Human Embryonic Stem Cell Therapy in Chronic Spinal Cord Injury: A Retrospective Study

Adverse events of cell therapy clinical trials in human chronic spinal cord injury, a systematic review and meta-analysis

Spinal cord injury is a lesion with high mortality and significant morbidities. After the primary injury, during six months, a cascade of secondary cellular and molecular events makes the lesion chronic. Recently, cell-based clinical trials as a new procedure have been gradually tested to improve the symptoms of patients. Each treatment method is associated with different adverse events. Based on the PRISMA flow diagram of the identified records, and after multistep screening, finally in 76 reviewed studies with 1633 cases and 189 controls, 64 types of adverse events in 12 categories were recorded in 45 studies. The most common adverse events were transient backache and meningism (90%) and cord malacia (80%). The cell therapy method in which the treatment was associated with more adverse events was Olfactory ensheathing cell and bone marrow mesenchymal stem cell combination therapy in 55%, and the adverse events were less with the embryonic stem cell in 2.33% of patients. In a meta-analysis, the total prevalence of adverse events in cell therapy was 19% and the highest pulled effect size belonged to urinary tract and localized adverse events. Also, the total prevalence of adverse events in 14 cell therapy methods was 18% and four cell types (neural stem cell, bone marrow hematopoietic stem cell, embryonic stem cell, and umbilical cord mesenchymal stem cell) had the most effect. None of the adverse events were reported on the 4 (life-threatening consequences) and 5 (death) grading scales. We concluded that the frequency of life-threatening adverse events following cell therapy clinical trials in chronic spinal cord injury patients is very scarce and can be ignored.

The Current Update of Conventional and Innovative Treatment Strategies for Central Nervous System Injury

This review explores the complex challenges and advancements in the treatment of traumatic brain injury (TBI) and spinal cord injury (SCI). Traumatic injuries to the central nervous system (CNS) trigger intricate pathophysiological responses, frequently leading to profound and enduring disabilities. This article delves into the dual phases of injury-primary impacts and the subsequent secondary biochemical cascades-that worsen initial damage. Conventional treatments have traditionally prioritized immediate stabilization, surgical interventions, and supportive medical care to manage both the primary and secondary damage associated with central nervous system injuries. We explore current surgical and medical management strategies, emphasizing the crucial role of rehabilitation and the promising potential of stem cell therapies and immune modulation. Advances in stem cell therapy, gene editing, and neuroprosthetics are revolutionizing treatment approaches, providing opportunities not just for recovery but also for the regeneration of impaired neural tissues. This review aims to emphasize emerging therapeutic strategies that hold promise for enhancing outcomes and improving the quality of life for affected individuals worldwide.

Enhancing regenerative potential: A comprehensive review of stem cell transplantation for sports-related neuronal injuries, with a focus on spinal cord injuries and peripheral nervous system damage

Neuronal injuries, as one of the consequences of sports-related incidents, exert a profound influence on the athletes' future, potentially leading to complete immobility and impeding their athletic pursuits. In cases of severe damage inflicted upon the spinal cord (SC) and peripheral nervous systems (PNS), the regenerative process is notably compromised, rendering it essentially inefficient. Among the pivotal therapeutic approaches for the enhancement and prevention of secondary SC injuries (SCI), stem cell transplantation (SCT) stands out prominently. Stem cells, whether directly involved in replacement and reconstruction or indirectly through modification and secretion of crucial bioenvironmental factors, engage in the intricate process of tissue regeneration. Stem cells, through the secretion of neurotrophic factors (NTFs) (aiming to modulate the immune system), reduction of inflammation, axonal growth stimulation, and myelin formation, endeavor to facilitate the regeneration of damaged SC tissue. The fundamental challenges of this approach encompass the proper selection of suitable stem cell candidates for transplantation and the establishment of an appropriate microenvironment conducive to SC repair. In this article, an attempt has been made to explore sports-related injuries, particularly SCI, to comprehensively review innovative methods for treating SCI, and to address the existing challenges. Additionally, some of the stem cells used in neural injuries and the process of their utilization have been discussed.

Systematic Review of Cell Therapy Efficacy in Human Chronic Spinal Cord Injury

Spinal cord injury (SCI) is one of the most debilitating problems for humans. About 6 months after the initial injury, a cascade of secondary cellular and molecular events occurs and the primary damage enters the chronic phase. Current treatments are not curative. One of the new treatment methods is the use of cell therapy, which is gradually being tested in clinical trials to improve the symptoms of SCI patients. In this review article, we investigated the effect of different cell therapy trials in improving patients' symptoms and their paraclinical indicators. In the 72 final reviewed studies with 1144 cases and 186 controls, 20 scores were recorded as outcomes. We categorized the scores into seven groups. In upper extremity motor score, daily living function, trunk stability, postural hypotension, somatosensory evoked potential, and motor evoked potential scores, the bone marrow hematopoietic stem cell therapy had a more healing effect. In the International Association of Neurorestoratology SCI Functional Rating Scale, light touch score, bowel function, decreased spasticity, Visual Analog Scale, and electromyography scores, the bone marrow mesenchymal stem cell had more impact. The olfactory ensheathing cell had a greater effect on lower extremity motor score and pinprick scores than other cells. The embryonic stem cell had the greatest effect in improving the important score of the American Spinal Injury Association scale. Based on the obtained results, it seems that a special cell should be used to improve each symptom of patients with chronic SCI, and if the improvement of several harms is involved, the combination of cells may be effective. Impact statement Compared to similar review articles published so far, we reviewed the largest number of published articles, and so the largest number of cases and controls, and the variety of cells we examined was more than other published articles. We concluded that different cells are effective for improving the symptoms and paraclinical indicators of patients with chronic spinal cord injury. Bone marrow hematopoietic stem cell and bone marrow mesenchymal stem cell have had the higher overall mean effect in more scores (each in six scores). If the improvement of several harms is involved, the combination of cells may be effective.

Current status and future perspectives on stem cell transplantation for spinal cord injury

BACKGROUND

Previous assessments of stem cell therapy for spinal cord injuries (SCI) have encountered challenges and constraints. Current research primarily emphasizes safety in early-phase clinical trials, while systematic reviews prioritize effectiveness, often overlooking safety and translational feasibility. This situation prompts inquiries regarding the readiness for clinical adoption.

AIM

To offer an up-to-date systematic literature review of clinical trial results con cerning stem cell therapy for SCI.

METHODS

A systematic search was conducted across major medical databases [PubMed, Embase, Reference Citation Analysis (RCA), and Cochrane Library] up to October 14, 2023. The search strategy utilized relevant Medical Subject Heading (MeSH) terms and keywords related to "spinal cord", "injury", "clinical trials", "stem cells", "functional outcomes", and "adverse events". Studies included in this review consisted of randomized controlled trials and non-randomized controlled trials reporting on the use of stem cell therapies for the treatment of SCI.

RESULTS

In a comprehensive review of 66 studies on stem cell therapies for SCI, 496 papers were initially identified, with 237 chosen for full-text analysis. Among them, 236 were deemed eligible after excluding 170 for various reasons. These studies encompassed 1086 patients with varying SCI levels, with cervical injuries being the most common (42.2%). Bone marrow stem cells were the predominant stem cell type used (71.1%), with various administration methods. Follow-up durations averaged around 84.4 months. The 32.7% of patients showed functional impro vement from American spinal injury association Impairment Scale (AIS) A to B, 40.8% from AIS A to C, 5.3% from AIS A to D, and 2.1% from AIS B to C. Sensory improvements were observed in 30.9% of patients. A relatively small number of adverse events were recorded, including fever (15.1%), headaches (4.3%), muscle tension (3.1%), and dizziness (2.6%), highlighting the potential for SCI recovery with stem cell therapy.

CONCLUSION

In the realm of SCI treatment, stem cell-based therapies show promise, but clinical trials reveal potential adverse events and limitations, underscoring the need for meticulous optimization of transplantation conditions and parameters, caution against swift clinical implementation, a deeper understanding of SCI pathophysiology, and addressing ethical, tumorigenicity, immunogenicity, and immunotoxicity concerns before gradual and careful adoption in clinical practice.

Embryonic stem cells overexpressing high molecular weight FGF2 isoform enhance recovery of pre-ganglionic spinal root lesion in combination with fibrin biopolymer mediated root repair

BACKGROUND

Spinal ventral root avulsion results in massive motoneuron degeneration with poor prognosis and high costs. In this study, we compared different isoforms of basic fibroblast growth factor 2 (FGF2), overexpressed in stably transfected Human embryonic stem cells (hESCs), following motor root avulsion and repair with a heterologous fibrin biopolymer (HFB).

METHODS

In the present work, hESCs bioengineered to overexpress 18, 23, and 31 kD isoforms of FGF2, were used in combination with reimplantation of the avulsed roots using HFB. Statistical analysis was conducted using GraphPad Prism software with one-way or two-way ANOVA, followed by Tukey's or Dunnett's multiple comparison tests. Significance was set at *p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001.

RESULTS

For the first set of experiments, rats underwent avulsion of the ventral roots with local administration of HFB and engraftment of hESCs expressing the above-mentioned FGF2 isoforms. Analysis of motoneuron survival, glial reaction, and synaptic coverage, two weeks after the lesion, indicated that therapy with hESCs overexpressing 31 kD FGF2 was the most effective. Consequently, the second set of experiments was performed with that isoform, so that ventral root avulsion was followed by direct spinal cord reimplantation. Motoneuron survival, glial reaction, synaptic coverage, and gene expression were analyzed 2 weeks post-lesion; while the functional recovery was evaluated by the walking track test and von Frey test for 12 weeks. We showed that engraftment of hESCs led to significant neuroprotection, coupled with immunomodulation, attenuation of astrogliosis, and preservation of inputs to the rescued motoneurons. Behaviorally, the 31 kD FGF2 - hESC therapy enhanced both motor and sensory recovery.

CONCLUSION

Transgenic hESCs were an effective delivery platform for neurotrophic factors, rescuing axotomized motoneurons and modulating glial response after proximal spinal cord root injury, while the 31 kD isoform of FGF2 showed superior regenerative properties over other isoforms in addition to the significant functional recovery.

Challenges in the clinical advancement of cell therapies for Parkinson's disease

Cell therapies as potential treatments for Parkinson's disease first gained traction in the 1980s, owing to the clinical success of trials that used transplants of foetal midbrain dopaminergic tissue. However, the poor standardization of the tissue for grafting, and constraints on its availability and ethical use, have hindered this treatment strategy. Recent advances in stem-cell technologies and in the understanding of the development of dopaminergic neurons have enabled preclinical advancements of promising stem-cell therapies. To move these therapies to the clinic, appropriate levels of safety screening, as well as optimization of the cell products and the scalability of their manufacturing, will be required. In this Review, we discuss how challenges pertaining to cell sources, functional and safety testing, manufacturing and storage, and clinical-trial design are being addressed to advance the translational and clinical development of cell therapies for Parkinson's disease.

Neural Stem Cells Overexpressing Arginine Decarboxylase Improve Functional Recovery from Spinal Cord Injury in a Mouse Model

Current therapeutic strategies for spinal cord injury (SCI) cannot fully facilitate neural regeneration or improve function. Arginine decarboxylase (ADC) synthesizes agmatine, an endogenous primary amine with neuroprotective effects. Transfection of human ADC (hADC) gene exerts protective effects after injury in murine brain-derived neural precursor cells (mNPCs). Following from these findings, we investigated the effects of hADC-mNPC transplantation in SCI model mice. Mice with experimentally damaged spinal cords were divided into three groups, separately transplanted with fluorescently labeled (1) control mNPCs, (2) retroviral vector (pLXSN)-infected mNPCs (pLXSN-mNPCs), and (3) hADC-mNPCs. Behavioral comparisons between groups were conducted weekly up to 6 weeks after SCI, and urine volume was measured up to 2 weeks after SCI. A subset of animals was euthanized each week after cell transplantation for molecular and histological analyses. The transplantation groups experienced significantly improved behavioral function, with the best recovery occurring in hADC-mNPC mice. Transplanting hADC-mNPCs improved neurological outcomes, induced oligodendrocyte differentiation and remyelination, increased neural lineage differentiation, and decreased glial scar formation. Moreover, locomotor and bladder function were both rehabilitated. These beneficial effects are likely related to differential BMP-2/4/7 expression in neuronal cells, providing an empirical basis for gene therapy as a curative SCI treatment option.

Pathophysiology and Therapeutic Approaches for Spinal Cord Injury

Spinal cord injury (SCI) is a disabling condition that disrupts motor, sensory, and autonomic functions. Despite extensive research in the last decades, SCI continues to be a global health priority affecting thousands of individuals every year. The lack of effective therapeutic strategies for patients with SCI reflects its complex pathophysiology that leads to the point of no return in its function repair and regeneration capacity. Recently, however, several studies started to uncover the intricate network of mechanisms involved in SCI leading to the development of new therapeutic approaches. In this work, we present a detailed description of the physiology and anatomy of the spinal cord and the pathophysiology of SCI. Additionally, we provide an overview of different molecular strategies that demonstrate promising potential in the modulation of the secondary injury events that promote neuroprotection or neuroregeneration. We also briefly discuss other emerging therapies, including cell-based therapies, biomaterials, and epidural electric stimulation. A successful therapy might target different pathologic events to control the progression of secondary damage of SCI and promote regeneration leading to functional recovery.

Clinical translation of stem cell therapy for spinal cord injury still premature: results from a single-arm meta-analysis based on 62 clinical trials

BACKGROUND

How much scientific evidence is there to show that stem cell therapy is sufficient in preclinical and clinical studies of spinal cord injury before it is translated into clinical practice? This is a complicated problem. A single, small-sample clinical trial is difficult to answer, and accurate insights into this question can only be given by systematically evaluating all the existing evidence.

METHODS

The PubMed, Ovid-Embase, Web of Science, and Cochrane databases were searched from inception to February 10, 2022. Two independent reviewers performed the literature search, identified and screened the studies, and performed a quality assessment and data extraction.

RESULTS

In total, 62 studies involving 2439 patients were included in the analysis. Of these, 42 were single-arm studies, and 20 were controlled studies. The meta-analysis showed that stem cells improved the ASIA impairment scale score by at least one grade in 48.9% [40.8%, 56.9%] of patients with spinal cord injury. Moreover, the rate of improvement in urinary and gastrointestinal system function was 42.1% [27.6%, 57.2%] and 52.0% [23.6%, 79.8%], respectively. However, 28 types of adverse effects were observed to occur due to stem cells and transplantation procedures. Of these, neuropathic pain, abnormal feeling, muscle spasms, vomiting, and urinary tract infection were the most common, with an incidence of > 20%. While no serious adverse effects such as tumorigenesis were reported, this could be due to the insufficient follow-up period.

CONCLUSIONS

Overall, the results demonstrated that although the efficacy of stem cell therapy is encouraging, the subsequent adverse effects remain concerning. In addition, the clinical trials had problems such as small sample sizes, poor design, and lack of prospective registration, control, and blinding. Therefore, the current evidence is not sufficiently strong to support the clinical translation of stem cell therapy for spinal cord injury, and several problems remain. Additional well-designed animal experiments and high-quality clinical studies are warranted to address these issues.

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.

Induced Pluripotent Stem Cells for Inherited Optic Neuropathies-Disease Modeling and Therapeutic Development

BACKGROUND

Inherited optic neuropathies (IONs) cause progressive irreversible visual loss in children and young adults. There are limited disease-modifying treatments, and most patients progress to become severely visually impaired, fulfilling the legal criteria for blind registration. The seminal discovery of the technique for reprogramming somatic nondividing cells into induced pluripotent stem cells (iPSCs) has opened several exciting opportunities in the field of ION research and treatment.

EVIDENCE ACQUISITION

A systematic review of the literature was conducted with PubMed using the following search terms: autosomal dominant optic atrophy, ADOA, dominant optic atrophy, DOA, Leber hereditary optic neuropathy, LHON, optic atrophy, induced pluripotent stem cell, iPSC, iPSC derived, iPS, stem cell, retinal ganglion cell, and RGC. Clinical trials were identified on the ClinicalTrials.gov website.

RESULTS

This review article is focused on disease modeling and the therapeutic strategies being explored with iPSC technologies for the 2 most common IONs, namely, dominant optic atrophy and Leber hereditary optic neuropathy. The rationale and translational advances for cell-based and gene-based therapies are explored, as well as opportunities for neuroprotection and drug screening.

CONCLUSIONS

iPSCs offer an elegant, patient-focused solution to the investigation of the genetic defects and disease mechanisms underpinning IONs. Furthermore, this group of disorders is uniquely amenable to both the disease modeling capability and the therapeutic potential that iPSCs offer. This fast-moving area will remain at the forefront of both basic and translational ION research in the coming years, with the potential to accelerate the development of effective therapies for patients affected with these blinding diseases.

Diamond Concept as Principle for the Development of Spinal Cord Scaffold: A Literature Review

INTRODUCTION: Spinal cord injury (SCI) has been bringing detrimental impacts on the affected individuals. However, not only that, it also brings a tremendous effect on the socioeconomic and health-care system. Treatment regimen and strategy for SCI patient have been under further research. DISCUSSION: The main obstacles of regeneration on neuronal structure are the neuroinflammatory process and poor debris clearance, causing a longer healing process and an extensive inflammation process due to this particular inflammatory process. To resolve all of the mentioned significant issues in SCIs neuronal regeneration, a comprehensive model is necessary to analyze each step of progressive condition in SCI. In this review, we would like to redefine a comprehensive concept of the “Diamond Concept” from previously used in fracture management to SCI management, which consists of cellular platform, cellular inductivity, cellular conductivity, and material integrity. The scaffolding treatment strategy for SCI has been widely proposed due to its flexibility. It enables the physician to combine another treatment method such as neuroprotective or neuroregenerative or both in one intervention. CONCLUSION: Diamond concept perspective in the implementation of scaffolding could be advantageous to increase the outcome of SCI treatment.

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.

Cell Therapy for Neurological Disorders: The Perspective of Promising Cells

Neurological disorders are big public health challenges that are afflicting hundreds of millions of people around the world. Although many conventional pharmacological therapies have been tested in patients, their therapeutic efficacies to alleviate their symptoms and slow down the course of the diseases are usually limited. Cell therapy has attracted the interest of many researchers in the last several decades and has brought new hope for treating neurological disorders. Moreover, numerous studies have shown promising results. However, none of the studies has led to a promising therapy for patients with neurological disorders, despite the ongoing and completed clinical trials. There are many factors that may affect the outcome of cell therapy for neurological disorders due to the complexity of the nervous system, especially cell types for transplantation and the specific disease for treatment. This paper provides a review of the various cell types from humans that may be clinically used for neurological disorders, based on their characteristics and current progress in related studies.

Review of the Current Trends in Clinical Trials Involving Induced Pluripotent Stem Cells

In 2006, the induced pluripotent stem cell (iPSC) was presented to the world, paving the way for the development of a magnitude of novel therapeutic alternatives, addressing a diverse range of diseases. However, despite the immense cell therapy potential, relatively few clinical trials evaluating iPSC-technology have actually translated into interventional, clinically applied treatment regimens. Herein, our aim was to determine trends in globally conducted clinical trials involving iPSCs. Data were derived both from well-known registries recording clinical trials from across the globe, and databases from individual countries. Comparisons were firstly drawn between observational and interventional studies before the latter was further analyzed in terms of therapeutic and nontherapeutic trials. Our main observations included global distribution, purpose, target size, and types of disorder relevant to evaluated trials. In terms of nontherapeutic trials, the USA conducted the majority, a large average number of participants-187-was included in the trials, and studies on circulatory system disorders comprised a slightly higher proportion of total studies. Conversely, Japan was the frontrunner in terms of conducting therapeutic trials, and the average number of participants was much lower, at roughly 29. Disorders of the circulatory, as well as nervous and visual systems, were all studied in equal measure. This review highlights the impact that iPSC-based cell therapies can have, should development thereof gain more traction. We lastly considered a few companies that are actively utilizing iPSCs in the development of therapies for various diseases, for whom the global trends in clinical trials could become increasingly important.

Trends of Chitosan Based Delivery Systems in Neuroregeneration and Functional Recovery in Spinal Cord Injuries

Spinal cord injury (SCI) is one of the most complicated nervous system injuries with challenging treatment and recovery. Regenerative biomaterials such as chitosan are being reported for their wide use in filling the cavities, deliver curative drugs, and also provide adsorption sites for transplanted stem cells. Biomaterial scaffolds utilizing chitosan have shown certain therapeutic effects on spinal cord injury repair with some limitations. Chitosan-based delivery in stem cell transplantation is another strategy that has shown decent success. Stem cells can be directed to differentiate into neurons or glia in vitro. Stem cell-based therapy, biopolymer chitosan delivery strategies, and scaffold-based therapeutic strategies have been advancing as a combinatorial approach for spinal cord injury repair. In this review, we summarize the recent progress in the treatment strategies of SCI due to the use of bioactivity of chitosan-based drug delivery systems. An emphasis on the role of chitosan in neural regeneration has also been highlighted.

Stem Cell Therapy for Spinal Cord Injury

Traumatic spinal cord injury (SCI) results in direct and indirect damage to neural tissues, which results in motor and sensory dysfunction, dystonia, and pathological reflex that ultimately lead to paraplegia or tetraplegia. A loss of cells, axon regeneration failure, and time-sensitive pathophysiology make tissue repair difficult. Despite various medical developments, there are currently no effective regenerative treatments. Stem cell therapy is a promising treatment for SCI due to its multiple targets and reactivity benefits. The present review focuses on SCI stem cell therapy, including bone marrow mesenchymal stem cells, umbilical mesenchymal stem cells, adipose-derived mesenchymal stem cells, neural stem cells, neural progenitor cells, embryonic stem cells, induced pluripotent stem cells, and extracellular vesicles. Each cell type targets certain features of SCI pathology and shows therapeutic effects via cell replacement, nutritional support, scaffolds, and immunomodulation mechanisms. However, many preclinical studies and a growing number of clinical trials found that single-cell treatments had only limited benefits for SCI. SCI damage is multifaceted, and there is a growing consensus that a combined treatment is needed.

Induced pluripotent stem cell technology for spinal cord injury: a promising alternative therapy

Spinal cord injury has long been a prominent challenge in the trauma repair process. Spinal cord injury is a research hotspot by virtue of its difficulty to treat and its escalating morbidity. Furthermore, spinal cord injury has a long period of disease progression and leads to complications that exert a lot of mental and economic pressure on patients. There are currently a large number of therapeutic strategies for treating spinal cord injury, which range from pharmacological and surgical methods to cell therapy and rehabilitation training. All of these strategies have positive effects in the course of spinal cord injury treatment. This review mainly discusses the problems regarding stem cell therapy for spinal cord injury, including the characteristics and action modes of all relevant cell types. Induced pluripotent stem cells, which represent a special kind of stem cell population, have gained impetus in cell therapy development because of a range of advantages. Induced pluripotent stem cells can be developed into the precursor cells of each neural cell type at the site of spinal cord injury, and have great potential for application in spinal cord injury therapy.

Global trends in clinical trials involving pluripotent stem cells: a systematic multi-database analysis

Pluripotent stem cells (PSCs) hold great potential for novel therapeutic approaches to regenerate or replace functionally impaired tissues. Since the introduction of the induced pluripotent stem cell technology in 2006, the number of scientific publications on this topic has constantly been increasing. However, so far no therapy based on PSCs has found its way into routine clinical use. In this study, we examined research trends related to clinical trials involving PSCs based on data obtained from ClinicalTrials.gov, the ICTRP database from the World Health Organization, as well as from a search of all individual databases that are included in the ICTRP using a multistep search algorithm. Following a stringent inclusion/exclusion procedure 131 studies remained that could be classified as clinical trials involving PSCs. The magnitude of these studies (77.1%) was observational, which implies that no cells were transplanted into patients, and only a minority of studies (22.9%) were of an interventional study type. The number of clinical trials involving induced pluripotent stem cells (iPSCs, 74.8%) was substantially higher than the one involving embryonic stem cells (ESCs, 25.2%). However, the picture changes completely when focusing on interventional studies, where in the majority (73.3%) of cases ESCs were used. Interestingly, also the study duration was significantly shorter for interventional versus observational trials (p = 0.002). When focusing on the geographical study regions, it became obvious that the greatest part of all observational trials was performed in the USA (41.6%) and in France (16.8%), while the magnitude of interventional studies was performed in Asian countries (China 36.7%, Japan 13.3%, South Korea 10.0%) and in the field of ophthalmology. In summary, these results indicate that only a limited number of trials were focusing on the actual transplantation of PSCs into patients in a rather narrow field of diagnoses. The future will tell us, if the iPSC technology will ultimately overcome the current challenges and will finally make its way into routine clinical use.

Regenerative medicine for spinal cord injury: focus on stem cells and biomaterials

INTRODUCTION

Spinal cord injury (SCI) is a dramatic medical pathology consequence of a trauma (primary injury). However, most of the post-traumatic degeneration of the tissue is caused by the so-called secondary injury, which is known to be a multifactorial process. This, indeed, includes a wide spectrum of events: blood-brain barrier dysfunction, local inflammation, neuronal death, demyelination and disconnection of nerve pathways.

AREAS COVERED

Cell therapy represents a promising cure to target diseases and disorders at the cellular level, by restoring cell population or using cells as carriers of therapeutic cargo. In particular, regenerative medicine with stem cells represents the most appealing category to be used, thanks to their peculiar features.

EXPERT OPINION

Many preclinical research studies demonstrated that cell treatment can improve animal sensory/motor functions and so demonstrated to be very promising for clinical trials. In particular, recent advances have led to the development of biomaterials aiming to promote in situ cell delivery. This review digs into this topic discussing the possibility of cell treatment to improve medical chances in SCI repair.

A review of novel trends in management of canine spinal cord injury

Severe spinal cord injury (SCI) causing significant morbidity and mortality remains one of the most challenging problems in both human and veterinary medicine. Due to the restricted regeneration potential of the central nervous system (CNS) in mammals, the neurological deficit caused by spinal cord (SC) injury is permanent, and no therapeutic measures are able to completely restore neurological functions either in primates or in non-primate animals with traumatic tetraparesis/tetraplegia or paraparesis/paraplegia. The constant progress in the understanding of pathophysiologic events developing after spinal cord trauma constitute an unremitting inspiration for neuroscientists and health care professionals to test novel medicaments and treatment strategies to cope with this situation. Recent experimental studies and preclinical trials have delivered promising results. The aim of this review is a presentation of generally accepted methods of management of dogs with SCI as well as a report on new therapeutic modalities, and comment on their potential for clinical translation. The research strategy involved a search of PubMed, Medline, and ISI Web of Science from January 2010 to December 2018 using the terms “spinal cord injuryˮ and “management of spinal traumaˮ in the English language literature. References from selected papers were also scanned and evaluated for relevance.

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

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

Bone Marrow Very Small Embryonic-Like Stem Cells: New Generation of Autologous Cell Therapy Soon Ready for Prime Time?

Very small embryonic-like stem cells (VSELs) are major pluripotent stem cells described in human and mouse. In this issue of Stem Cell Reviews and Reports, Shaikh and colleagues show in a valuable work that mouse bone marrow collected after 5FU treatment contains VSELs able to undergo in vitro multi-lineage differentiation into cells from all three germ layers and also in germ and hematopoietic cells. These findings are robust since no confounding factor such as feeder cell fusion with VSELs can occur here. This paper allows one to better appreciate bone marrow-VSELs differentiation potential and opens new perspectives for autologous cell therapy. Furthermore, it might help explaining lots of contradictive data from the past 20 years, in particular related to ability of bone marrow cells to differentiate into cardiomyocytes.

Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017)

Cell therapy has been shown to be a key clinical therapeutic option for central nervous system diseases or damage. Standardization of clinical cell therapy procedures is an important task for professional associations devoted to cell therapy. The Chinese Branch of the International Association of Neurorestoratology (IANR) completed the first set of guidelines governing the clinical application of neurorestoration in 2011. The IANR and the Chinese Association of Neurorestoratology (CANR) collaborated to propose the current version "Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017)". The IANR council board members and CANR committee members approved this proposal on September 1, 2016, and recommend it to clinical practitioners of cellular therapy. These guidelines include items of cell type nomenclature, cell quality control, minimal suggested cell doses, patient-informed consent, indications for undergoing cell therapy, contraindications for undergoing cell therapy, documentation of procedure and therapy, safety evaluation, efficacy evaluation, policy of repeated treatments, do not charge patients for unproven therapies, basic principles of cell therapy, and publishing responsibility.

Embryonic Stem Cells in Development and Regenerative Medicine

After progressive improvement in embryonic stem (ES) cell field, several studies have been conducted to explore the usage of ES cells in regenerative medicine. Unlimited self renewal and pluripoteny properties, combined with encouraging preclinical trials, remark that ES cell technology might be promising for clinical practice. ES cells, which can form three germ layers in vitro, are potential candidates to study development at the cellular and molecular level. Understanding the cell fate decision and differentiation processes during development might enable generating functional progenitor cells for tissue restoration. Progression in gene modifications and tissue engineering technology has facilitated the derivation of desired cells for therapy. Success in differentiation protocols and identification the regulatory pathways simplify the research for clinical applications. Although there are established protocols for cell differentiation in vitro and promising preclinical studies in vivo, many challenges need to be adressed before clinical translation. In this review, ES cells are discussed as a model of development in vitro and as a potential candidate for regenerative medicine. This review also dissusses current challenges for ES cell based therapy.

Current Options for Cell Therapy in Spinal Cord Injury

Spinal cord injury (SCI) is a complex pathology that evolves after primary acute mechanical injury, causing further damage to the spinal cord tissue that exacerbates clinical outcomes. Based on encouraging results from preclinical experiments, some cell treatments being translated into clinical practice demonstrate promising and effective improvement in sensory/motor function. Combinatorial treatments of cell and drug/biological factors have been demonstrated to be more effective than cell treatments alone. Recent advances have led to the development of biomaterials aiming to promote in situ cell delivery for SCI, together with combinatorial strategies using drugs/biomolecules to achieve a maximized multitarget approach. This review provides an overview of single and combinatorial regenerative cell treatments as well as potential delivery options to treat SCI.

Role of physiotherapy in the mobilization of patients with spinal cord injury undergoing human embryonic stem cells transplantation

Background

The major complication faced by patients with chronic static spinal cord injury (SCI) is the loss of mobilization. With the aim to rehabilitate SCI patients, physiotherapy is performed worldwide. However, it only helps the patients to live with their disabilities. An interdisciplinary management involving human embryonic stem cell (hESC) therapy along with physiotherapy as a supportive therapy offers regenerative treatment of the patients with SCI.

Main body

The present study focuses on the role of physiotherapy in the mobilization of patients with SCI (paraplegic 136; tetraplegics 90) undergoing hESC therapy. At admission, patients were assessed on the basis of clinical and American Spinal Injury Association Impairment Scale (AIS), where 153, 32, 36 and 5 patients were designated with AIS score A, B, C and D, respectively. After 8–12 weeks of hESC therapy and physiotherapy, the patients showed clinical and scoring improvement. The patients with AIS score A shifted to B (15.0 %) and C (37.3 %), whereas, patients with grade B moved to C (40.6 %) and D (3.1 %). Patients with AIS score C and D shifted to grade D (13.9 %) and E (60.0 %), respectively. Moreover, orthotic devices were reduced to simpler ones.

Conclusion

The physiotherapy aided in training of cells and took care of atrophy of limbs, whereas hESC therapy resulted in an overall improvement of the patients with SCI.

Electronic supplementary material

The online version of this article (doi:10.1186/s40169-016-0122-5) contains supplementary material, which is available to authorized users.