Current Status of Mesenchymal Stem/Stromal Cells for Treatment of Neurological Diseases

Transplantation of autologous mesenchymal stromal cells in complete cervical spinal cord injury: a pilot study

Objective

Spinal cord injury (SCI) is a serious condition that can lead to partial or complete paraplegia or tetraplegia. Currently, there are few therapeutic options for these conditions, which are mainly directed toward the acute phase, such as surgical intervention and high-dose steroid administration. Mesenchymal stromal cells (MSC) have been shown to improve neurological function following spinal cord injury. The aim of the study was to evaluate the safety, feasibility, and potential efficacy of MSC transplantation in patients with cervical traumatic SCI.

Methods

We included seven subjects with chronic traumatic SCI (> 1 year) at the cervical level, classified as American Spinal Cord Injury Association impairment scale (AIS) grade A. Subjects received two doses of autologous bone marrow derived MSC, the first by direct injection into the lesion site after hemilaminectomy and the second three months later by intrathecal injection. Neurologic evaluation, spinal magnetic resonance imaging (MRI), urodynamics, and life quality questionnaires were assessed before and after treatment.

Results

Cell transplantation was safe without severe or moderate adverse effects, and the procedures were well tolerated. Neurological evaluation revealed discrete improvements in sensitivity below the lesion level, following treatment. Five subjects showed some degree of bilateral sensory improvement for both superficial and deep mechanical stimuli compared to the pretreatment profile. No significant alterations in bladder function were observed during this study.

Conclusion

Transplantation of autologous MSC in patients with chronic cervical SCI is a safe and feasible procedure. Further studies are required to confirm the efficacy of this therapeutic approach.

Clinical trial registration

https://clinicaltrials.gov/study/NCT02574572, identifier NCT02574572.

Mesenchymal Stem Cells Promote an Increase in Neuronal Oscillation via Glutamate Tonic Release

Mesenchymal stromal cells (MSCs) hold therapeutic potential for neurological disorders, but their impact on neuronal activity remains unclear. We investigated the effects of SB623 cells (Notch-1 intracellular domain-transfected MSCs) and parental MSCs on human induced pluripotent stem cell (iPSC)-derived neurons using multi-electrode arrays. SB623 cells significantly increased neuronal activity and oscillation in a dose-dependent manner, surpassing astrocytes in promoting network bursts. Strikingly, glutamatergic neurons showed a rapid increase in activity and bursts compared to GABAergic neurons, suggesting glutamate release from SB623 cells. We confirmed this by finding high glutamate levels in SB623 cell conditioned medium, which were reduced by glutaminase inhibition. Glutamate release was further implicated by the reduced excitability in co-cultures with astrocytes, known glutamate scavengers. Our findings reveal a novel mechanism for MSCs: promoting neuronal activity and network formation through tonic glutamate release, with potential implications for MSC-based therapies.

Dimethyl Fumarate Preconditioning can Reinforce the Therapeutic Potential of Bone Marrow Mesenchymal Stem Cells through Trophic Factor Profile Enhancement

Background

Numerous studies have confirmed the therapeutic efficacy of bone marrow-derived mesenchymal stem cells (BM-MSCs) in addressing neurologic disorders. To date, several preconditioning strategies have been designed to improve the therapeutic potential of these stem cells. This study was designed to evaluate the preconditioning effect of dimethyl fumarate (DMF) on the expression of main trophic factors in human BM-MSCs.

Materials and Methods

Initially, the identity of stem cells was confirmed through the evaluation of surface markers and their capacity for osteogenic and adipogenic differentiation using flow cytometry and differentiation assay, respectively. Subsequently, stem cells were subjected to different concentrations of DMF for 72 hours and their viability was defined by MTT assay. Following 72-hour preconditioning period with 10 µM DMF, gene expression was assessed by quantitative RT-PCR.

Results

Our findings demonstrated that the isolated stem cells expressed cardinal MSC surface markers and exhibited osteogenic and adipogenic differentiation potential. MTT results confirmed that 10 µM DMF was an optimal dose for maintaining cell viability. Preconditioning of stem cells with DMF significantly upregulated the expression of BDNF, NGF, and NT-3. Despite a slight increase in transcript level of GDNF and VEGF after DMF preconditioning, this difference was not statistically significant.

Conclusions

Our findings suggest that DMF preconditioning can enhance the expression of major neurotrophic factors in human BM-MSCs. Given the curative potential of both BM-MSCs and DMF in various neurological disease models and preconditioning outcomes, their combined use may synergistically enhance their neuroprotective properties.

Extracellular vesicles containing miR-181a-5p as a novel therapy for experimental autoimmune encephalomyelitis-induced demyelination

Multiple sclerosis (MS) is an inflammatory demyelinating disorder of the central nervous system. Recent research has revealed that mesenchymal stem cell-derived extracellular vesicles (MSC-EVs), containing specific miRNAs, possess immunomodulatory properties and have demonstrated therapeutic potential in the treatment of MS. This study aimed to investigate the role MSC-EVs, containing microRNA-181a-5p (miR-181a-5p) in both experimental autoimmune encephalomyelitis (EAE), an established animal model of MS, and lipopolysaccharide-stimulated BV2 microglia. We evaluated clinical symptoms and inflammatory responses in EAE mice following intrathecal injections of MSC-EVs. MSC-EVs containing miR-181a-5p were co-cultured with microglia to explore their impact on inflammation and cell pyroptosis. We validated the interaction between miR-181a-5p and its downstream regulators and conducted in vivo verification by injecting manipulated EVs containing miR-181a-5p into EAE mice. Our results demonstrated that MSC-EVs, containing miR-181a-5p reduced the clinical symptoms of EAE mice. Furthermore, we observed downregulation of miR-181a-5p in EAE model mice, and its expression was restored after treatment with MSC-EVs, which corresponded to suppressed microglial inflammation and pyroptosis. Additionally, EVs containing miR-181a-5p mitigated spinal cord injury and demyelination in EAE mice. Mechanistically, ubiquitin-specific protease 15 (USP15) exhibited high expression in EAE mice, and miR-181a-5p was specifically targeted and bound to USP15, thereby regulating the RelA/NEK7 axis. In conclusion, MSC-EVs containing miR-181a-5p inhibit microglial inflammation and pyroptosis through the USP15-mediated RelA/NEK7 axis, thus alleviating the clinical symptoms of EAE. These findings present a potential therapeutic approach for the treatment of MS.

Mechanistic insights and emerging therapeutic stratagems for Alzheimer's disease

Alzheimer's disease (AD), a multi-factorial neurodegenerative disorder has affected over 30 million individuals globally and these numbers are expected to increase in the coming decades. Current therapeutic interventions are largely ineffective as they focus on a single target. Development of an effective drug therapy requires a deep understanding of the various factors influencing the onset and progression of the disease. Aging and genetic factors exert a major influence on the development of AD. Other factors like post-viral infections, iron overload, gut dysbiosis, and vascular dysfunction also exacerbate the onset and progression of AD. Further, post-translational modifications in tau, DRP1, CREB, and p65 proteins increase the disease severity through triggering mitochondrial dysfunction, synaptic loss, and differential interaction of amyloid beta with different receptors leading to impaired intracellular signalling. With advancements in neuroscience tools, new inter-relations that aggravate AD are being discovered including pre-existing diseases and exposure to other pathogens. Simultaneously, new therapeutic strategies involving modulation of gene expression through targeted delivery or modulation with light, harnessing the immune response to promote clearance of amyloid deposits, introduction of stem cells and extracellular vesicles to replace the destroyed neurons, exploring new therapeutic molecules from plant, marine and biological sources delivered in the free state or through nanoparticles and use of non-pharmacological interventions like music, transcranial stimulation and yoga. Polypharmacology approaches involving combination of therapeutic agents are also under active investigation for superior therapeutic outcomes. This review elaborates on various disease-causing factors, their underlying mechanisms, the inter-play between different disease-causing players, and emerging therapeutic options including those under clinical trials, for treatment of AD. The challenges involved in AD therapy and the way forward have also been discussed.

Role of transforming growth factor-β in peripheral nerve regeneration

Injuries caused by trauma and neurodegenerative diseases can damage the peripheral nervous system and cause functional deficits. Unlike in the central nervous system, damaged axons in peripheral nerves can be induced to regenerate in response to intrinsic cues after reprogramming or in a growth-promoting microenvironment created by Schwann cells. However, axon regeneration and repair do not automatically result in the restoration of function, which is the ultimate therapeutic goal but also a major clinical challenge. Transforming growth factor (TGF) is a multifunctional cytokine that regulates various biological processes including tissue repair, embryo development, and cell growth and differentiation. There is accumulating evidence that TGF-β family proteins participate in peripheral nerve repair through various factors and signaling pathways by regulating the growth and transformation of Schwann cells; recruiting specific immune cells; controlling the permeability of the blood-nerve barrier, thereby stimulating axon growth; and inhibiting remyelination of regenerated axons. TGF-β has been applied to the treatment of peripheral nerve injury in animal models. In this context, we review the functions of TGF-β in peripheral nerve regeneration and potential clinical applications.

Protective role of stem cells in POI: Current status and mechanism of action, a review article

Premature ovarian insufficiency (POI) has far-reaching consequences on women's life quality. Due to the lack of full recognition of the etiology and complexity of this disease, there is no appropriate treatment for infected patients. Recently, stem cell therapy has attracted the attention of regenerative medicine scholars and offered promising outcomes for POI patients. Several kinds of stem cells, such as embryonic stem cells (ESCs), mesenchymal stem cells (MSCs), and induced pluripotent stem cells (iPSCs) have been used for the treatment of ovarian diseases. However, their potential protective mechanisms are still unknown. Undoubtedly, a better understanding of the therapeutic molecular and cellular mechanisms of stem cells will address uncover strategies to increase their clinical application for multiple disorders such as POI. This paper describes a detailed account of the potential properties of different types of stem cells and provides a comprehensive review of their protective mechanisms, particularly MSC, in POI disorder. In addition, ongoing challenges and several strategies to improve the efficacy of MSC in clinical use are addressed. Therefore, this review will provide proof-of-concept for further clinical application of stem cells in POI.

Pathological and therapeutic effects of extracellular vesicles in neurological and neurodegenerative diseases

Extracellular vesicles are released by all cell types and contain proteins, microRNAs, mRNAs, and other bioactive molecules. Extracellular vesicles play an important role in intercellular communication and in the modulation of the immune system and neuroinflammation. The cargo of extracellular vesicles (e.g., proteins and microRNAs) is altered in pathological situations. Extracellular vesicles contribute to the pathogenesis of many pathologies associated with sustained inflammation and neuroinflammation, including cancer, diabetes, hyperammonemia and hepatic encephalopathy, and other neurological and neurodegenerative diseases. Extracellular vesicles may cross the blood-brain barrier and transfer pathological signals from the periphery to the brain. This contributes to inducing neuroinflammation and cognitive and motor impairment in hyperammonemia and hepatic encephalopathy and in neurodegenerative diseases. The mechanisms involved are beginning to be understood. For example, increased tumor necrosis factor α in extracellular vesicles from plasma of hyperammonemic rats induces neuroinflammation and motor impairment when injected into normal rats. Identifying the mechanisms by which extracellular vesicles contribute to the pathogenesis of these diseases will help to develop new treatments and diagnostic tools for their easy and early detection. In contrast, extracellular vesicles from mesenchymal stem cells have therapeutic utility in many of the above pathologies, by reducing inflammation and neuroinflammation and improving cognitive and motor function. These extracellular vesicles recapitulate the beneficial effects of mesenchymal stem cells and have advantages as therapeutic tools: they are less immunogenic, may not differentiate to malignant cells, cross the blood-brain barrier, and may reach more easily target organs. Extracellular vesicles from mesenchymal stem cells have beneficial effects in models of ischemic brain injury, Alzheimer's and Parkinson's diseases, hyperammonemia, and hepatic encephalopathy. Extracellular vesicles from mesenchymal stem cells modulate the immune system, promoting the shift from a pro-inflammatory to an anti-inflammatory state. For example, extracellular vesicles from mesenchymal stem cells modulate the Th17/Treg balance, promoting the anti-inflammatory Treg. Extracellular vesicles from mesenchymal stem cells may also act directly in the brain to modulate microglia activation, promoting a shift from a pro-inflammatory to an anti-inflammatory state. This reduces neuroinflammation and improves cognitive and motor function. Two main components of extracellular vesicles from mesenchymal stem cells which contribute to these beneficial effects are transforming growth factor-β and miR-124. Identifying the mechanisms by which extracellular vesicles from mesenchymal stem cells induce the beneficial effects and the main molecules (e.g., proteins and mRNAs) involved may help to improve their therapeutic utility. The aims of this review are to summarize the knowledge of the pathological effects of extracellular vesicles in different pathologies, the therapeutic potential of extracellular vesicles from mesenchymal stem cells to recover cognitive and motor function and the molecular mechanisms for these beneficial effects on neurological function.

Comparative Study of the Protective and Neurotrophic Effects of Neuronal and Glial Progenitor Cells-Derived Conditioned Media in a Model of Glutamate Toxicity In Vitro

Cell therapy represents a promising approach to the treatment of neurological diseases, offering potential benefits not only by cell replacement but also through paracrine secretory activities. However, this approach includes a number of limiting factors, primarily related to safety. The use of conditioned stem cell media can serve as an equivalent to cell therapy while avoiding its disadvantages. The present study was a comparative investigation of the antioxidant, neuroprotective and neurotrophic effects of conditioned media obtained from neuronal and glial progenitor cells (NPC-CM and GPC-CM) on the PC12 cell line in vitro. Neuronal and glial progenitor cells were obtained from iPSCs by directed differentiation using small molecules. GPC-CM reduced apoptosis, ROS levels and increased viability, expressions of the antioxidant response genes HMOX1 and NFE2L2 in a model of glutamate-induced oxidative stress. The neurotrophic effect was evidenced by a change in the morphology of pheochromocytoma cells to a neuron-like phenotype. Moreover, neurite outgrowth, expression of GAP43, TUBB3, MAP2, SYN1 genes and increased levels of the corresponding MAP2 and TUBB3 proteins. Treatment with NPC-CM showed moderate antiapoptotic effects and improved cell viability. This study demonstrated the potential application of CM in the field of regenerative medicine.

Human mini-blood-brain barrier models for biomedical neuroscience research: a review

The human blood-brain barrier (BBB) is a unique multicellular structure that is in critical demand for fundamental neuroscience studies and therapeutic evaluation. Despite substantial achievements in creating in vitro human BBB platforms, challenges in generating specifics of physiopathological relevance are viewed as impediments to the establishment of in vitro models. In this review, we provide insight into the development and deployment of in vitro BBB models that allow investigation of the physiology and pathology of neurological therapeutic avenues. First, we highlight the critical components, including cell sources, biomaterial glue collections, and engineering techniques to reconstruct a miniaturized human BBB. Second, we describe recent breakthroughs in human mini-BBBs for investigating biological mechanisms in neurology. Finally, we discuss the application of human mini-BBBs to medical approaches. This review provides strategies for understanding neurological diseases, a validation model for drug discovery, and a potential approach for generating personalized medicine.