CONTEXT

Substance P (SP) is a neuropeptide that can influence neural stem/progenitor cell (NSPC) proliferation and neurogenesis in the brain. However, we could not find any experimental study that investigates SP action in the spinal cord.

PURPOSE

The aims of our study were to investigate the potential of the neuropeptide SP in promoting the proliferation of spinal cord-derived NSPCs (SC-NSPCs) after spinal cord injury (SCI) and to clarify the roles of the mitogen-activated protein (MAP) kinase signaling pathway in the process.

STUDY DESIGN

This is a randomized animal study.

METHODS

The SC-NSPCs were suspended in 100 μL of a neurobasal medium containing SP (binds neurokinin-1 receptor [NK1R]) or L-703,606 (NK1R antagonist) and cultured in a 96-well plate for 5 days. A cell proliferation assay was performed using a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay. A cord clipping method was used for the SCI model. Substance P and the NK1R antagonist (L-703,606) were infused intrathecally in SCI and sham models. Neural stem/progenitor cell proliferation was evaluated with immunostaining for bromodeoxyuridine (BrdU) and the immature neural marker nestin. An immunoblotting method was used for evaluating the MAP kinase signaling protein that contains extracellular signal-regulated kinases (ERKs and p38) and β-actin as the control group.

RESULTS

In vitro, SP (0.01-10 μmol/L) increased the proliferation of cultured SC-NSPCs, with a peak increase of 35±2% at the 0.1 μmol/L concentration. Substance P of 0.1 μmol/L continuously increased SC-NSPC proliferation from 6 hours to 5 days, whereas the proliferation decreased from 18% to 98% with L-703,606 (1-10 μM). Intrathecal infusion of SP (1 μmol/L) for 7 days significantly increased the number of proliferating NPSCs (cells positive for both BrdU and nestin) in the spinal cord (by 120±17%, p<.05) in adult rats, but infusion of L-703,606 (10 μmol/L) significantly decreased the post-SCI induction of NPSC proliferation in the spinal cord (by 87±4%). Also, SP stimulates proliferation of SC-NSPCs via the MAP kinase signaling pathway, especially the phosphorylated ERK and phosphorylated p38 proteins. The phosphorylated ERK and phosphorylated p38 protein levels increased with SP (0.1 μmol/L, p<.05).

CONCLUSIONS

These data indicate that SP can promote proliferation of SC-NSPCs in SCI and normal conditions and have important roles in neuronal regeneration after SCI. Also, ERKs and p38 MAP kinases are important signaling proteins in this process.

Autologous bone marrow cell transplantation in acute spinal cord injury--an Indian pilot study

STUDY DESIGN

Phase- I/II, prospective, randomized, single-blind, controlled pilot study.

PRIMARY OBJECTIVE

To determine the safety and feasibility of autologous bone marrow transplantation in patients with acute spinal cord injury (SCI) via two routes of transplantation as compared with controls.

SETTING

Indian Spinal Injuries Center, New Delhi.

METHODS

Twenty-one subjects with acute, American Spinal Injury Association Impairment Scale (AIS) A (complete), traumatic SCI with neurological level T1-T12, were recruited and randomized into three groups of seven subjects each. Two groups underwent cell transplantation through the intrathecal or intralesional route, whereas the third served as control. Participants were assessed at baseline and followed up at 6 months and 12-months post enrollment. Safety and tolerability were evaluated by monitoring for any adverse events. Efficacy was assessed through neurological, functional and psychological evaluation, as well as through electrophysiological studies and urodynamics.

RESULTS

Surgery was tolerated well by all participants. There were no significant adverse events attributable to the procedure. There was no significant improvement in the neurological, electrophysiological or urodynamic efficacy variables. A statistically significant improvement in functional scores as evaluated by the Spinal Cord Independence Measure and International Spinal Cord Injury Scale was observed in all groups.

CONCLUSIONS

The procedure is safe and feasible in AIS A participants with thoracic-level injuries at 12-months follow-up. No efficacy could be demonstrated that could be attributed to the procedure.

Cell Therapy Augments Functional Recovery Subsequent to Spinal Cord Injury under Experimental Conditions

The spinal cord injury leads to enervation of normal tissue homeostasis ultimately leading to paralysis. Until now there is no proper cure for the treatment of spinal cord injury. Recently, cell therapy in animal spinal cord injury models has shown some progress of recovery. At present, clinical trials are under progress to evaluate the efficacy of cell transplantation for the treatment of spinal cord injury. Different types of cells such as pluripotent stem cells derived neural cells, mesenchymal stromal cells, neural stem cells, glial cells are being tested in various spinal cord injury models. In this review we highlight both the advances and lacuna in the field of spinal cord injury by discussing epidemiology, pathophysiology, molecular mechanism, and various cell therapy strategies employed in preclinical and clinical injury models and finally we discuss the limitations and ethical issues involved in cell therapy approach for treating spinal cord injury.

Comparative Study on the Effects of Ceftriaxone and Monocytes on Recovery after Spinal Cord Injury in Rat

PURPOSE

Comparison between the efficacy of ceftriaxone and monocytes on improvement of neuron protection and functional recovery after spinal cord injury (SCI) in rat.

METHODS

Rats were randomly divided into three groups of ten. Spinal cord injury was performed on rats under general anesthesia using the weight dropping method. Ceftriaxone was injected intraperitoneally 200 mg/kg/day for seven days after SCI. Monocytes were injected 2 × 105 cells 4 days after SCI. Hind limb motor function was assessed using the Basso, Beattie and Bresnahan (BBB) scale. Corticospinal tract (CST) axons were traced by injection of biotin dextran amine (BDA) into the sensorimotor cortex.

RESULTS

There were statistically significant differences in BBB scores in ceftriaxone in comparison to both monocytes receiving and control groups. On the other hand there were statistically significant differences in axon counting in both ceftriaxone and monocytes receiving groups in comparison to control group.

CONCLUSION

Our findings suggest that ceftriaxone improves functional recovery more effective than monocytes in rats after SCI. These results are from an experimental model and validation is required for further investigation.

Translating mechanisms of neuroprotection, regeneration, and repair to treatment of spinal cord injury

One of the big challenges in neuroscience that remains to be understood is why the central nervous system is not able to regenerate to the extent that the peripheral nervous system does. This is especially problematic after traumatic injuries, like spinal cord injury (SCI), since the lack of regeneration leads to lifelong deficits and paralysis. Treatment of SCI has improved during the last several decades due to standardized protocols for emergency medical response teams and improved medical, surgical, and rehabilitative treatments. However, SCI continues to result in profound impairments for the individual. There are many processes that lead to the pathophysiology of SCI, such as ischemia, vascular disruption, neuroinflammation, oxidative stress, excitotoxicity, demyelination, and cell death. Current treatments include surgical decompression, hemodynamic control, and methylprednisolone. However, these early treatments are associated with modest functional recovery. Some treatments currently being investigated for use in SCI target neuroprotective (riluzole, minocycline, G-CSF, FGF-2, and polyethylene glycol) or neuroregenerative (chondroitinase ABC, self-assembling peptides, and rho inhibition) strategies, while many cell therapies (embryonic stem cells, neural stem cells, induced pluripotent stem cells, mesenchymal stromal cells, Schwann cells, olfactory ensheathing cells, and macrophages) have also shown promise. However, since SCI has multiple factors that determine the progress of the injury, a combinatorial therapeutic approach will most likely be required for the most effective treatment of SCI.

Retinal glia promote dorsal root ganglion axon regeneration

Axon regeneration in the adult central nervous system (CNS) is limited by several factors including a lack of neurotrophic support. Recent studies have shown that glia from the adult rat CNS, specifically retinal astrocytes and Müller glia, can promote regeneration of retinal ganglion cell axons. In the present study we investigated whether retinal glia also exert a growth promoting effect outside the visual system. We found that retinal glial conditioned medium significantly enhanced neurite growth and branching of adult rat dorsal root ganglion neurons (DRG) in culture. Furthermore, transplantation of retinal glia significantly enhanced regeneration of DRG axons past the dorsal root entry zone after root crush in adult rats. To identify the factors that mediate the growth promoting effects of retinal glia, mass spectrometric analysis of retinal glial conditioned medium was performed. Apolipoprotein E and secreted protein acidic and rich in cysteine (SPARC) were found to be present in high abundance, a finding further confirmed by western blotting. Inhibition of Apolipoprotein E and SPARC significantly reduced the neuritogenic effects of retinal glial conditioned medium on DRG in culture, suggesting that Apolipoprotein E and SPARC are the major mediators of this regenerative response.