Small Molecule Induction of Human Umbilical Stem Cells into MBP-positive Oligodendrocytes in a Defined Three-Dimensional Environment

Chemogenetic activation of locus coeruleus neurons ameliorates the severity of multiple sclerosis

BACKGROUND

Most current disease-modifying therapies approved for multiple sclerosis (MS) are immunomodulatory drugs that counteract the aberrant activity of the immune system. Hence, new pharmacological interventions that drive anti-inflammatory activity and neuroprotection would represent interesting alternative therapeutic approaches or complementary strategies to treat progressive forms of MS. There is evidence of reduced noradrenaline levels and alterations to locus coeruleus (LC) noradrenergic neurons in MS patients, as well as in animal models of this disease, potentially factors contributing to the pathophysiology. Drugs that enhance noradrenaline appear to have some beneficial effects in MS, suggesting their potential to dampen the underlying pathology and disease progression.

METHODS

Therefore, we explored the consequences of chronic LC noradrenergic neurons activation by chemogenetics in experimental autoimmune encephalomyelitis (EAE) mice, the most widely used experimental model of MS. LC activation from the onset or the peak of motor symptoms was explored as two different therapeutic approaches, assessing the motor and non-motor behavioral changes as EAE progresses, and studying demyelination, inflammation and glial activation in the spinal cord and cerebral cortex during the chronic phase of EAE.

RESULTS

LC activation from the onset of motor symptoms markedly alleviated the motor deficits in EAE mice, as well as their anxiety-like behavior and sickness, in conjunction with reduced demyelination and perivascular infiltration in the spinal cord and glial activation in the spinal cord and prefrontal cortex (PFC). When animals exhibited severe paralysis, LC activation produced a modest alleviation of EAE motor symptoms and it enhanced animal well-being, in association with an improvement of the EAE pathology at the spinal cord and PFC level. Interestingly, the reduced dopamine beta-hydroxylase expression associated with EAE in the spinal cord and PFC was reversed through chemogenetic LC activation.

CONCLUSION

Therefore, clear anti-inflammatory and neuroprotective effects were produced by the selective activation of LC noradrenergic neurons in EAE mice, having greater benefits when LC activation commenced earlier. Overall, these data suggest noradrenergic LC neurons may be targets to potentially alleviate some of the motor and non-motor symptoms in MS.

Therapeutical growth in oligodendroglial fate induction via transdifferentiation of stem cells for neuroregenerative therapy

The merits of stem cell therapy and research are undisputed due to their widespread usage in the treatment of neurodegenerative diseases and demyelinating disorders. Cell replacement therapy especially revolves around stem cells and their induction into different cell lineages both adult and progenitor - belonging to each germ layer, prior to transplantation or disease modeling studies. The nervous system is abundant in glial cells and among these are oligodendrocytes capable of myelinating new-born neurons and remyelination of axons with lost or damaged myelin sheath. But demyelinating diseases generate tremendous deficit between myelin loss and recovery. To compensate for this loss, analyze the defects in remyelination mechanisms as well as to trigger full recovery in such patients mesenchymal stem cells (MSCs) have been induced to transdifferentiate into oligodendrocytes. But such experiments are riddled with problems like prolonged, tenuous and complicated protocols that stretch longer than the time taken for the spread of demyelination-associated after-effects. This review delves into such protocols and the combinations of different molecules and factors that have been recruited to derive bona fide oligodendrocytes from in vitro differentiation of embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and MSCs with special focus on MSC-derived oligodendrocytes.

Evaluation of Priming Efficiency of Forskolin in Tissue-Specific Human Mesenchymal Stem Cells into Dopaminergic Neurons: An In Vitro Comparative Study

Background: Human mesenchymal stem cells (hMSC) can be derived from various tissue sources and differentiated into dopaminergic (DAergic) neurons using various types of inducers. There are several strategies that have been reported to generate functional dopaminergic neuronal cells from hMSCs in the most efficient manner possible. However, this area is still under extensive research. In this study, we aim to compare hMSCs derived from bone marrow (BM), adipose tissue (AD) and dental pulp (DP) to generate functional dopaminergic neurons, using FGF2 and forskolin. Post-differentiation, multiple factors were used to characterize the cells at morphological, morphometric, ultra-structural, mRNA and protein levels for various markers (Nestin, NF, MAP2, Tuj1, TH, DAT, PitX3, Ngn2, Kv4.2, SCN5A). Cells’ functionality was studied by calcium ion imaging, along with the amount of dopamine secreted by the cells in the culture medium. Results: Data analysis revealed that forskolin has comparable effect on BM- and AD-derived MSC (28.43% and 29.46% DAergic neurons, respectively), whereas DP-MSC (42.78 ± 1.248% DAergic neurons) show better outcome in terms of efficient generation of DAergic neuronal cells, expression of neuronal associated markers, dopamine release and calcium ion efflux. Ultra-structural studies by SEM and TEM also revealed a substantial change in both cellular morphology and composition of cellular organelles. It was observed that AD-MSCs showed the best neuronal features, at morphological, gene, and protein levels upon induction with the above-mentioned induction cocktail. Conclusion: It may be concluded that a combination of FGF2 and forskolin yields functionally active dopaminergic neuronal cells in vitro, with highest percentage of the same from AD-MSCs, as compared to that in BM-MSCs and DP-MSCs. The outcomes and comparative evaluation provide a substantial platform for further studies on molecular pathways involved in the process of DAergic neurogenesis in individual cases.

Concentrations of toxic metals and essential trace elements vary among individual neurons in the human locus ceruleus

Objective

Damage to locus ceruleus neurons could play a part in the pathogenesis of neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis because of impairment of the blood-brain barrier and enhanced neuroinflammation. The locus ceruleus has connections throughout the brain and spinal cord, so the characteristic widespread multifocal pathology in these disorders could be due to damage to different subsets of locus ceruleus neurons. Previous studies have shown that only certain locus ceruleus neurons accumulate the neurotoxic metal mercury. To find out if concentrations of other toxic metals or of essential trace elements also vary between individual locus ceruleus neurons, we used synchrotron X-ray fluorescence microscopy on frozen sections of locus ceruleus neurons taken from people with multiple sclerosis, in whom the locus ceruleus is structurally intact.

Materials and methods

Paraffin embedded sections containing the locus ceruleus from seven people with multiple sclerosis were stained with autometallography that demonstrates accumulations of mercury, silver and bismuth. These were compared to maps of multiple elements obtained from frozen sections of locus ceruleus neurons from the same people using X-ray fluorescence microscopy. Neurons in the anterior pons from three of these donors were used as internal controls.

Results

Autometallography staining was observed in scattered locus ceruleus neurons from three of the seven donors. X-ray fluorescence microscopy showed variations among individual locus ceruleus neurons in levels of mercury, selenium, iron, copper, lead, bromine, and rubidium. Variations between donors of locus ceruleus neuronal average levels of mercury, iron, copper, and bromine were also detected. Anterior pons neurons contained no mercury, had varied levels of iron, and had lower copper levels than locus ceruleus neurons.

Conclusions

Individual human locus ceruleus neurons contain varying levels of toxic metals and essential trace elements. In contrast, most toxic metals are absent or at low levels in nearby anterior pons neurons. The locus ceruleus plays a role in numerous central nervous system functions, including maintaining the blood-brain-barrier and limiting neuroinflammation. Toxic metals, or alterations in essential trace metals within individual locus ceruleus neurons, could be one factor determining the non-random destruction of locus ceruleus neurons in normal aging and neurodegenerative diseases, and subsequently the sites of the widespread multifocal central nervous system pathology in these disorders.

Expanded Differentiation Capability of Human Wharton's Jelly Stem Cells Toward Pluripotency: A Systematic Review

Human Wharton's jelly stem cells (HWJSC) can be efficiently isolated from the umbilical cord, and numerous reports have demonstrated that these cells can differentiate into several cell lineages. This fact, coupled with the high proliferation potential of HWJSC, makes them a promising source of stem cells for use in tissue engineering and regenerative medicine. However, their real potentiality has not been established to date. In the present study, we carried out a systematic review to determine the multilineage differentiation potential of HWJSC. After a systematic literature search, we selected 32 publications focused on the differentiation potential of these cells. Analysis of these studies showed that HWJSC display expanded differentiation potential toward some cell types corresponding to all three embryonic cell layers (ectodermal, mesodermal, and endodermal), which is consistent with their constitutive expression of key pluripotency markers such as OCT4, SOX2, and NANOG, and the embryonic marker SSEA4. We conclude that HWJSC can be considered cells in an intermediate state between multipotentiality and pluripotentiality, since their proliferation capability is not unlimited and differentiation to all cell types has not been demonstrated thus far. These findings support the clinical use of HWJSC for the treatment of diseases affecting not only mesoderm-type tissues but also other cell lineages. Impact statement Human Wharton's jelly stem cells (HWJSC) are mesenchymal stem cells that are easy to isolate and handle, and that readily proliferate. Their wide range of differentiation capabilities supports the view that these cells can be considered pluripotent. Accordingly, HWJSC are one of the most promising cell sources for clinical applications in advanced therapies.

Hemmule: A Novel Structure with the Properties of the Stem Cell Niche

Stem cells are nurtured and regulated by a specialized microenvironment known as stem cell niche. While the functions of the niches are well defined, their structure and location remain unclear. We have identified, in rat bone marrow, the seat of hematopoietic stem cells—extensively vascularized node-like compartments that fit the requirements for stem cell niche and that we called hemmules. Hemmules are round or oval structures of about one millimeter in diameter that are surrounded by a fine capsule, have afferent and efferent vessels, are filled with the extracellular matrix and mesenchymal, hematopoietic, endothelial stem cells, and contain cells of the megakaryocyte family, which are known for homeostatic quiescence and contribution to the bone marrow environment. We propose that hemmules are the long sought hematopoietic stem cell niches and that they are prototypical of stem cell niches in other organs.

Mechanical regulation of oligodendrocyte biology

Oligodendrocytes (OL) are a subset of glial cells in the central nervous system (CNS) comprising the brain and spinal cord. The CNS environment is defined by complex biochemical and biophysical cues during development and response to injury or disease. In the last decade, significant progress has been made in understanding some of the key biophysical factors in the CNS that modulate OL biology, including their key role in myelination of neurons. Taken together, those studies offer translational implications for remyelination therapies, pharmacological research, identification of novel drug targets, and improvements in methods to generate human oligodendrocyte progenitor cells (OPCs) and OLs from donor stem cells in vitro. This review summarizes current knowledge of how various physical and mechanical cues affect OL biology and its implications for disease, therapeutic approaches, and generation of human OPCs and OLs.

The Healthy and Diseased Microenvironments Regulate Oligodendrocyte Properties: Implications for Regenerative Medicine

White matter disorders are characterized by deficient myelin or myelin loss, lead to a range of neurologic dysfunctions, and can result in early death. Oligodendrocytes, which are responsible for white matter formation, are the first targets for treatment. However, many studies indicate that failure of white matter repair goes beyond the intrinsic incapacity of oligodendrocytes to (re)generate myelin and that failed interactions with neighboring cells or factors in the diseased microenvironment can underlie white matter defects. Moreover, most of the white matter disorders show specific white matter pathology caused by different disease mechanisms. Herein, we review the factors within the cellular and the extracellular microenvironment regulating oligodendrocyte properties and discuss stem cell tools to identify microenvironmental factors of importance to the development of improved regenerative medicine for patients with white matter disorders.

Exome sequencing of case-unaffected-parents trios reveals recessive and de novo genetic variants in sporadic ALS

The contribution of genetic variants to sporadic amyotrophic lateral sclerosis (ALS) remains largely unknown. Either recessive or de novo variants could result in an apparently sporadic occurrence of ALS. In an attempt to find such variants we sequenced the exomes of 44 ALS-unaffected-parents trios. Rare and potentially damaging compound heterozygous variants were found in 27% of ALS patients, homozygous recessive variants in 14% and coding de novo variants in 27%. In 20% of patients more than one of the above variants was present. Genes with recessive variants were enriched in nucleotide binding capacity, ATPase activity, and the dynein heavy chain. Genes with de novo variants were enriched in transcription regulation and cell cycle processes. This trio study indicates that rare private recessive variants could be a mechanism underlying some case of sporadic ALS, and that de novo mutations are also likely to play a part in the disease.

‘Body-on-a-Chip’ Technology and Supporting Microfluidics

In order to effectively streamline current drug development protocols, there is a need to generate high information content preclinical screens capable of generating data with a predictive power in relation to the activity of novel therapeutics in humans. Given the poor predictive power of animal models, and the lack of complexity and interconnectivity of standard in vitro culture methodologies, many investigators are now moving toward the development of physiologically and functionally accurate culture platforms composed of human cells to investigate cellular responses to drug compounds in high-throughput preclinical studies. The generation of complex, multi-organ in vitro platforms, built to recapitulate physiological dimensions, flow rates and shear stresses, is being investigated as the logical extension of this drive. Production and application of a biologically accurate multi-organ platform, or ‘body-on-a-chip’, would facilitate the correct modelling of the dynamic and interconnected state of living systems for high-throughput drug studies as well as basic and applied biomolecular research. This chapter will discuss current technologies aimed at producing ‘body-on-a-chip’ models, as well as highlighting recent advances and important challenges still to be met in the development of biomimetic single-organ systems for drug development purposes.

In vitro and in vivo neurogenic potential of mesenchymal stem cells isolated from different sources

Regenerative medicine is an evolving interdisciplinary topic of research involving numerous technological methods that utilize stem cells to repair damaged tissues. Particularly, mesenchymal stem cells (MSCs) are a great tool in regenerative medicine because of their lack of tumorogenicity, immunogenicity and ability to perform immunomodulatory as well as anti-inflammatory functions. Numerous studies have investigated the role of MSCs in tissue repair and modulation of allogeneic immune responses. MSCs derived from different sources hold unique regenerative potential as they are self-renewing and can differentiate into chondrocytes, osteoblasts, adipocytes, cardiomyocytes, hepatocytes, endothelial and neuronal cells, among which neuronal-like cells have gained special interest. MSCs also have the ability to secrete multiple bioactive molecules capable of stimulating recovery of injured cells and inhibiting inflammation. In this review we focus on neural differentiation potential of MSCs isolated from different sources and how certain growth factors/small molecules can be used to derive neuronal phenotypes from MSCs. We also discuss the efficacy of MSCs when transplanted in vivo and how they can generate certain neurons and lead to relief or recovery of the diseased condition. Furthermore, we have tried to evaluate the appropriatemerits of different sources ofMSCs with respect to their propensity towards neurological differentiation as well as their effectiveness in preclinical studies.

Microphysiological systems and low-cost microfluidic platform with analytics

A multiorgan, functional, human in vitro assay system or 'Body-on-a-Chip' would be of tremendous benefit to the drug discovery and toxicology industries, as well as providing a more biologically accurate model for the study of disease as well as applied and basic biological research. Here, we describe the advances our team has made towards this goal, as well as the most pertinent issues facing further development of these systems. Description is given of individual organ models with appropriate cellular functionality, and our efforts to produce human iterations of each using primary and stem cell sources for eventual incorporation into this system. Advancement of the 'Body-on-a-Chip' field is predicated on the availability of abundant sources of human cells, capable of full differentiation and maturation to adult phenotypes, for which researchers are largely dependent on stem cells. Although this level of maturation is not yet achievable in all cell types, the work of our group highlights the high level of functionality that can be achieved using current technology, for a wide variety of cell types. As availability of functional human cell types for in vitro culture increases, the potential to produce a multiorgan in vitro system capable of accurately reproducing acute and chronic human responses to chemical and pathological challenge in real time will also increase.

Uptake of environmental toxicants by the locus ceruleus: a potential trigger for neurodegenerative, demyelinating and psychiatric disorders

BACKGROUND

Damage to the locus ceruleus, with a subsequent decrease of CNS noradrenaline, occurs in a wide range of neurodegenerative, demyelinating and psychiatric disorders. The cause of the initial locus ceruleus damage remains unknown. Recently, inorganic mercury was found to enter human locus ceruleus neurons selectively. This has led to the formulation of a new hypothesis as to the cause of these disorders.

HYPOTHESIS

Toxicants enter locus ceruleus neurons selectively, aided by the extensive exposure these neurons have to CNS capillaries, as well as by stressors that upregulate locus ceruleus activity. The resulting noradrenaline dysfunction affects a wide range of CNS cells and can trigger a number of neurodegenerative (Alzheimer's, Parkinson's and motor neuron disease), demyelinating (multiple sclerosis), and psychiatric (major depression and bipolar disorder) conditions.

CONCLUSIONS

This hypothesis proposes that environmental toxicants entering the locus ceruleus can give rise to a variety of CNS disorders. Proposals are made for experiments to gain further evidence for this hypothesis. If it is shown that toxicants in the locus ceruleus are responsible for these conditions, attempts can be made to prevent the toxicant exposures or to remove the toxicants from the nervous system.

Myelination and node of Ranvier formation on sensory neurons in a defined in vitro system

One of the most important developmental modifications of the nervous system is Schwann cell myelination of axons. Schwann cells ensheath axons to create myelin segments to provide protection to the axon as well as increase the conduction of action potentials. In vitro neuronal systems provide a unique modality to study a variety of factors influencing myelination as well as diseases associated with myelin sheath degradation. This work details the development of a patterned in vitro myelinating dorsal root ganglion culture. This defined system utilized a serum-free medium in combination with a patterned substrate, utilizing the cytophobic and cytophilic molecules (poly)ethylene glycol (PEG) and N-1[3 (trimethoxysilyl) propyl] diethylenetriamine (DETA), respectively. Directional outgrowth of the neurites and subsequent myelination was controlled by surface modifications, and conformity to the pattern was measured over the duration of the experiments. The myelinated segments and nodal proteins were visualized and quantified using confocal microscopy. This tissue-engineered system provides a highly controlled, reproducible model for studying Schwann cell interactions with sensory neurons, as well as the myelination process, and its effect on neuronal plasticity and peripheral nerve regeneration. It is also compatible for use in bio-hybrid constructs to reproduce the stretch reflex arc on a chip because the media combination used is the same that we have used previously for motoneurons, muscle, and for neuromuscular junction (NMJ) formation. This work could have application for the study of demyelinating diseases such as diabetes induced peripheral neuropathy and could rapidly translate to a role in the discovery of drugs promoting enhanced peripheral nervous system (PNS) remyelination.

Functional neuroanatomy of the central noradrenergic system

The central noradrenergic neurone, like the peripheral sympathetic neurone, is characterized by a diffusely arborizing terminal axonal network. The central neurones aggregate in distinct brainstem nuclei, of which the locus coeruleus (LC) is the most prominent. LC neurones project widely to most areas of the neuraxis, where they mediate dual effects: neuronal excitation by α₁-adrenoceptors and inhibition by α₂-adrenoceptors. The LC plays an important role in physiological regulatory networks. In the sleep/arousal network the LC promotes wakefulness, via excitatory projections to the cerebral cortex and other wakefulness-promoting nuclei, and inhibitory projections to sleep-promoting nuclei. The LC, together with other pontine noradrenergic nuclei, modulates autonomic functions by excitatory projections to preganglionic sympathetic, and inhibitory projections to preganglionic parasympathetic neurones. The LC also modulates the acute effects of light on physiological functions ('photomodulation'): stimulation of arousal and sympathetic activity by light via the LC opposes the inhibitory effects of light mediated by the ventrolateral preoptic nucleus on arousal and by the paraventricular nucleus on sympathetic activity. Photostimulation of arousal by light via the LC may enable diurnal animals to function during daytime. LC neurones degenerate early and progressively in Parkinson's disease and Alzheimer's disease, leading to cognitive impairment, depression and sleep disturbance.

Overexpression of SIRT1 protein in neurons protects against experimental autoimmune encephalomyelitis through activation of multiple SIRT1 targets

Treatment of experimental autoimmune encephalomyelitis (EAE) with resveratrol, an activator of sirtuin 1 (SIRT1), reduces disease severity. This suggested that activators of SIRT1, a highly conserved NAD-dependent protein deacetylase, might have immune-modulating or neuroprotective therapeutic effects in EAE. Previously, we showed that SIRT1 expression increases in EAE, suggesting that it is an adaptive response. In this study, we investigated the potential function of SIRT1 in regulating EAE using SIRT1-overexpressing mice. The current studies examine potential neuroprotective and immunomodulatory effects of SIRT1 overexpression in chronic EAE induced by immunization of C57BL/6 mice with myelin oligodendrocyte glycoprotein peptide 35-55. SIRT1 suppressed EAE clinical symptoms compared with wild-type EAE mice and prevented or altered the phenotype of inflammation in spinal cords; as a result, demyelination and axonal injury were reduced. Significant neuroprotective effects were observed, with fewer apoptotic cells found in the spinal cords of SIRT1-overexpressing EAE mice associated with increased brain-derived neurotrophic factor and NAD levels. Earlier, we showed that brain-derived neurotrophic factor and NAD play crucial neuroprotective roles in EAE. These results suggest that SIRT1 reduces neuronal loss in this chronic demyelinating disease model and that this is associated with a reduction in inflammation.

Converted neural cells: induced to a cure?

Many neurodegenerative disorders such as Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and others often occur as a result of progressive loss of structure or function of neurons. Recently, many groups were able to generate neural cells, either differentiated from induced pluripotent stem cells (iPSCs) or converted from somatic cells. Advances in converted neural cells have opened a new era to ease applications for modeling diseases and screening drugs. In addition, the converted neural cells also hold the promise for cell replacement therapy (Kikuchi et al., 2011; Krencik et al., 2011; Kriks et al., 2011; Nori et al., 2011; Rhee et al., 2011; Schwartz et al., 2012). Here we will mainly discuss most recent progress on using converted functional neural cells to treat neurological diseases and highlight potential clinical challenges and future perspectives.