Intraventricular injections of mesenchymal stem cells activate endogenous functional remyelination in a chronic demyelinating murine model

Novel Approaches to the Treatment of Preterm White Matter Injury through Targeting Remyelination

Preterm white matter injury (WMI) is a common cause of cerebral palsy and cognitive disability after premature birth. Preterm WMI is caused by a differentiation arrest in the oligodendrocyte (OL) lineage, and a failure of myelination. As there are no specific treatments, care is supportive and focused on rehabilitation. However, novel high-throughput screening methods have enabled the identification of "pro-myelinating" compounds that promote OL differentiation and myelination. Many of these compounds stimulate remyelination in animal models and patients with demyelinating disorders. The shared mechanisms of remyelination and developmental myelination suggest that pro-myelinating compounds may have potential utility in preterm WMI.

Overexpression of OLIG2 and MYT1L Transcription Factors Enhance the Differentiation Potential of Human Mesenchymal Stem Cells into Oligodendrocytes

BACKGROUND

Demyelinating diseases represent a broad spectrum of disorders and are characterized by the loss of specialized glial cells (oligodendrocytes), which eventually leads to neuronal degeneration. Stem cell-based regenerative approaches provide therapeutic options to regenerate demyelination-induced neurodegeneration.

OBJECTIVES

The current study aims to explore the role of oligodendrocyte-specific transcription factors (OLIG2 and MYT1L) under suitable media composition to facilitate human umbilical-cord-derived mesenchymal stem cells (hUC-MSCs) differentiation toward oligodendrocyte for their potential use to treat demyelinating disorders.

METHODOLOGY

hUC-MSCs were isolated, cultured, and characterized based on their morphological and phenotypic characteristics. hUC-MSCs were transfected with OLIG2 and MYT1L transcription factors individually and in synergistic (OLIG2 + MYT1L) groups using a lipofectamine-based transfection method and incubated under two different media compositions (normal and oligo induction media). Transfected hUC-MSCs were assessed for lineage specification and differentiation using qPCR. Differentiation was also analyzed via immunocytochemistry by determining the expression of oligodendrocyte-specific proteins.

RESULTS

All the transfected groups showed significant upregulation of GFAP and OLIG2 with downregulation of NES, demonstrating the MSC commitment toward the glial lineage. Transfected groups also presented significant overexpression of oligodendrocyte-specific markers (SOX10, NKX2.2, GALC, CNP, CSPG4, MBP, and PLP1). Immunocytochemical analysis showed intense expression of OLIG2, MYT1L, and NG2 proteins in both normal and oligo induction media after 3 and 7 days.

CONCLUSIONS

The study concludes that OLIG2 and MYT1L have the potential to differentiate hUC-MSCs into oligodendrocyte-like cells, which is greatly facilitated by the oligo induction medium. The study may serve as a promising cell-based therapeutic strategy against demyelination-induced neuronal degeneration.

Cell-based experimental strategies for myelin repair in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system (CNS), diagnosed at a mean age of 32 years. CNS glia are crucial players in the onset of MS, primarily involving astrocytes and microglia that can cause/allow massive oligodendroglial cells death, without immune cell infiltration. Current therapeutic approaches are aimed at modulating inflammatory reactions during relapsing episodes, but lack the ability to induce very significant repair mechanisms. In this review article, different experimental approaches based mainly on the application of different cell types as therapeutic strategies applied for the induction of myelin repair and/or the amelioration of the disease are discussed. Regarding this issue, different cell sources were applied in various experimental models of MS, with different results, both in significant improvements in remyelination and the reduction of neuroinflammation and glial activation, or in neuroprotection. All cell types tested have advantages and disadvantages, which makes it difficult to choose a better option for therapeutic application in MS. New strategies combining cell-based treatment with other applications would result in further improvements and would be good candidates for MS cell therapy and myelin repair.

Remyelination in Multiple Sclerosis: Findings in the Cuprizone Model

Remyelination therapies, which are currently under development, have a great potential to delay, prevent or even reverse disability in multiple sclerosis patients. Several models are available to study the effectiveness of novel compounds in vivo, among which is the cuprizone model. This model is characterized by toxin-induced demyelination, followed by endogenous remyelination after cessation of the intoxication. Due to its high reproducibility and ease of use, this model enjoys high popularity among various research and industrial groups. In this review article, we will summarize recent findings using this model and discuss the potential of some of the identified compounds to promote remyelination in multiple sclerosis patients.

Editing a gateway for cell therapy across the blood-brain barrier

Stem cell therapy has been shown to improve stroke outcomes in animal models and is currently advancing towards clinical practice. However, uncertainty remains regarding the optimal route for cell delivery to the injured brain. Local intracerebral injections are effective in precisely delivering cells into the stroke cavity but carry the risk of damaging adjacent healthy tissue. Systemic endovascular injections, meanwhile, are minimally invasive, but most injected cells do not cross CNS barriers and become mechanically trapped in peripheral organs. Although the blood-brain barrier and the blood-CSF barrier tightly limit the entrance of cells and molecules into the brain parenchyma, immune cells can cross these barriers especially under pathological conditions, such as stroke. Deciphering the cell surface signature and the molecular mechanisms underlying this pathophysiological process holds promise for improving the targeted delivery of systemic injected cells to the injured brain. In this review, we describe experimental approaches that have already been developed in which (i) cells are either engineered to express cell surface proteins mimicking infiltrating immune cells; or (ii) cell grafts are preconditioned with hypoxia or incubated with pharmacological agents or cytokines. Modified cell grafts can be complemented with strategies to temporarily increase the permeability of the blood-brain barrier. Although these approaches could significantly enhance homing of stem cells into the injured brain, cell entrapment in off-target organs remains a non-negligible risk. Recent developments in safety-switch systems, which enable the precise elimination of transplanted cells on the administration of a drug, represent a promising strategy for selectively removing stem cells stuck in untargeted organs. In sum, the techniques described in this review hold great potential to substantially improve efficacy and safety of future cell therapies in stroke and may be relevant to other brain diseases.

Stem cell therapy for cuprizone model of multiple sclerosis focusing on the effectiveness of different injection methods and cell labeling

Multiple Sclerosis (MS) is a chronic and autoimmune disease of the central nervous system that causes inflammation in the brain and spinal cord, progressive degeneration of central nervous system tissue, damage to neuronal axons, and loss of function of central nervous system neurons. Experimental encephalomyelitis is an alternative animal model of MS that can simulate the symptoms of this disease. Cuprizone is one of the factors creating this model. Various researchers are testing the use of different cells to reduce the symptoms of cuprizone-demyelinated mice. The different injection methods explained in this article include intracerebral, intraperitoneal, intravenous, and intranasal. The intracerebral method, in contrast to the intranasal method, was widely employed by researchers. In each technique, the researchers try to inject a specific type of stem cell (SC) and monitor their efficiency. For monitoring SCs various labeling procedures are available, however, there is an upward trend in using magnetic resonance imaging (MRI). Two main barriers to using this method are high cost and complexity. In the current review, we try to make review cell therapy in the cuprizone model of MS.

Combination effects of mesenchymal stem cells transplantation and anodal transcranial direct current stimulation on a cuprizone-induced mouse model of multiple sclerosis

Multiple sclerosis (MS) has no absolute treatment, and researchers are still exploring to introduce promising therapy for MS. Transcranial direct current stimulation (tDCS), is a safe, non-invasive procedure for brain stimulating which can enhance working memory, cognitive neurohabitation and motor recovery. Here, we evaluated the effects of tDCS treatment and Mesenchymal stem cells (MSCs) transplantation on remyelination ability of a Cuprizone (CPZ)-induced demyelination mouse model. tDCS significantly increased the motor coordination and balance abilities in CPZ + tDCS and CPZ + tDCS + MSCs mice in comparison to the CPZ mice. Luxol fast blue (LFB) staining showed that tDCS and MSCs transplantation could increase remyelination capacity in CPZ + tDCS and CPZ + MSCs mice compared to the CPZ mice. But, the effect of tDCS with MSCs transplantation on remyelination process was larger than each of treatment alone. Immunofluorescence technique indicated that the numbers of Olig2⁺ cells were increased by tDCS and MSCs transplantation in CPZ + tDCS and CPZ + MSCs mice compared to the CPZ mice. Interestingly, the combination effect of tDCS and MSCs was larger than each of treatment alone on Oligodendrocytes population. MSCs transplantation significantly decreased the TUNEL⁺ cells in CPZ + MSCs and CPZ + tDCS + MSCs mice in comparison to the CPZ mice. Also, the combination effects of tDCS and MSCs transplantation was much larger than each of treatment alone on increasing the mRNA expression of BDNF and Sox2, while decreasing P53 as compared to CPZ mice. It can be concluded that the combination usage of tDCS and MSCs transplantation enhance remyelination process in CPZ-treated mice by increasing transplanted stem cell homing, oligodendrocyte generation and decreasing apoptosis.

Next-generation Tumor-homing Induced Neural Stem Cells as an Adjuvant to Radiation for the Treatment of Metastatic Lung Cancer

The spread of non-small cell lung cancer (NSCLC) to the leptomeninges is devastating with a median survival of only a few months. Radiation offers symptomatic relief, but new adjuvant therapies are desperately needed. Spheroidal, human induced neural stem cells (hiNeuroS) secreting the cytotoxic protein, TRAIL, have innate tumoritropic properties. Herein, we provide evidence that hiNeuroS-TRAIL cells can migrate to and suppress growth of NSCLC metastases in combination with radiation. In vitro cell tracking and post-mortem tissue analysis showed that hiNeuroS-TRAIL cells migrate to NSCLC tumors. Importantly, isobolographic analysis suggests that TRAIL with radiation has a synergistic cytotoxic effect on NSCLC tumors. In vivo, mice treated with radiation and hiNeuroS-TRAIL showed significant (36.6%) improvements in median survival compared to controls. Finally, bulk mRNA sequencing analysis showed both NSCLC and hiNeuroS-TRAIL cells showed changes in genes involved in migration following radiation. Overall, hiNeuroS-TRAIL cells +/- radiation have the capacity to treat NSCLC metastases.

Rg1 exerts protective effect in CPZ-induced demyelination mouse model via inhibiting CXCL10-mediated glial response

Myelin damage and abnormal remyelination processes lead to central nervous system dysfunction. Glial activation-induced microenvironment changes are characteristic features of the diseases with myelin abnormalities. We previously showed that ginsenoside Rg1, a main component of ginseng, ameliorated MPTP-mediated myelin damage in mice, but the underlying mechanisms are unclear. In this study we investigated the effects of Rg1 and mechanisms in cuprizone (CPZ)-induced demyelination mouse model. Mice were treated with CPZ solution (300 mg· kg^-1· d^-1, ig) for 5 weeks; from week 2, the mice received Rg1 (5, 10, and 20 mg· kg^-1· d^-1, ig) for 4 weeks. We showed that Rg1 administration dose-dependently alleviated bradykinesia and improved CPZ-disrupted motor coordination ability in CPZ-treated mice. Furthermore, Rg1 administration significantly decreased demyelination and axonal injury in pathological assays. We further revealed that the neuroprotective effects of Rg1 were associated with inhibiting CXCL10-mediated modulation of glial response, which was mediated by NF-κB nuclear translocation and CXCL10 promoter activation. In microglial cell line BV-2, we demonstrated that the effects of Rg1 on pro-inflammatory and migratory phenotypes of microglia were related to CXCL10, while Rg1-induced phagocytosis of microglia was not directly related to CXCL10. In CPZ-induced demyelination mouse model, injection of AAV-CXCL10 shRNA into mouse lateral ventricles 3 weeks prior CPZ treatment occluded the beneficial effects of Rg1 administration in behavioral and pathological assays. In conclusion, CXCL10 mediates the protective role of Rg1 in CPZ-induced demyelination mouse model. This study provides new insight into potential disease-modifying therapies for myelin abnormalities.

Recent Stem Cell Research on Hemorrhagic Stroke : An Update

Although technological advances and clinical studies on stem cells have been increasingly reported in stroke, research targeting hemorrhagic stroke is still lacking compared to that targeting ischemic stroke. Studies on hemorrhagic stroke are also being conducted, mainly in the USA and China. However, little research has been conducted in Korea. In reality, stem cell research or treatment is unfamiliar to many domestic neurosurgeons. Nevertheless, given the increased interest in regenerative medicine and the increase of life expectancy, attention should be paid to this topic. In this paper, we summarized pre-clinical rodent studies and clinical trials using stem cells for hemorrhagic stroke. In addition, we discussed results of domestic investigations and future perspectives on stem cell research for a better understanding.

Mesenchymal Stem Cells Ameliorate Cuprizone-Induced Demyelination by Targeting Oxidative Stress and Mitochondrial Dysfunction

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. The main causes of MS disease progression, demyelination, and tissue damage are oxidative stress and mitochondrial dysfunction. Hence, the latter are considered as important therapeutic targets. Recent studies have demonstrated that mesenchymal stem cells (MSCs) possess antioxidative properties and are able to target mitochondrial dysfunction. Therefore, we investigated the effect of transplanting Wharton's jelly-derived MSCs in a demyelination mouse model of MS in which mice were fed cuprizone (CPZ) for 12 weeks. CPZ is a copper chelator that impairs the activity of cytochrome oxidase, decreases oxidative phosphorylation, and produces degenerative changes in oligodendrocytes, leading to toxic demyelination similar to those found in MS patients. Results showed that MSCs caused a significant increase in the percentage of myelinated areas and in the number of myelinated fibers in the corpus callosum of the CPZ + MSC group, compared to the CPZ group, as assessed by Luxol fast blue staining and transmission electron microscopy. In addition, transplantation of MSCs significantly increased the number of oligodendrocytes while decreasing astrogliosis and microgliosis in the corpus callosum of the CPZ + MSC group, evaluated by immunofluorescence. Moreover, the mechanism by which MSCs exert these physiological effects was found to be through abolishing the effect of CPZ on oxidative stress markers and mitochondrial dysfunction. Indeed, malondialdehyde significantly decreased while glutathione and superoxide dismutase significantly increased in CPZ + MSC mice group, in comparison witth the CPZ group alone. Furthermore, cell therapy with MSC transplantation increased the expression levels of mitochondrial biogenesis transcripts PGC1α, NRF1, MFN2, and TFAM. In summary, these results demonstrate that MSCs may attenuate MS by promoting an antioxidant response, reducing oxidative stress, and improving mitochondrial homeostasis.

Effect of CSF1R inhibitor on glial cells population and remyelination in the cuprizone model

Multiple sclerosis is a kind of autoimmune and demyelinating disease with pathological symptoms such as inflammation, myelin loss, astrocytosis, and microgliosis. The colony stimulating factor 1 receptor (CSF1R) is an essential factor for the microglial function, and PLX3397 (PLX) is its specific inhibitor. In this wstudy, we assessed the effect of different doses of PLX for microglial ablation on glial cell population and remyelination process. Sixty male C57BL/6 mice (8 weeks old) were divided into 6 groups. The animals were fed with 0.2% cuprizone diet for 12 weeks. For microglial ablation, PLX (290 mg/kg) was added to the animal food for 3, 7, 14 and 21 days. Glial cell population was measured using immunohistochemistry. The rate of remyelination was evaluated using electron microscopy and Luxol Fast Blue staining. The expression levels of all genes were assessed by qRT-PCR method. Data were analysed using GraphPad Prism and SPSS software. The results showed that the administration of different doses of PLX significantly reduced microglial cells (p ≤ .001). PLX administration also significantly increased oligodendrocytes population (p ≤ .001) and remyelination compared to the cuprizone mice, which was aligned with the results of LFB and TEM. Gene results showed that PLX treatment reduced CSF1R expression. According to the results, the administration of PLX for 21 days enhanced remyelination by increasing oligodendrocytes in the chronic demyelination model. These positive effects could be related to the reduction of microglia.

The effect of microglial ablation and mesenchymal stem cell transplantation on a cuprizone-induced demyelination model

Multiple sclerosis (MS) is a demyelinating autoimmune disease of the central nervous system with symptoms such as neuroinflammation, astrocytosis, microgliosis, and axonal degeneration. Mesenchymal stem cells (MSCs) with their immunomodulation, differentiation, and neuroprotection abilities can influence the remyelination process. The goal of this study is to investigate the impact of microglial ablation and MSCs transplantation on remyelination processes in the corpus callosum (CC) of the cuprizone demyelination model. For the induction of a chronic demyelination model, C57BL6 mice were fed with chow containing 0.2% cuprizone (wt/wt) for 12 weeks. For the depletion of microglia, PLX3397 was used as a colony-stimulating factor 1 receptor inhibitor for 21 days. MSCs were injected to the right lateral ventricle and after 2 weeks, the mice were killed. We assessed glial cells using specific markers such as APC, Iba-1, and GFAP using the immunohistochemistry method. Remyelination was evaluated by Luxol fast blue (LFB) staining and transmission electron microscope (TEM). The specific genes of microglia and MSCs were evaluated by a quantitative real-time polymerase chain reaction. According to the results of the study, 21 days of PLX3397 treatment significantly reduced microglial cells, and MSCs transplantation decreased the number of astrocytes, whereas the oligodendrocytes population increased significantly in PLX + MSC group in comparison with the cuprizone mice. Furthermore, PLX and MSC treatment elevated levels of remyelination compared with the cuprizone group, as confirmed by LFB staining and TEM analysis. The molecular results showed that MSC transplantation significantly decreased the number of microglia through the CX3CL1/CX3CR1 axis. These results revealed that PLX3397 treatment and MSCs injection reduced microgliosis and astrocytosis. It also increased the oligodendrocytes population by enhancing remyelination in the CC of the cuprizone model of MS.

Co-culture of exogenous oligodendrocytes with unmyelinated cerebella: Revisiting ex vivo models and new tools to study myelination

Common in vitro models used to study the mechanisms regulating myelination rely on co-cultures of oligodendrocyte precursor cells (OPCs) and neurons. In such models, myelination occurs in an environment that does not fully reflect cell-cell interactions and environmental cues present in vivo. To avoid these limitations while specifically manipulating oligodendroglial cells, we developed a reliable ex vivo model of myelination by seeding OPCs on cerebellar slices, deprived of their endogenous oligodendrocytes. We showed that exogenous OPCs seeded on unmyelinated cerebella, efficiently differentiate and form compact myelin. Spectral confocal reflectance microscopy and electron microscopy analysis revealed that the density of compacted myelin sheaths highly increases all along the culture. Importantly, we defined the appropriate culture time frame to study OPC differentiation and myelination, using accurate quantification resources we generated. Thus, this model is a powerful tool to study the cellular and molecular mechanisms of OPC differentiation and myelination. Moreover, it is suitable for the development and validation of new therapies for myelin-related disorders such as multiple sclerosis and psychiatric diseases.

Alterations of mesenchymal stromal cells in cerebrospinal fluid: insights from transcriptomics and an ALS clinical trial

Background

Mesenchymal stromal cells (MSCs) have been studied with increasing intensity as clinicians and researchers strive to understand the ability of MSCs to modulate disease progression and promote tissue regeneration. As MSCs are used for diverse applications, it is important to appreciate how specific physiological environments may stimulate changes that alter the phenotype of the cells. One need for neuroregenerative applications is to characterize the spectrum of MSC responses to the cerebrospinal fluid (CSF) environment after their injection into the intrathecal space. Mechanistic understanding of cellular biology in response to the CSF environment may predict the ability of MSCs to promote injury repair or provide neuroprotection in neurodegenerative diseases.

Methods

In this study, we characterized changes in morphology, metabolism, and gene expression occurring in human adipose-derived MSCs cultured in human (hCSF) or artificial CSF (aCSF) as well as examined relevant protein levels in the CSF of subjects treated with MSCs for amyotrophic lateral sclerosis (ALS).

Results

Our results demonstrated that, under intrathecal-like conditions, MSCs retained their morphology, though they became quiescent. Large-scale transcriptomic analysis of MSCs revealed a distinct gene expression profile for cells cultured in aCSF. The aCSF culture environment induced expression of genes related to angiogenesis and immunomodulation. In addition, MSCs in aCSF expressed genes encoding nutritional growth factors to expression levels at or above those of control cells. Furthermore, we observed a dose-dependent increase in growth factors and immunomodulatory cytokines in CSF from subjects with ALS treated intrathecally with autologous MSCs.

Conclusions

Overall, our results suggest that MSCs injected into the intrathecal space in ongoing clinical trials remain viable and may provide a therapeutic benefit to patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02241-9.

Intracerebroventricular Administration of hNSCs Improves Neurological Recovery after Cardiac Arrest in Rats

Irreversible brain injury and neurological dysfunction induced by cardiac arrest (CA) have long been a clinical challenge due to lack of effective therapeutic interventions to reverse neuronal loss and prevent secondary reperfusion injury. The neuronal regenerative potential of neural stem cells (NSCs) provides a possible solution to this clinical deficit. We investigated the neuronal recovery potential of human neural stem cells (hNSCs) via intracerebroventricular (ICV) xenotransplantation after CA in rats and the effects of transplanted NSCs on the proliferation and migration of endogenous NSCs. Outcome measures included neurological functional recovery measured by neurological deficit score (NDS), electrophysiologic analysis of EEG, and assessment of proliferation and migration at the cellular level and the Wnt/β-catenin pathway at the molecular level. Neurological functional assessment based on aggregate neurological deficit score (NDS) showed better recovery of function after hNSCs therapy (P < 0.05). Tracking of stem cells' proliferation with Ki67 antibody suggested that the NSCs group had more prominent proliferation compared to control group (number of Ki67+ cells, Control VS. NSC: 89.0 ± 31.6 VS. 352.7 ± 97.3, P < 0.05). In addition, cell migration tracked by Dcx antibody showed more Dcx + cells migrated to the far distance zone from SVZ in the treatment group (P < 0.05). Further immunofluorescence staining confirmed that the expression of the Wnt signaling pathway protein (β-catenin) was upregulated in the NSC group (P < 0.05). ICV delivery of hNSCs promotes endogenous NSC proliferation and migration and ultimately enhances neuronal survival and neurological functional recovery. Wnt/β-catenin pathway may be involved in the initiation and maintenance of this enhancement.Graphical abstract.

Optimizing Stem Cell Therapy after Ischemic Brain Injury

Stem cells have been used for regenerative and therapeutic purposes in a variety of diseases. In ischemic brain injury, preclinical studies have been promising, but have failed to translate results to clinical trials. We aimed to explore the application of stem cells after ischemic brain injury by focusing on topics such as delivery routes, regeneration efficacy, adverse effects, and in vivo potential optimization. PUBMED and Web of Science were searched for the latest studies examining stem cell therapy applications in ischemic brain injury, particularly after stroke or cardiac arrest, with a focus on studies addressing delivery optimization, stem cell type comparison, or translational aspects. Other studies providing further understanding or potential contributions to ischemic brain injury treatment were also included. Multiple stem cell types have been investigated in ischemic brain injury treatment, with a strong literature base in the treatment of stroke. Studies have suggested that stem cell administration after ischemic brain injury exerts paracrine effects via growth factor release, blood-brain barrier integrity protection, and allows for exosome release for ischemic injury mitigation. To date, limited studies have investigated these therapeutic mechanisms in the setting of cardiac arrest or therapeutic hypothermia. Several delivery modalities are available, each with limitations regarding invasiveness and safety outcomes. Intranasal delivery presents a potentially improved mechanism, and hypoxic conditioning offers a potential stem cell therapy optimization strategy for ischemic brain injury. The use of stem cells to treat ischemic brain injury in clinical trials is in its early phase; however, increasing preclinical evidence suggests that stem cells can contribute to the down-regulation of inflammatory phenotypes and regeneration following injury. The safety and the tolerability profile of stem cells have been confirmed, and their potent therapeutic effects make them powerful therapeutic agents for ischemic brain injury patients.

Application of fibrin-based hydrogels for nerve protection and regeneration after spinal cord injury

Traffic accidents, falls, and many other events may cause traumatic spinal cord injuries (SCIs), resulting in nerve cells and extracellular matrix loss in the spinal cord, along with blood loss, inflammation, oxidative stress (OS), and others. The continuous development of neural tissue engineering has attracted increasing attention on the application of fibrin hydrogels in repairing SCIs. Except for excellent biocompatibility, flexibility, and plasticity, fibrin, a component of extracellular matrix (ECM), can be equipped with cells, ECM protein, and various growth factors to promote damage repair. This review will focus on the advantages and disadvantages of fibrin hydrogels from different sources, as well as the various modifications for internal topographical guidance during the polymerization. From the perspective of further improvement of cell function before and after the delivery of stem cell, cytokine, and drug, this review will also evaluate the application of fibrin hydrogels as a carrier to the therapy of nerve repair and regeneration, to mirror the recent development tendency and challenge.

Transplantation of induced neural stem cells (iNSCs) into chronically demyelinated corpus callosum ameliorates motor deficits

Multiple Sclerosis (MS) causes neurologic disability due to inflammation, demyelination, and neurodegeneration. Immunosuppressive treatments can modify the disease course but do not effectively promote remyelination or prevent long term neurodegeneration. As a novel approach to mitigate chronic stage pathology, we tested transplantation of mouse induced neural stem cells (iNSCs) into the chronically demyelinated corpus callosum (CC) in adult mice. Male C57BL/6 mice fed 0.3% cuprizone for 12 weeks exhibited CC atrophy with chronic demyelination, astrogliosis, and microglial activation. Syngeneic iNSCs were transplanted into the CC after ending cuprizone and perfused for neuropathology 2 weeks later. Magnetic resonance imaging (MRI) sequences for magnetization transfer ratio (MTR), diffusion-weighted imaging (T2), and diffusion tensor imaging (DTI) quantified CC pathology in live mice before and after iNSC transplantation. Each MRI technique detected progressive CC pathology. Mice that received iNSCs had normalized DTI radial diffusivity, and reduced astrogliosis post-imaging. A motor skill task that engages the CC is Miss-step wheel running, which demonstrated functional deficits from cuprizone demyelination. Transplantation of iNSCs resulted in marked recovery of running velocity. Neuropathology after wheel running showed that iNSC grafts significantly increased host oligodendrocytes and proliferating oligodendrocyte progenitors, while modulating axon damage. Transplanted iNSCs differentiated along astrocyte and oligodendrocyte lineages, without myelinating, and many remained neural stem cells. Our findings demonstrate the applicability of neuroimaging and functional assessments for pre-clinical interventional trials during chronic demyelination and detect improved function from iNSC transplantation. Directly reprogramming fibroblasts into iNSCs facilitates the future translation towards exogenous autologous cell therapies.

Endogenous oligodendroglial alpha-synuclein and TPPP/p25α orchestrate alpha-synuclein pathology in experimental multiple system atrophy models

Multiple system atrophy (MSA) is characterized by the presence of distinctive glial cytoplasmic inclusions (GCIs) within oligodendrocytes that contain the neuronal protein alpha-synuclein (aSyn) and the oligodendroglia-specific phosphoprotein TPPP/p25α. However, the role of oligodendroglial aSyn and p25α in the formation of aSyn-rich GCIs remains unclear. To address this conundrum, we have applied human aSyn (haSyn) pre-formed fibrils (PFFs) to rat wild-type (WT)-, haSyn-, or p25α-overexpressing oligodendroglial cells and to primary differentiated oligodendrocytes derived from WT, knockout (KO)-aSyn, and PLP-haSyn-transgenic mice. HaSyn PFFs are readily taken up by oligodendroglial cells and can recruit minute amounts of endogenous aSyn into the formation of insoluble, highly aggregated, pathological assemblies. The overexpression of haSyn or p25α accelerates the recruitment of endogenous protein and the generation of such aberrant species. In haSyn PFF-treated primary oligodendrocytes, the microtubule and myelin networks are disrupted, thus recapitulating a pathological hallmark of MSA, in a manner totally dependent upon the seeding of endogenous aSyn. Furthermore, using oligodendroglial and primary cortical cultures, we demonstrated that pathology-related S129 aSyn phosphorylation depends on aSyn and p25α protein load and may involve different aSyn “strains” present in oligodendroglial and neuronal synucleinopathies. Importantly, this hypothesis was further supported by data obtained from human post-mortem brain material derived from patients with MSA and dementia with Lewy bodies. Finally, delivery of haSyn PFFs into the mouse brain led to the formation of aberrant aSyn forms, including the endogenous protein, within oligodendroglia and evoked myelin decompaction in WT mice, but not in KO-aSyn mice. This line of research highlights the role of endogenous aSyn and p25α in the formation of pathological aSyn assemblies in oligodendrocytes and provides in vivo evidence of the contribution of oligodendroglial aSyn in the establishment of aSyn pathology in MSA.

Mesenchymal stem cells in dogs with demyelinating leukoencephalitis as an experimental model of multiple sclerosis

Researchers have used dogs with neurological sequelae caused by distemper as an experimental model for multiple sclerosis, owing to the similarities of the neuropathological changes between distemper virus-induced demyelinating leukoencephalitis and multiple sclerosis in humans. However, little is known about the role of mesenchymal stem cells in treating such clinical conditions. Therefore, we investigated the use of mesenchymal stem cells in four dogs with neurological lesions caused by the distemper virus. During the first year after cellular therapy, the animals did not demonstrate significant changes in their locomotive abilities. However, the intense (Grade V) myoclonus in three animals was reduced to a moderate (Grade IV) level. At one year after the mesenchymal stem cell infusions, three animals regained functional ambulation (Grade I), and all four dogs started to move independently (Grades I and II). In two animals, the myoclonic severity had become mild (Grade III). It was concluded that the use of mesenchymal stem cells could improve the quality of life of dogs with neurological sequelae caused by canine distemper, thus presenting hope for similar positive results in human patients with multiple sclerosis.

Distinctive functional deficiencies in axonal conduction associated with two forms of cerebral white matter injury

Aims

This study determines whether assessment with compound action potentials (CAPs) can distinguish two different forms of cerebral white matter injury at the functional levels.

Methods

A pure demyelination model was induced in C57/BL6 adult mice by dietary supplementation of cuprizone (0.2%) for 6 weeks. Callosal L‐N5‐(1‐Iminoethyl) ornithine (L‐NIO) hydrochloride (27 mg/mL) was injected into the corpus callosum (CC) to induce a focal white matter stroke (WMS), resulting in both demyelination and axonal injury. White matter integrity was assessed by performing CAP recording, electron microscopy, and immunohistological and luxol fast blue (LFB) staining.

Results

Immunohistological and electron microscopic analyses confirmed the induction of robust demyelination in CC with cuprizone, and mixed demyelination and axonal damage with L‐NIO. Electrophysiologically, cuprizone‐induced demyelination significantly reduced the amplitude of negative peak 1 (N1), but increased the amplitude of negative peak 2 (N2), of the CAPs compared to the sham controls. However, cuprizone did not affect the axonal conduction velocity. In contrast, the amplitude and area of both N1 and N2 along with N1 axonal conduction velocity were dramatically decreased in L‐NIO‐induced WMS.

Conclusions

Concertedly, parameters of the CAPs offer a novel functional assessment strategy for cerebral white matter injury in rodent models.

The Potential of Stem Cell Therapy to Repair White Matter Injury in Preterm Infants: Lessons Learned From Experimental Models

Diffuse white matter injury (dWMI) is a major cause of morbidity in the extremely preterm born infant leading to life-long neurological impairments, including deficits in cognitive, motor, sensory, psychological, and behavioral functioning. At present, no treatment options are clinically available to combat dWMI and therefore exploration of novel strategies is urgently needed. In recent years, the pathophysiology underlying dWMI has slowly started to be unraveled, pointing towards the disturbed maturation of oligodendrocytes (OLs) as a key mechanism. Immature OL precursor cells in the developing brain are believed to be highly sensitive to perinatal inflammation and cerebral oxygen fluctuations, leading to impaired OL differentiation and eventually myelination failure. OL lineage development under normal and pathological circumstances and the process of (re)myelination have been studied extensively over the years, often in the context of other adult and pediatric white matter pathologies such as stroke and multiple sclerosis (MS). Various studies have proposed stem cell-based therapeutic strategies to boost white matter regeneration as a potential strategy against a wide range of neurological diseases. In this review we will discuss experimental studies focusing on mesenchymal stem cell (MSC) therapy to reduce white matter injury (WMI) in multiple adult and neonatal neurological diseases. What lessons have been learned from these previous studies and how can we translate this knowledge to application of MSCs for the injured white matter in the preterm infant? A perspective on the current state of stem cell therapy will be given and we will discuss different important considerations of MSCs including cellular sources, timing of treatment and administration routes. Furthermore, we reflect on optimization strategies that could potentially reinforce stem cell therapy, including preconditioning and genetic engineering of stem cells or using cell-free stem cell products, to optimize cell-based strategy for vulnerable preterm infants in the near future.

Novel 18F-Labeled Radioligands for Positron Emission Tomography Imaging of Myelination in the Central Nervous System

Myelin is the protective sheath that surrounds nerves in vertebrates to protect axons, which thereby facilitates impulse conduction. Damage to myelin is associated with many neurodegenerative diseases such as multiple sclerosis and also includes spinal cord injury (SCI). The small size of the spinal cord poses formidable challenges to in vivo monitoring of myelination, which we investigated via conducting a structure-activity relationship study to determine the optimum positron-emitting agent to use for imaging myelin using positron emission tomography (PET). From these studies, [¹⁸F]PENDAS was identified as the lead agent to use in conjunction with PET imaging to delineate the integrity of spinal cord myelin. A subsequent in vivo PET imaging study of [¹⁸F]PENDAS in rats with SCI showed promising pharmacokinetic results that justify further development of imaging markers for diagnosing myelin-related diseases. Additionally, [¹⁸F]PENDAS could be valuable in determining the efficacy of therapies that are currently under development.

Mesenchymal stem cell mediated effects on microglial phenotype in cuprizone-induced demyelination model

Microglial cells have an essential role in neurodegenerative disorders, such as multiple sclerosis. They are divided into two subgroups: M1 and M2 phenotypes. Mesenchymal stem cells (MSC), with neuroprotective and immunomodulating properties, could improve these diseases. We evaluate the immunomodulating effects of MSC on microglial phenotypes and the improvement of demyelination in a cuprizone (CPZ) model of multiple sclerosis (MS). For inducing the chronic demyelination model, C57BL6 mice were given a diet with 0.2% CPZ (w/w) for 12 weeks. In the MSC group, cells were transplanted into the right lateral ventricle of mice. The expression of targeted genes was assessed by real-time polymerase chain reaction. M1 and M2 microglial phenotypes were assessed by immunohistochemistry of inducible nitric oxide synthase (iNOS) and Arg-1, respectively. Remyelination was studied by luxal fast blue (LFB) staining and electron microscopy (EM). We found that MSC transplantation reduced the expression level of M1-specific messenger RNA (mRNA; iNOS and CD86) but increased the expression level of M2 specific genes (CD206, Arg-1, and CX3CR1) in comparison to the CPZ group. Moreover, cell therapy significantly decreased the M1 marker (iNOS⁺ cells), but M2 marker (Arg-1⁺ cells) significantly increased in comparison with the CPZ group. In addition, MSC treatment significantly increased the CX3CL1 expression level in comparison with the CPZ group and led to improvement in remyelination, which was confirmed by LFB and EM images. The results showed that MSC transplantation increases the M2 and decreases the M1 phenotype in MS. This change was accompanied by decrease in demyelination and axonal injury and indicated that MSCs have a positive effect on MS by modification of microglia cells.

Secretome of Mesenchymal Stem Cells and Its Potential Protective Effects on Brain Pathologies

Previous studies have indicated that mesenchymal stem cells (MSCs) have a fundamental role in the repair and regeneration of damaged tissues. There is strong evidence showing that much of the beneficial effects of these cells are due to the secretion of bioactive molecules-besides microRNAs, hormones, and neurotrophins-with anti-inflammatory, immunoregulatory, angiogenic, and trophic effects. These factors have been reported by many studies to possess protective effects on the nervous tissue. Although the beneficial effects of the secretory factors of MSCs have been suggested for various neurological diseases, their actions on astrocytic cells are not well understood. Hence, it is important to recognize the specific effects of MSCs derived from adipose tissue, in addition to the differences presented by the secretome, depending on the source and methods of analysis. In this paper, the different sources of MSCs and their main characteristics are described, as well as the most significant advances in regeneration and protection provided by the secretome of MSCs. Also, we discuss the possible neuroprotective mechanisms of action of the MSC-derived biomolecules, with special emphasis on the effect of MSCs derived from adipose tissue and their impact on glial cells and brain pathologies.

Novel approaches using mesenchymal stem cells for curing peripheral nerve injuries

Peripheral nerve injury (PNI) is a common life-changing disability of peripheral nervous system with significant socioeconomic consequences. Conventional therapeutic approaches for PNI have several drawbacks such as need to autologous nerve scarifying, surplus surgery, and difficult accessibility to donor nerve; therefore, other therapeutic strategies such as mesenchymal stem cells (MSCs) therapy are getting more interesting. MSCs have been proved to be safe and efficient in numerous degenerative diseases of central and peripheral nervous systems. In this paper, we review novel biotechnological advancements in treating PNI using MSCs.

Effect of the CSF1R inhibitor PLX3397 on remyelination of corpus callosum in a cuprizone-induced demyelination mouse model

Multiple sclerosis (MS) is a chronic inflammatory disease affecting the central nervous system (CNS). Despite introducing multiple immunomodulatory approaches for MS, there are still major concerns about possible ways for improving remyelination in this disease. Microglia exert essential roles in regulation of myelination processes, and interaction between colony-stimulating factor 1 (CSF1) with its receptor CSF1R is considered as a key regulator of microglial differentiation and survival. The aim of this study was to investigate possible roles for a CSF1R inhibitor PLX3397 in recovery of central myelination processes. Chronic demyelination was induced in mice by addition of 0.2% cuprizone to the chow for 12 weeks. Next, animals were undergoing a diet containing 290 mg/kg PLX3397 to induce microglial ablation. The PLX3397 treatment caused a significant decrease in the rate of expression for the CSF1/CSF1R axis, and a reduction in the protein expressions for the microglial marker Iba-1 and for the oligodendrocyte marker Olig-2. Findings from Luxol fast blue (LFB) staining and transmission electron microscopy (TEM) showed an increase in the rate of myelination for the mice receiving PLX3397. The rate of destruction in the nerve fibers and the extent of the gaps formed between layers of myelin sheaths was also reduced after the treatment with PLX3397. In addition, animals experienced an improvement in recovery of motor deficit after receiving PLX3397 (for all P < 0.05). It could be concluded that PLX3397 could retain myelination in the MS model possibly through regulation of the myelin environment.

Co-administration of aspirin and adipose-derived stem cell conditioned medium improves the functional recovery of the optic pathway in a lysolecithin-induced demyelination model

INTRODUCTION

Based on beneficial effects of aspirin and mesenchymal stem cells (MSCs) on myelin repair, in a preset study, effects of co-administration of aspirin and conditioned medium from adipose tissue-derived stem cells (ADSC-CM) on functional recovery of optic pathway, demyelination levels, and astrocytes' activation were evaluated in a lysolecithin (LPC)-induced demyelination model of optic chiasm.

METHODS

LPC (1%, 2 µL) was injected into the rat optic chiasm and animals underwent daily intraperitoneal (i.p.) injections of ADSCs-CM and oral gavage of aspirin at a dose of 25 mg/kg for 14 days post LPC injection. The conductivity of visual signals was assessed using visual evoked potential recordings (VEPs) before LPC injection and on days 7 and 14 post lesion. Immunostaining against PDGFRα as oligodendrocyte precursor cells marker, MOG as mature myelin marker, and GFAP as astrocyte marker was performed on brain sections at day 14 post LPC injection. FluoroMyelin staining was also used to measure the extent of demyelination areas.

RESULTS

Our results showed that administration of ADSCs-CM and aspirin significantly reduced the latency of VEP waves in LPC receiving animals. In addition, demyelination levels and GFAP expressing cells were attenuated while the number of oligodendrocyte precursor cells significantly increased in rats treated with ADSCs-CM and aspirin.

CONCLUSION

Overall, our results suggest that co-administration of ADSCs-CM and aspirin improves the functional recovery of optic pathway through amelioration of astrocyte activation and attenuation of demyelination level.

Therapeutic effect of hepatocyte growth factor-overexpressing bone marrow-derived mesenchymal stem cells on CCl4-induced hepatocirrhosis

Hepatocirrhosis is one of the most severe complications of chronic hepatic disease in terms of medical intervention, and the available therapies are limited and not very successful. In this study, bone marrow-derived mesenchymal stem cells (BM-MSCs) from host rats were transduced with an adenoviral vector labelled with green fluorescent protein (EGFP) to overexpress hepatocyte growth factor (HGF). The therapeutic effect of these modified stem cells (HGF-BM-MSC group) transplanted intravenously into hepatocirrhosis model rats treated with CCl₄ was evaluated using serological, biochemical and histological approaches. We compared the rats in the HGF-BM-MSC group with those in the other groups (rats treated with BM-MSCs, rats treated with HGF and untreated rats (Controls)) in detail. The localisation of EGFP-tagged BM-MSCs in the injured liver was evaluated using a microscope, and the cells co-expressed hepatocyte nuclear factor 4α, albumin and cytokeratin 18. After treatment for 4 weeks, the HGF-BM-MSC, BM-MSC and HGF groups exhibited increased protein and mRNA levels of hepatocyte nuclear factor 4α, albumin and cytokeratin 18, but decreased levels of aspartate aminotransferase, alanine aminotransferase and total bilirubin. These findings indicate that BM-MSC transplantation and HGF application have great potential for the treatment of hepatocirrhosis.

Lowering the concentration affects the migration and viability of intracerebroventricular-delivered human mesenchymal stem cells

Due to their widely known therapeutic benefits, mesenchymal stem cells have been proposed as a novel treatment option for a wide range of diseases including Alzheimer's disease. To maximize these benefits, critical factors such as delivery route, cell viability, and cell migration must be accounted for. Out of the various delivery routes to the brain, the intracerebroventricular (ICV) route stands out due to the widespread distribution that can occur via cerebrospinal fluid flow. The major objective of this present study was to observe how altering cell concentration influences the migration and viability of human umbilical cord blood derived-mesenchymal stem cells (hUCB-MSCs), delivered via ICV injection, in the brains of wild-type (WT) mice. C3H/C57 WT mice were divided into three groups and were injected with 1 × 10⁵ hUCB-MSCs suspended in varying volumes: high (3 μl), middle (5 μl), and low (7 μl) concentrations, respectively. Lowering the concentration increased the migratory capabilities and elevated the viability of hUCB-MSCs. These results suggest that cell concentration can affect the physiological state of hUCB-MSCs, and thus the extent of therapeutic efficacy that can be achieved.