cAMP initiates early phase neuron-like morphology changes and late phase neural differentiation in mesenchymal stem cells

Quercetin enhances decidualization through AKT-ERK-p53 signaling and supports a role for senescence in endometriosis

BACKGROUND

Patients with endometriosis suffer with chronic pelvic pain and infertility, and from the lack of pharmacologic therapies that consistently halt disease progression. Differences in the endometrium of patients with endometriosis vs. unaffected controls are well-documented. Specifically, shed endometrial tissues (delivered to the pelvic cavity via retrograde menstruation) reveal that a subset of stromal cells exhibiting pro-inflammatory, pro-fibrotic, and pro-senescence-like phenotypes is enhanced in endometriosis patients compared to controls. Additionally, cultured biopsy-derived endometrial stromal cells from endometriosis patients exhibit impaired decidualization, a defined differentiation process required for human embryo implantation and pregnancy. Quercetin, a senolytic agent, shows therapeutic potential for pulmonary fibrosis, a disorder attributed to senescent pulmonary fibroblasts. In rodent models of endometriosis, quercetin shows promise, and quercetin improves decidualization in vitro. However, the exact mechanisms are not completely understood. Therefore, we investigated the effects of quercetin on menstrual effluent-derived endometrial stromal cells from endometriosis patients and unaffected controls to define the signaling pathways underlying quercetin's effects on endometrial stromal cells.

METHODS

Menstrual effluent-derived endometrial stromal cells were collected and cultured from unaffected controls and endometriosis patients and then, low passage cells were treated with quercetin (25 µM) under basal or standard decidualization conditions. Decidualization responses were analyzed by measuring the production of IGFBP1 and PRL. Also, the effects of quercetin on intracellular cAMP levels and cellular oxidative stress responses were measured. Phosphokinase arrays, western blotting, and flow cytometry methods were performed to define the effects of quercetin on various signaling pathways and the potential mechanistic roles of quercetin.

RESULTS

Quercetin significantly promotes decidualization of control- and endometriosis-endometrial stromal cells. Quercetin substantially reduces the phosphorylation of multiple signaling molecules in the AKT and ERK1/2 pathways, while enhancing the phosphorylation of p53 and total p53 levels. Furthermore, p53 inhibition blocks decidualization while p53 activation promotes decidualization. Finally, we provide evidence that quercetin increases apoptosis of endometrial stromal cells with a senescent-like phenotype.

CONCLUSIONS

These data provide insight into the mechanisms of action of quercetin on endometrial stromal cells and warrant future clinical trials to test quercetin and other senolytics for treating endometriosis.

Carbachol, along with calcium, indicates new strategy in neural differentiation of human adipose tissue-derived mesenchymal stem cells in vitro

INTRODUCTION

Over the past few years, stem cells have represented a promising treatment in neurological disorders due to the well-defined characteristics of their capability to proliferate and differentiate into any cell type, both in vitro and in vivo. Additionally, previous studies have shown that calcium signaling modulates the proliferation and differentiation of neural progenitor cells. The present study investigated the effect of carbachol (CCh), a cholinergic agonist activating acetylcholine receptors, with and without calcium, on the neural differentiation of human adipose tissue-derived mesenchymal stem cells (hADSCs) in neural media, including forskolin and 3-isobutyl-1-methyl-xanthine and retinoic acid.

METHODS

For this purpose, first, the MTT assay and acridine orange staining were studied to obtain the optimal concentration of CCh. Next, the differentiation tests, such as cellular calcium assay as well as evaluation of qualitative and quantitative expression of neuronal index markers through immunofluorescence staining and gene expression analysis, respectively, were performed on days 7 and 14 of the differentiation period.

RESULTS

According to the results, CCh at 1 μM concentration had no cytotoxicity on hADSCs and also induced cell proliferation. Furthermore, CCh with and without calcium increased the expression of neural-specific genes (NSE, MAP2, β-III-tubulin, and MAPK3) and proteins (γ-enolase, MAP2, and β-III-tubulin) as well as the amount of calcium in differentiated hADSCs at 7 and 14 days after induction.

CONCLUSIONS

In conclusion, the findings suggest that CCh acts as an influential therapeutic factor in the field of neural regenerative medicine and research.

Neural Differentiation of Human-Induced Pluripotent Stem Cells (hiPSc) on Surface-Modified Nanofibrous Scaffolds Coated with Platelet-Rich Plasma

The field of tissue engineering exploits living cells in a variety of ways to restore, maintain, or enhance tissues and organs. Between stem cells, human induced pluripotent stem cells (hiPSCs), are very important due to their wide abilities. Growth factors can support proliferation, differentiation, and migration of hiPSCs. Platelet-rich plasma (PRP) could be used as the source of growth factors for hiPSCs. In the present study, proliferation and neural differentiation of hiPSCs on surface-modified nanofibrous Poly-L-lactic acid (PLLA) coated with platelet-rich plasma was investigated. The results of in vitro analysis showed that on the surface, which was modified nanofibrous scaffolds coated with platelet-rich plasma, significantly enhanced hiPSCs proliferation and neural differentiation were observed. Whereas the MTT ([3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide]) results showed biocompatibility of surface-modified nanofibrous scaffolds coated with platelet-rich plasma and the usage of these modified nanoscaffolds in neural tissue engineering in vivo is promising for the future.

Gelatin methacrylate hydrogel loaded with brain-derived neurotrophic factor enhances small molecule-induced neurogenic differentiation of stem cells from apical papilla

The limited neurogenic potential of adult stem cells and their non-specific lineage differentiation pose major challenges in cell-replacement therapy for neurological disorders. In our previous study, we demonstrated that the neurogenic potential of stem cells from apical papilla (SCAPs) was significantly improved upon induction with a small molecule cocktail. This study attempted to investigate whether neuronal differentiation of SCAPs induced by a small molecule cocktail can be further enhanced in a three-dimensional gelatin methacrylate hydrogel loaded with brain-derived neurotrophic factor (BDNF-GelMA). The physiological properties and neural differentiation of SCAPs treated with a combination of small molecules and BDNF-GelMA were evaluated by CCK8, Live/Dead assay, quantitative reverse transcription-polymerase chain reaction, western blot and immunocytochemistry. SCAPs embedded in BDNF-GelMA displayed superior morphological characteristics when induced by a small molecule cocktail, similar to neuronal phenotypes as compared to pure GelMA. There was significant upregulation of neural markers including Tuj1 and MAP2 by SCAPs embedded in BDNF-GelMA, as compared to pure GelMA. Hence, GelMA hydrogel loaded with a potent neurotrophic factor (BDNF) provides a conducive scaffold that can further enhance the differentiation of small molecule-treated SCAPs into neuronal-like cells, which may provide a therapeutic platform for the management of neurological disorders.

Neural Basis of Dental Pulp Stem Cells and its Potential Application in Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease. Though significant insights into the molecular-biochemical-cellular-behavioral basis of PD have been understood, there is no appreciable treatment available till date. Current therapies provide symptomatic relief without any influence on the progression of the disease. Stem cell therapy has been vigorously explored to treat PD. In this comprehensive review, we analyze various stem cell candidates for treating PD and discuss the possible mechanisms. We advocate the advantage of using neural crest originated dental pulp stem cells (DPSC) due to their predisposition towards neural differentiation and their potential to regenerate neurons far better than commonly used bone marrow derived mesenchymal stem cells (BM-MSCs). Eventually, we highlight the current challenges in the field and the strategies which may be used for overcoming the impediments.

Nuclear actin regulates cell proliferation and migration via inhibition of SRF and TEAD

Actin dynamics regulate cell behaviour in response to physiological signals. Here we demonstrate a novel role for nuclear actin in inhibiting cell proliferation and migration. We demonstrate that physiological signals that elevate cAMP, which is anti-mitogenic in vascular smooth muscle cells, increases nuclear actin monomer levels. Expression of a nuclear-targeted polymerisation-defective actin mutant (NLS-ActinR62D) inhibited proliferation and migration. Preventing nuclear actin monomer accumulation by enhancing its nuclear export or polymerisation reversed the anti-mitogenic and anti-migratory effects of cAMP. Transcriptomic analysis identified repression of proliferation and migration associated genes regulated by serum response factor (SRF) and TEA Domain (TEAD) transcription factors. Accordingly, NLS-ActinR62D inhibited SRF and TEAD activity and target gene expression, and these effects were reversed by constitutively-active mutants of the TEAD and SRF co-factors YAP, TAZ and MKL1. In summary, intranuclear actin inhibits proliferation and migration by inhibiting YAP-TEAD and MKL-SRF activity. This mechanism explains the anti-mitogenic and anti-migratory properties of physiological signals that elevate cAMP. SUMMARY: McNeill et al show that increased levels of intranuclear actin monomer inhibit cell proliferation and migration by inhibiting MKL1-SRF and YAP/TAZ-TEAD-dependent gene expression. This mechanism mediates the anti-mitogenic and anti-migratory effects of physiological signals that elevate cyclic-AMP.

Exploitation of fibrin-based signaling niche for deriving progenitors from human adipose-derived mesenchymal stem cells towards potential neural engineering applications

Adipose-derived mesenchymal stem cells (hADMSC) retaining proliferation and multi-differentiation potential may support the central nervous system (CNS) regeneration. Multipotency of MSC may result in both desirable and undesirable cells, post-transplantation. A better strategy to attain desired cells may be in vitro commitment of hADMSCs to uni-/bi- potent neural progenitor cells (NPCs), prior to transplantation. Derivation of stable NPCs may require a suitable niche eliciting proliferation and differentiation signals. The present study designed a biomimetic niche comprising insoluble fibrin supported adhesion matrix and exogenously added growth factors (GFs) for deriving different neural cells and established the role of Notch and Wnt signals for proliferation and differentiation of hADMSCs, respectively. The stable transformation of hADMSCs into neurospheres (NS) comprising Nestin^+ve NPCs was achieved consistently. Slight modifications of niche enable differentiation of NS to NPCs; NPCs to neurons; NPCs to oligodendrocyte progenitor cells (OPCs); and OPCs to oligodendrocytes (OLG). Fibrin plays a crucial role in the conversion of hADMSC to NS and NPCs to OPCs; but, not essential for OPC to OLG maturation. Co-survival and cell-cell interaction of NPC derived neurons and OPCs promoting OLG maturation is illustrated. The designed biomimetic niche shows the potential for directing autologous ADMSCs to neural cells for applications in regenerative medicine.

Elevated cyclic-AMP represses expression of exchange protein activated by cAMP (EPAC1) by inhibiting YAP-TEAD activity and HDAC-mediated histone deacetylation

Ligand-induced activation of Exchange Protein Activated by cAMP-1 (EPAC1) is implicated in numerous physiological and pathological processes, including cardiac fibrosis where changes in EPAC1 expression have been detected. However, little is known about how EPAC1 expression is regulated. Therefore, we investigated regulation of EPAC1 expression by cAMP in cardiac fibroblasts. Elevation of cAMP using forskolin, cAMP-analogues or adenosine A2B-receptor activation significantly reduced EPAC1 mRNA and protein levels and inhibited formation of F-actin stress fibres. Inhibition of actin polymerisation with cytochalasin-D, latrunculin-B or the ROCK inhibitor, Y-27632, mimicked effects of cAMP on EPAC1 mRNA and protein levels. Elevated cAMP also inhibited activity of an EPAC1 promoter-reporter gene, which contained a consensus binding element for TEAD, which is a target for inhibition by cAMP. Inhibition of TEAD activity using siRNA-silencing of its co-factors YAP and TAZ, expression of dominant-negative TEAD or treatment with YAP-TEAD inhibitors, significantly inhibited EPAC1 expression. However, whereas expression of constitutively-active YAP completely reversed forskolin inhibition of EPAC1-promoter activity it did not rescue EPAC1 mRNA levels. Chromatin-immunoprecipitation detected a significant reduction in histone3-lysine27-acetylation at the EPAC1 proximal promoter in response to forskolin stimulation. HDAC1/3 inhibition partially reversed forskolin inhibition of EPAC1 expression, which was completely rescued by simultaneously expressing constitutively active YAP. Taken together, these data demonstrate that cAMP downregulates EPAC1 gene expression via disrupting the actin cytoskeleton, which inhibits YAP/TAZ-TEAD activity in concert with HDAC-mediated histone deacetylation at the EPAC1 proximal promoter. This represents a novel negative feedback mechanism controlling EPAC1 levels in response to cAMP elevation.

Forskolin and IBMX Induce Neural Transdifferentiation of MSCs Through Downregulation of the NRSF

Neural differentiation of mesenchymal stem cells is a controversial phenomenon, as it would require transdifferentiation across the mesoderm-ectoderm barrier. However, several laboratories have observed that MSCs are able to be induced to express neural characteristics. Previously, we demonstrated that the cAMP-elevating agents, forskolin and IBMX, induced neural-like differentiation of MSCs, including expression of neural markers and increased sensitivity to neurotransmitters. However, due to the broad range of effects that forskolin and IBMX can elicit through the intracellular second messenger, cAMP, a better mechanistic understanding is required. Here, we show that neural induction by forskolin and IBMX is dependent on downregulation of expression of the master transcriptional regulator, neuron restrictive silencer factor (NRSF), and its downstream target genes. Since silencing of NRSF is known to initiate neural differentiation, it suggests that forskolin and IBMX result in transdifferentiation of MSCs into a neural lineage.

Effects of Passage Number and Differentiation Protocol on the Generation of Dopaminergic Neurons from Rat Bone Marrow-Derived Mesenchymal Stem Cells

Multiple studies have demonstrated the ability of mesenchymal stem cells (MSCs) to differentiate into dopamine-producing cells, in vitro and in vivo, indicating their potential to be used in the treatment of Parkinson’s disease (PD). However, there are discrepancies among studies regarding the optimal time (i.e., passage number) and method for dopaminergic induction, in vitro. In the current study, we compared the ability of early (P4) and later (P40) passaged bone marrow-derived MSCs to differentiate into dopaminergic neurons using two growth-factor-based approaches. A direct dopaminergic induction (DDI) was used to directly convert MSCs into dopaminergic neurons, and an indirect dopaminergic induction (IDI) was used to direct MSCs toward a neuronal lineage prior to terminal dopaminergic differentiation. Results indicate that both early and later passaged MSCs exhibited positive expression of neuronal and dopaminergic markers following either the DDI or IDI protocols. Additionally, both early and later passaged MSCs released dopamine and exhibited spontaneous neuronal activity following either the DDI or IDI. Still, P4 MSCs exhibited significantly higher spiking and bursting frequencies as compared to P40 MSCs. Findings from this study provide evidence that early passaged MSCs, which have undergone the DDI, are more efficient at generating dopaminergic-like cells in vitro, as compared to later passaged MSCs or MSCs that have undergone the IDI.

Effect of small molecules on cell reprogramming

The essential idea of regenerative medicine is to fix or replace tissues or organs with alive and patient-specific implants. Pluripotent stem cells are able to indefinitely self-renew and differentiate into all cell types of the body which makes them a potent substantial player in regenerative medicine. The easily accessible source of induced pluripotent stem cells may allow obtaining and cultivating tissues in vitro. Reprogramming refers to regression of mature cells to its initial pluripotent state. One of the approaches affecting pluripotency is the usage of low molecular mass compounds that can modulate enzymes and receptors leading to the formation of pluripotent stem cells (iPSCs). It would be great to assess the general character of such compounds and reveal their new derivatives or modifications to increase the cell reprogramming efficiency. Many improvements in the methods of pluripotency induction have been made by various groups in order to limit the immunogenicity and tumorigenesis, increase the efficiency and accelerate the kinetics. Understanding the epigenetic changes during the cellular reprogramming process will extend the comprehension of stem cell biology and lead to potential therapeutic approaches. There are compounds which have been already proven to be or for now only putative inducers of the pluripotent state that may substitute for the classic reprogramming factors (Oct3/4, Sox2, Klf4, c-Myc) in order to improve the time and efficiency of pluripotency induction. The effect of small molecules on gene expression is dosage-dependent and their application concentration needs to be strictly determined. In this review we analysed the role of small molecules in modulations leading to pluripotency induction, thereby contributing to our understanding of stem cell biology and uncovering the major mechanisms involved in that process.

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.

Rapid Induction of Neural Differentiation in Human Umbilical Cord Matrix Mesenchymal Stem Cells by cAMP-elevating Agents

Human umbilical cord matrix (hUCM) is considered as a promising source of mesenchymal stem cells (MSCs) due to several advantages over other tissues. The potential of neural differentiation of hUCM-MSCs is of great interest in the context of treating neurodegenerative diseases. In recent years, considerable efforts have been made to establish in vitro conditions for improving the differentiation of hUCM-MSCs toward neuronal cells. In the present study, we evaluated the neural differentiation potential of hUCM-MSCs in the presence of cAMP-elevating agents forskolin and 3-isobutyl-1-methylxanthine (IBMX). hUCM-MSCs were isolated from fetal umbilical cord and characterized by flow cytometry analysis for mesenchymal specific markers. Mesodermal differentiation potential was assessed through selective media with lineage-specific induction factors. For assessment of neural differentiation, cells were cultured in the presence of cAMP-elevating agents for 8 and 24 h. The neuronal differentiated MSCs were characterized for neuronal specific markers by immunocytochemistry and western blotting. Isolated hUCM-MSCs were found positive for mesenchymal markers (CD73, CD90, and CD105) while negative for hematopoietic markers (CD34 and CD45) .Following neural induction, most cells represented neural-like cells morphology. Neural markers including β-tubulin III (Tuj-1), neuron-specific enolase (NSE), microtubule-associated protein-2 (MAP-2) and nestin were expressed in treated cells with respect to control group. The astrocyte specific marker, glial fibrillary acidic protein (GFAP) was also shown by immunofluorescence in treated cells. (These findings demonstrate that hUCM-MSCs have the ability to rapidly differentiate into neural cell types of neuron-like cells and astrocytes by cAMP-elevating agents without the presence of growth factors.

Rapid fine conformational epitope mapping using comprehensive mutagenesis and deep sequencing

Knowledge of the fine location of neutralizing and non-neutralizing epitopes on human pathogens affords a better understanding of the structural basis of antibody efficacy, which will expedite rational design of vaccines, prophylactics, and therapeutics. However, full utilization of the wealth of information from single cell techniques and antibody repertoire sequencing awaits the development of a high throughput, inexpensive method to map the conformational epitopes for antibody-antigen interactions. Here we show such an approach that combines comprehensive mutagenesis, cell surface display, and DNA deep sequencing. We develop analytical equations to identify epitope positions and show the method effectiveness by mapping the fine epitope for different antibodies targeting TNF, pertussis toxin, and the cancer target TROP2. In all three cases, the experimentally determined conformational epitope was consistent with previous experimental datasets, confirming the reliability of the experimental pipeline. Once the comprehensive library is generated, fine conformational epitope maps can be prepared at a rate of four per day.

The tumor suppressor PTEN regulates motor responses to striatal dopamine in normal and Parkinsonian animals

Phosphatase and Tensin homolog deleted on chromosome 10 (PTEN) is a dual lipid-protein phosphatase known primarily as a growth preventing tumor suppressor. PTEN is also expressed in neurons, and pathways modulated by PTEN can influence neuronal function. Here we report a novel function of PTEN as a regulator of striatal dopamine signaling in a model of Parkinson's disease (PD). Blocking PTEN expression with an adeno-associated virus (AAV) vector expressing a small hairpin RNA (shRNA) resulted in reduced responses of cultured striatal neurons to dopamine, which appeared to be largely due to reduction in D2 receptor activation. Co-expression of shRNA-resistant wild-type and mutant forms of PTEN indicated that the lipid-phosphatase activity was essential for this effect. In both normal and Parkinsonian rats, inhibition of striatal PTEN in vivo resulted in motor dysfunction and impaired responses to dopamine, particularly D2 receptor agonists. Expression of PTEN mutants confirmed the lipid-phosphatase activity as critical, while co-expression of a dominant-negative form of Akt overcame the PTEN shRNA effect. These results identify PTEN as a key mediator of striatal responses to dopamine, and suggest that drugs designed to potentiate PTEN expression or activity, such as cancer chemotherapeutics, may also be useful for improving striatal responses to dopamine in conditions of dopamine depletion such as PD. This also suggests that strategies which increase Akt or decrease PTEN expression or function, such as growth factors to prevent neuronal death, may have a paradoxical effect on neurological functioning by inhibiting striatal responses to dopamine.

Different forms of tenascin-C with tenascin-R regulate neural differentiation in bone marrow-derived human mesenchymal stem cells

Mesenchymal stem cells (MSCs) are currently thought to transdifferentiate into neural lineages under specific microenvironments. Studies have reported that the tenascin family members, tenascin-C (TnC) and tenascin-R (TnR), regulate differentiation and migration, in addition to neurite outgrowth and survival in numerous types of neurons and mesenchymal progenitor cells. However, the mechanisms by which TnC and TnR affect neuronal differentiation are not well understood. In this study, we hypothesized that different forms of tenascin might regulate the neural transdifferentiation of human bone marrow-derived mesenchymal stem cells. Human MSCs were cultured in media incorporated with soluble tenascins, or on precoated tenascins. In a qualitative polymerase chain reaction analysis, adding a soluble TnC and TnR mixture to the medium significantly enhanced the expression of neuronal and glial markers, whereas no synaptic markers were expressed. Conversely, in groups of cells treated with coated TnC, hMSCs showed neurite outgrowth and synaptic marker expression. After being treated with coated TnR, hMSCs exhibited neuronal differentiation; however, it inhibited neurite outgrowth and synaptic marker expression. A combination of TnC and TnR significantly promoted hMSC differentiation in neurons or oligodendrocytes, induced neurite formation, and inhibited differentiation into astrocytes. Furthermore, the effect of the tenascin mixture showed dose-dependent effects, and a mixture ratio of 1:1 to 1:2 (TnC:TnR) provided the most obvious differentiation of neurons and oligodendrocytes. In a functional blocking study, integrin α7 and α9β1-blocking antibodies inhibited, respectively, 80% and 20% of mRNA expression by hMSCs in the coated tenascin mixture. In summary, the coated combination of TnC and TnR appeared to regulate neural differentiation signaling through integrin α7 and α9β1 in bone marrow-derived hMSCs. Our findings demonstrate novel mechanisms by which tenascin regulates neural differentiation, and enable the use of cell therapy to treat neurodegenerative diseases.

CREB modulates calcium signaling in cAMP-induced bone marrow stromal cells (BMSCs)

Calcium signaling has a versatile role in many important cellular functions. Despite its importance, regulation of calcium signaling in bone marrow stromal cells (BMSCs, also known as bone marrow-derived mesenchymal stem cells) has not been explored extensively. Our previous study revealed that cyclic adenosine monophosphate (cAMP) enabled BMSCs to generate calcium signal upon stimulation by dopamine, KCl and glutamate. Concurrently, cAMP transiently activated the transcription factor cAMP response element binding protein (CREB) in BMSCs. Activity of CREB can be modulated by the calcium/calmodulin-dependent kinase signaling pathway, however, whether the calcium signaling observed in cAMP-induced BMSCs requires CREB has not been investigated. In an effort to uncover the role of CREB in the generation of calcium signaling in response to modulators such as dopamine and KCl, we knocked down CREB activity in BMSCs. Our study indicated that BMSCs, but not its close relative fibroblasts, are responsive to dopamine and KCl after cAMP treatment. Calcium signal elicited by dopamine depends, in part, on calcium influx whereas that elicited by KCl depends completely on calcium influx. Knock-down of CREB activity significantly reduced or abolished the cAMP-induced calcium response, and reintroducing a constitutively active CREB partially restored the calcium response.

IPAF inflammasome is involved in interleukin-1β production from astrocytes, induced by palmitate; implications for Alzheimer's Disease

Inflammatory response has been strongly implicated in the pathogenesis of numerous diseases, including Alzheimer's disease (AD). However, little is known about the molecular mechanisms initiating the generation of inflammatory molecules in the central nervous system, such as interleukin-1β (IL-1β). Previously we identified that palmitate can induce primary astrocytes to produce cytokines, causing AD-like changes in primary neurons. Here we investigated and identified that palmitate induced the activation of ice protease-activating factor (IPAF)-apoptosis-associated speck-like protein containing a caspase activation and recruitment domains (CARD) (ASC) inflammasome in astrocytes leading to the maturation of IL-1β, thereby implicating that not only pathogen-related factors can activate the IPAF-ASC inflammasome. Moreover, downregulating IPAF (which was found to be regulated by cAMP response element-binding protein) in astrocytes through silencing to decrease IL-1β secretion from the astrocytes reduced the generation of amyloid-β42 by primary neurons. Furthermore, the expression levels of IPAF and ASC were found significantly elevated in a subgroup of sporadic AD patients, suggesting an involvement of the IPAF-ASC inflammasome in the inflammatory response associated with AD, and thus could be a potential therapeutic target for AD.

Palmitate induces transcriptional regulation of BACE1 and presenilin by STAT3 in neurons mediated by astrocytes

Deregulation of calcium has been implicated in neurodegenerative diseases, including Alzheimer's disease (AD). Previously, we showed that saturated free-fatty acid, palmitate, causes AD-like changes in primary cortical neurons mediated by astrocytes. However, the molecular mechanisms by which conditioned medium from astrocytes cultured in palmitate induce AD-like changes in neurons are unknown. This study demonstrates that this condition medium from astrocytes elevates calcium level in the neurons, which subsequently increases calpain activity, a calcium-dependent protease, leading to enhance p25/Cdk5 activity and phosphorylation and activation of the STAT3 (signal transducer and activator of transcription) transcription factor. Inhibiting calpain or Cdk5 significantly reduces the upregulation in nuclear level of pSTAT3, which we found to transcriptionally regulate both BACE1 and presenilin-1, the latter is a catalytic subunit of γ-secretase. Decreasing pSTAT3 levels reduced the mRNA levels of both BACE1 and presenilin-1 to near control levels. These data demonstrate a signal pathway leading to the activation of STAT3, and the generation of the amyloid peptide. Thus, our results suggest that STAT3 is an important potential therapeutic target of AD pathogenesis.

Concise review: adult mesenchymal stem cells, adult neural crest stem cells, and therapy of neurological pathologies: a state of play

Adult stem cells are endowed with in vitro multilineage differentiation abilities and constitute an attractive autologous source of material for cell therapy in neurological disorders. With regard to lately published results, the ability of adult mesenchymal stem cells (MSCs) and neural crest stem cells (NCSCs) to integrate and differentiate into neurons once inside the central nervous system (CNS) is currently questioned. For this review, we collected exhaustive data on MSC/NCSC neural differentiation in vitro. We then analyzed preclinical cell therapy experiments in different models for neurological diseases and concluded that neural differentiation is probably not the leading property of adult MSCs and NCSCs concerning neurological pathology management. A fine analysis of the molecules that are secreted by MSCs and NCSCs would definitely be of significant interest regarding their important contribution to the clinical and pathological recovery after CNS lesions.

Quantitative, solution-phase profiling of multiple transcription factors in parallel

Transcription factors are regulatory proteins that bind to specific sites of chromosomal DNA to enact responses to intracellular and extracellular stimuli. Transcription factor signalling networks are branched and interconnected so that any single transcription factor can activate many different genes and one gene can be activated by a combination of different transcription factors. Thus, trying to characterize a cellular response to a stimulus by measuring the level of only one transcription factor potentially ignores important simultaneous events that contribute to the response. Hence, parallel measurements of transcription factors are necessary to capture the breadth of valuable information about cellular responses that would not be obtained by measuring only a single transcription factor. We have sought to develop a new, scalable, flexible, and sensitive approach to analysis of transcription factor levels that complements existing parallel approaches. Here, we describe proof-of-principle analyses of purified human transcription factors and breast cancer nuclear extracts. Our assay can successfully quantify transcription factors in parallel with ~10-fold better sensitivity than current techniques. Sensitivity of the assay can be further increased by 200-fold through the use of PCR for signal amplification.

Potencial de transdiferenciação neural das células-tronco mesenquimais da medula óssea de equino

Os primeiros estudos demonstrando o potencial de trandiferenciação neural das células-tronco mesenquimais (CTMs) provenientes da medula óssea (MO) foram conduzidos em camundogos e humanos no início da década de 2000. Após esse período, o número de pesquisas e publicações com o mesmo propósito tem aumentado, mas com raros ou escassos estudos na espécie equina. Nesse sentindo, o objetivo desse trabalho foi avaliar o potencial in vitro da transdiferenciação neural das CTMs provenientes da MO de equinos utilizando-se dois protocolos: P1 (forksolin e ácido retinóico) e P2 (2-βmecarptoetanol). Após a confirmação das linhagens mesenquimais, pela positividade para o marcador CD90 (X=97,94%), negatividade para o marcador CD34 e resposta positiva a diferenciação osteogênica, as CTMs foram submetidas a transdiferenciação neural (P1 e P2) para avaliação morfológica e expressão dos marcadores neurais GFAP e β3 tubulina por citometria de fluxo. Os resultados revelaram mudanças morfológicas em graus variados entre os protocolos testados. No protocolo 1, vinte quatro horas após a incubação com o meio de diferenciação neural, grande proporção de células (>80%) apresentaram morfologia semelhante a células neurais, caracterizadas por retração do corpo celular e grande número de projeções protoplasmáticas (filopodia). Por outro lado, de forma comparativa, já nos primeiros 30 minutos após a exposição ao antioxidante β-mercaptoetanol (P2) as CTMs apresentaram rápida mudança morfológica caracterizada principalmente por retração do corpo celular e menor número de projeções protoplasmáticas. Também ficou evidenciado com o uso deste protocolo, menor aderência das células após tempo de exposição ao meio de diferenciação, quando comparado ao P1. Com relação a análise imunofenotípica foi observado uma maior (P<0,001) expressão dos marcadores GFAP e β3 tubulina ao término do P2 quando comparado ao P1. A habilidade das CTMs em gerar tipos celulares relacionados a linhagem neural é complexa e multifatorial, dependendo não só dos agentes indutores, mas também do ambiente no qual estas células são cultivadas. Desta forma um maior número de estudos é necessário para o melhor entendimento do processo de transdiferenciação neural a partir de CTMs de equinos.

Repair mechanisms of bone marrow mesenchymal stem cells in myocardial infarction

The prognosis of patients with myocardial infarction (MI) and resultant chronic heart failure remains extremely poor despite advances in optimal medical therapy and interventional procedures. Animal experiments and clinical trials using adult stem cell therapy following MI have shown a global improvement of myocardial function. Bone marrow-derived mesenchymal stem cells (MSCs) hold promise for cardiac repair following MI, due to their multilineage, self-renewal and proliferation potential. In addition, MSCs can be easily isolated, expanded in culture, and have immunoprivileged properties to the host tissue. Experimental studies and clinical trials have revealed that MSCs not only differentiate into cardiomyocytes and vascular cells, but also secrete amounts of growth factors and cytokines which may mediate endogenous regeneration via activation of resident cardiac stem cells and other stem cells, as well as induce neovascularization, anti-inflammation, anti-apoptosis, anti-remodelling and cardiac contractility in a paracrine manner. It has also been postulated that the anti-arrhythmic and cardiac nerve sprouting potential of MSCs may contribute to their beneficial effects in cardiac repair. Most molecular and cellular mechanisms involved in the MSC-based therapy after MI are still unclear at present. This article reviews the potential repair mechanisms of MSCs in the setting of MI.

Immortalized mesenchymal stem cells: an alternative to primary mesenchymal stem cells in neuronal differentiation and neuroregeneration associated studies

Background

Mesenchymal stem cells (MSCs) can be induced to differentiate into neuronal cells under appropriate cellular conditions and transplanted in brain injury and neurodegenerative diseases animal models for neuroregeneration studies. In contrast to the embryonic stem cells (ESCs), MSCs are easily subject to aging and senescence because of their finite ability of self-renewal. MSCs senescence seriously affected theirs application prospects as a promising tool for cell-based regenerative medicine and tissue engineering. In the present study, we established a reversible immortalized mesenchymal stem cells (IMSCs) line by using SSR#69 retrovirus expressing simian virus 40 large T (SV40T) antigen as an alternative to primary MSCs.

Methods

The retroviral vector SSR#69 expressing simian virus 40 large T (SV40T) antigen was used to construct IMSCs. IMSCs were identified by flow cytometry to detect cell surface makers. To investigate proliferation and differentiation potential of IMSCs, cell growth curve determination and mesodermal trilineage differentiation tests were performed. Neuronal differentiation characteristics of IMSCs were detected in vitro. Before IMSCs transplantation, we excluded its tumorigenicity in nude mice firstly. The Morris water maze tests and shuttle box tests were performed five weeks after HIBD models received cells transplantation therapy.

Results

In this study, reversible IMSCs were constructed successfully and had the similar morphology and cell surface makers as primary MSCs. IMSCs possessed better ability of proliferation and anti-senescence compared with primary MSCs, while maintained multilineage differentiation capacity. Neural-like cells derived from IMSCs had similar expressions of neural-specific genes, protein expression patterns and resting membrane potential (RMP) compared with their counterparts derived from primary MSCs. There was no bump formation in nude mice subcutaneously injected with IMSCs. IMSCs played same role as primary MSCs to improve learning ability and spatial memory of HIBD rats.

Conclusions

IMSCs not only retain their features of primary MSCs but also possess the ability of high proliferation and anti-senescence. IMSCs can definitely be induced to differentiate into neuronal cells in vitro and take the place of primary MSCs for cell transplantation therapy without tumorigenesis in vivo. The stable cell line is particularly useful and valuable as an alternative to MSCs in neuronal differentiation and neuroregeneration associated studies.

Identification of novel targets for breast cancer by exploring gene switches on a genome scale

BACKGROUND

An important feature that emerges from analyzing gene regulatory networks is the "switch-like behavior" or "bistability", a dynamic feature of a particular gene to preferentially toggle between two steady-states. The state of gene switches plays pivotal roles in cell fate decision, but identifying switches has been difficult. Therefore a challenge confronting the field is to be able to systematically identify gene switches.

RESULTS

We propose a top-down mining approach to exploring gene switches on a genome-scale level. Theoretical analysis, proof-of-concept examples, and experimental studies demonstrate the ability of our mining approach to identify bistable genes by sampling across a variety of different conditions. Applying the approach to human breast cancer data identified genes that show bimodality within the cancer samples, such as estrogen receptor (ER) and ERBB2, as well as genes that show bimodality between cancer and non-cancer samples, where tumor-associated calcium signal transducer 2 (TACSTD2) is uncovered. We further suggest a likely transcription factor that regulates TACSTD2.

CONCLUSIONS

Our mining approach demonstrates that one can capitalize on genome-wide expression profiling to capture dynamic properties of a complex network. To the best of our knowledge, this is the first attempt in applying mining approaches to explore gene switches on a genome-scale, and the identification of TACSTD2 demonstrates that single cell-level bistability can be predicted from microarray data. Experimental confirmation of the computational results suggest TACSTD2 could be a potential biomarker and attractive candidate for drug therapy against both ER+ and ER- subtypes of breast cancer, including the triple negative subtype.