Immunomodulation in stem cell differentiation into neurons and brain repair

Glycan Epitope and Integrin Expression Dynamics Characterize Neural Crest Epithelial-to-Mesenchymal Transition (EMT) in Human Pluripotent Stem Cell Differentiation

The neural crest gives rise to progeny as diverse as peripheral neurons, myelinating cells, cranial muscle, bone and cartilage tissues, and melanocytes. Neural crest derivation encompasses complex morphological change, including epithelial-to-mesenchymal transition (EMT) and migration to the eventual target locations throughout the body. Neural crest cultures derived from stem cells provide an attractive source for developmental studies in human model systems, of immediate biomedical relevance for neurocristopathies, neural cancer biology and regenerative medicine, if only appropriate markers for lineage and cell type definition and quality control criteria were available. Implementing a defined, scalable protocol to generate neural crest cells from embryonic stem cells, we identify stage-defining cluster-of-differentiation (CD) surface markers during human neural crest development in vitro. Acquisition of increasingly mesenchymal phenotype was characterized by absence of neuroepithelial stemness markers (CD15, CD133, CD49f) and by decrease of CD57 and CD24. Increased per-cell-expression of CD29, CD44 and CD73 correlated with established EMT markers as determined by immunofluorescence and immunoblot analysis. The further development towards migratory neural crest was associated with decreased CD24, CD49f (ITGA6) and CD57 (HNK1) versus an enhanced CD49d (ITGA4), CD49e (ITGA5) and CD51/CD61 (ITGAV/ITGB3) expression. Notably, a shift from CD57 to CD51/CD61 was identified as a sensitive surrogate surface indicator of EMT in neural crest in vitro development. The reported changes in glycan epitope and integrin surface expression may prove useful for elucidating neural crest stemness, EMT progression and malignancies.

Toll-like receptors 2 and 4 differentially regulate the self-renewal and differentiation of spinal cord neural precursor cells

BACKGROUND

Toll-like receptors (TLRs) represent critical effectors in the host defense response against various pathogens; however, their known function during development has also highlighted a potential role in cell fate determination and neural differentiation. While glial cells and neural precursor cells (NPCs) of the spinal cord express both TLR2 and TLR4, their influence on self-renewal and cell differentiation remains incompletely described.

METHODS

TLR2, TLR4 knock-out and the wild type mice were employed for spinal cord tissue analysis and NPCs isolation at early post-natal stage. Sox2, FoxJ1 and Ki67 expression among others served to identify the undifferentiated and proliferative NPCs; GFAP, Olig2 and β-III-tubulin markers served to identify astrocytes, oligodendrocytes and neurons respectively after NPC spontaneous differentiation. Multiple comparisons were analyzed using one-way ANOVA, with appropriate corrections such as Tukey's post hoc tests used for comparisons.

RESULTS

We discovered that the deletion of TLR2 or TLR4 significantly reduced the number of Sox2-expressing NPCs in the neonatal mouse spinal cord. While TLR2-knockout NPCs displayed enhanced self-renewal, increased proliferation and apoptosis, and delayed neural differentiation, the absence of TLR4 promoted the neural differentiation of NPCs without affecting proliferation, producing long projecting neurons. TLR4 knock-out NPCs showed significantly higher expression of Neurogenin1, that would be involved in the activation of this neurogenic program by a ligand and microenvironment-independent mechanism. Interestingly, the absence of both TLR2 and TLR4, which induces also a significant reduction in the expression of TLR1, in NPCs impeded oligodendrocyte precursor cell maturation to a similar degree.

CONCLUSIONS

Our data suggest that Toll-like receptors are needed to maintain Sox2 positive neural progenitors in the spinal cord, however possess distinct regulatory roles in mouse neonatal spinal cord NPCs-while TLR2 and TLR4 play a similar role in oligodendrocytic differentiation, they differentially influence neural differentiation.

HBO Alleviates Neural Stem Cell Pyroptosis via lncRNA-H19/miR-423-5p/NLRP3 Axis and Improves Neurogenesis after Oxygen Glucose Deprivation

Due to the limited neurogenesis capacity, there has been a big challenge in better recovery from neurological dysfunction caused by stroke for a long time. Neural stem cell (NSC) programmed death is one of the unfavorable factors for neural regeneration after stroke. The types of death such as apoptosis and necroptosis have been deeply investigated while the pyroptosis of NSCs is not quite understood. Although it is well accepted that hyperbaric oxygen (HBO) alleviates the oxygen-glucose deprivation (OGD) injury after stroke and reduces programmed death of NSCs, whether NSC pyroptosis is involved in this process is still unknown. Therefore, this study is aimed at studying the potential effect of HBO treatment on NSC pyroptosis following OGD exposure, as well as its influence on NSC proliferation and differentiation in vitro. The results revealed that OGD increased NOD-like receptor protein 3 (NLRP3) expression to induce the pyroptotic death of NSCs, which was rescued by HBO treatment. And the upregulated lncRNA-H19 functioned as a molecular sponge of miR-423-5p to target NLRP3 for NSC pyroptosis following OGD. Most importantly, it was confirmed that HBO exerted protection of NSCs against pyroptosis by inhibiting lncRNA-H19/miR-423-5p/NLRP3 axis. Moreover, HBO restraint of lncRNA-H19-associated pyroptosis benefited the proliferation and neuronal differentiation of NSCs. It was concluded that HBO attenuated NSC pyroptosis via lncRNA-H19/miR-423-5p/NLRP3 axis and enhanced neurogenesis following OGD. The findings provide new insight into NSC programmed death and enlighten therapeutic strategy after stroke.

Remimazolam alleviates neuropathic pain via regulating bradykinin receptor B1 and autophagy

OBJECTIVES

Neuropathic pain (NP) represents a broad scope of various pathological ramifications of the nervous system. Remimazolam is a proved sedative in treating neuropathic pain. Considering the Bradykinin receptor's vital role and the potentials of Bradykinin receptor B1 (BDKRB1) in the neuropathic pain-signalling pathway, we nominated them as a primary target for remimazolam.

METHODS

In this study, rats were injected with complete freund's adjuvant (CFA) to construct NP models in vivo. BV2 microglia cells were treated with LPS to establish NP model in vitro. qRT-PCR, ELISA, western blot and immunofluorescence were applied to determine gene expression.

KEY FINDINGS

Our findings revealed that BDKRB1 was overexpressed in NP models in vivo, while R715 (an antagonist of BDKRB1) suppressed the levels of BDKRB1 and inhibited the hyperpathia induced by spinal nerve litigation surgery. Moreover, remimazolam inactivated BDKRB1 signalling via suppressing NF-κB translocation and decreased the release of pro-inflammatory cytokines. Additionally, remimazolam suppressed the translocation of NF-κB, and inhibited autophagic lysosome formation in vivo and in vitro. However, R838 (an agonist of BDKRB1) reversed the effects of remimazolam.

CONCLUSIONS

Remimazolam downregulated BDKRB1, inhibited BDKRB1/RAS/MEK signalling pathway and regulated the autophagic lysosome induction, exhibiting a better outcome in the NP.

Adaptive biomimicry: design of neural interfaces with enhanced biointegration

Neural interfaces (NIs) have traditionally used inorganic device constructs paired with electrical stimulation to bypass injured or diseased electroactive tissues. These bioinert devices have significant impact on the neural tissue, being synthetic and causing large volumetric changes to the biological environment. The concept of biomimicry has become popular for tissue engineering technologies, reflecting biological properties as a component of material design. Tissue engineering strategies can be harnessed in bioelectronic device design to improve biological tolerance, but the need for improved integration with the native tissue remains an unmet need. Adaptive biomimetic designs that respond to the changing neural tissue environment associated with wound healing can actively address the immune response to improve biointegration. These adaptive approaches include responsive materials paired with stem cells and bioactive molecules as integrated components of NIs. Combining adaptive biomimetics with NIs provides a new, more natural approach for communicating with the nervous system.

Nitro-Oleic Acid Inhibits Stemness Maintenance and Enhances Neural Differentiation of Mouse Embryonic Stem Cells via STAT3 Signaling

Nitro-oleic acid (NO₂-OA), pluripotent cell-signaling mediator, was recently described as a modulator of the signal transducer and activator of transcription 3 (STAT3) activity. In our study, we discovered new aspects of NO₂-OA involvement in the regulation of stem cell pluripotency and differentiation. Murine embryonic stem cells (mESC) or mESC-derived embryoid bodies (EBs) were exposed to NO₂-OA or oleic acid (OA) for selected time periods. Our results showed that NO₂-OA but not OA caused the loss of pluripotency of mESC cultivated in leukemia inhibitory factor (LIF) rich medium via the decrease of pluripotency markers (NANOG, sex-determining region Y-box 1 transcription factor (SOX2), and octamer-binding transcription factor 4 (OCT4)). The effects of NO₂-OA on mESC correlated with reduced phosphorylation of STAT3. Subsequent differentiation led to an increase of the ectodermal marker orthodenticle homolog 2 (Otx2). Similarly, treatment of mESC-derived EBs by NO₂-OA resulted in the up-regulation of both neural markers Nestin and β-Tubulin class III (Tubb3). Interestingly, the expression of cardiac-specific genes and beating of EBs were significantly decreased. In conclusion, NO₂-OA is able to modulate pluripotency of mESC via the regulation of STAT3 phosphorylation. Further, it attenuates cardiac differentiation on the one hand, and on the other hand, it directs mESC into neural fate.

TLR-4 Signaling vs. Immune Checkpoints, miRNAs Molecules, Cancer Stem Cells, and Wingless-Signaling Interplay in Glioblastoma Multiforme-Future Perspectives

Toll-like-receptor (TLR) family members were detected in the central nervous system (CNS). TLR occurrence was noticed and widely described in glioblastomamultiforme (GBM) cells. After ligand attachment, TLR-4 reorients domains and dimerizes, activates an intracellular cascade, and promotes further cytoplasmatic signaling. There is evidence pointing at a strong relation between TLR-4 signaling and micro ribonucleic acid (miRNA) expression. The TLR-4/miRNA interplay changes typical signaling and encourages them to be a target for modern immunotherapy. TLR-4 agonists initiate signaling and promote programmed death ligand-1 (PD-1L) expression. Most of those molecules are intensively expressed in the GBM microenvironment, resulting in the autocrine induction of regional immunosuppression. Another potential target for immunotreatment is connected with limited TLR-4 signaling that promotes Wnt/DKK-3/claudine-5 signaling, resulting in a limitation of GBM invasiveness. Interestingly, TLR-4 expression results in bordering proliferative trends in cancer stem cells (CSC) and GBM. All of these potential targets could bring new hope for patients suffering from this incurable disease. Clinical trials concerning TLR-4 signaling inhibition/promotion in many cancers are recruiting patients. There is still a lot to do in the field of GBM immunotherapy.

Toll-like receptor bioactivity in endothelial progenitor cells

Cardiovascular disease is the main cause of death globally that can be mitigated by the modulation of angiogenesis. To achieve this goal, the application of endothelial progenitor cells and other stem cell types is useful. Following the onset of cardiovascular disease and pro-inflammatory conditions as seen during bacterial sepsis, endothelial progenitor cells enter systemic circulation in response to multiple cytokines and activation of various intracellular mechanisms. The critical role of Toll-like receptors has been previously identified in the dynamics of various cell types, in particular, immune cells. To our knowledge, there are a few experiments related to the role of Toll-like receptors in endothelial progenitor cell activity. Emerging data point of endothelial progenitor cells and other stem cells having the potential to express Toll-like receptors to control different activities such as multipotentiality and dynamics of growth. In this review article, we aim to collect data related to the role of Toll-like receptors in endothelial progenitor cells bioactivity and angiogenic potential.

The spleen may be an important target of stem cell therapy for stroke

Stroke is the most common cerebrovascular disease, the second leading cause of death behind heart disease and is a major cause of long-term disability worldwide. Currently, systemic immunomodulatory therapy based on intravenous cells is attracting attention. The immune response to acute stroke is a major factor in cerebral ischaemia (CI) pathobiology and outcomes. Over the past decade, the significant contribution of the spleen to ischaemic stroke has gained considerable attention in stroke research. The changes in the spleen after stroke are mainly reflected in morphology, immune cells and cytokines, and these changes are closely related to the stroke outcomes. Autonomic nervous system (ANS) activation, release of central nervous system (CNS) antigens and chemokine/chemokine receptor interactions have been documented to be essential for efficient brain-spleen cross-talk after stroke. In various experimental models, human umbilical cord blood cells (hUCBs), haematopoietic stem cells (HSCs), bone marrow stem cells (BMSCs), human amnion epithelial cells (hAECs), neural stem cells (NSCs) and multipotent adult progenitor cells (MAPCs) have been shown to reduce the neurological damage caused by stroke. The different effects of these cell types on the interleukin (IL)-10, interferon (IFN), and cholinergic anti-inflammatory pathways in the spleen after stroke may promote the development of new cell therapy targets and strategies. The spleen will become a potential target of various stem cell therapies for stroke represented by MAPC treatment.

Regenerative Medicine Therapies for Targeting Neuroinflammation After Stroke

Inflammation is a major pathological event following ischemic stroke that contributes to secondary brain tissue damage leading to poor functional recovery. Following the initial ischemic insult, post-stroke inflammatory damage is driven by initiation of a central and peripheral innate immune response and disruption of the blood-brain barrier (BBB), both of which are triggered by the release of pro-inflammatory cytokines and infiltration of circulating immune cells. Stroke therapies are limited to early cerebral blood flow reperfusion, and whilst current strategies aim at targeting neurodegeneration and/or neuroinflammation, innovative research in the field of regenerative medicine aims at developing effective treatments that target both the acute and chronic phase of inflammation. Anti-inflammatory regenerative strategies include the use of nanoparticles and hydrogels, proposed as therapeutic agents and as a delivery vehicle for encapsulated therapeutic biological factors, anti-inflammatory drugs, stem cells, and gene therapies. Biomaterial strategies-through nanoparticles and hydrogels-enable the administration of treatments that can more effectively cross the BBB when injected systemically, can be injected directly into the brain, and can be 3D-bioprinted to create bespoke implants within the site of ischemic injury. In this review, these emerging regenerative and anti-inflammatory approaches will be discussed in relation to ischemic stroke, with a perspective on the future of stroke therapies.

Establishing an Organotypic System for Investigating Multimodal Neural Repair Effects of Human Mesenchymal Stromal Stem Cells

Human mesenchymal stromal stem cells (hMSCs) hold regenerative medicine potential due to their availability, in vitro expansion readiness, and autologous feasibility. For neural repair, hMSCs show translational value in research on stroke, spinal cord injury (SCI), and traumatic brain injury. It is pivotal to establish multimodal in vitro systems to investigate molecular mechanisms underlying neural actions of hMSCs. Here, we describe a platform protocol on how to set up organotypic co-cultures of hMSCs (alone or polymer-scaffolded) with explanted adult rat dorsal root ganglia (DRGs) to determine neural injury and recovery events for designing implants to counteract neurotrauma sequelae. We emphasize in vitro hMSC propagation, polymer scaffolding, hMSC stemness maintenance, hMSC-DRG interaction profiling, and analytical formulas of neuroinflammation, trophic factor expression, DRG neurite outgrowth and tropic tracking, and in vivo verification of tailored implants in rodent models of SCI. © 2018 by John Wiley & Sons, Inc.

Lipid, Protein, and MicroRNA Composition Within Mesenchymal Stem Cell-Derived Exosomes

Mesenchymal stem cells (MSCs) were regarded as one of the most promising type of seed cells in tissue engineering due to its easy accessibility and multipotent feature of being able to differentiate into adipocyte, osteoblast, cardiomyocytes, and neurons. For years, MSCs have been applied in treating cardiovascular disease, reconstructing kidney injury, and remodeling immune system with remarkable achievements. Basic researches revealed that its clinic effects are not only due to their pluripotent ability but also through their paracrine function that they synthesize and secrete a broad spectrum of growth factors and cytokines. Recent studies show that exosomes is the main paracrine executor of MSCs. The lipid bilayer of exosome maintains its stability and integrity and keeps biological potency of biological substance within it. MSC-derived exosomes were shown to be successful in treating many diseases, including tumor and cardiovascular diseases. However, the exact composition of MSC-derived exosomes is not known yet. In this review, we will discuss the lipid, protein, and microRNA contents within MSC-derived exosomes based on current studies to guide further research and clinical applications of MSC-derived exosomes.

Kinin-B1 Receptor Stimulation Promotes Invasion and is Involved in Cell-Cell Interaction of Co-Cultured Glioblastoma and Mesenchymal Stem Cells

Glioblastoma multiforme (GBM) represents the most lethal brain tumour, and these tumours have very limited treatment options. Mesenchymal stem cells (MSC) are considered as candidates for advanced cell therapies, due to their tropism towards GBM, possibly affecting their malignancy, thus also representing a potential therapeutic vector. Therefore, we aimed to compare the effects of bone-marrow-derived versus adipose-tissue-derived MSC (BM-/AT-MSC) on heterogeneous populations of tumour cells. This cells' interplay was addressed by the in-vitro two-dimensional (monolayer) and three-dimensional (spheroid) co-culture models, using U87 and U373 GBM cell lines, expressing genotypically different mesenchymal transcriptome profiles. U87 cell low mesenchymal profile expressed high levels of kinin receptor 1 (B1R) and their invasion was greatly enhanced by the B1R agonist des-Arg⁹-bradykinin upon BM-MSC co-culturing in 3D co-cultures. This correlated to significantly higher cell-cell interactions in U87/BM-MSC mixed spheroids. This was not observed with the U373 cells and not in AT-MSC co-cultures. Altogether, these data support the on-going exploration of B1R as target for adjuvant approach in GBM therapy. Secondly, the results emphasize the need for further careful exploration of the selectivity regarding the origin of MSC as potential candidates for cell therapies, particular in cancer, where they may adversely affect heterogeneous tumour cell populations.

Stem Cell Recipes of Bone Marrow and Fish: Just What the Stroke Doctors Ordered

Stem cell therapy for stroke has advanced from the laboratory to the clinic, but remains as an experimental treatment. Two lines of transplant regimens have emerged, namely the "early bird" peripheral injections in subacute stroke patients and the "late night" direct intracerebral treatments in chronic stroke patients. Autologous bone marrow-derived stem cells, which only required minimal manipulations during graft cell preparation, gained fast-track entry into the clinic, while gene modified stem cells necessitated overcoming more stringent regulatory criteria before they were approved for clinical use. Safety of the stem cell therapy can be declared from these clinical trials, but efficacy warrants further investigations. Here, we offer insights into the translation of cell therapy from the laboratory to the clinic, in the hopes that highlighting the lessons we learned from this experience will guide the optimization of functional outcomes of future clinical trials of stem cell therapy for stroke.

Influences of age-related changes in mesenchymal stem cells on macrophages during in-vitro culture

BACKGROUND

Mesenchymal stem cells (MSCs) have been widely used in cytotherapy and tissue engineering due to their immunosuppressive ability and regenerative potential. Recently, the immunomodulatory influence of MSCs has been gaining increasing attention because their functional roles in modulating immune responses likely have high clinical significance.

METHODS

In this study, we investigated the influence of MSCs on macrophages (Mφs) in in-vitro cell culture systems. Given evidence that aged MSCs are functionally compromised, bone marrow-derived MSCs (BMSCs) isolated from both young and aged mice (YMSCs and AMSCs) were evaluated and contrasted.

RESULTS

We found that YMSCs exhibited greater proliferative and osteo-differentiation potential compared to AMSCs. When cocultured with RAW264.7 cells (an Mφ cell line), both YMSCs and AMSCs coaxed polarization of Mφs toward an M2 phenotype and induced secretion of anti-inflammatory and immunomodulatory cytokines. Compared to AMSCs, YMSCs exhibited a more potent immunomodulatory effect. While Mφs cocultured with either YMSCs or AMSCs displayed similar phagocytic ability, AMSC coculture was found to enhance Mφ migration in Transwell systems. When BMSCs were prestimulated with interferon gamma before coculture with RAW264.7 cells, their regulatory effects on Mφs appeared to be modified. Here, compared to stimulated AMSCs, stimulated YMSCs also exhibited enhanced cellular influence on cocultured RAW264.7 cells.

CONCLUSIONS

Our data suggest that BMSCs exert an age-related regulatory effect on Mφs with respect to their phenotype and functions but an optimized stimulation to enhance MSC immunomodulation is in need of further investigation.

An Overview of Neural Differentiation Potential of Human Adipose Derived Stem Cells

There is wide interest in application of adult stem cells due to easy to obtain with a minimal patient discomfort, capable of producing cell numbers in large quantities and their immunocompatible properties without restriction by ethical concerns. Among these stem cells, multipotent mesenchymal stem cells (MSCs) from human adipose tissue are considered as an ideal source for various regenerative medicine. In spite of mesodermal origin of human adipose-derived stem cells (hADSCs), these cells have differentiation potential toward mesodermal and non-mesodermal lineages. Up to now, several studies have shown that hADSCs can undergo transdifferentiation and produce cells outside of their lineage, especially into neural cells when they are transferred to a specific cell environment. The purpose of this literature review is to provide an overview of the existing state of knowledge of the differentiation potential of hADSCs, specifically their ability to give rise to neuronal cells. The following review discusses different protocols considered for differentiation of hADSCs to neural cells, the neural markers that are used in each procedure and possible mechanisms that are involved in this differentiation.

Deletion of RBPJK in Mesenchymal Stem Cells Enhances Osteogenic Activity by Up-Regulation of BMP Signaling

Recently we have demonstrated the importance of RBPjk-dependent Notch signaling in the regulation of mesenchymal stem cell (MSC) differentiation during skeletogenesis both in vivo and in vitro. Here we further performed RBPJK loss-of-function experiments to demonstrate for the first time that RBPJK deficient MSC shows enhanced differentiation and osteogenesis acts via up-regulation of the BMP signaling. In the present study, we first compared the spontaneous and osteogenic differentiation in normal and recombination signal binding protein for immunoglobulin kappa J region (RBPJK) deficient human bone marrow-derived mesenchymal stem cells (MSCs). It was found that RBPJK highly expressed in fresh isolated MSCs and its expression was progressing down-regulated during spontaneous differentiation and even greater in osteogenic media inducted differentiation. Deletion of RBPJK in MSCs not only enhances cell spontaneous differentiation, but also significantly accelerates condition media inducted osteogenic differentiation by showing enhanced alkaline phosphatase (ALP) activity, Alizarin red staining, gene expression of Runx2, Osteopontin (OPN), Type I collagen (COL1a1) in culture. Additionally, BMP signaling responsive reporter activity and phosphor-smad1/5/8 expression were also significantly increased upon removal of RBPJK in MSCs. These data proved that inhibition of Notch signaling in MSCs promotes cell osteogenic differentiation by up-regulation of BMP signaling, and RBPJK deficient MSC maybe a better cell population for cell-based bone tissue engineering.

Long noncoding RNA SPRY4-IT1 predicts poor patient prognosis and promotes tumorigenesis in gastric cancer

Gastric cancer (GC) is the second common cause of cancer-related death worldwide. Long noncoding RNAs (lncRNAs) are emerging as novel regulators in the cancer paradigm. However, investigation of lncRNAs on GC is still in its infancy. In this study, we focused on lncRNA SPRY4 intronic transcript 1 (SPRY4-IT1) and investigated its expression pattern, clinical significance, biological function, and molecular mechanism in GC. SPRY4-IT1 expression was examined, and its correlation with clinicopathological characteristics and patient prognosis was analyzed. A series of assays were performed to understand the role of SPRY4-IT1 in GC. SPRY4-IT1 expression was elevated in GC tissues and cell lines, and SPRY4-IT1 levels were highly positively correlated with tumor size, invasion depth, distant metastasis, TNM stage, and reduced overall survival (OS) and disease-free survival (DFS). A multivariate analysis showed that SPRY4-IT1 expression is an independent prognostic factor of OS and DFS in patients with GC. Additionally, the results of in vitro assays showed that the suppression of SPRY4-IT1 expression in GC cell line MKN-45 significantly reduced cell proliferation, colony formation, and cell migration/invasion. Moreover, the tumorigenic effects of SPRY4-IT1 were partially mediated by the regulation of certain cyclins and matrix metalloproteinases (MMPs)-related genes. Our data suggest that SPRY4-IT1 plays a critical role in GC tumorigenesis and may represent a novel prognostic marker and potential therapeutic target in patients with GC.