Opinion: more mouse models and more translation needed for ALS

Promising breakthroughs in amyotrophic lateral sclerosis treatment through nanotechnology's unexplored frontier

This review explores the transformative potential of nanotechnology in the treatment and diagnosis of amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disorder characterized by motor neuron degeneration, muscle weakness, and eventual paralysis. Nanotechnology offers innovative solutions across various domains, including targeted drug delivery, neuroprotection, gene therapy and editing, biomarker detection, advanced imaging techniques, and tissue engineering. By enhancing the precision and efficacy of therapeutic interventions, nanotechnology facilitates key advancements such as crossing the blood-brain barrier, targeting specific cell types, achieving sustained therapeutic release, and enabling combination therapies tailored to the complex pathophysiology of ALS. Despite its immense promise, the clinical translation of these approaches faces challenges, including potential cytotoxicity, biocompatibility, and regulatory compliance, which must be addressed through rigorous research and testing. This review emphasizes the application of nanotechnology in targeted drug delivery and gene therapy/editing for ALS, drawing on the author's prior work with various nanotechnological platforms to illustrate strategies for overcoming similar obstacles in drug and gene delivery. By bridging the gap between cutting-edge technology and clinical application, this article aims to highlight the vital role of nanotechnology in shaping the future of ALS treatment.

n-Butylidenephthalide recovered calcium homeostasis to ameliorate neurodegeneration of motor neurons derived from amyotrophic lateral sclerosis iPSCs

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease that causes muscle atrophy and primarily targets motor neurons (MNs). Approximately 20% of familial ALS cases are caused by gain-of-function mutations in superoxide dismutase 1 (SOD1), leading to MN degeneration and ion channel dysfunction. Previous studies have shown that n-Butylidenephthalide (BP) delays disease progression and prolongs survival in animal models of ALS. However, no studies have been conducted on models from human sources. Herein, we examined the protective efficacy of BP on MNs derived from induced pluripotent stem cells (iPSCs) of an ALS patient harboring the SOD1G85R mutation as well as on those derived from genetically corrected iPSCs (SOD1G85G). Our results demonstrated that the motor neurons differentiated from iPSC with SOD1G85R mutation exhibited characteristics of neuron degeneration (as indicated by the reduction of neurofilament expression) and ion channel dysfunction (in response to potassium chloride (KCl) and L-glutamate stimulation), in contrast to those derived from the gene corrected iPSC (SOD1G85G). Meanwhile, BP treatment effectively restored calcium ion channel function by reducing the expression of glutamate receptors including glutamate ionotropic receptor AMPA type subunit 3 (GluR3) and glutamate ionotropic receptor NMDA type subunit 1 (NMDAR1). Additionally, BP treatment activated autophagic pathway to attenuate neuron degeneration. Overall, this study supports the therapeutic effects of BP on ALS patient-derived neuron cells, and suggests that BP may be a promising candidate for future drug development.

Promising animal models for amyotrophic lateral sclerosis drug discovery: a comprehensive update

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neurons. Several animal models have been generated to understand ALS pathogenesis. They have provided valuable insight into disease mechanisms and the development of therapeutic strategies.

AREAS COVERED

In this review, the authors provide a concise overview of simple genetic model organisms, including C. elegans, Drosophila, zebrafish, and mouse genetic models that have been generated to study ALS. They emphasize the benefits of each model and their application in translational research for discovering new chemicals, gene therapy approaches, and antibody-based strategies for treating ALS.

EXPERT OPINION

Significant progress is being made in identifying new therapeutic targets for ALS. This progress is being enabled by promising animal models of the disease using increasingly effective genetic and pharmacological strategies. There are still challenges to be overcome in order to achieve improved success rates for translating drugs from animal models to clinics for treating ALS. Several promising future directions include the establishment of novel preclinical protocol standards, as well as the combination of animal models with human induced pluripotent stem cells (iPSCs).

Advancements in Pharmacological Interventions and Novel Therapeutic Approaches for Amyotrophic Lateral Sclerosis

(1) Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease in which the patient suffers from an affection of both upper and lower motor neurons at the spinal and brainstem level, causing a progressive paralysis that leads to the patient's demise. Gender is also considered a predisposing risk factor for developing the disease. A brief review of the pathophysiological mechanisms of the disease is also described in this work. Despite the fact that a cure for ALS is currently unknown, there exists a variety of pharmacological and non-pharmacological therapies that can help reduce the progression of the disease over a certain period of time and alleviate symptoms. (2) We aim to analyze these pharmacological and non-pharmacological therapies through a systematic review. A comprehensive, multidisciplinary approach to treatment is necessary. (3) Drugs such as riluzole, edaravone, and sodium phenylbutyrate, among others, have been investigated. Additionally, it is important to stay updated on research on new drugs, such as masitinib, from which very good results have been obtained. (4) Therapies aimed at psychological support, speech and language, and physical therapy for the patient are also available, which increase the quality of life of the patients.

Towards an integrated approach for understanding glia in Amyotrophic Lateral Sclerosis

Substantial advances in technology are permitting a high resolution understanding of the salience of glia, and have helped us to transcend decades of predominantly neuron-centric research. In particular, recent advances in 'omic' technologies have enabled unique insights into glial biology, shedding light on the cellular and molecular aspects of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Here, we review studies using omic techniques to attempt to understand the role of glia in ALS across different model systems and post mortem tissue. We also address caveats that should be considered when interpreting such studies, and how some of these may be mitigated through either using a multi-omic approach and/or careful low throughput, high fidelity orthogonal validation with particular emphasis on functional validation. Finally, we consider emerging technologies and their potential relevance in deepening our understanding of glia in ALS.

Histone post-translational modification and heterochromatin alterations in neurodegeneration: revealing novel disease pathways and potential therapeutics

Alzheimer's disease (AD), Parkinson's disease (PD), Frontotemporal Dementia (FTD), and Amyotrophic lateral sclerosis (ALS) are complex and fatal neurodegenerative diseases. While current treatments for these diseases do alleviate some symptoms, there is an imperative need for novel treatments able to stop their progression. For all of these ailments, most cases occur sporadically and have no known genetic cause. Only a small percentage of patients bear known mutations which occur in a multitude of genes. Hence, it is clear that genetic factors alone do not explain disease occurrence. Chromatin, a DNA-histone complex whose basic unit is the nucleosome, is divided into euchromatin, an open form accessible to the transcriptional machinery, and heterochromatin, which is closed and transcriptionally inactive. Protruding out of the nucleosome, histone tails undergo post-translational modifications (PTMs) including methylation, acetylation, and phosphorylation which occur at specific residues and are connected to different chromatin structural states and regulate access to transcriptional machinery. Epigenetic mechanisms, including histone PTMs and changes in chromatin structure, could help explain neurodegenerative disease processes and illuminate novel treatment targets. Recent research has revealed that changes in histone PTMs and heterochromatin loss or gain are connected to neurodegeneration. Here, we review evidence for epigenetic changes occurring in AD, PD, and FTD/ALS. We focus specifically on alterations in the histone PTMs landscape, changes in the expression of histone modifying enzymes and chromatin remodelers as well as the consequences of these changes in heterochromatin structure. We also highlight the potential for epigenetic therapies in neurodegenerative disease treatment. Given their reversibility and pharmacological accessibility, epigenetic mechanisms provide a promising avenue for novel treatments. Altogether, these findings underscore the need for thorough characterization of epigenetic mechanisms and chromatin structure in neurodegeneration.

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.

Mis-localization of endogenous TDP-43 leads to ALS-like early-stage metabolic dysfunction and progressive motor deficits

BACKGROUND

The key pathological signature of ALS/ FTLD is the mis-localization of endogenous TDP-43 from the nucleus to the cytoplasm. However, TDP-43 gain of function in the cytoplasm is still poorly understood since TDP-43 animal models recapitulating mis-localization of endogenous TDP-43 from the nucleus to the cytoplasm are missing.

METHODS

CRISPR/Cas9 technology was used to generate a zebrafish line (called CytoTDP), that mis-locates endogenous TDP-43 from the nucleus to the cytoplasm. Phenotypic characterization of motor neurons and the neuromuscular junction was performed by immunostaining, microglia were immunohistochemically localized by whole-mount tissue clearing and muscle ultrastructure was analyzed by scanning electron microscopy. Behavior was investigated by video tracking and quantitative analysis of swimming parameters. RNA sequencing was used to identify mis-regulated pathways with validation by molecular analysis.

RESULTS

CytoTDP fish have early larval phenotypes resembling clinical features of ALS such as progressive motor defects, neurodegeneration and muscle atrophy. Taking advantage of zebrafish's embryonic development that solely relys on yolk usage until 5 days post fertilization, we demonstrated that microglia proliferation and activation in the hypothalamus is independent from food intake. By comparing CytoTDP to a previously generated TDP-43 knockout line, transcriptomic analyses revealed that mis-localization of endogenous TDP-43, rather than TDP-43 nuclear loss of function, leads to early onset metabolic dysfunction.

CONCLUSIONS

The new TDP-43 model mimics the ALS/FTLD hallmark of progressive motor dysfunction. Our results suggest that functional deficits of the hypothalamus, the metabolic regulatory center, might be the primary cause of weight loss in ALS patients. Cytoplasmic gain of function of endogenous TDP-43 leads to metabolic dysfunction in vivo that are reminiscent of early ALS clinical non-motor metabolic alterations. Thus, the CytoTDP zebrafish model offers a unique opportunity to identify mis-regulated targets for therapeutic intervention early in disease progression.

Exploring amyotrophic lateral sclerosis patients' experiences of psychological distress during the disease course in China: a qualitative study

OBJECTIVE

This study aims to explore the psychological distress course of Chinese amyotrophic lateral sclerosis (ALS) patients after the onset of the disease and to provide targeted nursing guidance.

DESIGN

The interview content was analysed qualitatively. We used seven steps of Colaizzi's method to analyse the participants' data.

SETTING

Wuhan, China, Traditional Chinese Medicine Hospital.

PARTICIPANTS

A semistructured face-to-face interview were performed among 22 people with ALS from the motor neuron disease rehabilitation centre of a tertiary Chinese medicine hospital in China.

RESULT

This study included a total of 22 participants, from whom three main themes regarding the psychological distress trajectory of ALS patients were extracted from the interview data: 'Time begins to run out' include tormented and restless waiting and shock and doubt in ALS disease confirmation, 'Family out of control' include the burden of stigma and function loss, the burden of missing family roles, the burden of marriage's emotional needs and the burden of offspring health, 'Way forward' include struggle between live and death and struggle between quality of life and the value of life.

CONCLUSION

This study outlines the psychologically distressing journey of ALS patients. Studies have pointed out the need for targeted care to address patients' various sources of psychological distress to improve their quality of life and coping ability, increase their psychological resilience and reconstruct their life beliefs.

Use of biomarkers in clinical trials and future developments that will help identify novel biomarkers

Engineering new solutions for therapeutic benefit in Amyotrophic Lateral Sclerosis (ALS) has proved a difficult task to accomplish. This is largely the reflection of complexities at multiple levels, that require solutions to improve cost-effectiveness and outcomes. The main obstacle related to the condition's clinical heterogeneity, chiefly the broad difference in survival observed among ALS patients, imposes large populations studies and long follow-up to evaluate any efficacy. The emerging solution is composite clinical and biological parameters enabling prognostic stratification into homogeneous phenotypes for more affordable studies. From a therapeutic development perspective, the choice of a medicinal product requires the availability of treatment-specific biomarkers of target engagement to identify off-target effects based on the compound's putative modality of action. More importantly, there are no established biomarkers of treatment response that can complement clinical outcome measures and support futility and end of treatment analyses of efficacy. Ultimately the onus rests on the development of biomarkers encompassing the unmet needs of clinical trial design, from inclusion to efficacy. These readouts of the pathological process may be used in combination with clinical and paraclinical outcome measured, significantly reducing the time and financial burden of clinical studies. Progress towards a biomarker-driven clinical trial design in ALS has been possible thanks to the accurate detection of neurofilaments and of other immunological mediators in biological fluids with the disease progression, a step change enabling the testing of novel therapeutic agents in a new clinical trial setting. However, further progress remains to be made to find treatment specific target engagement biomarkers along with readouts of treatment response that can be reliably applied to all emerging therapies and clinical studies. Here we will cover the basic notions of biomarker development in ALS clinical trials, the most crucial unanswered questions and the unmet needs in the ALS biomarkers space.

Current neuroprotective therapies and future prospects for motor neuron disease

Four medications with neuroprotective disease-modifying effects are now in use for motor neuron disease (MND). With FDA approvals for tofersen, relyvrio and edaravone in just the past year, 2022 ended a quarter of a century when riluzole was the sole such drug to offer to patients. The acceleration of approvals may mean we are witnessing the beginning of a step-change in how MND can be treated. Improvements in understanding underlying disease biology has led to more therapies being developed to target specific and multiple disease mechanisms. Consideration for how the pipeline of new therapeutic agents coming through in clinical and preclinical development can be more effectively evaluated with biomarkers, advances in patient stratification and clinical trial design pave the way for more successful translation for this archetypal complex neurodegenerative disease. While it must be cautioned that only slowed rates of progression have so far been demonstrated, pre-empting rapid neurodegeneration by using neurofilament biomarkers to signal when to treat, as is currently being trialled with tofersen, may be more effective for patients with known genetic predisposition to MND. Early intervention with personalized medicines could mean that for some patients at least, in future we may be able to substantially treat what is considered by many to be one of the most distressing diseases in medicine.

New developments in pre-clinical models of ALS to guide translation

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder in which selective death of motor neurons leads to muscle weakness and paralysis. Most research has focused on understanding and treating monogenic familial forms, most frequently caused by mutations in SOD1, FUS, TARDBP and C9orf72, although ALS is mostly sporadic and without a clear genetic cause. Rodent models have been developed to study monogenic ALS, but despite numerous pre-clinical studies and clinical trials, few disease-modifying therapies are available. ALS is a heterogeneous disease with complex underlying mechanisms where several genes and molecular pathways appear to play a role. One reason for the high failure rate of clinical translation from the current models could be oversimplification in pre-clinical studies. Here, we review advances in pre-clinical models to better capture the heterogeneous nature of ALS and discuss the value of novel model systems to guide translation and aid in the development of precision medicine.

FM19G11-loaded nanoparticles modulate energetic status and production of reactive oxygen species in myoblasts from ALS mice

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting motor neurons. Considerable evidence indicates that early skeletal muscle atrophy plays a crucial role in the disease pathogenesis, leading to an altered muscle-motor neuron crosstalk that, in turn, may contribute to motor neuron degeneration. Currently, there is no effective treatment for ALS, highlighting the need to dig deeper into the pathological mechanisms for developing innovative therapeutic strategies. FM19G11 is a novel drug able to modulate the global cellular metabolism, but its effects on ALS skeletal muscle atrophy and mitochondrial metabolism have never been evaluated, yet. This study investigated whether FM19G11-loaded nanoparticles (NPs) may affect the bioenergetic status in myoblasts isolated from G93A-SOD1 mice at different disease stages. We found that FM19G1-loaded NP treatment was able to increase transcriptional levels of Akt1, Akt3, Mef2a, Mef2c and Ucp2, which are key genes associated with cell proliferation (Akt1, Akt3), muscle differentiation (Mef2c), and mitochondrial activity (Ucp2), in G93A-SOD1 myoblasts. These cells also showed a significant reduction of mitochondrial area and networks, in addition to decreased ROS production after treatment with FM19G11-loaded NPs, suggesting a ROS clearance upon the amelioration of mitochondrial dynamics. Our overall findings demonstrate a significant impact of FM19G11-loaded NPs on muscle cell function and bioenergetic status in G93A-SOD1 myoblasts, thus promising to open new avenues towards possible adoption of FM19G11-based nanotherapies to slow muscle degeneration in the frame of ALS and muscle disorders.

VEGF expression disparities in brainstem motor neurons of the SOD1G93A ALS model: Correlations with neuronal vulnerability

Amyotrophic lateral sclerosis (ALS) is a rare neuromuscular disease characterized by severe muscle weakness mainly due to degeneration and death of motor neurons. A peculiarity of the neurodegenerative processes is the variable susceptibility among distinct neuronal populations, exemplified by the contrasting resilience of motor neurons innervating the ocular motor system and the more vulnerable facial and hypoglossal motor neurons. The crucial role of vascular endothelial growth factor (VEGF) as a neuroprotective factor in the nervous system is well-established since a deficit of VEGF has been related to motoneuronal degeneration. In this study, we investigated the survival of ocular, facial, and hypoglossal motor neurons utilizing the murine SOD1G93A ALS model at various stages of the disease. Our primary objective was to determine whether the survival of the different brainstem motor neurons was linked to disparate VEGF expression levels in resilient and susceptible motor neurons throughout neurodegeneration. Our findings revealed a selective loss of motor neurons exclusively within the vulnerable nuclei. Furthermore, a significantly higher level of VEGF was detected in the more resistant motor neurons, the extraocular ones. We also examined whether TDP-43 dynamics in the brainstem motor neuron of SOD mice was altered. Our data suggests that the increased VEGF levels observed in extraocular motor neurons may potentially underlie their resistance during the neurodegenerative processes in ALS in a TDP-43-independent manner. Our work might help to better understand the underlying mechanisms of selective vulnerability of motor neurons in ALS.

Neuropathogenesis-on-chips for neurodegenerative diseases

Developing diagnostics and treatments for neurodegenerative diseases (NDs) is challenging due to multifactorial pathogenesis that progresses gradually. Advanced in vitro systems that recapitulate patient-like pathophysiology are emerging as alternatives to conventional animal-based models. In this review, we explore the interconnected pathogenic features of different types of ND, discuss the general strategy to modelling NDs using a microfluidic chip, and introduce the organoid-on-a-chip as the next advanced relevant model. Lastly, we overview how these models are being applied in academic and industrial drug development. The integration of microfluidic chips, stem cells, and biotechnological devices promises to provide valuable insights for biomedical research and developing diagnostic and therapeutic solutions for NDs.

Reactive gliosis in traumatic brain injury: a comprehensive review

Traumatic brain injury (TBI) is one of the most common pathological conditions impacting the central nervous system (CNS). A neurological deficit associated with TBI results from a complex of pathogenetic mechanisms including glutamate excitotoxicity, inflammation, demyelination, programmed cell death, or the development of edema. The critical components contributing to CNS response, damage control, and regeneration after TBI are glial cells-in reaction to tissue damage, their activation, hypertrophy, and proliferation occur, followed by the formation of a glial scar. The glial scar creates a barrier in damaged tissue and helps protect the CNS in the acute phase post-injury. However, this process prevents complete tissue recovery in the late/chronic phase by producing permanent scarring, which significantly impacts brain function. Various glial cell types participate in the scar formation, but this process is mostly attributed to reactive astrocytes and microglia, which play important roles in several brain pathologies. Novel technologies including whole-genome transcriptomic and epigenomic analyses, and unbiased proteomics, show that both astrocytes and microglia represent groups of heterogenic cell subpopulations with different genomic and functional characteristics, that are responsible for their role in neurodegeneration, neuroprotection and regeneration. Depending on the representation of distinct glia subpopulations, the tissue damage as well as the regenerative processes or delayed neurodegeneration after TBI may thus differ in nearby or remote areas or in different brain structures. This review summarizes TBI as a complex process, where the resultant effect is severity-, region- and time-dependent and determined by the model of the CNS injury and the distance of the explored area from the lesion site. Here, we also discuss findings concerning intercellular signaling, long-term impacts of TBI and the possibilities of novel therapeutical approaches. We believe that a comprehensive study with an emphasis on glial cells, involved in tissue post-injury processes, may be helpful for further research of TBI and be the decisive factor when choosing a TBI model.

Prostaglandins in the Inflamed Central Nervous System: Potential Therapeutic Targets

The global burden of neurological disorders is evident, yet there remains limited efficacious therapeutics for their treatment. There is a growing recognition of the role of inflammation in diseases of the central nervous system (CNS); among the numerous inflammatory mediators involved, prostaglandins play a crucial role. Prostaglandins are small lipid mediators derived from arachidonic acid via multi-enzymatic pathways. The actions of prostaglandins are varied, with each prostaglandin having a specific role in maintaining homeostasis. In the CNS, prostaglandins can have neuroprotective or neurotoxic properties depending on their specific G-protein receptor. These G-protein receptors have varying subfamilies, tissue distribution, and signal transduction cascades. Further studies into the impact of prostaglandins in CNS-based diseases may contribute to the clarification of their actions, hopefully leading to the development of efficacious therapeutic strategies. This review focuses on the roles played by prostaglandins in neural degeneration, with a focus on Alzheimer's Disease, Multiple Sclerosis, and Amyotrophic Lateral Sclerosis in both preclinical and clinical settings. We further discuss current prostaglandin-related agonists and antagonists concerning suggestions for their use as future therapeutics.

The Secretome of Human Dental Pulp Stem Cells and Its Components GDF15 and HB-EGF Protect Amyotrophic Lateral Sclerosis Motoneurons against Death

Amyotrophic lateral sclerosis (ALS) is a fatal and incurable paralytic disorder caused by the progressive death of upper and lower motoneurons. Although numerous strategies have been developed to slow disease progression and improve life quality, to date only a few therapeutic treatments are available with still unsatisfactory therapeutic benefits. The secretome of dental pulp stem cells (DPSCs) contains numerous neurotrophic factors that could promote motoneuron survival. Accordingly, DPSCs confer neuroprotective benefits to the SOD1G93A mouse model of ALS. However, the mode of action of DPSC secretome on motoneurons remains largely unknown. Here, we used conditioned medium of human DPSCs (DPSCs-CM) and assessed its effect on survival, axonal length, and electrical activity of cultured wildtype and SOD1G93A motoneurons. To further understand the role of individual factors secreted by DPSCs and to circumvent the secretome variability bias, we focused on GDF15 and HB-EGF whose neuroprotective properties remain elusive in the ALS pathogenic context. DPSCs-CM rescues motoneurons from trophic factor deprivation-induced death, promotes axon outgrowth of wildtype but not SOD1G93A mutant motoneurons, and has no impact on the spontaneous electrical activity of wildtype or mutant motoneurons. Both GDF15 and HB-EGF protect SOD1G93A motoneurons against nitric oxide-induced death, but not against death induced by trophic factor deprivation. GDF15 and HB-EGF receptors were found to be expressed in the spinal cord, with a two-fold increase in expression for the GDF15 low-affinity receptor in SOD1G93A mice. Therefore, the secretome of DPSCs appears as a new potential therapeutic candidate for ALS.

iPSC-based research in ALS precision medicine

Clinical trials in amyotrophic lateral sclerosis (ALS) are challenged by the lack of pre-clinical models and biomarkers of disease onset and progression. In this issue, Morimoto et al. use induced pluripotent stem cell (iPSC)-derived motor neurons from patients with ALS to study therapeutic mechanisms of ropinirole in a clinical trial and identify treatment responders.