Transplantation of spinal cord-derived neural stem cells for ALS: Analysis of phase 1 and 2 trials

Transplantation of embryonic spinal motor neurons into peripheral nerves enables functional reconstruction of a denervated diaphragm

Respiratory muscle paralysis due to trauma or neurodegenerative diseases can have devastating consequences. Only a few studies have investigated the reconstruction of motor function in denervated diaphragms caused by such conditions. Here, we studied the efficacy of transplanting E14 embryonic spinal motor neurons (SMNs) into peripheral nerve grafts for functionally reconstructing a denervated diaphragm in a rat model. The diaphragms of 8-week-old male Fischer 344 rats were first denervated by transecting the phrenic nerves. Subsequently, peripheral nerve grafts taken from the lower limb were used for neurotization of the denervated diaphragms. One week later, fetal E14 SMNs were transplanted into the peripheral nerve grafts. After 3 months, we observed functional contraction of the diaphragm following neuromuscular electrical stimulation (NMES) of the peripheral nerve graft. Additionally, we confirmed that SMN transplantation into the peripheral nerve graft had an inhibitory effect on diaphragm muscle atrophy. The SMNs transplanted into the peripheral nerve grafts formed a structure similar to the spinal cord, and the neuromuscular junction of the denervated diaphragm was reinnervated. These findings suggest the establishment of an ectopic motor neuron pool in the peripheral nerve graft. Free peripheral intra-nerve SMN transplantation in combination with NMES, which can be applied for diaphragmatic pacing, offers novel insights into the development of neuroregenerative therapies for treating life-threatening and intractable respiratory muscle paralysis caused by severe nerve damage and degenerative diseases.

Cell therapy for neurological disorders

Cell therapies for neurological disorders are entering the clinic and present unique challenges and opportunities compared with conventional medicines. They have the potential to replace damaged nervous tissue and integrate into the brain or spinal cord to produce functional effects for the lifetime of the patient, which could revolutionize the way clinicians treat debilitating neurological disorders. The major challenge has been cell sourcing, which historically relied mainly on fetal brain tissue. This has largely been overcome with the advent of pluripotent stem cell technology and the ability to make almost any cell of the nervous system at scale. Furthermore, advances in gene editing now allow the generation of genetically modified cells that could perform better and evade the immune system. With all the remarkable new approaches to treat neurological disorders, we take a critical look at the state of current clinical trials and how challenges may be overcome with the evolving technology and innovation occurring in the stem cell field.

Current status and new avenues of stem cell-based preclinical and therapeutic approaches in amyotrophic lateral sclerosis

INTRODUCTION

Cell therapy development represents a critical challenge in amyotrophic lateral sclerosis (ALS) research. Despite more than 20 years of basic and clinical research, no definitive safety and efficacy results of cell-based therapies for ALS have been published.

AREAS COVERED

This review summarizes advances using stem cells (SCs) in pre-clinical studies to promote clinical translation and in clinical trials to treat ALS. New technologies have been developed and new experimental in vitro and animal models are now available to facilitate pre-clinical research in this field and to determine the most promising approaches to pursue in patients. New clinical trial designs aimed at developing personalized SC-based treatment with biological endpoints are being defined.

EXPERT OPINION

Knowledge of the basic biology of ALS and on the use of SCs to study and potentially treat ALS continues to grow. However, a consensus has yet to emerge on how best to translate these results into therapeutic applications. The selection and follow-up of patients should be based on clinical, biological, and molecular criteria. Planning of SC-based clinical trials should be coordinated with patient profiling genetically and molecularly to achieve personalized treatment. Much work within basic and clinical research is still needed to successfully transition SC therapy in ALS.

Immunosuppression in stem cell clinical trials of neural and retinal cell types: A systematic review

BACKGROUND

Pharmacologic immunosuppression regimes are commonly employed in stem cell clinical trials to mitigate host immune rejection and promote survival and viability of transplanted cells. Immunosuppression and cell survival has been extensively studied in retinal and spinal tissues. The applicability of stem cell therapy is rapidly expanding to other sensory organs such as the ear and hearing. As regenerative therapy is directed to new areas, a greater understanding of immunosuppression strategies and their efficacy is required to facilitate translation to organ-specific biologic microenvironments.

OBJECTIVE

This systematic review appraises the current literature regarding immunosuppression strategies employed in stem cell trials of retinal and neural cells.

METHODS

This systematic review was performed in line with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Inclusion criteria included studies presenting data on neural or retinal cells as part of an in-human clinical trial that detailed the immunosuppression regime used. Exclusion criteria included non-English language studies, animal studies, review articles, case reports, editorials, and letters. The databases Medline, Embase, Scopus, Web of Science, and the Cochrane Library were searched from inception to February 2024. Risk of bias was evaluated using the ROBINS-I tool.

RESULTS

Eighteen articles fit the inclusion criteria. Nine articles concerned retinal cells, 5 concerned spinal cord injury, and 4 concerned amyotrophic lateral sclerosis. A multi-drug and short-term immunosuppression regime were commonly employed in the identified studies. Detected immune responses in treated patients were rare. Common immunosuppression paradigms included tacrolimus, mycophenolate mofetil and tapering doses of steroids. Local immunosuppression with steroids was employed in some studies concerning retinal diseases.

DISCUSSION

A short-term course of systemic immunosuppression seemed efficacious for most included studies, with some showing grafted cells viable months to years after immunosuppression had stopped. Longer-term follow-up is required to see if this remains the case. Side effects related to immunosuppression were uncommon.

Stem cell therapeutics and gene therapy for neurologic disorders

Rapid advances in biological knowledge and technological innovation have greatly advanced the fields of stem cell and gene therapies to combat a broad spectrum of neurologic disorders. Researchers are currently exploring a variety of stem cell types (e.g., embryonic, progenitor, induced pluripotent) and various transplantation strategies, each with its own advantages and drawbacks. Similarly, various gene modification techniques (zinc finger, TALENs, CRISPR-Cas9) are employed with various delivery vectors to modify underlying genetic contributors to neurologic disorders. While these two individual fields continue to blaze new trails, it is the combination of these technologies which enables genetically engineered stem cells and vastly increases investigational and therapeutic opportunities. The capability to culture and expand stem cells outside the body, along with their potential to correct genetic abnormalities in patient-derived cells or enhance cells with extra gene products, unleashes the full biological potential for innovative, multifaceted approaches to treat complex neurological disorders. In this review, we provide an overview of stem cell and gene therapies in the context of neurologic disorders, highlighting recent advances and current shortcomings, and discuss prospects for future therapies in clinical settings.

Therapeutic role of neural stem cells in neurological diseases

The failure of endogenous repair is the main feature of neurological diseases that cannot recover the damaged tissue and the resulting dysfunction. Currently, the range of treatment options for neurological diseases is limited, and the approved drugs are used to treat neurological diseases, but the therapeutic effect is still not ideal. In recent years, different studies have revealed that neural stem cells (NSCs) have made exciting achievements in the treatment of neurological diseases. NSCs have the potential of self-renewal and differentiation, which shows great foreground as the replacement therapy of endogenous cells in neurological diseases, which broadens a new way of cell therapy. The biological functions of NSCs in the repair of nerve injury include neuroprotection, promoting axonal regeneration and remyelination, secretion of neurotrophic factors, immune regulation, and improve the inflammatory microenvironment of nerve injury. All these reveal that NSCs play an important role in improving the progression of neurological diseases. Therefore, it is of great significance to better understand the functional role of NSCs in the treatment of neurological diseases. In view of this, we comprehensively discussed the application and value of NSCs in neurological diseases as well as the existing problems and challenges.

New Insights into Oxidative Stress and Inflammatory Response in Neurodegenerative Diseases

Oxidative stress (OS) and inflammation are two important and well-studied pathological hallmarks of neurodegenerative diseases (NDDs). Due to elevated oxygen consumption, the high presence of easily oxidizable polyunsaturated fatty acids and the weak antioxidant defenses, the brain is particularly vulnerable to oxidative injury. Uncertainty exists over whether these deficits contribute to the development of NDDs or are solely a consequence of neuronal degeneration. Furthermore, these two pathological hallmarks are linked, and it is known that OS can affect the inflammatory response. In this review, we will overview the last findings about these two pathways in the principal NDDs. Moreover, we will focus more in depth on amyotrophic lateral sclerosis (ALS) to understand how anti-inflammatory and antioxidants drugs have been used for the treatment of this still incurable motor neuron (MN) disease. Finally, we will analyze the principal past and actual clinical trials and the future perspectives in the study of these two pathological mechanisms.

An optogenetic cell therapy to restore control of target muscles in an aggressive mouse model of amyotrophic lateral sclerosis

Breakdown of neuromuscular junctions (NMJs) is an early pathological hallmark of amyotrophic lateral sclerosis (ALS) that blocks neuromuscular transmission, leading to muscle weakness, paralysis and, ultimately, premature death. Currently, no therapies exist that can prevent progressive motor neuron degeneration, muscle denervation, or paralysis in ALS. Here, we report important advances in the development of an optogenetic, neural replacement strategy that can effectively restore innervation of severely affected skeletal muscles in the aggressive SOD1G93A mouse model of ALS, thus providing an interface to selectively control the function of targeted muscles using optical stimulation. We also identify a specific approach to confer complete survival of allogeneic replacement motor neurons. Furthermore, we demonstrate that an optical stimulation training paradigm can prevent atrophy of reinnervated muscle fibers and results in a tenfold increase in optically evoked contractile force. Together, these advances pave the way for an assistive therapy that could benefit all ALS patients.

Cell and gene therapy for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal and incurable neurodegenerative disorder with rapidly progressive skeletal muscle weakness, which can also cause a variable cognitive deficit. Genetic causes are only identified in approximately 10% of all cases, with complex genotype-phenotype associations, making it challenging to identify treatment targets. What further hampers therapeutic development is a broad heterogeneity in mechanisms, possible targets, and disturbances across various cell types, aside from the cortical and spinal motor neurons that lie at the heart of the pathology of ALS. Over the last decade, significant progress in biotechnologic techniques, cell and ribonucleic acid (RNA) engineering, animal models, and patient-specific human stem cell and organoid models have accelerated both mechanistic and therapeutic discoveries. The growing number of clinical trials mirrors this. This chapter reviews the current state of human preclinical models supporting trial strategies as well as recent clinical cell and gene therapy approaches.

Cell Transplantation for Repair of the Spinal Cord and Prospects for Generating Region-Specific Exogenic Neuronal Cells

Spinal cord injury (SCI) is associated with currently irreversible consequences in several functional components of the central nervous system. Despite the severity of injury, there remains no approved treatment to restore function. However, with a growing number of preclinical studies and clinical trials, cell transplantation has gained significant potential as a treatment for SCI. Researchers have identified several cell types as potential candidates for transplantation. To optimize successful functional outcomes after transplantation, one key factor concerns generating neuronal cells with regional and subtype specificity, thus calling on the developmental transcriptome patterning of spinal cord cells. A potential source of spinal cord cells for transplantation is the generation of exogenic neuronal progenitor cells via the emerging technologies of gene editing and blastocyst complementation. This review highlights the use of cell transplantation to treat SCI in the context of relevant developmental gene expression patterns useful for producing regionally specific exogenic spinal cells via in vitro differentiation and blastocyst complementation.

Therapeutic targeting of ALS pathways: Refocusing an incomplete picture

Numerous potential amyotrophic lateral sclerosis (ALS)-relevant pathways have been hypothesized and studied preclinically, with subsequent translation to clinical trial. However, few successes have been observed with only modest effects. Along with an improved but incomplete understanding of ALS as a neurodegenerative disease is the evolution of more sophisticated and diverse in vitro and in vivo preclinical modeling platforms, as well as clinical trial designs. We highlight proposed pathological pathways that have been major therapeutic targets for investigational compounds. It is likely that the failures of so many of these therapeutic compounds may not have occurred because of lack of efficacy but rather because of a lack of preclinical modeling that would help define an appropriate disease pathway, as well as a failure to establish target engagement. These challenges are compounded by shortcomings in clinical trial design, including lack of biomarkers that could predict clinical success and studies that are underpowered. Although research investments have provided abundant insights into new ALS-relevant pathways, most have not yet been developed more fully to result in clinical study. In this review, we detail some of the important, well-established pathways, the therapeutics targeting them, and the subsequent clinical design. With an understanding of some of the shortcomings in translational efforts over the last three decades of ALS investigation, we propose that scientists and clinicians may choose to revisit some of these therapeutic pathways reviewed here with an eye toward improving preclinical modeling, biomarker development, and the investment in more sophisticated clinical trial designs.

Muscle Involvement in Amyotrophic Lateral Sclerosis: Understanding the Pathogenesis and Advancing Therapeutics

Amyotrophic lateral sclerosis (ALS) is a fatal condition characterized by the selective loss of motor neurons in the motor cortex, brainstem, and spinal cord. Muscle involvement, muscle atrophy, and subsequent paralysis are among the main features of this disease, which is defined as a neuromuscular disorder. ALS is a persistently progressive disease, and as motor neurons continue to degenerate, individuals with ALS experience a gradual decline in their ability to perform daily activities. Ultimately, muscle function loss may result in paralysis, presenting significant challenges in mobility, communication, and self-care. While the majority of ALS research has traditionally focused on pathogenic pathways in the central nervous system, there has been a great interest in muscle research. These studies were carried out on patients and animal models in order to better understand the molecular mechanisms involved and to develop therapies aimed at improving muscle function. This review summarizes the features of ALS and discusses the role of muscle, as well as examines recent studies in the development of treatments.

Umbilical cord mesenchymal stem cell-conditioned medium inhibits microglial activation to ameliorate neuroinflammation in amyotrophic lateral sclerosis mice and cell models

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease for which few effective therapeutic strategies are available. Increasing evidence indicates that neuroinflammation plays a significant role in ALS pathogenesis. Mesenchymal stem cell (MSC)-based therapy has been proposed for the treatment of neurodegenerative diseases, including ALS. In this study, we first demonstrated that systemic administration of conditioned medium derived from umbilical cord MSCs (UCMSC-CM) extends the lifespan of transgenic SOD1-G93A mice, a well-characterized model of familial ALS. Moreover, UCMSC-CM inhibits microglial activation and astrogliosis and alleviates the inflammatory milieu by reducing the release of proinflammatory cytokines and the expression of iNOS in the spinal cord. Using BV-2 cells overexpressing the SOD1-G93A mutant as an ALS cellular model, we uncovered that UCMSC-CM also suppresses the lipopolysaccharide (LPS)-induced inflammatory response, including reduced expression of proinflammatory cytokines and iNOS. Importantly, by culturing astrocytes alone in microglia-conditioned medium (MCM) or together with microglia in a transwell coculture system, we found that UCMSC-CM modulates the secretome of microglia exposed to inflammatory stimuli, thereby preventing the conversion of astrocytes to the A1 neurotoxic phenotype. This study revealed the anti-inflammatory properties of UCMSC-CM and its regulatory effect on glial activation in the treatment of neuroinflammation in ALS, providing strong evidence for the clinical application of UCMSC-CM.

Clinical results of neurorestorative cell therapies and therapeutic indications according to cellular bio-proprieties

Cell therapies have been explored to treat patients with nervous diseases for over 20 years. Even though most kinds of cell therapies demonstrated neurorestorative effects in non-randomized clinical trials; the effects of the majority type cells could not be confirmed by randomized controlled trials. In this review, clinical therapeutic results of neurorestorative cell therapies according to cellular bio-proprieties or cellular functions were introduced. Currently it was demonstrated from analysis of this review that some indications of cell therapies were not appropriate, they might be reasons why their neurorestorative effects could not be proved by multicenter, randomized, double blind, placebo-controlled clinical trials. Theoretically if one kind of cell therapy has neurorestorative effects according to its cellular bio-proprieties, it should have appropriate indications. The cell therapies with special bio-properties is promising if the indication selections are appropriate, such as olfactory ensheathing cells for chronic ischemic stroke, and their neurorestorative effects can be confirmed by higher level clinical trials of evidence-based medicine.

Mn-Based Methacrylated Gellan Gum Hydrogels for MRI-Guided Cell Delivery and Imaging

This work aims to engineer a new stable injectable Mn-based methacrylated gellan gum (Mn/GG-MA) hydrogel for real-time monitored cell delivery into the central nervous system. To enable the hydrogel visualization under Magnetic Resonance Imaging (MRI), GG-MA solutions were supplemented with paramagnetic Mn2+ ions before its ionic crosslink with artificial cerebrospinal fluid (aCSF). The resulting formulations were stable, detectable by T1-weighted MRI scans and also injectable. Cell-laden hydrogels were prepared using the Mn/GG-MA formulations, extruded into aCSF for crosslink, and after 7 days of culture, the encapsulated human adipose-derived stem cells remained viable, as assessed by Live/Dead assay. In vivo tests, using double mutant MBPshi/shi/rag2 immunocompromised mice, showed that the injection of Mn/GG-MA solutions resulted in a continuous and traceable hydrogel, visible on MRI scans. Summing up, the developed formulations are suitable for both non-invasive cell delivery techniques and image-guided neurointerventions, paving the way for new therapeutic procedures.

Cell therapy in ALS: An update on preclinical and clinical studies

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the loss of motor neurons and neuromuscular impairment leading to complete paralysis, respiratory failure and premature death. The pathogenesis of the disease is multifactorial and noncell-autonomous involving the central and peripheral compartments of the neuromuscular axis and the skeletal muscle. Advanced clinical trials on specific ALS-related pathways have failed to significantly slow the disease. Therapy with stem cells from different sources has provided a promising strategy to protect the motor units exerting their effect through multiple mechanisms including neurotrophic support and excitotoxicity and neuroinflammation modulation, as evidenced from preclinical studies. Several phase I and II clinical trial of ALS patients have been developed showing positive effects in terms of safety and tolerability. However, the modest results on functional improvement in ALS patients suggest that only a coordinated effort between basic and clinical researchers could solve many problems, such as selecting the ideal stem cell source, identifying their mechanism of action and expected clinical outcomes. A promising approach may be stem cells selected or engineered to deliver optimal growth factor support at multiple sites along the neuromuscular pathway. This review covers recent advances in stem cell therapies in animal models of ALS, as well as detailing the human clinical trials that have been done and are currently undergoing development.

Neural stem/progenitor cell-derived extracellular vesicles: A novel therapy for neurological diseases and beyond

As bilayer lipid membrane vesicles secreted by neural stem/progenitor cells (NSCs), NSC-derived extracellular vesicles (NSC-EVs) have attracted growing attention for their promising potential to serve as novel therapeutic agents in treatment of neurological diseases due to their unique physicochemical characteristics and biological functions. NSC-EVs exhibit advantages such as stable physical and chemical properties, low immunogenicity, and high penetration capacity to cross blood-brain barrier to avoid predicaments of the clinical applications of NSCs that include autoimmune responses, ethical/religious concerns, and the problematic logistics of acquiring fetal tissues. More importantly, NSC-EVs inherit excellent neuroprotective and neuroregenerative potential and immunomodulatory capabilities from parent cells, and display outstanding therapeutic effects on mitigating behavioral alterations and pathological phenotypes of patients or animals with neurological diseases. In this review, we first comprehensively summarize the progress in functional research and application of NSC-EVs in different neurological diseases, including neurodegenerative diseases, acute neurological diseases, dementia/cognitive dysfunction, and peripheral diseases. Next, we provide our thoughts on current limitations/concerns as well as tremendous potential of NSC-EVs in clinical applications. Last, we discuss future directions of further investigations on NSC-EVs and their probable applications in both basic and clinical research.

Molecular Mechanisms and Clinical Application of Multipotent Stem Cells for Spinal Cord Injury

Spinal Cord Injury (SCI) is a common neurological disorder with devastating psychical and psychosocial sequelae. The majority of patients after SCI suffer from permanent disability caused by motor dysfunction, impaired sensation, neuropathic pain, spasticity as well as urinary complications, and a small number of patients experience a complete recovery. Current standard treatment modalities of the SCI aim to prevent secondary injury and provide limited recovery of lost neurological functions. Stem Cell Therapy (SCT) represents an emerging treatment approach using the differentiation, paracrine, and self-renewal capabilities of stem cells to regenerate the injured spinal cord. To date, multipotent stem cells including mesenchymal stem cells (MSCs), neural stem cells (NSCs), and hematopoietic stem cells (HSCs) represent the most investigated types of stem cells for the treatment of SCI in preclinical and clinical studies. The microenvironment of SCI has a significant impact on the survival, proliferation, and differentiation of transplanted stem cells. Therefore, a deep understanding of the pathophysiology of SCI and molecular mechanisms through which stem cells act may help improve the treatment efficacy of SCT and find new therapeutic approaches such as stem-cell-derived exosomes, gene-modified stem cells, scaffolds, and nanomaterials. In this literature review, the pathogenesis of SCI and molecular mechanisms of action of multipotent stem cells including MSCs, NSCs, and HSCs are comprehensively described. Moreover, the clinical efficacy of multipotent stem cells in SCI treatment, an optimal protocol of stem cell administration, and recent therapeutic approaches based on or combined with SCT are also discussed.

Patching Up the Permeability: The Role of Stem Cells in Lessening Neurovascular Damage in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a debilitating disease with poor prognosis. The pathophysiology of ALS is commonly debated, with theories involving inflammation, glutamate excitotoxity, oxidative stress, mitochondria malfunction, neurofilament accumulation, inadequate nutrients or growth factors, and changes in glial support predominating. These underlying pathological mechanisms, however, act together to weaken the blood brain barrier and blood spinal cord barrier, collectively considered as the blood central nervous system barrier (BCNSB). Altering the impermeability of the BCNSB impairs the neurovascular unit, or interdependent relationship between the brain and advances the concept that ALS is has a significant neurovascular component contributing to its degenerative presentation. This unique categorization of ALS opens a variety of treatment options targeting the reestablishment of BCNSB integrity. This review will critically assess the evidence implicating the significant neurovascular components of ALS pathophysiology, while also offering an in-depth discussion regarding the use of stem cells to repair these pathological changes within the neurovascular unit.

Transplantation of human neural progenitor cells secreting GDNF into the spinal cord of patients with ALS: a phase 1/2a trial

Amyotrophic lateral sclerosis (ALS) involves progressive motor neuron loss, leading to paralysis and death typically within 3–5 years of diagnosis. Dysfunctional astrocytes may contribute to disease and glial cell line-derived neurotrophic factor (GDNF) can be protective. Here we show that human neural progenitor cells transduced with GDNF (CNS10-NPC-GDNF) differentiated to astrocytes protected spinal motor neurons and were safe in animal models. CNS10-NPC-GDNF were transplanted unilaterally into the lumbar spinal cord of 18 ALS participants in a phase 1/2a study (NCT02943850). The primary endpoint of safety at 1 year was met, with no negative effect of the transplant on motor function in the treated leg compared with the untreated leg. Tissue analysis of 13 participants who died of disease progression showed graft survival and GDNF production. Benign neuromas near delivery sites were common incidental findings at post-mortem. This study shows that one administration of engineered neural progenitors can provide new support cells and GDNF delivery to the ALS patient spinal cord for up to 42 months post-transplantation.

A phase 1/2a study shows that human neural progenitor cells modified to release the growth factor GDNF are safely transplanted into the spinal cord of patients with ALS, with cell survival and GDNF production for over 3 years.

Pharmacotherapy for Amyotrophic Lateral Sclerosis: A Review of Approved and Upcoming Agents

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder involving loss of upper and lower motor neurons, with most cases ending in death within 3-5 years of onset. Several molecular and cellular pathways have been identified to cause ALS; however, treatments to stop or reverse disease progression are yet to be found. Riluzole, a neuroprotective agent offering only a modest survival benefit, has long been the sole disease-modifying therapy for ALS. Edaravone, which demonstrated statistically significant slowing of ALS disease progression, is gaining approval in an increasing number of countries since its first approval in 2015. Sodium phenylbutyrate and taurursodiol (PB-TURSO) was conditionally approved in Canada in 2022, having shown significant slowing of disease progression and prolonged survival. Most clinical trials have focused on testing small molecules affecting common cellular pathways in ALS: targeting glutamatergic, apoptotic, inflammatory, and oxidative stress mechanisms among others. More recently, clinical trials utilizing stem cell transplantation and other biologics have emerged. This rich and ever-growing pipeline of investigational products, along with innovative clinical trial designs, collaborative trial networks, and an engaged ALS community', provide renewed hope to finding a cure for ALS. This article reviews existing ALS therapies and the current clinical drug development pipeline.

Monoclonal antibody-mediated immunosuppression enables long-term survival of transplanted human neural stem cells in mouse brain

BACKGROUND

As the field of stem cell therapy advances, it is important to develop reliable methods to overcome host immune responses in animal models. This ensures survival of transplanted human stem cell grafts and enables predictive efficacy testing. Immunosuppressive drugs derived from clinical protocols are frequently used but are often inconsistent and associated with toxic side effects. Here, using a molecular imaging approach, we show that immunosuppression targeting costimulatory molecules CD4 and CD40L enables robust survival of human xenografts in mouse brain, as compared to conventional tacrolimus and mycophenolate mofetil.

METHODS

Human neural stem cells were modified to express green fluorescent protein and firefly luciferase. Cells were implanted in the fimbria fornix of the hippocampus and viability assessed by non-invasive bioluminescent imaging. Cell survival was assessed using traditional pharmacologic immunosuppression as compared to monoclonal antibodies directed against CD4 and CD40L. This paradigm was also implemented in a transgenic Alzheimer's disease mouse model.

RESULTS

Graft rejection occurs within 7 days in non-immunosuppressed mice and within 14 days in mice on a traditional regimen. The addition of dual monoclonal antibody immunosuppression extends graft survival past 7 weeks (p < .001) on initial studies. We confirm dual monoclonal antibody treatment is superior to either antibody alone (p < .001). Finally, we demonstrate robust xenograft survival at multiple cell doses up to 6 months in both C57BL/6J mice and a transgenic Alzheimer's disease model (p < .001). The dual monoclonal antibody protocol demonstrated no significant adverse effects, as determined by complete blood counts and toxicity screen.

CONCLUSIONS

This study demonstrates an effective immunosuppression protocol for preclinical testing of stem cell therapies. A transition towards antibody-based strategies may be advantageous by enabling stem cell survival in preclinical studies that could inform future clinical trials.

Hunting for the cause: Evidence for prion-like mechanisms in Huntington’s disease

The hypothesis that pathogenic protein aggregates associated with neurodegenerative diseases spread from cell-to-cell in the brain in a manner akin to infectious prions has gained substantial momentum due to an explosion of research in the past 10–15 years. Here, we review current evidence supporting the existence of prion-like mechanisms in Huntington’s disease (HD), an autosomal dominant neurodegenerative disease caused by expansion of a CAG repeat tract in exon 1 of the huntingtin (HTT) gene. We summarize information gained from human studies and in vivo and in vitro models of HD that strongly support prion-like features of the mutant HTT (mHTT) protein, including potential involvement of molecular features of mHTT seeds, synaptic structures and connectivity, endocytic and exocytic mechanisms, tunneling nanotubes, and nonneuronal cells in mHTT propagation in the brain. We discuss mechanisms by which mHTT aggregate spreading and neurotoxicity could be causally linked and the potential benefits of targeting prion-like mechanisms in the search for new disease-modifying therapies for HD and other fatal neurodegenerative diseases.

Stem cell therapy for central nervous system disorders: Metabolic interactions between transplanted cells and local microenvironments

Stem cell therapy is a promising and rapidly advancing treatment strategy for a multitude of neurologic disorders. Yet, while early phase clinical trials are being pursued in many disorders, the mechanism of action often remains unclear. One important potential mechanism by which stem cells provide neuroprotection is through metabolic signaling with diseased neurons, glia, and other cell types in the nervous system microenvironment. Early studies exploring such interactions report normalization of glucose metabolism, induction of protective mitochondrial genes, and even interactions with supportive neurovasculature. Local metabolic conditions also impact stem cell biology, which can have a large impact on transplant viability and efficacy. Epigenetic changes that occur in the donor prior to collection of stem cells, and even during in vitro culture conditions, may have effects on stem cell biology that are carried into the host upon stem cell transplantation. Transplanted stem cells also face potentially toxic metabolic microenvironments at the targeted transplant site. Novel approaches for metabolically "preconditioning" stem cells prior to transplant harness metabolic machinery to optimize stem cell survival upon transplant. Ultimately, an improved understanding of the metabolic cross-talk between implanted stem cells and the local nervous system environment, in both disease and injury states, will increase the likelihood of success in translating stem cell therapy to early trials in neurological disease.

Highly feasible procedure for laparoscopic transplantation of cell sheets under pneumoperitoneum in porcine model

INTRODUCTION

Cell sheet technology is one of the most successful methodologies in regenerative medicine. Various applications of cell sheets have been introduced in first-in-human studies in several clinical fields. When transplanting a cell sheet into internal organs, a relatively large incision is required for delivery due to difficulty handling the sheet. We developed a laparoscopic delivery procedure for safe and easy transplantation of cell sheets in a porcine model.

METHODS

Pneumoperitoneum was established by inflation with CO₂. First, to increase the strength during handling, fibrin was sprayed onto the surface of the cell sheet, and then a myoblast sheet was placed onto the newly developed carrier. The sheets were pinched with laparoscopic forceps to insert into the abdominal cavity through the laparoscopic port. Myoblast sheets were then applied to the surface of the liver, colon, small intestine, and stomach, and procedure times were measured. At three days post transplantation, a histopathological examination was performed to confirm engraftment of the sheet. The function and engraftment were also analyzed in a duodenal endoscopic submucosal dissection (ESD) model.

RESULTS

The fibrin-processed myoblast sheet was able to be managed with conventional laparoscopic forceps without breaking. Despite the drastic change in air pressure by passing through the laparoscopic port, the sheets suffered no apparent damage. The transplantation procedure times did not markedly differ among transplant sites. A histopathological examination revealed thin-layered, desmin-positive cells at each transplant site. With transplantation following ESD, the engrafted myoblast sheets effectively prevented delayed perforation.

CONCLUSIONS

Our procedure is simple, and the system involves a carrier made of medically fit silicon, commercially available fibrin glue and conventional laparoscopic forceps. Our procedure is a powerful tool for laparoscopical cell sheet transplantation.

Transplantation of Human Glial Progenitors to Immunodeficient Neonatal Mice with Amyotrophic Lateral Sclerosis (SOD1/rag2)

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal disease with no effective therapy. The neurodegenerative character of ALS was an appealing target for stem cell-based regenerative approaches. Different types of stem cells have been transplanted in both preclinical and clinical settings, but no convincing outcomes have been noted. Human glial restricted precursors (hGRPs) transplanted intraventricularly to neonatal, immunodeficient mice rescued lifespan of dysmyelinated mice. Intraspinal injection of hGRPs also provided benefits in the mouse model of ALS. Therefore, we have recently developed an immunodeficient model of ALS (double mutant SOD1/rag2), and, in this study, we tested the strategy previously used in dysmyelinated mice of intraventricular transplantation of hGRPs to immunodeficient mice. To maximize potential therapeutic benefits, the cells were implanted into neonates. We used magnetic resonance imaging to investigate the progression of neurodegeneration and therapeutic responses. A cohort of animals was devoted to survival assessment. Postmortem analysis included immunohistochemistry, Nissl staining, and Western blots. Cell transplantation was not associated with improved animal survival, slowing neurodegeneration, or accumulation of misfolded superoxide dismutase 1. Postmortem analysis did not reveal any surviving hGRPs. Grafting into neonatal immunodeficient recipients did not prevent ALS-induced cell loss, which might explain the lack of positive therapeutic effects. The results of this study are in line with the modest effects of clinical neurotransplantations. Therefore, we urge stem cell and ALS communities to develop and implement cell tracking methods to better understand cell fates in the clinic.

Potential of Cellular Therapy for ALS: Current Strategies and Future Prospects

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive upper and lower motor neuron (MN) degeneration with unclear pathology. The worldwide prevalence of ALS is approximately 4.42 per 100,000 populations, and death occurs within 3-5 years after diagnosis. However, no effective therapeutic modality for ALS is currently available. In recent years, cellular therapy has shown considerable therapeutic potential because it exerts immunomodulatory effects and protects the MN circuit. However, the safety and efficacy of cellular therapy in ALS are still under debate. In this review, we summarize the current progress in cellular therapy for ALS. The underlying mechanism, current clinical trials, and the pros and cons of cellular therapy using different types of cell are discussed. In addition, clinical studies of mesenchymal stem cells (MSCs) in ALS are highlighted. The summarized findings of this review can facilitate the future clinical application of precision medicine using cellular therapy in ALS.

Are Cell-Based Therapies Safe and Effective in the Treatment of Neurodegenerative Diseases? A Systematic Review with Meta-Analysis

Over the past two decades, significant advances have been made in the field of regenerative medicine. However, despite being of the utmost clinical urgency, there remains a paucity of therapeutic strategies for conditions with substantial neurodegeneration such as (progressive) multiple sclerosis (MS), spinal cord injury (SCI), Parkinson's disease (PD) and Alzheimer's disease (AD). Different cell types, such as mesenchymal stromal cells (MSC), neuronal stem cells (NSC), olfactory ensheathing cells (OEC), neurons and a variety of others, already demonstrated safety and regenerative or neuroprotective properties in the central nervous system during the preclinical phase. As a result of these promising findings, in recent years, these necessary types of cell therapies have been intensively tested in clinical trials to establish whether these results could be confirmed in patients. However, extensive research is still needed regarding elucidating the exact mechanism of action, possible immune rejection, functionality and survival of the administered cells, dose, frequency and administration route. To summarize the current state of knowledge, we conducted a systematic review with meta-analysis. A total of 27,043 records were reviewed by two independent assessors and 71 records were included in the final quantitative analysis. These results show that the overall frequency of serious adverse events was low: 0.03 (95% CI: 0.01-0.08). In addition, several trials in MS and SCI reported efficacy data, demonstrating some promising results on clinical outcomes. All randomized controlled studies were at a low risk of bias due to appropriate blinding of the treatment, including assessors and patients. In conclusion, cell-based therapies in neurodegenerative disease are safe and feasible while showing promising clinical improvements. Nevertheless, given their high heterogeneity, the results require a cautious approach. We advocate for the harmonization of study protocols of trials investigating cell-based therapies in neurodegenerative diseases, adverse event reporting and investigation of clinical outcomes.

Motor neuron replacement therapy for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a motor neuron degenerative disease that is also known as Lou Gehrig's disease in the United States, Charcot's disease in France, and motor neuron disease in the UK. The loss of motor neurons causes muscle wasting, paralysis, and eventually death, which is commonly related to respiratory failure, within 3-5 years after onset of the disease. Although there are a limited number of drugs approved for amyotrophic lateral sclerosis, they have had little success at treating the associated symptoms, and they cannot reverse the course of motor neuron degeneration. Thus, there is still a lack of effective treatment for this debilitating neurodegenerative disorder. Stem cell therapy for amyotrophic lateral sclerosis is a very attractive strategy for both basic and clinical researchers, particularly as transplanted stem cells and stem cell-derived neural progenitor/precursor cells can protect endogenous motor neurons and directly replace the lost or dying motor neurons. Stem cell therapies may also be able to re-establish the motor control of voluntary muscles. Here, we review the recent progress in the use of neural stem cells and neural progenitor cells for the treatment of amyotrophic lateral sclerosis. We focus on MN progenitor cells derived from fetal central nervous system tissue, embryonic stem cells, and induced pluripotent stem cells. In our recent studies, we found that transplanted human induced pluripotent stem cell-derived motor neuron progenitors survive well, differentiate into motor neurons, and extend axons into the host white matter, not only in the rostrocaudal direction, but also along motor axon tracts towards the ventral roots in the immunodeficient rat spinal cord. Furthermore, the significant motor axonal extension after neural progenitor cell transplantation in amyotrophic lateral sclerosis models demonstrates that motor neuron replacement therapy could be a promising therapeutic strategy for amyotrophic lateral sclerosis, particularly as a variety of stem cell derivatives, including induced pluripotent stem cells, are being considered for clinical trials for various diseases.

The Safety and Efficacy of Stem Cell Therapy as an Emerging Therapy for ALS: A Systematic Review of Controlled Clinical Trials

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with a heterogeneous course that ultimately leads to death. Currently, there is no cure, and new treatments that can slow the progression of the disease are needed. Stem cell (SC) transplantation is an emerging therapy that has shown a lot of potential in recent clinical trials. This review is aimed to examine the results of various clinical trials on this topic, thus assessing the safety and efficacy of SC transplantation as a potential treatment for ALS. We identified 748 studies in our search, of which 134 full-text studies were assessed for eligibility. Six studies met the inclusion criteria and were included in this review. Although some of the included studies showed the positive effect of SC transplantation, other studies found that there was no significant difference compared to the control group. We observed more positive effects with bone marrow mesenchymal stem cells (BM-MSC) treatments than Granulocyte colony-stimulating factor (G-CSF) ones. However, other factors, such as route of administration, number of doses, and number of cells per dose, could also play a role in this discrepancy. Based on this information, we conclude that more properly conducted clinical trials are needed to appreciate the benefit of this treatment.

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.

Human Neural Stem Cells for Cell-Based Medicinal Products

Neural stem cells represent an attractive tool for the development of regenerative therapies and are being tested in clinical trials for several neurological disorders. Human neural stem cells can be isolated from the central nervous system or can be derived in vitro from pluripotent stem cells. Embryonic sources are ethically controversial and other sources are less well characterized and/or inefficient. Recently, isolation of NSC from the cerebrospinal fluid of patients with spina bifida and with intracerebroventricular hemorrhage has been reported. Direct reprogramming may become another alternative if genetic and phenotypic stability of the reprogrammed cells is ensured. Here, we discuss the advantages and disadvantages of available sources of neural stem cells for the production of cell-based therapies for clinical applications. We review available safety and efficacy clinical data and discuss scalability and quality control considerations for manufacturing clinical grade cell products for successful clinical application.

A perspective on therapies for amyotrophic lateral sclerosis: can disease progression be curbed?

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease involving both upper and lower motor neurons, leading to paralysis and eventually death. Symptomatic treatments such as inhibition of salivation, alleviation of muscle cramps, and relief of spasticity and pain still play an important role in enhancing the quality of life. To date, riluzole and edaravone are the only two drugs approved by the Food and Drug Administration for the treatment of ALS in a few countries. While there is adequate consensus on the modest efficacy of riluzole, there are still open questions concerning the efficacy of edaravone in slowing the disease progression. Therefore, identification of novel therapeutic strategies is urgently needed. Impaired autophagic process plays a critical role in ALS pathogenesis. In this review, we focus on therapies modulating autophagy in the context of ALS. Furthermore, stem cell therapies, gene therapies, and newly-developed biomaterials have great potentials in alleviating neurodegeneration, which might halt the disease progression. In this review, we will summarize the current and prospective therapies for ALS.

Interplay between immunity and amyotrophic lateral sclerosis: Clinical impact

Amyotrophic lateral sclerosis (ALS) is a debilitating and rapidly fatal neurodegenerative disease. Despite decades of research and many new insights into disease biology over the 150 years since the disease was first described, causative pathogenic mechanisms in ALS remain poorly understood, especially in sporadic cases. Our understanding of the role of the immune system in ALS pathophysiology, however, is rapidly expanding. The aim of this manuscript is to summarize the recent advances regarding the immune system involvement in ALS, with particular attention to clinical translation. We focus on the potential pathophysiologic mechanism of the immune system in ALS, discussing local and systemic factors (blood, cerebrospinal fluid, and microbiota) that influence ALS onset and progression in animal models and people. We also explore the potential of Positron Emission Tomography to detect neuroinflammation in vivo, and discuss ongoing clinical trials of therapies targeting the immune system. With validation in human patients, new evidence in this emerging field will serve to identify novel therapeutic targets and provide realistic hope for personalized treatment strategies.

Therapies to Restore Consciousness in Patients with Severe Brain Injuries: A Gap Analysis and Future Directions

Background/Objective

For patients with disorders of consciousness (DoC) and their families, the search for new therapies has been a source of hope and frustration. Almost all clinical trials in patients with DoC have been limited by small sample sizes, lack of placebo groups, and use of heterogeneous outcome measures. As a result, few therapies have strong evidence to support their use; amantadine is the only therapy recommended by current clinical guidelines, specifically for patients with DoC caused by severe traumatic brain injury. To foster and advance development of consciousness-promoting therapies for patients with DoC, the Curing Coma Campaign convened a Coma Science Work Group to perform a gap analysis.

Methods

We consider five classes of therapies: (1) pharmacologic; (2) electromagnetic; (3) mechanical; (4) sensory; and (5) regenerative. For each class of therapy, we summarize the state of the science, identify gaps in knowledge, and suggest future directions for therapy development.

Results

Knowledge gaps in all five therapeutic classes can be attributed to the lack of: (1) a unifying conceptual framework for evaluating therapeutic mechanisms of action; (2) large-scale randomized controlled trials; and (3) pharmacodynamic biomarkers that measure subclinical therapeutic effects in early-phase trials. To address these gaps, we propose a precision medicine approach in which clinical trials selectively enroll patients based upon their physiological receptivity to targeted therapies, and therapeutic effects are measured by complementary behavioral, neuroimaging, and electrophysiologic endpoints.

Conclusions

This personalized approach can be realized through rigorous clinical trial design and international collaboration, both of which will be essential for advancing the development of new therapies and ultimately improving the lives of patients with DoC.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12028-021-01227-y.

A data value metric for quantifying information content and utility

Data-driven innovation is propelled by recent scientific advances, rapid technological progress, substantial reductions of manufacturing costs, and significant demands for effective decision support systems. This has led to efforts to collect massive amounts of heterogeneous and multisource data, however, not all data is of equal quality or equally informative. Previous methods to capture and quantify the utility of data include value of information (VoI), quality of information (QoI), and mutual information (MI). This manuscript introduces a new measure to quantify whether larger volumes of increasingly more complex data enhance, degrade, or alter their information content and utility with respect to specific tasks. We present a new information-theoretic measure, called Data Value Metric (DVM), that quantifies the useful information content (energy) of large and heterogeneous datasets. The DVM formulation is based on a regularized model balancing data analytical value (utility) and model complexity. DVM can be used to determine if appending, expanding, or augmenting a dataset may be beneficial in specific application domains. Subject to the choices of data analytic, inferential, or forecasting techniques employed to interrogate the data, DVM quantifies the information boost, or degradation, associated with increasing the data size or expanding the richness of its features. DVM is defined as a mixture of a fidelity and a regularization terms. The fidelity captures the usefulness of the sample data specifically in the context of the inferential task. The regularization term represents the computational complexity of the corresponding inferential method. Inspired by the concept of information bottleneck in deep learning, the fidelity term depends on the performance of the corresponding supervised or unsupervised model. We tested the DVM method for several alternative supervised and unsupervised regression, classification, clustering, and dimensionality reduction tasks. Both real and simulated datasets with weak and strong signal information are used in the experimental validation. Our findings suggest that DVM captures effectively the balance between analytical-value and algorithmic-complexity. Changes in the DVM expose the tradeoffs between algorithmic complexity and data analytical value in terms of the sample-size and the feature-richness of a dataset. DVM values may be used to determine the size and characteristics of the data to optimize the relative utility of various supervised or unsupervised algorithms.

Long-Term Clinical and Immunological Effects of Repeated Mesenchymal Stem Cell Injections in Patients With Progressive Forms of Multiple Sclerosis

Background: Mesenchymal stem cells (MSC) were shown to possess immunomodulatory and neurotrophic effects. Our previous trials, have shown that intrathecal (IT) and intravenous (IV) administration of MSCs were safe and provided indications of beneficial clinical effects.

Methods: This is an open prospective study to evaluate the safety and the long-term clinical and immunological effects of multiple injections of autologous MSCs in 24 patients with active-progressive MS. At inclusion, the mean age of the patients was 47.0 ± 9.22, and the mean EDSS score was 6.75 ± 0.68 (range: 5.5–7.5). Patients were initially treated with 1 ×10⁶ MSCS/kg of body weight (IT + IV) and subsequently with up to additional eight courses of MSCs, at intervals of 6–12 months. The duration of the trial was 4 years.

Results: No serious, treatment-related adverse events were observed during the follow-up period. Twenty-two of the 24 patients were either stable or improved at the last follow-up visit. Ten patients had a lower than baseline EDSS at the last follow-up (nine were among those who received >2 treatments and one in the subgroup of ≤ 2 treatments, p = 0.04). The mean EDSS score reduced from 6.75 ± 0.68 at baseline to 6.42 ± 0.84 at the last visit, during a median follow-up period of 27.8 months (p = 0.028). Immunological follow-up showed a transient upregulation of CD4+CD25+FoxP3+ cells and downregulation of the proliferative ability of lymphocytes.

Conclusions: Repeated MSC treatments in patients with progressive MS were shown safe at the short/intermediate term and induced clinical benefits (especially in patients treated with >2 injections) that lasted for up to 4 years, paralleled by short-term immunomodulatory effects.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT04823000.

The unfolded protein response in amyotrophic later sclerosis: results of a phase 2 trial

Strong evidence suggests that endoplasmic reticulum (ER) stress plays a critical role in the pathogenesis of amyotrophic lateral sclerosis (ALS) through an altered regulation of proteostasis. Robust preclinical findings demonstrated that guanabenz selectively inhibits ER stress-induced eIF2α-phosphatase allowing misfolded protein clearance, reduces neuronal death and prolongs survival in in vitro and in vivo models. Its efficacy and safety in ALS patients are unknown. To address these issues, we conducted a multicentre, randomised, double-blind trial, with futility design. ALS patients with onset of symptoms within the previous 18 months were randomly assigned to receive in a 1:1:1:1 ratio guanabenz 64 mg, 32 mg, 16 mg or placebo daily for 6 months as add-on therapy to riluzole. The purpose of the placebo group blinding was safety but not efficacy. The primary outcome was the proportion of patients progressing to higher stages of disease in 6 months as measured by the ALS Milano-Torino staging compared to a historical cohort of 200 ALS patients. The secondary outcomes were the rate of decline in ALSFRS-R total score, slow vital capacity change, time to death, tracheotomy or permanent ventilation and serum light neurofilament level at 6 months. The primary analysis of efficacy was performed by intention-to-treat. Guanabenz 64 mg and 32 mg arms, both alone and combined, reached the primary hypothesis of non-futility with proportions of patients who progressed to higher stage of disease at 6 months significantly lower than that expected under the hypothesis of non-futility and significantly lower difference in the median rate of change of the ALSFRS-R total score. This effect was driven by patients with bulbar onset, none of whom (0/18) progressed to a higher stage of disease at 6 months compared with those in guanabenz 16 mg (4/8; 50%), historical cohort alone (21/49; 43%; p = 0.001) or plus placebo (25/60; 42%; p = 0.001). The proportion of patients who experienced at least one adverse event was higher in any guanabenz arm than in the placebo arm, with higher dosing arms having significantly higher proportion of drug-related side effects and the 64 mg arm significantly higher drop-out rate. The number of serious adverse events did not significantly differ between guanabenz arms and placebo. Our findings indicate that a larger trial with a molecule targeting the UPR pathway without the alpha-2 adrenergic related side-effect profile of guanabenz is warranted.

Looking backward to move forward: a meta-analysis of stem cell therapy in amyotrophic lateral sclerosis

Transplantation of several types of stem cells (SC) for the treatment of amyotrophic lateral sclerosis (ALS) has been evaluated in numerous Phase I/II clinical trials with inconclusive results. Here, we conducted a meta-analysis to systematically assess the outcome of SC therapy trials which report the evolution of each patient before and after cell administration. In this way, we aimed to determine the effect of the SC intervention despite individual heterogeneity in disease progression. We identified 670 references by electronic search and 90 full-text studies were evaluated according to the eligibility criteria. Eleven studies were included comprising 220 cell-treated patients who received mesenchymal (M) SC (n = 152), neural (N) SC (n = 57), or mononuclear cells (MNC: CD34, CD117, and CD133 positive cells) (n = 11). Our analyses indicate that whereas intrathecal injection of mesenchymal stromal cells appears to have a transient positive effect on clinical progression, as measured by the ALS functional rating score, there was a worsening of respiratory function measured by forced vital capacity after all interventions. Based on current evidence, we conclude that optimal cell product and route of administration need to be determined in properly controlled preclinical models before further advancing into ALS patients. In addition, in-depth understanding of disease mechanisms in subsets of patients will help tailoring SC therapy to specific targets and increase the likelihood of improving outcomes.

A Stereotactic Device for Intraparenchymal Spinal Cord Injections: Latest Developments for Practical Clinical Use

This manuscript introduces the latest generation of a patient-mounted platform designed for segmental injections of therapeutics direct into the spinal cord parenchyma. It emphasizes its importance and it presents the rationale for developing this delivery methodology. It compares the newest with the previous generations, detailing how the modifications can streamline transportation, assembly, sterilization, and utilization of the platform by different surgeons. Finally, the illustrations depict the main alterations, as well as a cadaveric assessment of the device prototype in the cervical and thoracolumbar regions.

Overview of stem cells therapy in amyotrophic lateral sclerosis

Background: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of upper and lower motor neurons with high burden on society. Despite tremendous efforts over the last several decades, there is still no definite cure for ALS. Up to now, only two disease-modifying agents, riluzole and edaravone, are approved by U.S. Food and Drug Administration (FDA) for ALS treatment, which only modestly improves survival and disease progression. Major challenging issues to find an effective therapy are heterogeneity in the pathogenesis and genetic variability of ALS. As such, stem cell therapy has been recently a focus of both preclinical and clinical investigations of ALS. This is because stem cells have multifaceted features that can potentially target multiple pathogenic mechanisms in ALS even though its underlying mechanisms are not completely elucidated. Methods & Results: Here, we will have an overview of stem cell therapy in ALS, including their therapeutic mechanisms, the results of recent clinical trials as well as ongoing clinical trials. In addition, we will further discuss complications and limitations of stem cell therapy in ALS. Conclusion: The determination of whether stem cells offer a viable treatment strategy for ALS rests on well-designed and appropriately powered future clinical trials. Randomized, double-blinded, and sham-controlled studies would be valuable.

A body-mounted device for MRI-guided spinal therapy

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with no cure and limited treatment options. Recent studies have shown that delivering cellular therapeutics to the ventral horn of the spinal cord can effectively halt neurodegeneration associated with ALS in small animal models.

METHODS

We developed a robotic system that assists with MRI-guided percutaneous injections to the spinal cord. The needle positioning robot consists of two linear axes with motorised translational sleds for two-degree-of-freedom (2-DOF) needle translation and a radial template for 2-DOF discrete rotation.

RESULTS

The robot's targeting capability, evaluated using phantom models and swine cadavers, showed mean targeting errors of 0.48 and 2.84 mm, respectively. The duration of the targeting procedure is approximately 60 min, with an extra 10 min for each additional injection.

CONCLUSIONS

The presented robot does not affect imaging quality during MRI-guided procedures, and it enables a simplified workflow for MRI-guided spinal therapy.

Neuroregeneration and functional recovery after stroke: advancing neural stem cell therapy toward clinical application

Stroke is a main cause of death and disability worldwide. The ability of the brain to self-repair in the acute and chronic phases after stroke is minimal; however, promising stem cell-based interventions are emerging that may give substantial and possibly complete recovery of brain function after stroke. Many animal models and clinical trials have demonstrated that neural stem cells (NSCs) in the central nervous system can orchestrate neurological repair through nerve regeneration, neuron polarization, axon pruning, neurite outgrowth, repair of myelin, and remodeling of the microenvironment and brain networks. Compared with other types of stem cells, NSCs have unique advantages in cell replacement, paracrine action, inflammatory regulation and neuroprotection. Our review summarizes NSC origins, characteristics, therapeutic mechanisms and repair processes, then highlights current research findings and clinical evidence for NSC therapy. These results may be helpful to inform the direction of future stroke research and to guide clinical decision-making.

Cell-Based Therapy for Canavan Disease Using Human iPSC-Derived NPCs and OPCs

Canavan disease (CD) is a fatal leukodystrophy caused by mutation of the aspartoacylase (ASPA) gene, which leads to deficiency in ASPA activity, accumulation of the substrate N-acetyl-L-aspartate (NAA), demyelination, and spongy degeneration of the brain. There is neither a cure nor a standard treatment for this disease. In this study, human induced pluripotent stem cell (iPSC)-based cell therapy is developed for CD. A functional ASPA gene is introduced into patient iPSC-derived neural progenitor cells (iNPCs) or oligodendrocyte progenitor cells (iOPCs) via lentiviral transduction or TALEN-mediated genetic engineering to generate ASPA iNPC or ASPA iOPC. After stereotactic transplantation into a CD (Nur7) mouse model, the engrafted cells are able to rescue major pathological features of CD, including deficient ASPA activity, elevated NAA levels, extensive vacuolation, defective myelination, and motor function deficits, in a robust and sustainable manner. Moreover, the transplanted mice exhibit much prolonged survival. These genetically engineered patient iPSC-derived cellular products are promising cell therapies for CD. This study has the potential to bring effective cell therapies, for the first time, to Canavan disease children who have no treatment options. The approach established in this study can also benefit many other children who have deadly genetic diseases that have no cure.

MicroRNAs in amyotrophic lateral sclerosis: from pathogenetic involvement to diagnostic biomarker and therapeutic agent development

MicroRNAs (miRNAs) are a class of endogenous non-coding small single-stranded RNAs that are 21-25 nucleotides (NTs) in length and participate in post-transcriptional gene regulation. Studies have shown that miRNA dysfunction plays a critical role in the occurrence and development of a variety of nervous system diseases, including neurodegenerative diseases. Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with an unclear etiology and is characterized by the selective invasion of motor neurons in the brain and spinal cord. Symptoms can range from mild spasms in the limbs or medulla oblongata muscles to paralysis in almost all skeletal muscles. The role of miRNAs in the pathogenesis, diagnosis, and treatment of ALS has become of greater importance to those studying ALS. In this review, we reviewed experimentally confirmed miRNAs shown to be involved in the pathogenesis of ALS and that are used as diagnostic biomarkers or therapeutic ALS agents. At present, there are at least 20-30 genes clearly related to the pathogenesis of ALS. Multiple miRNAs have been reported in different pathogenic gene models. MiRNAs could be used as biomarkers for the diagnosis of ALS; the differential expression of some miRNAs could be related to ALS prognosis. As therapeutic agents, miRNAs are still in the exploratory stage. Although encouraging results have been achieved using animal models, much research is still needed before clinical trials can ensue. However, with additional miRNA studies in ALS patients and animal models, the pathogenesis, early diagnosis, and therapy of ALS should be elucidated.

Minimally Invasive Injection to the Phrenic Nerve in a Porcine Hemidiaphragmatic Paralysis Model: A Pilot Study

BACKGROUND

Neurodegenerative diseases and spinal cord injury can affect respiratory function often through motor neuron loss innervating the diaphragm. To reinnervate this muscle, new motor neurons could be transplanted into the phrenic nerve (PN), allowing them to extend axons to the diaphragm. These neurons could then be driven by an optogenetics approach to regulate breathing. This type of approach has already been demonstrated in the peripheral nerves of mice. However, there is no established thoracoscopic approach to PN injection. Also, there is currently a lack of preclinical large animal models of diaphragmatic dysfunction in order to evaluate the efficacy of potential treatments.

OBJECTIVE

To evaluate the feasibility of thoracoscopic drug delivery into the PN and to assess the viability of hemidiaphragmatic paralysis in a porcine model.

METHODS

Two Landrace farm pigs underwent a novel procedure for thoracoscopic PN injections, including 1 nonsurvival and 1 survival surgery. Nonsurvival surgery involved bilateral PN injections and ligation. Survival surgery included a right PN injection and transection proximal to the injection site to induce hemidiaphragmatic paralysis.

RESULTS

PN injections were successfully performed in both procedures. The animal that underwent survival surgery recovered postoperatively with an established right hemidiaphragmatic paralysis. Over the 5-d postoperative period, the animal displayed stable vital signs and oxygenation saturation on room air with voluntary breathing.

CONCLUSION

Thoracoscopic targeting of the porcine PN is a feasible approach to administer therapeutic agents. A swine model of hemidiaphragmatic paralysis induced by unilateral PN ligation or transection may be potentially used to study diaphragmatic reinnervation following delivery of therapeutics.

Novel therapeutic targets for amyotrophic lateral sclerosis: ribonucleoproteins and cellular autonomy

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a devastating disease with a lifetime risk of approximately 1:400. It is incurable and invariably fatal. Average survival is between 3 and 5 years and patients become increasingly paralyzed, losing the ability to speak, eat, and breathe. Therapies in development either (i) target specific familial forms of ALS (comprising a minority of around 10% of cases) or ii) emanate from (over)reliance on animal models or non-human/non-neuronal cell models. There is a desperate and unmet clinical need for effective treatments. Deciphering the primacy and relative contributions of defective protein homeostasis and RNA metabolism in ALS across different model systems will facilitate the identification of putative therapeutic targets.

AREAS COVERED

This review examines the putative common primary molecular events that lead to ALS pathogenesis. We focus on deregulated RNA metabolism, protein mislocalization/pathological aggregation and the role of glia in ALS-related motor neuron degeneration. Finally, we describe promising targets for therapeutic evaluation.

EXPERT OPINION

Moving forward, an effective strategy could be achieved by a poly-therapeutic approach which targets both deregulated RNA metabolism and protein dyshomeostasis in the relevant cell types, at the appropriate phase of disease.

Magnetic resonance imaging of human neural stem cells in rodent and primate brain

Stem cell transplantation therapies are currently under investigation for central nervous system disorders. Although preclinical models show benefit, clinical translation is somewhat limited by the absence of reliable noninvasive methods to confirm targeting and monitor transplanted cells in vivo. Here, we assess a novel magnetic resonance imaging (MRI) contrast agent derived from magnetotactic bacteria, magneto‐endosymbionts (MEs), as a translatable methodology for in vivo tracking of stem cells after intracranial transplantation. We show that ME labeling provides robust MRI contrast without impairment of cell viability or other important therapeutic features. Labeled cells were visualized immediately post‐transplantation and over time by serial MRI in nonhuman primate and mouse brain. Postmortem tissue analysis confirmed on‐target grft location, and linear correlations were observed between MRI signal, cell engraftment, and tissue ME levels, suggesting that MEs may be useful for determining graft survival or rejection. Overall, these findings indicate that MEs are an effective tool for in vivo tracking and monitoring of cell transplantation therapies with potential relevance to many cellular therapy applications.

The clinical trial landscape in amyotrophic lateral sclerosis-Past, present, and future

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease marked by progressive loss of muscle function. It is the most common adult-onset form of motor neuron disease, affecting about 16 000 people in the United States alone. The average survival is about 3 years. Only two interventional drugs, the antiglutamatergic small-molecule riluzole and the more recent antioxidant edaravone, have been approved for the treatment of ALS to date. Therapeutic strategies under investigation in clinical trials cover a range of different modalities and targets, and more than 70 different drugs have been tested in the clinic to date. Here, we summarize and classify interventional therapeutic strategies based on their molecular targets and phenotypic effects. We also discuss possible reasons for the failure of clinical trials in ALS and highlight emerging preclinical strategies that could provide a breakthrough in the battle against this relentless disease.

Immune dysregulation in amyotrophic lateral sclerosis: mechanisms and emerging therapies

Neuroinflammation is a common pathological feature of many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), and is characterised by activated CNS microglia and astroglia, proinflammatory peripheral lymphocytes, and macrophages. Data from clinical studies show that multiple genetic mutations linked to ALS (eg, mutations in SOD1, TARDBP, and C9orf72) enhance this neuroinflammation, which provides compelling evidence for immune dysregulation in the pathogenesis of ALS. Transgenic rodent models expressing these mutations induce an ALS-like disease with accompanying inflammatory responses, confirming the immune system's involvement in disease progression. Even in the absence of known genetic alterations, immune dysregulation has been shown to lead to dysfunctional regulatory T lymphocytes and increased proinflammatory macrophages in clinical studies. Therefore, an improved understanding of the biological processes that induce this immune dysregulation will help to identify therapeutic strategies that circumvent or ameliorate the pathogenesis of ALS. Emerging cell-based therapies hold the promise of accomplishing this goal and, therefore, improving quality of life and extending survival in patients with ALS.