pinecone/core-2020-05-10-deduplication huggingface dataset:
Generation of Induced Cardiospheres via Reprogramming of Skin Fibroblasts for Myocardial Regeneration

© 2016 The Authors STEM CELLS published by Wiley Periodicals, Inc. on behalf of AlphaMed PressRecent pre-clinical and clinical studies have suggested that endogenous cardiospheres (eCS) are potentially safe and effective for cardiac regeneration following myocardial infarction (MI). Nevertheless the preparation of autologous eCS requires invasive myocardial biopsy with limited yield. We describe a novel approach to generate induced cardiospheres (iCS) from adult skin fibroblasts via somatic reprogramming. After infection with Sox2, Klf4, and Oct4, iCS were generated from mouse adult skin fibroblasts treated with Gsk3β inhibitor-(2′Z,3′E)- 6-Bromoindirubin-3′-oxime and Oncostatin M. They resembled eCS, but contained a higher percentage of cells expressing Mesp1, Isl1, and Nkx2.5. They were differentiated into functional cardiomyocytes in vitro with similar electrophysiological properties, calcium transient and contractile function to eCS and mouse embryonic stem cell-derived cardiomyocytes. Transplantation of iCS (1 × 106 cells) into mouse myocardium following MI had similar effects to transplantation of eCS but significantly better than saline or fibroblast in improving left ventricular ejection fraction, increasing anterior/septal ventricular wall thickness and capillary density in the infarcted region 4 weeks after transplantation. No tumor formation was observed. iCS generated from adult skin fibroblasts by somatic reprogramming and a cocktail of Gsk3β inhibitor-6-Bromoindirubin-3′-oxime and Oncostatin M may represent a novel source for cell therapy in MI. Stem Cells 2016;34:2693–2706.published_or_final_versioncsl 17020
Characterization of a Fetal Liver Cell Population Endowed with Long-Term Multi-Organ Endothelial Reconstitution Potential

Stable reconstitution of vascular endothelial beds upon transplantation of progenitor cells represents an important challenge due to the paucity and generally limited integration/expansion potential of most identified vascular related cell subsets. We previously showed that mouse fetal liver (FL) hemato/vascular cells from day 12 of gestation (E12), expressing the Stem Cell Leukaemia (SCL) gene enhancer transgene (SCL-PLAP$^+$ cells), had robust endothelial engraftment potential when transferred to the blood stream of newborns or adult conditioned recipients, compared to the scarce vascular contribution of adult bone marrow cells. However, the specific SCL-PLAP$^+$ hematopoietic or endothelial cell subset responsible for the long-term reconstituting endothelial cell (LTR-EC) activity and its confinement to FL developmental stages remained unknown. Using a busulfan-treated newborn transplantation model, we show that LTR-EC activity is restricted to the SCL-PLAP$^+$VE-cadherin$^+$CD45$^-$ cell population, devoid of hematopoietic reconstitution activity and largely composed by Lyve1$^+$ endothelial-committed cells. SCL-PLAP$^+$ Ve-cadherin$^+$CD45$^-$ cells contributed to the liver sinusoidal endothelium and also to the heart, kidney and lung microvasculature. LTR-EC activity was detected at different stages of FL development, yet marginal activity was identified in the adult liver, revealing unknown functional differences between fetal and adult liver endothelial/endothelial progenitors. Importantly, the observations that expanding donor-derived vascular grafts colocalize with proliferating hepatocyte-like cells and participate in the systemic circulation, support their functional integration into young livers. These findings offer new insights into the engraftment, phonotypical, and developmental characterization of a novel endothelial/endothelial progenitor cell subtype with multiorgan LTR-EC activity, potentially instrumental for the treatment/genetic correction of vascular diseases.Spanish Ministry of Economy and Competitiveness (Grant IDs: BFU2010- 15801, CSD-2007-00008), Junta de Andalucıa Regional Government (Grant ID: CVI-295), European Regional Development Funds, Wellcome Trust, Medical Research CouncilThis is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/stem.249
Bistable epigenetic states explain age-dependent decline in mesenchymal stem cell heterogeneity

This is an Open Access Article. It is published by AlphaMed Press under the Creative Commons Attribution -NonCommercial-NoDerivatives 4.0 International Licence (CC BY-NC-ND). Full details of this licence are available at: http://creativecommons.org/licenses/by-nc-nd/4.0/The molecular mechanisms by which heterogeneity, a major characteristic of stem cells, is achieved are yet unclear. We here study the expression of the membrane stem cell antigen-1 (Sca-1) in mouse bone marrow Mesenchymal Stem Cell (MSC) clones. We show that subpopulations with varying Sca-1 expression profiles regenerate the Sca-1 profile of the mother population within a few days. However, after extensive replication in vitro the expression profiles shift to lower values and the regeneration time increases. Study of the promoter of Ly6a unravels that the expression level of Sca-1 is related to the promoter occupancy by the activating histone mark H3K4me3. We demonstrate that these findings can be consistently explained by a computational model that considers positive feedback between promoter H3K4me3 modification and gene transcription. This feedback implicates bistable epigenetic states which the cells occupy with an age-dependent frequency due to persistent histone (de-)modification. Our results provide evidence that MSC heterogeneity, and presumably that of other stem cells, is associated with bistable epigenetic states and suggest that MSCs are subject to permanent state fluctuations. This article is protected by copyright. All rights reserved
Concise review: Emerging Drugs Targeting Epithelial Cancer Stem-like Cells

Increasing evidence suggests that cancer cell populations contain a small proportion of cells that display stem‐like cell properties and which may be responsible for overall tumor maintenance. These cancer stem‐like cells (CSCs) appear to have unique tumor‐initiating ability and innate survival mechanisms that allow them to resist cancer therapies, consequently promoting relapses. Selective targeting of CSCs may provide therapeutic benefit and several recent reports have indicated this may be possible. In this article, we review drugs targeting CSCs, in selected epithelial cell‐derived cancers
Reprogramming Antagonizes the Oncogenicity of HOXA13-Long Noncoding RNA HOTTIP Axis in Gastric Cancer Cells

Reprogramming of cancer cells into induced pluripotent stem cells (iPSCs) is a compelling idea for inhibiting oncogenesis, especially through modulation of homeobox proteins in this reprogramming process. We examined the role of various long noncoding RNAs (lncRNAs)-homeobox protein HOXA13 axis on the switching of the oncogenic function of bone morphogenetic protein 7 (BMP7), which is significantly lost in the gastric cancer cell derived iPS-like cells (iPSLCs). BMP7 promoter activation occurred through the corecruitment of HOXA13, mixed-lineage leukemia 1 lysine N-methyltransferase, WD repeat-containing protein 5, and lncRNA HoxA transcript at the distal tip (HOTTIP) to commit the epigenetic changes to the trimethylation of lysine 4 on histone H3 in cancer cells. By contrast, HOXA13 inhibited BMP7 expression in iPSLCs via the corecruitment of HOXA13, enhancer of zeste homolog 2, Jumonji and AT rich interactive domain 2, and lncRNA HoxA transcript antisense RNA (HOTAIR) to various cis-element of the BMP7 promoter. Knockdown experiments demonstrated that HOTTIP contributed positively, but HOTAIR regulated negatively to HOXA13-mediated BMP7 expression in cancer cells and iPSLCs, respectively. These findings indicate that the recruitment of HOXA13–HOTTIP and HOXA13–HOTAIR to different sites in the BMP7 promoter is crucial for the oncogenic fate of human gastric cells. Reprogramming with octamer-binding protein 4 and Jun dimerization protein 2 can inhibit tumorigenesis by switching off BMP7. Stem Cells 2017;35:2115–212
An iPSC patient specific model of CFH (Y402H) polymorphism displays characteristic features of AMD and indicates a beneficial role for UV light exposure.

Age related macular degeneration (AMD) is the most common cause of blindness, accounting for 8.7% of all blindness globally. Vision loss is caused ultimately by apoptosis of the retinal pigment epithelium (RPE) and overlying photoreceptors. Treatments are evolving for the wet form of the disease, however these do not exist for the dry form. Complement factor H (CFH) polymorphism in exon 9 (Y402H) has shown a strong association with susceptibility to AMD resulting in complement activation, recruitment of phagocytes, retinal pigment epithelium (RPE) damage and visual decline. We have derived and characterised induced pluripotent stem cell (iPSCs) lines from two patients without AMD and low risk genotype and two patients with advanced AMD and high risk genotype and generated RPE cells that show local secretion of several proteins involved in the complement pathway including factor H (FH), factor I (FI) and factor H like 1 (FHL-1). The iPSC RPE cells derived from high risk patients mimic several key features of AMD including increased inflammation and cellular stress, accumulation of lipid droplets, impaired autophagy and deposition of “drüsen” like deposits. The low and high risk RPE cells respond differently to intermittent exposure to UV light which leads to an improvement in cellular and functional phenotype only in the high risk AMD-RPE cells. Taken together our data indicate that the patient specific iPSC model provides a robust platform for understanding the role of complement activation in AMD, evaluating new therapies based on complement modulation and drug testing
Neuroprotective Effects of Human Mesenchymal Stem Cells and Platelet-Derived Growth Factor on Human Retinal Ganglion Cells

Optic neuropathies such as glaucoma occur when retinal ganglion cells (RGCs) in the eye are injured. Strong evidence suggests mesenchymal stem cells (MSCs) could be a potential therapy to protect RGCs, however little is known regarding their effect on the human retina. We, therefore, investigated if human MSCs (hMSCs), or platelet-derived growth factor (PDGF) as produced by hMSC, could delay RGC death in a human retinal explant model of optic nerve injury. Our results showed hMSCs and the secreted growth factor PDGF-AB could substantially reduce human RGC loss and apoptosis following axotomy. The neuroprotective pathways AKT, ERK, and STAT3 were activated in the retina shortly after treatments with labeling seen in the RGC layer. A dose dependent protective effect of PDGF-AB was observed in human retinal explants but protection was not as substantial as that achieved by culturing hMSCs on the retina surface which resulted in RGC cell counts similar to those immediately post dissection. These results demonstrate that hMSCs and PDGF have strong neuroprotective action on human RGCs and may offer a translatable, therapeutic strategy to reduce degenerative visual loss. Stem Cells 201
Graft-Versus-Host Disease Amelioration by Human Bone Marrow Mesenchymal Stromal/Stem Cell-Derived Extracellular Vesicles Is Associated with Peripheral Preservation of Naive T Cell Populations

A substantial proportion of patients with acute graft‐versus‐host disease (aGVHD) respond to cell therapy with culture‐expanded human bone marrow mesenchymal stromal/stem cells (BM‐MSCs). However, the mechanisms by which these cells can ameliorate aGVHD‐associated complications remain to be clarified. We show here that BM‐MSC‐derived extracellular vesicles (EVs) recapitulated the therapeutic effects of BM‐MSCs against aGVHD. Systemic infusion of human BM‐MSC‐derived EVs prolonged the survival of mice with aGVHD and reduced the pathologic damage in multiple GVHD‐targeted organs. In EV‐treated GVHD mice, CD4+ and CD8+ T cells were suppressed. Importantly, the ratio of CD62L‐CD44+ to CD62L + CD44‐ T cells was decreased, suggesting that BM‐MSC‐derived EVs suppressed the functional differentiation of T cells from a naive to an effector phenotype. BM‐MSC‐derived EVs also preserved CD4 + CD25 + Foxp3+ regulatory T cell populations. In a culture of CD3/CD28‐stimulated human peripheral blood mononuclear cells with BM‐MSC‐derived EVs, CD3+ T cell activation was suppressed. However, these cells were not suppressed in cultures with EVs derived from normal human dermal fibroblasts (NHDFs). NHDF‐derived EVs did not ameliorate the clinical or pathological characteristics of aGVHD in mice, suggesting an immunoregulatory function unique to BM‐MSC‐derived EVs. Microarray analysis of microRNAs in BM‐MSC‐derived EVs versus NHDF‐derived EVs showed upregulation of miR‐125a‐3p and downregulation of cell proliferative processes, as identified by Gene Ontology enrichment analysis. Collectively, our findings provide the first evidence that amelioration of aGVHD by therapeutic infusion of BM‐MSC‐derived EVs is associated with the preservation of circulating naive T cells, possibly due to the unique microRNA profiles of BM‐MSC‐derived EVs
Novel Hyperactive Transposons for Genetic Modification of Induced Puripotent and Adult Stem Cells: A Non-Viral Paradigm for Coaxed Differentiation

Adult stem cells and induced pluripotent stem cells (iPS) hold great promise for regenerative medicine. The development of robust non-viral approaches for stem cell gene transfer would facilitate functional studies and potential clinical applications. We have previously generated hyperactive transposases derived from Sleeping Beauty, using an in vitro molecular evolution and selection paradigm. We now demonstrate that these hyperactive transposases resulted in superior gene transfer efficiencies and expression in mesenchymal and muscle stem/progenitor cells, consistent with higher expression levels of therapeutically relevant proteins including coagulation factor IX. Their differentiation potential and karyotype was not affected. Moreover, stable transposition could also be achieved in iPS which retained their ability to differentiate along neuronal, cardiac and hepatic lineages without causing cytogenetic abnormalities. Most importantly, transposon-mediated delivery of the myogenic PAX3 transcription factor into iPS coaxed their differentiation into MYOD(+) myogenic progenitors and multinucleated myofibers, suggesting that PAX3 may serve as a myogenic "molecular switch" in iPS. Hence, this hyperactive transposon system represents an attractive non-viral gene transfer platform with broad implications for regenerative medicine, cell and gene therapy.status: publishe
Microchimerism, dendritic cell progenitors and transplantation tolerance

The recent discovery of multilineage donor leukocyte microchimerism in allograft recipients up to three decades after organ transplantation implies the migration and survival of donor stem cells within the host. It has been postulated that in chimeric graft recipients, reciprocal modulation of immune responsiveness between donor and recipient leukocytes may lead, eventually, to the induction of mutual immunologic nonreactivity (tolerance). A prominent donor leukocyte, both in human organ transplant recipients and in animals, has invariably been the bone marrow‐derived dendritic cell (DC). These cells have been classically perceived as the most potent antigen‐presenting cells but evidence also exists for their tolerogenicity. The liver, despite its comparatively heavy leukocyte content, is the whole organ that is most capable of inducing tolerance. We have observed that DC progenitors propagated from normal mouse liver in response to GM‐CSF express only low levels of major histocompatibility complex (MHC) class II antigen and little or no cell surface B7 family T cell costimulatory molecules. They fail to activate resting naive allogeneic T cells. When injected into normal allogeneic recipients, these DC progenitors migrate to T‐dependent areas of host lymphoid tissue, where some at least upregulate cell surface MHC class II. These donor‐derived cells persist indefinitely, recapitulating the behavior pattern of donor leukocytes after the successful transplantation of all whole organs, but most dramatically after the orthotopic (replacement) engraftment of the liver. A key finding is that in mice, progeny of these donor‐derived DC progenitors can be propagated ex vivo from the bone marrow and other lymphoid tissues of nonimmunosuppressed spontaneously tolerant liver allograft recipients. In humans, donor DC can also be grown from the blood of organ allograft recipients whose organ‐source chimerism is augmented with donor bone marrow infusion. DC progenitors cannot, however, be propagated from the lymphoid tissue of nonimmunosuppressed cardiac‐allografted mice that reject their grafts. These findings are congruent with the possibility that bidirectional leukocyte migration and donor cell chimerism play key roles in acquired transplantation tolerance. Although the cell interactions are undoubtedly complex, a discrete role can be identified for DC under well‐defined experimental conditions. Bone marrow‐derived DC progenitors (MHC class II+, B7–1dim, B7–2−) induce alloantigen‐specific hyporesponsiveness (anergy) in naive T cells in vitro. Moreover, costimulatory molecule‐deficient DC progenitors administered systemically prolong the survival of mouse heart or pancreatic islet allografts. How the regulation of donor DC phenotype and function relates to the balance between the immunogenicity and tolerogenicity of organ allografts remains to be determined. Copyright © 1995 AlphaMed Pres
Human mesenchymal stem cells reprogram adult cardiomyocytes toward a progenitor-like state through partial cell fusion and mitochondria transfer
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Cell fusion-mediated cardiomyocyte reprogramming.

International audienceBecause stem cells are often found to improve repair tissue including heart without evidence of engraftment or differentiation, mechanisms underlying wound healing are still elusive. Several studies have reported that stem cells can fuse with cardiomyocytes either by permanent or partial cell fusion processes. However, the respective physiological impact of these two processes remains unknown in part because of the lack of knowledge of the resulting hybrid cells. To further characterize cell fusion, we cocultured mouse fully differentiated cardiomyocytes with human multipotent adipose-derived stem (hMADS) cells as a model of adult stem cells. We found that heterologous cell fusion promoted cardiomyocyte reprogramming back to a progenitor-like state. The resulting hybrid cells expressed early cardiac commitment and proliferation markers such as GATA-4, myocyte enhancer factor 2C, Nkx2.5, and Ki67 and exhibited a mouse genotype. Interestingly, human bone marrow-derived stem cells shared similar reprogramming properties than hMADS cells but not human fibroblasts, which suggests that these features might be common to multipotent cells. Furthermore, cardiac hybrid cells were preferentially generated by partial rather than permanent cell fusion and that intercellular structures composed of f-actin and microtubule filaments were involved in the process. Finally, we showed that stem cell mitochondria were transferred into cardiomyocytes, persisted in hybrids and were required for somatic cell reprogramming. In conclusion, by providing new insights into previously reported cell fusion processes, our data might contribute to a better understanding of stem cell-mediated regenerative mechanisms and thus, the development of more efficient stem cell-based heart therapies. STEM CELLS 2011;29:812-824
Epithelial Cells Derived from Human Embryonic Stem Cells Display P16INK4A Senescence, Hypermotility, and Differentiation Properties Shared by Many P63+ Somatic Cell Types

Human embryonic stem (hES) cells can generate cells expressing p63, K14, and involucrin, which have been proposed to be keratinocytes. Although these hES-derived, keratinocyte-like (hESderK) cells form epithelioid colonies when cultured in a fibroblast feeder system optimal for normal tissue-derived keratinocytes, they have a very short replicative lifespan unless engineered to express HPV16 E6E7. We report here that hESderK cells undergo senescence associated with p16INK4A expression, unrelated to telomere status. Transduction to express bmi1, a repressor of the p16INK4A/p14ARF locus, conferred upon hESderK cells and keratinocytes a substantially extended lifespan. When exposed to transforming growth factor beta or to an incompletely processed form of Laminin-332, three lifespan-extended or immortalized hESderK lines that we studied became directionally hypermotile, a wound healing and invasion response previously characterized in keratinocytes. In organotypic culture, hESderK cells stratified and expressed involucrin and K10, as do epidermal keratinocytes in vivo. However, their growth requirements were less stringent than keratinocytes. We then extended the comparison to endoderm-derived, p63+/K14+ urothelial and tracheobronchial epithelial cells. Primary and immortalized lines of these cell types had growth requirements and hypermotility responses similar to keratinocytes and bmi1 expression facilitated their immortalization by engineering to express the catalytic subunit of telomerase (TERT). In organotypic culture, they stratified and exhibited squamous metaplasia, expressing involucrin and K10. Thus, hESderK cells proved to be distinct from all three normal p63+ cell types tested. These results indicate that hESderK cells cannot be identified conclusively as keratinocytes or even as ectodermal cells, but may represent an incomplete form of, or deviation from, normal p63+ lineage development.Molecular and Cellular Biolog
Reprogramming of postnatal neurons into induced pluripotent stem cells by defined factors

Pluripotent cells can be derived from different types of somatic cells by nuclear reprogramming through the ectopic expression of four transcription factors, Oct3/4, Sox2, Klf4, and c-Myc. However, it is unclear whether postmitotic neurons are susceptible to direct reprogramming. Here, we show that postnatal cortical neurons, the vast majority of which are postmitotic, are amenable to epigenetic reprogramming. However, ectopic expression of the four canonical reprogramming factors is not sufficient to reprogram postnatal neurons. Efficient reprogramming was only achieved after forced cell proliferation by p53 suppression. Additionally, overexpression of repressor element-1 silencing transcription, a suppressor of neuronal gene activity, increased reprogramming efficiencies in combination with the reprogramming factors. Our findings indicate that terminally differentiated postnatal neurons are able to acquire the pluripotent state by direct epigenetic reprogramming, and this process is made more efficient through the suppression of lineage specific gene expression. STEM CELLS 2011;29:992–1000National Institutes of Health (U.S.) (Grant NIH HD045022)National Institutes of Health (U.S.) (Grant 5R37CA084198)Howard Hughes Medical Institut