Mesenchymal Stem Cell Therapy for Huntington Disease: A Meta-Analysis

Human striatal progenitor cells that contain inducible safeguards and overexpress BDNF rescue Huntington's disease phenotypes

Huntington's disease (HD) is an autosomal-dominant neurodegenerative disorder characterized by striatal atrophy. Reduced trophic support due to decreased striatal levels of neurotrophins (NTs), mainly brain-derived neurotrophic factor (BDNF), contributes importantly to HD pathogenesis; restoring NTs has significant therapeutic potential. Human pluripotent stem cells (hPSCs) offer a scalable platform for NT delivery but have potential safety risks including teratoma formation. We engineered hPSCs to constitutively produce BDNF and contain inducible safeguards to eliminate these cells if safety concerns arise. This study examined the efficacy of intrastriatally transplanted striatal progenitor cells (STRpcs) derived from these hPSCs against HD phenotypes in R6/2 mice. Engrafted STRpcs overexpressing BDNF alleviated motor and cognitive deficits and reduced mutant huntingtin aggregates. Activating the inducible safety switch with rapamycin safely eliminated the engrafted cells. These results demonstrate that BDNF delivery via a novel hPSC-based platform incorporating safety switches could be a safe and effective HD therapeutic.

Translational Approach using Advanced Therapy Medicinal Products for Huntington's Disease

Current therapeutic approaches for Huntington's disease (HD) focus on symptomatic treatment. Therefore, the unavailability of efficient disease-modifying medicines is a significant challenge. Regarding the molecular etiology, targeting the mutant gene or advanced translational steps could be considered promising strategies. The evidence in gene therapy suggests various molecular techniques, including knocking down mHTT expression using antisense oligonucleotides and small interfering RNAs and gene editing with zinc finger proteins and CRISPR-Cas9-based techniques. Several post-transcriptional and post-translational modifications have also been proposed. However, the efficacy and long-term side effects of these modalities have yet to be verified. Currently, cell therapy can be employed in combination with conventional treatment and could be used for HD in which the structural and functional restoration of degenerated neurons can occur. Several animal models have been established recently to develop cell-based therapies using renewable cell sources such as embryonic stem cells, induced pluripotent stem cells, mesenchymal stromal cells, and neural stem cells. These models face numerous challenges in translation into clinics. Nevertheless, investigations in Advanced Therapy Medicinal Products (ATMPs) open a promising window for HD research and their clinical application. In this study, the ATMPs entry pathway in HD management was highlighted, and their advantages and disadvantages were discussed.

Brain-Derived Neurotrophic Factor (BDNF) in Huntington's Disease: Neurobiology and Therapeutic Potential

Huntington's disease is a hereditary neurodegenerative disorder marked by severe neurodegeneration in the striatum and cortex. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors. It plays a crucial role in maintaining the survival and proper function of striatal neurons. Depletion of BDNF has been linked to impairment and death of striatal neurons, leading to the manifestation of motor, cognitive, and behavioral dysfunctions characteristic of Huntington's disease. This review highlights the current update on the neurobiology of BDNF in the pathogenesis of Huntington's disease. The molecular evidence and the affected signaling pathways are also discussed. In addition, the impact of experimental manipulation of BDNF levels and its pharmaceutical potential for Huntington's disease treatment are explicitly reviewed.

VCAM-1+ Mesenchymal Stem/Stromal Cells Reveal Preferable Efficacy Upon an Experimental Autoimmune Encephalomyelitis Mouse Model of Multiple Sclerosis Over the VCAM-1- Counterpart

Despite the considerable progress in mesenchymal stem/stromal cells (MSCs)-based novel intervention of multiple sclerosis (MS), yet the disease-modifying effect of VCAM-1- MSCs and novel VCAM-1+ counterpart is largely obscure. In this study, we took advantage of the EAE mouse model and VCAM-1+ human umbilical cord-derived MSCs (hUC-MSCs) for the evaluation of the therapeutic effect of systematic MSCs infusion. On the one hand, we compared the protective effect of VCAM-1- and VCAM-1+ hUC-MSCs against the clinical symptoms, demyelination, active glia cells and neuroinflammation in EAE mice by conducting multifaceted detections upon spinal cord and brain tissues. On the other hand, we conducted RNA-sequencing (RNA-SEQ) and multidimensional bioinformatics analyses for the evaluation of the transcriptomic features of spinal cord tissue in EAE mice after systematic hUC-MSCs infusion. Compared to those with VCAM-1- hUC-MSCs injection, VCAM-1+ mice showed further remission in clinical manifestations, and in particular, the inflammatory infiltration and active glial cells. Mice in all groups revealed conservations in overall gene expression profiling and somatic mutation spectrum. The differentially expressed genes (DEGs) between EAE mice and those with hUC-MSCs infusion were mainly involved in neuroinflammation and inflammatory response. Our findings indicated the feasibility of VCAM-1+ hUC-MSCs for multiple sclerosis treatment, which would supply new references for the development of novel VCAM-1+ MSCs-based cytotherapy in future.

Human Umbilical Cord-Mesenchymal Stem Cells Promote Extracellular Matrix Remodeling in Microglia

Human mesenchymal stem cells modulate the immune response and are good candidates for cell therapy in neuroinflammatory brain disorders affecting both adult and premature infants. Recent evidence indicates that through their secretome, mesenchymal stem cells direct microglia, brain-resident immune cells, toward pro-regenerative functions, but the mechanisms underlying microglial phenotypic transition are still under investigation. Using an in vitro coculture approach combined with transcriptomic analysis, we identified the extracellular matrix as the most relevant pathway altered by the human mesenchymal stem cell secretome in the response of microglia to inflammatory cytokines. We confirmed extracellular matrix remodeling in microglia exposed to the mesenchymal stem cell secretome via immunofluorescence analysis of the matrix component fibronectin and the extracellular crosslinking enzyme transglutaminase-2. Furthermore, an analysis of hallmark microglial functions revealed that changes in the extracellular matrix enhance ruffle formation by microglia and cell motility. These findings point to extracellular matrix changes, associated plasma membrane remodeling, and enhanced microglial migration as novel mechanisms by which mesenchymal stem cells contribute to the pro-regenerative microglial transition.

Advances in Gene and Cellular Therapeutic Approaches for Huntington's Disease

Huntington's disease (HD) is an inherited neurodegenerative disorder caused by the abnormal expansion of CAG trinucleotide repeats in the Huntingtin gene (HTT) located on chromosome 4. It is transmitted in an autosomal dominant manner and is characterized by motor dysfunction, cognitive decline, and emotional disturbances. To date, there are no curative treatments for HD have been developed; current therapeutic approaches focus on symptom relief and comprehensive care through coordinated pharmacological and non-pharmacological methods to manage the diverse phenotypes of the disease. International clinical guidelines for the treatment of HD are continually being revised in an effort to enhance care within a multidisciplinary framework. Additionally, innovative gene and cell therapy strategies are being actively researched and developed to address the complexities of the disorder and improve treatment outcomes. This review endeavours to elucidate the current and emerging gene and cell therapy strategies for HD, offering a detailed insight into the complexities of the disorder and looking forward to future treatment paradigms. Considering the complexity of the underlying mechanisms driving HD, a synergistic treatment strategy that integrates various factors-such as distinct cell types, epigenetic patterns, genetic components, and methods to improve the cerebral microenvironment-may significantly enhance therapeutic outcomes. In the future, we eagerly anticipate ongoing innovations in interdisciplinary research that will bring profound advancements and refinements in the treatment of HD.

Neuroprotective effect of human cord blood-derived extracellular vesicles by improved neuromuscular function and reduced gliosis in a rat model of Huntington's disease

Huntington's disease (HD) is a hereditary condition characterized by the gradual deterioration of nerve cells in the striatum. Recent scientific investigations have revealed the promising potential of Extracellular vesicles (EVs) as a therapy to mitigate inflammation and enhance motor function. This study aimed to examine the impact of administering EVs derived from human umbilical cord blood (HUCB) on the motor abilities and inflammation levels in a rat model of HD. After ultracentrifugation to prepare EVs from HUCB to determine the nature of the obtained contents, the expression of CD markers 81 and 9, the average size and also the morphology of its particles were investigated by DLS and Transmission electron microscopy (TEM). Then, in order to induce the HD model, 3-nitropropionic acid (3-NP) neurotoxin was injected intraperitoneal into the rats, after treatment by HUCB-EVs, rotarod, electromyogram (EMG) and the open field tests were performed on the rats. Finally, after rat sacrifice and the striatum was removed, Hematoxylin and eosin staining (H&E), stereology, immunohistochemistry, antioxidant tests, and western blot were performed. Our results showed that the contents of the HUCB-EVs express the CD9 and CD81 markers and have spherical shapes. In addition, the injection of HUCB-EVs improved motor and neuromuscular function, reduced gliosis, increased antioxidant activity and inflammatory factor, and partially prevented the decrease of neurons. The findings generally show that HUCB-EVs have neuroprotective effects and reduce neuroinflammation from the toxic effects of 3-NP, which can be beneficial for the recovery of HD.

Perinatal Tissue-Derived Stem Cells: An Emerging Therapeutic Strategy for Challenging Neurodegenerative Diseases

Over the past 20 years, stem cell therapy has been considered a promising option for treating numerous disorders, in particular, neurodegenerative disorders. Stem cells exert neuroprotective and neurodegenerative benefits through different mechanisms, such as the secretion of neurotrophic factors, cell replacement, the activation of endogenous stem cells, and decreased neuroinflammation. Several sources of stem cells have been proposed for transplantation and the restoration of damaged tissue. Over recent decades, intensive research has focused on gestational stem cells considered a novel resource for cell transplantation therapy. The present review provides an update on the recent preclinical/clinical applications of gestational stem cells for the treatment of protein-misfolding diseases including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS). However, further studies should be encouraged to translate this promising therapeutic approach into the clinical setting.

Using gene or cell therapies to treat Huntington's disease

Huntington's disease is caused by a CAG repeat expansion in the first exon of the HTT gene, leading to the production of gain-of-toxic-function mutant huntingtin protein species and consequent transcriptional dysregulation and disrupted cell metabolism. The brunt of the disease process is borne by the striatum from the earliest disease stages, with striatal atrophy beginning approximately a decade prior to the onset of neurologic signs. Although the expanded CAG repeat in the HTT gene is necessary and sufficient to cause HD, other genes can influence the age at onset of symptoms and how they progress. Many of these modifier genes have roles in DNA repair and are likely to modulate the stability of the CAG repeat in somatic cells. Currently, there are no disease-modifying treatments for HD that can be prescribed to patients and few symptomatic treatments, but there is a lot of interest in therapeutics that can target the pathogenic pathways at the DNA and RNA levels, some of which have reached the stage of human studies. In contrast, cell therapies aim to replace key neural cells lost to the disease process and/or to support the host vulnerable striatum by direct delivery of cells to the brain. Ultimately it may be possible to combine gene and cell therapies to both slow disease processes and provide some level of neural repair. In this chapter we consider the current status of these therapeutic strategies along with their prospects and challenges.