Transplantation of stem cell-derived astrocytes for the treatment of amyotrophic lateral sclerosis and spinal cord injury

CpG methylation changes in human mesenchymal and neural stem cells in response to in vitro niche modifications

Stem cell therapies hold promise in addressing the burden of neurodegenerative diseases with human embryonic neural stem cells (hNSC-H9s) and bone marrow-derived human mesenchymal stem cells (hMSCs) as viable candidates. The induction of hMSC neurospheres (hMSC-IN) generate a more lineage-restricted common neural progenitor-like cell population, potentially tunable by heparan sulfate proteoglycans (HSPGs). We examined CpG (5 mC) site methylation patterns using Illumina Infinium 850 K EPIC arrays in hNSC-H9, hMSCs and hMSC-IN cultures with HSPG agonist heparin at early and late phases of growth. We identified key regulatory CpG sites in syndecans (SDC2; SDC4) that potentially regulate gene expression in monolayers. Unique hMSC-IN hypomethylation in glypicans (GPC3; GPC4) underscore their significance in neural lineages with Sulfatase 1 and 2 (SULF1 &2) CpG methylation changes potentially driving the neurogenic shift. hMSC-INs methylation levels at SULF1 CpG sites and SULF2:cg25401628 were more closely aligned with hNSC-H9 cells than with hMSCs. We further suggest SOX2 regulation governed by lncSOX2-Overall Transcript (lncSOX2-OT) methylation changes with preferential activation of ENO2 over other neuronal markers within hMSC-INs. Our findings illuminate epigenetic dynamics governing neural lineage commitment of hMSC-INs offering insights for targeted mechanisms for regenerative medicine and therapeutic strategies.

Astrocytes and brain-derived neurotrophic factor (BDNF)

Astrocytes are emerging in the neuroscience field as crucial modulators of brain functions, from the molecular control of synaptic plasticity to orchestrating brain-wide circuit activity for cognitive processes. The cellular pathways through which astrocytes modulate neuronal activity and plasticity are quite diverse. In this review, we focus on neurotrophic pathways, mostly those mediated by brain-derived neurotrophic factor (BDNF). Neurotrophins are a well-known family of trophic factors with pleiotropic functions in neuronal survival, maturation and activity. Within the brain, BDNF is the most abundantly expressed and most studied of all neurotrophins. While we have detailed knowledge of the effect of BDNF on neurons, much less is known about its physiology on astroglia. However, over the last years new findings emerged demonstrating that astrocytes take an active part into BDNF physiology. In this work, we discuss the state-of-the-art knowledge about astrocytes and BDNF. Indeed, astrocytes sense extracellular BDNF through its specific TrkB receptors and activate intracellular responses that greatly vary depending on the brain area, stage of development and receptors expressed. Astrocytes also uptake and recycle BDNF / proBDNF at synapses contributing to synaptic plasticity. Finally, experimental evidence is now available describing deficits in astrocytic BDNF in several neuropathologies, suggesting that astrocytic BDNF may represent a promising target for clinical translation.

Decellularised spinal cord matrix manipulates glial niche into repairing phase via serglycin-mediated signalling pathway

Astrocytes are the most abundant and widespread glial cells in the central nervous system. The heterogeneity of astrocytes plays an essential role in spinal cord injury (SCI) repair. Decellularised spinal cord matrix (DSCM) is advantageous for repairing SCI, but little is known regarding the exact mechanisms and niche alterations. Here, we investigated the DSCM regulatory mechanism of glial niche in the neuro-glial-vascular unit using single-cell RNA sequencing. Our single cell sequencing, molecular and biochemical experiments validated that DSCM facilitated the differentiation of neural progenitor cells through increasing the number of immature astrocytes. Upregulation of mesenchyme-related genes, which maintained astrocyte immaturity, causing insensitivity to inflammatory stimuli. Subsequently, we identified serglycin (SRGN) as a functional component of DSCM, which involves inducing CD44-AKT signalling to trigger human spinal cord-derived primary astrocytes (hspASCs) proliferation and upregulation of genes related to epithelial-mesenchymal transition, thus impeding astrocyte maturation. Finally, we verified that SRGN-COLI and DSCM had similar functions in the human primary cell co-culture system to mimic the glia niche. In conclusion, our work revealed that DSCM reverted astrocyte maturation and altered the glia niche into the repairing phase through the SRGN-mediated signalling pathway.

Transcription factor combinations that define human astrocyte identity encode significant variation of maturity and function

Increasing evidence indicates that cellular identity can be reduced to the distinct gene regulatory networks controlled by transcription factors (TFs). However, redundancy exists in these states as different combinations of TFs can induce broadly similar cell types. We previously demonstrated that by overcoming gene silencing, it is possible to deterministically reprogram human pluripotent stem cells directly into cell types of various lineages. In the present study we leverage the consistency and precision of our approach to explore four different TF combinations encoding astrocyte identity, based on previously published reports. Analysis of the resulting induced astrocytes (iAs) demonstrated that all four cassettes generate cells with the typical morphology of in vitro astrocytes, which expressed astrocyte-specific markers. The transcriptional profiles of all four iAs clustered tightly together and displayed similarities with mature human astrocytes, although maturity levels differed between cells. Importantly, we found that the TF cassettes induced iAs with distinct differences with regards to their cytokine response and calcium signaling. In vivo transplantation of selected iAs into immunocompromised rat brains demonstrated long term stability and integration. In conclusion, all four TF combinations were able to induce stable astrocyte-like cells that were morphologically similar but showed subtle differences with respect to their transcriptome. These subtle differences translated into distinct differences with regards to cell function, that could be related to maturation state and/or regional identity of the resulting cells. This insight opens an opportunity to precision-engineer cells to meet functional requirements, for example, in the context of therapeutic cell transplantation.

Neurodegeneration and inflammation crosstalk: Therapeutic targets and perspectives

Glia, which was formerly considered to exist just to connect neurons, now plays a key function in a wide range of physiological events, including formation of memory, learning, neuroplasticity, synaptic plasticity, energy consumption, and homeostasis of ions. Glial cells regulate the brain's immune responses and confers nutritional and structural aid to neurons, making them an important player in a broad range of neurological disorders. Alzheimer's, ALS, Parkinson's, frontotemporal dementia (FTD), and epilepsy are a few of the neurodegenerative diseases that have been linked to microglia and astroglia cells, in particular. Synapse growth is aided by glial cell activity, and this activity has an effect on neuronal signalling. Each glial malfunction in diverse neurodegenerative diseases is distinct, and we will discuss its significance in the progression of the illness, as well as its potential for future treatment.

Distribution Features and Potential Effects of Serotonin in the Cerebrum of SOD1 G93A Transgenic Mice

Serotonin (5-HT) participates in the pathogenesis of amyotrophic lateral sclerosis (ALS), but its effects have not been completely clarified. Therefore, we observed the distribution features and potential effects of 5-HT in the cerebrum of G93A SOD1 transgenic (TG) and wild-type (WT) mice by fluorescence immunohistochemistry, Western blotting, ELISA, as well as motor function measurements. Both 5-HT and tryptophan hydroxylase-2 (TPH2) were mainly present in the limbic systems of the cerebrum, such as the glomerular layer of the olfactory bulb, nucleus accumbens, cingulate, fimbria of the hippocampus, mediodorsal thalamic nucleus, habenular nucleus, ventromedial hypothalamus nucleus, lateral hypothalamus area, dorsal raphe nucleus, and piriform cortex. TPH2 and 5-HT were expressed in cell bodies in the dorsal raphe nucleus and piriform cortex, while in other regions they were distributed as filaments and clump shapes in axons. The TPH2 distribution in the cerebrum of TG was significantly lower than that in WT in preset, onset, and progression stages. TPH2 expression in the fimbria of the hippocampus, mediodorsal thalamic nucleus, habenular nucleus, ventromedial hypothalamus nucleus and lateral hypothalamus area was increased in the onset stage and decreased in the progression stage, gradually decreased in the cingulate with disease progression and significantly decreased in the glomerular layer of the olfactory bulb and nucleus accumbens in the onset stage in TG. The number of mammalian achaete-scute homolog-1 in the subventricular zone (SVZ) in TG was significantly lower than that in WT, which was correlated with the TPH2 distribution. Double immunofluorescence staining showed that TPH2, mammalian achaete-scute homolog-1 and 5-HT were mainly expressed in neurons but rarely expressed in microglia or astrocytes in the piriform cortex. The relative fluorescence density of TPH2 in the cingulate region was negatively correlated with the disease severity. Our findings suggest that 5-HT plays a protective role in ALS, likely by regulating neural stem cells in the subventricular zone that might be involved in neuron development in the piriform cortex.

Morphological Characterization of Astrocytes in a Xenograft of Human iPSC-Derived Neural Precursor Cells

Transplantation of a mixed astrocyte and neuron culture is of interest in the development of cell therapies for neurodegenerative diseases. In this case, an assessment of engraftment requires a detailed morphological characterization, in particular an analysis of the neuronal and glial populations. In the experiment performed, human iPSC-derived neural progenitors transplanted into a rat striatum produced a mixed neuron and astrocyte population in vivo by the sixth month after transplantation. The morphological characteristics and neurochemical profile of the xenografted astrocytes were similar to those of mature human astroglia. Unlike neurons, astrocytes migrated to the surrounding structures and the density and pattern of their distribution in the striatum and cerebral cortex differed, which indicates that the microenvironment affects human glia integration. The graft was characterized by the zonal features of glial cell morphology, which was a reflection of cell maturation in the central area, glial shaft formation around the transplanted neurons, and migration to the surrounding structures.

The consequence of endothelial remodelling on the blood spinal cord barrier and nociception

Nociception is a fundamental acute protective mechanism that prevents harm to an organism. Understanding the integral processes that control nociceptive processing are fundamental to our appreciation of which cellular and molecular features underlie this process. There is an extensive understanding of how sensory neurons interpret differing sensory modalities and intensities. However, it is widely appreciated that the sensory neurons do not act alone. These work in harmony with inflammatory and vascular systems to modulate pain perception. The spinal cord has an extensive interaction with the capillary network in the form of a blood spinal cord barrier to ensure homeostatic control of the spinal cord neuron milieu. However, there is an extensive appreciation that disturbances in the blood spinal cord barrier contribute to the onset of chronic pain. Enhanced vascular permeability and impaired blood perfusion have both been highlighted as contributors to chronic pain manifestation. Here, we discuss the evidence that demonstrates alterations in the blood spinal cord barrier influences nociceptive processing and perception of pain.

Whole and fractionated human platelet lysate biomaterials-based biotherapy induces strong neuroprotection in experimental models of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease of motor neurons leading to death within 3 years and without a curative treatment. Neurotrophic growth factors (NTFs) are pivotal for cell survival. A reason for the lack of patient efficacy with single recombinant NTF brain infusion is likely to be due to the synergistic neuroprotective action of multiple NTFs on a diverse set of signaling pathways. Fractionated (protein size <50, <30, <10, <3 kDa) heat-treated human platelet lysate (HHPL) preparations were adapted for use in brain tissue with the aim of demonstrating therapeutic value in ALS models and further elucidation of the mechanisms of action. In neuronal culture all fractions induced Akt-dependent neuroprotection as well as a strong anti-apoptotic and anti-ferroptotic action. In the <3 kDa fraction anti-ferroptotic properties were shown to be GPX4 dependent highlighting a role for other platelet elements associated with NTFs. In the SOD1^G86R mouse model, lifespan was strongly increased by intracerebroventricular delivery of HHPL or by intranasal administration of <3 kDa fraction. Our results suggest that the platelet lysate biomaterials are neuroprotective in ALS. Further studies would now validate theragnostic biomarker on its antiferroptotic action, for further clinical development.

Neuronal cell-based medicines from pluripotent stem cells: Development, production, and preclinical assessment

Brain degeneration and damage is difficult to cure due to the limited endogenous repair capability of the central nervous system. Furthermore, drug development for treatment of diseases of the central nervous system remains a major challenge. However, it now appears that using human pluripotent stem cell-derived neural cells to replace degenerating cells provides a promising cell-based medicine for rejuvenation of brain function. Accordingly, a large number of studies have carried out preclinical assessments, which have involved different neural cell types in several neurological diseases. Recent advances in animal models identify the transplantation of neural derivatives from pluripotent stem cells as a promising path toward the clinical application of cell therapies [Stem Cells Transl Med 2019;8:681-693; Drug Discov Today 2019;24:992-999; Nat Med 2019;25:1045-1053]. Some groups are moving toward clinical testing in humans. However, the difficulty in selection of valuable critical quality criteria for cell products and the lack of functional assays that could indicate suitability for clinical effect continue to hinder neural cell-based medicine development [Biologicals 2019;59:68-71]. In this review, we summarize the current status of preclinical studies progress in this area and outline the biological characteristics of neural cells that have been used in new developing clinical studies. We also discuss the requirements for translation of stem cell-derived neural cells in examples of stem cell-based clinical therapy.

Regenerative replacement of neural cells for treatment of spinal cord injury

Introduction: Traumatic Spinal Cord Injury (SCI) results from primary physical injury to the spinal cord, which initiates a secondary cascade of neural cell death. Current therapeutic approaches can attenuate the consequences of the primary and secondary events, but do not address the degenerative aspects of SCI. Transplantation of neural stem/progenitor cells (NPCs) for the replacement of the lost/damaged neural cells is suggested here as a regenerative approach that is complementary to current therapeutics.Areas Covered: This review addresses how neurons, oligodendrocytes, and astrocytes are impacted by traumatic SCI, and how current research in regenerative-NPC therapeutics aims to restore their functionality. Methods used to enhance graft survival, as well as bias progenitor cells towards neuronal, oligodendrogenic, and astroglia lineages are discussed.Expert Opinion: Despite an NPC's ability to differentiate into neurons, oligodendrocytes, and astrocytes in the transplant environment, their potential therapeutic efficacy requires further optimization prior to translation into the clinic. Considering the temporospatial identity of NPCs could promote neural repair in region specific injuries throughout the spinal cord. Moreover, understanding which cells are targeted by NPC-derived myelinating cells can help restore physiologically-relevant myelin patterns. Finally, the duality of astrocytes is discussed, outlining their context-dependent importance in the treatment of SCI.

Glial Cell-Based Vascular Mechanisms and Transplantation Therapies in Brain Vessel and Neurodegenerative Diseases

Neurodevelopmental and neurodegenerative diseases (NDDs) with severe neurological/psychiatric symptoms, such as cerebrovascular pathology in AD, CAA, and chronic stroke, have brought greater attention with their incidence and prevalence having markedly increased over the past few years. Causes of the significant neuropathologies, especially those observed in neurological diseases in the CNS, are commonly believed to involve multiple factors such as an age, a total environment, genetics, and an immunity contributing to their progression, neuronal, and vascular injuries. We primarily focused on the studies of glial involvement/dysfunction in part with the blood-brain barrier (BBB) and the neurovascular unit (NVU) changes, and the vascular mechanisms, which have been both suggested as critical roles in chronic stroke and many other NDDs. It has been noted that glial cells including astrocytes (which outnumber other cell types in the CNS) essentially contribute more to the BBB integrity, extracellular homeostasis, neurotransmitter release, regulation of neurogenic niches in response to neuroinflammatory stimulus, and synaptic plasticity. In a recent study for NDDs utilizing cellular and molecular biology and genetic and pharmacological tools, the role of reactive astrocytes (RACs) and gliosis was demonstrated, able to trigger pathophysiological/psychopathological detrimental changes during the disease progression. We speculate, in particular, the BBB, the NVU, and changes of the astrocytes (potentially different populations from the RACs) not only interfere with neuronal development and synaptogenesis, but also generate oxidative damages, contribute to beta-amyloid clearances and disrupted vasculature, as well as lead to neuroinflammatory disorders. During the past several decades, stem cell therapy has been investigated with a research focus to target related neuro-/vascular pathologies (cell replacement and repair) and neurological/psychiatric symptoms (paracrine protection and homeostasis). Evidence shows that transplantation of neurogenic or vasculogenic cells could be achieved to pursue differentiation and maturation within the diseased brains as expected. It would be hoped that, via regulating functions of astrocytes, astrocytic involvement, and modulation of the BBB, the NVU and astrocytes should be among major targets for therapeutics against NDDs pathogenesis by drug and cell-based therapies. The non-invasive strategies in combination with stem cell transplantation such as the well-tested intranasal deliveries for drug and stem cells by our and many other groups show great translational potentials in NDDs. Neuroimaging and clinically relevant analyzing tools need to be evaluated in various NDDs brains.

Regenerative Stem Cell Therapy for Neurodegenerative Diseases: An Overview

Neurodegenerative diseases resulting from the progressive loss of structure and/or function of neurons contribute to different paralysis degrees and loss of cognition and sensation. The lack of successful curative therapies for neurodegenerative disorders leads to a considerable burden on society and a high economic impact. Over the past 20 years, regenerative cell therapy, also known as stem cell therapy, has provided an excellent opportunity to investigate potentially powerful innovative strategies for treating neurodegenerative diseases. This is due to stem cells' capability to repair injured neuronal tissue by replacing the damaged or lost cells with differentiated cells, providing a conducive environment that is in favor of regeneration, or protecting the existing healthy neurons and glial cells from further damage. Thus, in this review, the various types of stem cells, the current knowledge of stem-cell-based therapies in neurodegenerative diseases, and the recent advances in this field are summarized. Indeed, a better understanding and further studies of stem cell technologies cause progress into realistic and efficacious treatments of neurodegenerative disorders.

Induced pluripotent stem cell technology for spinal cord injury: a promising alternative therapy

Spinal cord injury has long been a prominent challenge in the trauma repair process. Spinal cord injury is a research hotspot by virtue of its difficulty to treat and its escalating morbidity. Furthermore, spinal cord injury has a long period of disease progression and leads to complications that exert a lot of mental and economic pressure on patients. There are currently a large number of therapeutic strategies for treating spinal cord injury, which range from pharmacological and surgical methods to cell therapy and rehabilitation training. All of these strategies have positive effects in the course of spinal cord injury treatment. This review mainly discusses the problems regarding stem cell therapy for spinal cord injury, including the characteristics and action modes of all relevant cell types. Induced pluripotent stem cells, which represent a special kind of stem cell population, have gained impetus in cell therapy development because of a range of advantages. Induced pluripotent stem cells can be developed into the precursor cells of each neural cell type at the site of spinal cord injury, and have great potential for application in spinal cord injury therapy.

Boosting Antioxidant Self-defenses by Grafting Astrocytes Rejuvenates the Aged Microenvironment and Mitigates Nigrostriatal Toxicity in Parkinsonian Brain via an Nrf2-Driven Wnt/β-Catenin Prosurvival Axis

Astrocyte (As) bidirectional dialog with neurons plays a fundamental role in major homeostatic brain functions, particularly providing metabolic support and antioxidant self-defense against reactive oxygen (ROS) and nitrogen species (RNS) via the activation of NF-E2-related factor 2 (Nrf2), a master regulator of oxidative stress. Disruption of As-neuron crosstalk is chiefly involved in neuronal degeneration observed in Parkinson's disease (PD), the most common movement disorder characterized by the selective degeneration of dopaminergic (DAergic) cell bodies of the substantia nigra (SN) pars compacta (SNpc). Ventral midbrain (VM)-As are recognized to exert an important role in DAergic neuroprotection via the expression of a variety of factors, including wingless-related MMTV integration site 1 (Wnt1), a principal player in DAergic neurogenesis. However, whether As, by themselves, might fulfill the role of chief players in DAergic neurorestoration of aged PD mice is presently unresolved. Here, we used primary postnatal mouse VM-As as a graft source for unilateral transplantation above the SN of aged 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mice after the onset of motor symptoms. Spatio-temporal analyses documented that the engrafted cells promoted: (i) a time-dependent nigrostriatal rescue along with increased high-affinity synaptosomal DA uptake and counteraction of motor deficit, as compared to mock-grafted counterparts; and (ii) a restoration of the impaired microenvironment via upregulation of As antioxidant self-defense through the activation of Nrf2/Wnt/β-catenin signaling, suggesting that grafting As has the potential to switch the SN neurorescue-unfriendly environment to a beneficial antioxidant/anti-inflammatory prosurvival milieu. These findings highlight As-derived factors/mechanisms as the crucial key for successful therapeutic outcomes in PD.

Glia in amyotrophic lateral sclerosis and spinal cord injury: common therapeutic targets

The toolkit for repairing damaged neurons in amyotrophic lateral sclerosis (ALS) and spinal cord injury (SCI) is extremely limited. Here, we reviewed the in vitro and in vivo studies and clinical trials on nonneuronal cells in the neurodegenerative processes common to both these conditions. Special focus was directed to microglia and astrocytes, because their activation and proliferation, also known as neuroinflammation, is a key driver of neurodegeneration. Neuroinflammation is a multifaceted process that evolves during the disease course, and can be either beneficial or toxic to neurons. Given the fundamental regulatory functions of glia, pathogenic mechanisms in neuroinflammation represent promising therapeutic targets. We also discussed neuroprotective, immunosuppressive, and stem-cell based approaches applicable to both ALS and SCI.

Spinal cord injury: pathophysiology, treatment strategies, associated challenges, and future implications

Axonal regeneration and formation of tripartite (axo-glial) junctions at damaged sites is a prerequisite for early repair of injured spinal cord. Transplantation of stem cells at such sites of damage which can generate both neuronal and glial population has gained impact in terms of recuperation upon infliction with spinal cord injury. In spite of the fact that a copious number of pre-clinical studies using different stem/progenitor cells have shown promising results at acute and subacute stages, at the chronic stages of injury their recovery rates have shown a drastic decline. Therefore, developing novel therapeutic strategies are the need of the hour in order to assuage secondary morbidity and effectuate improvement of the spinal cord injury (SCI)-afflicted patients' quality of life. The present review aims at providing an overview of the current treatment strategies and also gives an insight into the potential cell-based therapies for the treatment of SCI.

Amelioration of Amyotrophic Lateral Sclerosis in SOD1G93A Mice by M2 Microglia from Transplanted Marrow

Background/Aim: The cause of fatal neuromuscular amyotrophic lateral sclerosis (ALS) is not known. Materials and Methods: Ninety-day-old superoxide-dismutase-1 G93A (SOD1 G93A ) mice demonstrating level 1 paralysis, received 9.0 Gy total body irradiation (TBI) from a cesium source at 340 cGy per minute, and intravenous transplantation with 1×10 6 C57BL/6 green fluorescent protein (GFP)+ donor bone marrow cells. Results: Paralysis-free survival was prolonged in TBI and bone marrow-transplanted SOD1 G93A mice from 100 to over 250 days (p=0.0018). Other mice transplanted with SOD1 G93A marrow or marrow treated with the free-radical scavenger MMS350 showed no therapeutic effect. GFP+ macrophage-2 (M2) microglial cells of bone marrow origin, were seen at sites of degenerating anterior horn motor neurons. SOD1 G93A mice had a disruption in the blood-brain barrier permeability which was reversed by marrow transplant from C57BL/6 mice. SOD1 G93A marrow showed unexpected robust hematopoiesis in vitro, and radioresistance. Conclusion: After TBI, M2 microglial cells from transplanted donor marrow extended the paralysis-free interval in SOD1 G93A mice.

Derivation of Specific Neural Populations From Pluripotent Cells for Understanding and Treatment of Spinal Cord Injury

Due to the nature of the biological response to traumatic spinal cord injury, there are very limited therapeutic options available to patients. Recent advances in cell transplantation have demonstrated the therapeutic potential of transplanting supportive cell types following spinal cord injury. In particular, pluripotent stem cell derived neural cells are of interest for future investigation. Use of pluripotent stem cells as the source allows many cell types to be produced from a population that can be expanded in vitro. In this review, we will discuss the signaling pathways that have been used to differentiate spinal neural phenotypes from pluripotent stem cells. Additionally, we will highlight methods that have been developed to direct the differentiation of pluripotent stem cells to specific neural fates. Further refinement and elaboration of these techniques might aid in elucidating the multitude of neuronal subtypes endogenous to the spinal cord, as well as produce further therapeutic options for spinal cord injury recovery. Developmental Dynamics 248:78-87, 2019. © 2018 Wiley Periodicals, Inc.

Human- and mouse-derived neurons can be simultaneously obtained by co-cultures of human oral mucosal stem cells and mouse neural stem cells

OBJECTIVE

To observe simultaneous differentiation and analyse possible interactions between co-cultured human oral mucosal stem cells (hOMSC) and mouse neural stem cells (mNSC).

MATERIALS AND METHODS

hOMSC and mNSC were co-cultured in mouse and in human medium, and their immunocytochemical characterization to detect survival rate and differentiation pattern was performed. Co-cultures in different media were compared to hOMSC in human medium and mNSC in mouse medium as controls.

RESULTS

Co-culture of hOMSC and mNSC in medium for human cells led to normal differentiation pattern of human cells, while mNSC were directed towards astrocytes. When the same cells were cultivated in the mouse medium, both cell types succeeded to form neurons, although mNSC showed a tendency to overgrow hOMSC. hOMSC alone in the human-specific medium differentiated towards ectodermal (Oct4, Map2) and mesodermal (Osterix) cell populations. mNSC in the mouse-specific medium differentiated towards Map2-, β3-tubulin- and NeuN-positive neurons.

CONCLUSIONS

hOMSC and mNSC can form co-cultures. Different media considerably affected the differentiation pattern of co-cultures, whereas one cell population itself modestly influenced differentiation of the other cell type. The in vitro differentiation pattern of hOMSC in the mouse neural tissue environment suggested that hOMSC could be beneficial in the brain tissue affected by ischaemia.

Safety and efficacy of human embryonic stem cell-derived astrocytes following intrathecal transplantation in SOD1G93A and NSG animal models

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a motor neuron (MN) disease characterized by the loss of MNs in the central nervous system. As MNs die, patients progressively lose their ability to control voluntary movements, become paralyzed and eventually die from respiratory/deglutition failure. Despite the selective MN death in ALS, there is growing evidence that malfunctional astrocytes play a crucial role in disease progression. Thus, transplantation of healthy astrocytes may compensate for the diseased astrocytes.

METHODS

We developed a good manufacturing practice-grade protocol for generation of astrocytes from human embryonic stem cells (hESCs). The first stage of our protocol is derivation of astrocyte progenitor cells (APCs) from hESCs. These APCs can be expanded in large quantities and stored frozen as cell banks. Further differentiation of the APCs yields an enriched population of astrocytes with more than 90% GFAP expression (hES-AS). hES-AS were injected intrathecally into hSOD1G93A transgenic mice and rats to evaluate their therapeutic potential. The safety and biodistribution of hES-AS were evaluated in a 9-month study conducted in immunodeficient NSG mice under good laboratory practice conditions.

RESULTS

In vitro, hES-AS possess the activities of functional healthy astrocytes, including glutamate uptake, promotion of axon outgrowth and protection of MNs from oxidative stress. A secretome analysis shows that these hES-AS also secrete several inhibitors of metalloproteases as well as a variety of neuroprotective factors (e.g. TIMP-1, TIMP-2, OPN, MIF and Midkine). Intrathecal injections of the hES-AS into transgenic hSOD1G93A mice and rats significantly delayed disease onset and improved motor performance compared to sham-injected animals. A safety study in immunodeficient mice showed that intrathecal transplantation of hES-AS is safe. Transplanted hES-AS attached to the meninges along the neuroaxis and survived for the entire duration of the study without formation of tumors or teratomas. Cell-injected mice gained similar body weight to the sham-injected group and did not exhibit clinical signs that could be related to the treatment. No differences from the vehicle control were observed in hematological parameters or blood chemistry.

CONCLUSION

Our findings demonstrate the safety and potential therapeutic benefits of intrathecal injection of hES-AS for the treatment of ALS.

Affected astrocytes in the spinal cord of the leukodystrophy vanishing white matter

Leukodystrophies are often devastating diseases, presented with progressive clinical signs as spasticity, ataxia and cognitive decline, and lack proper treatment options. New therapy strategies for leukodystrophies mostly focus on oligodendrocyte replacement to rescue lack of myelin in the brain, even though disease pathology also often involves other glial cells and the spinal cord. In this study we investigated spinal cord pathology in a mouse model for Vanishing White Matter disease (VWM) and show that astrocytes in the white matter are severely affected. Astrocyte pathology starts postnatally in the sensory tracts, followed by changes in the astrocytic populations in the motor tracts. Studies in post-mortem tissue of two VWM patients, a 13-year-old boy and a 6-year-old girl, confirmed astrocyte abnormalities in the spinal cord. For proper development of new treatment options for VWM and, possibly, other leukodystrophies, future studies should investigate spinal cord involvement.

Astrocytes as targets for drug discovery

Recent studies have illuminated the crucial role of astrocytes in maintaining proper neuronal health and function. Abnormalities in astrocytic functions have now been implicated in the pathogenesis of neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS). Historically, drug development programs for neurodegenerative diseases generally target only neurons, overlooking the contributions of astrocytes. Therefore, targeting both disease neurons and astrocytes offers a new approach for drug development for the treatment of neurological diseases. Looking forward, the co-culturing of human neurons with astrocytes could be the next evolutionary step in drug discovery for neurodegenerative diseases.

Protective effect of epigenetic silencing of CyclinD1 against spinal cord injury using bone marrow-derived mesenchymal stem cells in rats

This study focuses on the protective effect of epigenetic silencing of CyclinD1 against spinal cord injury (SCI) using bone marrow-derived mesenchymal stem cells (BMSCs) in rats. Eighty-eight adult female Wistar rats were randomly assigned into the sham group, the control group, the si-CyclinD1 + BMSCs group and the BMSCs group. CyclinD1 protein and mRNA expressions after siRNA transfection were detected by Western blotting and qRT-PCR. The siRNA-CyclinD1 BMSCs were transplanted into rats in the si-CyclinD1 + BMSCs group using stereotaxic method 6 hr after SCI. Hindlimb locomotor performance was determined using inclined plane test and Basso-Beattie-Bresnahan (BBB) locomotor rating scale. Expressions of glial fibrillary acidic protein (GFAP) and nerve growth factor (NGF) were detected by immunohistochemistry. Inclined plane and BBB scores in the control, si-CyclinD1 + BMSCs, and BMSCs groups were significantly lower than the sham group, but these scores were evidently decreased in the control group and increased in the si-CyclinD1 + BMSCs group compared with the BMSCs group. The repair degree of spinal cord tissues of rats in the si-CyclinD1 + BMSCs group was obvious than the BMSCs group. GFAP and NGF protein expressions were markedly decreased in the control, si-CyclinD1 + BMSCs and BMSCs groups when compared with the sham group. GFAP- and NGF-positive cells were significantly increased in the si-CyclinD1 + BMSCs group while decreased in the control group. Our study provides evidence that epigenetic silencing of CyclinD1 using BMSCs might accelerate the repair of SCI in rats.

Bioinformatics Genes and Pathway Analysis for Chronic Neuropathic Pain after Spinal Cord Injury

It is well known spinal cord injury (SCI) can cause chronic neuropathic pain (NP); however its underlying molecular mechanisms remain elusive. This study aimed to disclose differentially expressed genes (DEGs) and activated signaling pathways in association with SCI induced chronic NP, in order to identify its diagnostic and therapeutic targets. Microarray dataset GSE5296 has been downloaded from Gene Expression Omnibus (GEO) database. Significant analysis of microarray (SAM), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and pathway network analysis have been used to compare changes of DEGs and signaling pathways between the SCI and sham-injury group. As a result, DEGs analysis showed there were 592 DEGs with significantly altered expression; among them Ccl3 expression showed the highest upregulation which implicated its association with SCI induced chronic NP. Moreover, KEGG analysis found 209 pathways changed significantly; among them the most significantly activated one is MAPK signaling pathway, which is in line with KEGG analysis results. Our results show Ccl3 is highly associated with SCI induced chronic NP; as the exosomes with Ccl3 can be easily and efficiently detected in peripheral blood, Ccl3 may serve as a potential prognostic target for the diagnosis and treatment of SCI induced chronic NP.

Treatment of refractory epilepsy patients with autologous mesenchymal stem cells reduces seizure frequency: An open label study

PURPOSE

Existing anti-epileptic drugs (AED) have limited efficiency in many patients, necessitating the search for alternative approaches such as stem cell therapy. We report the use of autologous patient-derived mesenchymal stem cells (MSC) as a therapeutic agent in symptomatic drug-resistant epilepsy in a Phase I open label clinical trial (registered as NCT02497443).

PATIENTS AND METHODS

The patients received either standard treatment with AED (control group), or AED supplemented with single intravenous administration of undifferentiated autologous MSC (target dose of 1×10⁶cells/kg), followed by a single intrathecal injection of neurally induced autologous MSC (target dose of 0.1×10⁶cells/kg).

RESULTS

MSC injections were well tolerated and did not cause any severe adverse effects. Seizure frequency was designated as the main outcome and evaluated at 1 year time point. 3 out of 10 patients in MSC therapy group achieved remission (no seizures for one year and more), and 5 additional patients became responders to AEDs, while only 2 out of 12 patients became responders in control group (difference significant, P=0.0135).

CONCLUSIONS

MSC possess unique immunomodulatory properties and are a safe and promising candidate for cell therapy in AED resistant epilepsy patients.

Transplantation of Hematopoietic Stem Cells Promotes Functional Improvement Associated with NT-3-MEK-1 Activation in Spinal Cord-Transected Rats

Transected spinal cord injury (SCT) is a devastating clinical disease that strongly affects a patient’s daily life and remains a great challenge for clinicians. Stem-cell therapy has been proposed as a potential therapeutic modality for SCT. To investigate the effects of hematopoietic stem cells (HSCs) on the recovery of structure and function in SCT rats and to explore the mechanisms associated with recovery, 57 adult Sprague-Dawley rats were randomly divided into sham (n = 15), SCT (n = 24), and HSC transplantation groups (n = 15). HSCs (passage 3) labeled by Hoechst 33342, were transplanted intraspinally into the rostral, scar and caudal sites of the transected lesion at 14 days post-operation. Both in vitro and in vivo, HSCs exhibited a capacity for cell proliferation and differentiation. Following HSC transplantation, the animals’ Basso, Beattie, and Bresnahan (BBB). locomotion scale scores increased significantly between weeks 4 and 24 post-SCT, which corresponded to an increased number of 5-hydroxytryptamine (5-HT) fibers and oligodendrocytes. The amount of astrogliosis indicated by immunohistochemical staining, was markedly decreased. Moreover, the decreased expression of neurotrophin- 3 (NT-3) and mitogen-activated protein kinase kinase-1 (MEK-1) after SCT was effectively restored by HSC transplantation. The data from the current study indicate that intraspinally administered HSCs in the chronic phase of SCT results in an improvement in neurological function. Further, the results indicate that intraspinally administered HSCs benefit the underlying mechanisms involved in the enhancement of 5-HT-positive fibers and oligogenesis, the suppression of excessive astrogliosis and the upregulation of NT3-regulated MEK-1 activation in the spinal cord. These crucial findings reveal not only the mechanism of cell therapy, but may also contribute to a novel therapeutic target for the treatment of spinal cord injury (SCI).

The Role of Astrocytes in Neuroprotection after Brain Stroke: Potential in Cell Therapy

Astrocytes are commonly involved in negative responses through their hyperreactivity and glial scar formation in excitotoxic and/or mechanical injuries. But, astrocytes are also specialized glial cells of the nervous system that perform multiple homeostatic functions for the survival and maintenance of the neurovascular unit. Astrocytes have neuroprotective, angiogenic, immunomodulatory, neurogenic, and antioxidant properties and modulate synaptic function. This makes them excellent candidates as a source of neuroprotection and neurorestoration in tissues affected by ischemia/reperfusion, when some of their deregulated genes can be controlled. Therefore, this review analyzes pro-survival responses of astrocytes that would allow their use in cell therapy strategies.

Stem cells for spinal cord injury: Strategies to inform differentiation and transplantation

The complex pathology of spinal cord injury (SCI), involving a cascade of secondary events and the formation of inhibitory barriers, hampers regeneration across the lesion site and often results in irreversible loss of motor function. The limited regenerative capacity of endogenous cells after SCI has led to a focus on the development of cell therapies that can confer both neuroprotective and neuroregenerative benefits. Stem cells have emerged as a candidate cell source because of their ability to self-renew and differentiate into a multitude of specialized cell types. While ethical and safety concerns impeded the use of stem cells in the past, advances in isolation and differentiation methods have largely mitigated these issues. A confluence of work in stem cell biology, genetics, and developmental neurobiology has informed the directed differentiation of specific spinal cell types. After transplantation, these stem cell-derived populations can replace lost cells, provide trophic support, remyelinate surviving axons, and form relay circuits that contribute to functional recovery. Further refinement of stem cell differentiation and transplantation methods, including combinatorial strategies that involve biomaterial scaffolds and drug delivery, is critical as stem cell-based treatments enter clinical trials. Biotechnol. Bioeng. 2017;114: 245-259. © 2016 Wiley Periodicals, Inc.

A Review of Stem Cell Therapy for Spinal Cord Injury: Large Animal Models and the Frontier in Humans

OBJECTIVE

To review the literature of spinal cord injury and stem cell therapy for large animal models and incorporate those results into an understanding of stem cell therapy for human cord injury.

METHODS

Review of the literature.

RESULTS

Eleven canine studies were identified and 3 sub-human primate studies were identified showing variable results.

CONCLUSIONS

Stem cell therapy is a promising therapeutic option for patients with spinal cord injury; however, the technology has many un-answered questions and further research is needed.

Serotonin 1A Receptors on Astrocytes as a Potential Target for the Treatment of Parkinson's Disease

Astrocytes are the most abundant neuron-supporting glial cells in the central nervous system. The neuroprotective role of astrocytes has been demonstrated in various neurological disorders such as amyotrophic lateral sclerosis, spinal cord injury, stroke and Parkinson’s disease (PD). Astrocyte dysfunction or loss-of-astrocytes increases the susceptibility of neurons to cell death, while astrocyte transplantation in animal studies has therapeutic advantage. We reported recently that stimulation of serotonin 1A (5-HT_1A) receptors on astrocytes promoted astrocyte proliferation and upregulated antioxidative molecules to act as a neuroprotectant in parkinsonian mice. PD is a progressive neurodegenerative disease with motor symptoms such as tremor, bradykinesia, rigidity and postural instability, that are based on selective loss of nigrostriatal dopaminergic neurons, and with non-motor symptoms such as orthostatic hypotension and constipation based on peripheral neurodegeneration. Although dopaminergic therapy for managing the motor disability associated with PD is being assessed at present, the main challenge remains the development of neuroprotective or disease-modifying treatments. Therefore, it is desirable to find treatments that can reduce the progression of dopaminergic cell death. In this article, we summarize first the neuroprotective properties of astrocytes targeting certain molecules related to PD. Next, we review neuroprotective effects induced by stimulation of 5-HT_1A receptors on astrocytes. The review discusses new promising therapeutic strategies based on neuroprotection against oxidative stress and prevention of dopaminergic neurodegeneration.

Advances in Stem Cell Research- A Ray of Hope in Better Diagnosis and Prognosis in Neurodegenerative Diseases

Neurodegeneration and neurodegenerative disorders have been a global health issue affecting the aging population worldwide. Recent advances in stem cell biology have changed the current face of neurodegenerative disease modeling, diagnosis, and transplantation therapeutics. Stem cells also serve the purpose of a simple in-vitro tool for screening therapeutic drugs and chemicals. We present the application of stem cells and induced pluripotent stem cells (iPSCs) in the field of neurodegeneration and address the issues of diagnosis, modeling, and therapeutic transplantation strategies for the most prevalent neurodegenerative disorders. We have discussed the progress made in the last decade and have largely focused on the various applications of stem cells in the neurodegenerative research arena.

Distributed Features of Vimentin-Containing Neural Precursor Cells in Olfactory Bulb of SOD1G93A Transgenic Mice: a Study about Resource of Endogenous Neural Stem Cells

No any effective treatments can prevent from the motor neuron degeneration in amyotrophic lateral sclerosis (ALS) at present. In order to modulating the endogenous neural precursor cells (NPCs) to repairing the degenerative motor neurons in ALS, we studied the alteration of endogenous vimentin-containing NPCs in olfactory bulb (OB) at the different stages of SOD1 wlid-type and G93A transgenic mice. The results showed that the vimentin-containing cells (VCCs) were mainly distributed in the glomerular layer (Gl), the accessory OB (AOB), the OB core, the granular cell layer (GRO) and the mitral cell layer (MI)+the internal plexiform layer (IPL) of the OB of adult mice. Almost all VCCs in Gl, OB core and GRO were the GFAP positive cells. Almost all VCCs in AOB were the Oligo-2 positive cells. Fewer VCCs in MI+IPL were the NeuN positive cells. VCCs significantly increased in the OB core and Gl of adult OB at the pre-onset, onset and progression stages of ALS-like G93A transgenic disease, particularly in OB core. All increased VCCs were the GFAP positive cells. Our data suggested that there extensively existed the endogenous vimentin-containing NPCs in the OB of adult mice, which was a potential resource of neural stem cells, they could differentiate into astrocyte, oligodendrocyte and neuron cells, were a potential astrocyte neuroregenerative response in adult OB in the ALS-like disease, were a potential pathway to repair the degenerated motor neurons.

Denervated hippocampus provides a favorable microenvironment for neuronal differentiation of endogenous neural stem cells

Fimbria-fornix transection induces both exogenous and endogenous neural stem cells to differentiate into neurons in the hippocampus. This indicates that the denervated hippocampus provides an environment for neuronal differentiation of neural stem cells. However, the pathways and mechanisms in this process are still unclear. Seven days after fimbria fornix transection, our reverse transcription polymerase chain reaction, western blot assay, and enzyme linked immunosorbent assay results show a significant increase in ciliary neurotrophic factor mRNA and protein expression in the denervated hippocampus. Moreover, neural stem cells derived from hippocampi of fetal (embryonic day 17) Sprague-Dawley rats were treated with ciliary neurotrophic factor for 7 days, with an increased number of microtubule associated protein-2-positive cells and decreased number of glial fibrillary acidic protein-positive cells detected. Our results show that ciliary neurotrophic factor expression is up-regulated in the denervated hippocampus, which may promote neuronal differentiation of neural stem cells in the denervated hippocampus.

Astrocytes: inexplicable cells in neurodegeneration

Astrocytes are the most explored non-neuronal cells in the brain under neurophysiological and neurodegenerative conditions. Extensive research has been done to understand their specific role during neuropathological conditions but still the existing findings could not conclude their mechanism of action and their specific role in neurodegenerative conditions. This review discusses their physiological and pathological roles, their activation, morphological alterations and their probable use in search of new therapeutic targets for the treatment of neurodegenerative diseases.

Human neural progenitors differentiate into astrocytes and protect motor neurons in aging rats

Age-associated health decline presents a significant challenge to healthcare, although there are few animal models that can be used to test potential treatments. Here, we show that there is a significant reduction in both spinal cord motor neurons and motor function over time in the aging rat. One explanation for this motor neuron loss could be reduced support from surrounding aging astrocytes. Indeed, we have previously shown using in vitro models that aging rat astrocytes are less supportive to rat motor neuron function and survival over time. Here, we test whether rejuvenating the astrocyte niche can improve the survival of motor neurons in an aging spinal cord. We transplanted fetal-derived human neural progenitor cells (hNPCs) into the aging rat spinal cord and found that the cells survive and differentiate into astrocytes with a much higher efficiency than when transplanted into younger animals, suggesting that the aging environment stimulates astrocyte maturation. Importantly, the engrafted astrocytes were able to protect against motor neuron loss associated with aging, although this did not result in an increase in motor function based on behavioral assays. We also transplanted hNPCs genetically modified to secrete glial cell line-derived neurotrophic factor (GDNF) into the aging rat spinal cord, as this combination of cell and protein delivery can protect motor neurons in animal models of ALS. During aging, GDNF-expressing hNPCs protected motor neurons, though to the same extent as hNPCs alone, and again had no effect on motor function. We conclude that hNPCs can survive well in the aging spinal cord, protect motor neurons and mature faster into astrocytes when compared to transplantation into the young spinal cord. While there was no functional improvement, there were no functional deficits either, further supporting a good safety profile of hNPC transplantation even into the older patient population.

Heterogeneous astrocytes: Active players in CNS

Astrocytes, the predominant cell type that are broadly distributed in the brain and spinal cord, play key roles in maintaining homeostasis of the central nerve system (CNS) in physiological and pathological conditions. Increasing evidence indicates that astrocytes are a complex colony with heterogeneity on morphology, gene expression, function and many other aspects depending on their spatio-temporal distribution and activation level. In pathological conditions, astrocytes differentially respond to all kinds of insults, including injury and disease, and participate in the neuropathological process. Based on current studies, we here give an overview of the roles of heterogeneous astrocytes in CNS, especially in neuropathologies, which focuses on biological and functional diversity of astrocytes. We propose that a precise understanding of the heterogeneous astrocytes is critical to unlocking the secrets about pathogenesis and treatment of the mazy CNS.

Parkinson Disease-Mediated Gastrointestinal Disorders and Rational for Combinatorial Therapies

A gradual loss of dopamine-producing nerve cells gives rise to a common neurodegenerative Parkinson’s disease (PD). This disease causes a neurotransmitter imbalance in the brain and initiates a cascade of complications in the rest of the body that appears as distressing symptoms which include gait problems, tremor, gastrointestinal (GI) disorders and cognitive decline. To aid dopamine deficiency, treatment in PD patients includes oral medications, in addition to other methods such as deep brain stimulation and surgical lesioning. Scientists are extensively studying molecular and signaling mechanisms, particularly those involving phenotypic transcription factors and their co-regulatory proteins that are associated with neuronal stem cell (SC) fate determination, maintenance and disease state, and their role in the pathogenesis of PD. Advancement in scientific research and “personalized medicine” to augment current therapeutic intervention and minimize the side effects of chemotherapy may lead to the development of more effective therapeutic strategies in the near future. This review focuses on PD and associated GI complications and summarizes the current therapeutic modalities that include stem cell studies and combinatorial drug treatment.

Stem cell transplantation therapy in Parkinson's disease

Ineffective therapeutic treatments and inadequate repair ability in the central nervous system are disturbing problems for several neurological diseases. Fortunately, the development of clinically applicable populations of stem cells has provided an avenue to overcome the failure of endogenous repair systems and substitute new cells into the damaged brain. However, there are still several existing obstacles to translating into clinical application. Here we review the stem-cell based therapies for Parkinson’s disease and discuss the potential advantages and drawbacks. We hope this review may provide suggestions for viable strategies to overcome the current technical and biological issues associated with the application of stem cells in Parkinson’s disease.

Drug delivery, cell-based therapies, and tissue engineering approaches for spinal cord injury

Spinal cord injury (SCI) results in devastating neurological and pathological consequences, causing major dysfunction to the motor, sensory, and autonomic systems. The primary traumatic injury to the spinal cord triggers a cascade of acute and chronic degenerative events, leading to further secondary injury. Many therapeutic strategies have been developed to potentially intervene in these progressive neurodegenerative events and minimize secondary damage to the spinal cord. Additionally, significant efforts have been directed toward regenerative therapies that may facilitate neuronal repair and establish connectivity across the injury site. Despite the promise that these approaches have shown in preclinical animal models of SCI, challenges with respect to successful clinical translation still remain. The factors that could have contributed to failure include important biologic and physiologic differences between the preclinical models and the human condition, study designs that do not mirror clinical reality, discrepancies in dosing and the timing of therapeutic interventions, and dose-limiting toxicity. With a better understanding of the pathobiology of events following acute SCI, developing integrated approaches aimed at preventing secondary damage and also facilitating neuroregenerative recovery is possible and hopefully will lead to effective treatments for this devastating injury. The focus of this review is to highlight the progress that has been made in drug therapies and delivery systems, and also cell-based and tissue engineering approaches for SCI.

Pharmacological Alternatives for the Treatment of Neurodegenerative Disorders: Wasp and Bee Venoms and Their Components as New Neuroactive Tools

Neurodegenerative diseases are relentlessly progressive, severely impacting affected patients, families and society as a whole. Increased life expectancy has made these diseases more common worldwide. Unfortunately, available drugs have insufficient therapeutic effects on many subtypes of these intractable diseases, and adverse effects hamper continued treatment. Wasp and bee venoms and their components are potential means of managing or reducing these effects and provide new alternatives for the control of neurodegenerative diseases. These venoms and their components are well-known and irrefutable sources of neuroprotectors or neuromodulators. In this respect, the present study reviews our current understanding of the mechanisms of action and future prospects regarding the use of new drugs derived from wasp and bee venom in the treatment of major neurodegenerative disorders, including Alzheimer’s Disease, Parkinson’s Disease, Epilepsy, Multiple Sclerosis and Amyotrophic Lateral Sclerosis.