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Reprogramming of Embryonic Human Fibroblasts into Fetal Hematopoietic Progenitors by Fusion with Human Fetal Liver CD34+ Cells  [PDF]
Vladislav M. Sandler,Nathalie Lailler,Eric E. Bouhassira
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0018265
Abstract: Experiments with somatic cell nuclear transfer, inter-cellular hybrid formation_ENREF_3, and ectopic expression of transcription factors have clearly demonstrated that cell fate can be dramatically altered by changing the epigenetic state of cell nuclei. Here we demonstrate, using chemical fusion, direct reprogramming of the genome of human embryonic fibroblasts (HEF) into the state of human fetal liver hFL CD34+ (hFL) hematopoietic progenitors capable of proliferating and differentiating into multiple hematopoietic lineages. We show that hybrid cells retain their ploidy and can differentiate into several hematopoietic lineages. Hybrid cells follow transcription program of differentiating hFL cells as shown by genome-wide transcription profiling. Using whole-genome single nucleotide polymorphism (SNP) profiling of both donor genomes we demonstrate reprogramming of HEF genome into the state of hFL hematopoietic progenitors. Our results prove that it is possible to convert the fetal somatic cell genome into the state of fetal hematopoietic progenitors by fusion. This suggests a possibility of direct reprogramming of human somatic cells into tissue specific progenitors/stem cells without going all the way back to the embryonic state. Direct reprogramming of terminally differentiated cells into the tissue specific progenitors will likely prove useful for the development of novel cell therapies.
Conditionally Immortalized Mouse Embryonic Fibroblasts Retain Proliferative Activity without Compromising Multipotent Differentiation Potential  [PDF]
Enyi Huang, Yang Bi, Wei Jiang, Xiaoji Luo, Ke Yang, Jian-Li Gao, Yanhong Gao, Qing Luo, Qiong Shi, Stephanie H. Kim, Xing Liu, Mi Li, Ning Hu, Hong Liu, Jing Cui, Wenwen Zhang, Ruidong Li, Xiang Chen, Jikun Shen, Yuhan Kong, Jiye Zhang, Jinhua Wang, Jinyong Luo, Bai-Cheng He, Huicong Wang, Russell R. Reid, Hue H. Luu, Rex C. Haydon, Li Yang, Tong-Chuan He
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0032428
Abstract: Mesenchymal stem cells (MSCs) are multipotent cells which reside in many tissues and can give rise to multiple lineages including bone, cartilage and adipose. Although MSCs have attracted significant attention for basic and translational research, primary MSCs have limited life span in culture which hampers MSCs' broader applications. Here, we investigate if mouse mesenchymal progenitors can be conditionally immortalized with SV40 large T antigen and maintain long-term cell proliferation without compromising their multipotency. Using the system which expresses SV40 large T antigen flanked with Cre/loxP sites, we demonstrate that mouse embryonic fibroblasts (MEFs) can be efficiently immortalized by SV40 large T antigen. The conditionally immortalized MEFs (iMEFs) exhibit an enhanced proliferative activity and maintain long-term cell proliferation, which can be reversed by Cre recombinase. The iMEFs express most MSC markers and retain multipotency as they can differentiate into osteogenic, chondrogenic and adipogenic lineages under appropriate differentiation conditions in vitro and in vivo. The removal of SV40 large T reduces the differentiation potential of iMEFs possibly due to the decreased progenitor expansion. Furthermore, the iMEFs are apparently not tumorigenic when they are subcutaneously injected into athymic nude mice. Thus, the conditionally immortalized iMEFs not only maintain long-term cell proliferation but also retain the ability to differentiate into multiple lineages. Our results suggest that the reversible immortalization strategy using SV40 large T antigen may be an efficient and safe approach to establishing long-term cell culture of primary mesenchymal progenitors for basic and translational research, as well as for potential clinical applications.
The piggyBac Transposon-Mediated Expression of SV40 T Antigen Efficiently Immortalizes Mouse Embryonic Fibroblasts (MEFs)  [PDF]
Ning Wang, Wenwen Zhang, Jing Cui, Hongmei Zhang, Xiang Chen, Ruidong Li, Ningning Wu, Xian Chen, Sheng Wen, Junhui Zhang, Liangjun Yin, Fang Deng, Zhan Liao, Zhonglin Zhang, Qian Zhang, Zhengjian Yan, Wei Liu, Jixing Ye, Youlin Deng, Zhongliang Wang, Min Qiao, Hue H. Luu, Rex C. Haydon, Lewis L. Shi, Houjie Liang, Tong-Chuan He
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0097316
Abstract: Mouse embryonic fibroblasts (MEFs) are mesenchymal stem cell (MSC)-like multipotent progenitor cells and can undergo self-renewal and differentiate into to multiple lineages, including bone, cartilage and adipose. Primary MEFs have limited life span in culture, which thus hampers MEFs’ basic research and translational applications. To overcome this challenge, we investigate if piggyBac transposon-mediated expression of SV40 T antigen can effectively immortalize mouse MEFs and that the immortalized MEFs can maintain long-term cell proliferation without compromising their multipotency. Using the piggyBac vector MPH86 which expresses SV40 T antigen flanked with flippase (FLP) recognition target (FRT) sites, we demonstrate that mouse embryonic fibroblasts (MEFs) can be efficiently immortalized. The immortalized MEFs (piMEFs) exhibit an enhanced proliferative activity and maintain long-term cell proliferation, which can be reversed by FLP recombinase. The piMEFs express most MEF markers and retain multipotency as they can differentiate into osteogenic, chondrogenic and adipogenic lineages upon BMP9 stimulation in vitro. Stem cell implantation studies indicate that piMEFs can form bone, cartilage and adipose tissues upon BMP9 stimulation, whereas FLP-mediated removal of SV40 T antigen diminishes the ability of piMEFs to differentiate into these lineages, possibly due to the reduced expansion of progenitor populations. Our results demonstrate that piggyBac transposon-mediated expression of SV40 T can effectively immortalize MEFs and that the reversibly immortalized piMEFs not only maintain long-term cell proliferation but also retain their multipotency. Thus, the high transposition efficiency and the potential footprint-free natures may render piggyBac transposition an effective and safe strategy to immortalize progenitor cells isolated from limited tissue supplies, which is essential for basic and translational studies.
Identification of Genes to Differentiate Closely Related Salmonella Lineages  [PDF]
Qing-Hua Zou, Ren-Qing Li, Ye-Jun Wang, Shu-Lin Liu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0055988
Abstract: Background Salmonella are important human and animal pathogens. Though highly related, the Salmonella lineages may be strictly adapted to different hosts or cause different diseases, from mild local illness like gastroenteritis to fatal systemic infections like typhoid. Therefore, rapid and accurate identification of Salmonella is essential for timely and correct diagnosis of Salmonella infections. The current identification methods such as 16S rRNA sequencing and multilocus sequence typing are expensive and time consuming. Additionally, these methods often do not have sufficient distinguishing resolution among the Salmonella lineages. Methodologies/Principal Findings We compared 27 completely sequenced Salmonella genomes to identify possible genomic features that could be used for differentiation of individual lineages. We concatenated 2372 core genes in each of the 27 genomes and constructed a neighbor-joining tree. On the tree, strains of each serotype were clustered tightly together and different serotypes were unambiguously separated with clear genetic distances, demonstrating systematic genomic divergence among the Salmonella lineages. We made detailed comparisons among the 27 genomes and identified distinct sets of genomic differences, including nucleotide variations and genomic islands (GIs), among the Salmonella lineages. Two core genes STM4261 and entF together could unambiguously distinguish all Salmonella lineages compared in this study. Additionally, strains of a lineage have a common set of GIs and closely related lineages have similar sets of GIs. Conclusions Salmonella lineages have accumulated distinct sets of mutations and laterally acquired DNA (e.g., GIs) in evolution. Two genes entF and STM4261 have diverged sufficiently among the Salmonella lineages to be used for their differentiation. Further investigation of the distinct sets of mutations and GIs will lead to novel insights into genomic evolution of Salmonella and greatly facilitate the elucidation of pathogeneses of Salmonella infections.
Effects of rat mesenchymal stem cells as a feeder layer in isolation and culture of mouse embryonic stem cells
Nasim Forghani,Mehdi Kadivar,Parechehr Yagmaei,Saeedeh Kargar
Koomesh , 2009,
Abstract: Introduction: Embryonic stem cells (ESCs) are pluripotent cells derived from the inner cell mass(ICM) of blastocysts. A feeder layer and cytokines are necessary for culture of these embryonic cellsin most species. The aim of this study was application of rat mesenchymal stem cells (MSCs) as afeeder layer for the isolation and culture of mouse embryonic stem cells.Materials and Methods: Mesenchymal stem cells were isolated from rat bone marrow and culturedin DMEM (Dulbecco's modified Eagle's medium) medium supplemented with 10% FBS (fetal bovineserum). To verify the isolated cells, they were affected by osteocyte differentiation inducer to becomebone mass. After twenty-one days, the differentiation was evaluated by Alizarin red staining.Blastocysts were obtained from Balb/c pregnant mice and cultured on this MSCs feeder layer. Twodays later; after hatching of blastocysts, the cells were trypsinized and the inner cell mass dissociatedto the small cell clumps. These clumps were cultured on 12-well plates covered by the same MSCswithout applying any cytokines or growth inducer. Two to three days after the passage, coloniesappeared which were similar to embryonic stem cell colonies in morphology. These colonies werepassaged two more times using the mentioned procedure and their identities were examined bymorphological observation and alkalin phosphatase staining.Results: In this study we could easily cultured MSCs using DMEM media. The mesenchimic originof cultured cells, which showed fibroblastic morphology, was proved by differentiation to bonemasses using osteocyte inducer and detection with Alizarin red. By applying DMEM media and MSCscells, as feeder layer, we could culture ESC without any need to cytokines or growth factors. Afterpassage to the inner cell mass colonies were formed. These colonies were formed in two more otherpassages. The colonies were verified with alkalin phosphatase assay.Conclusion: Results of this study showed mesenchymal stem cells isolated from rat bone marrowcan differentiate to osteoblaste line and can be used as feeder layer for isolation, culture and formingembryonic stem cells colonies. This method, by using MSCs as feeder layer and bypassing the need ofcytokine and growth factors, seems to be a simple efficient method for culture and isolation ofembryonic stem cells.
Differential Adhesion Molecule Expression during Murine Embryonic Stem Cell Commitment to the Hematopoietic and Endothelial Lineages  [PDF]
Basha L. Stankovich, Esmeralda Aguayo, Fatima Barragan, Aniket Sharma, Maria G. Pallavicini
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023810
Abstract: Mouse embryonic stem cells (ESC) make cell fate decisions based on intrinsic and extrinsic factors. The decision of ESC to differentiate to multiple lineages in vitro occurs during the formation of embryoid bodies (EB) and is influenced by cell-environment interactions. However, molecular mechanisms underlying cell-environmental modulation of ESC fate decisions are incompletely understood. Since adhesion molecules (AM) influence proliferation and differentiation in developing and adult tissues, we hypothesized that specific AM interactions influence ESC commitment toward hematopoietic and endothelial lineages. Expression of AM in the adherens, tight and gap junction pathways in ESC subpopulations were quantified. E-cadherin (E-cad), Claudin-4 (Cldn4), Connexin-43 (Cx43), Zona Occludens-1 (ZO-1) and Zona Occludens-2 (ZO-2) transcript levels were differentially expressed during early stages of hematopoietic/endothelial commitment. Stable ESC lines were generated with reduced expression of E-cad, Cldn4, Cx43, ZO-1 and ZO-2 using shRNA technology. Functional and phenotypic consequences of modulating AM expression were assessed using hematopoietic colony forming assays, endothelial sprouting assays and surface protein expression. A decrease in E-cad, Cldn4, Cx43 and ZO-1 expression was associated with less commitment to the hematopoietic lineage and increased endothelial differentiation as evidenced by functional and phenotypic analysis. A reduction in ZO-2 expression did not influence endothelial differentiation, but decreased hematopoietic commitment two-fold. These data indicate that a subset of AM influence ESC decisions to commit to endothelial and hematopoietic lineages. Furthermore, differentially expressed AM may provide novel markers to delineate early stages of ESC commitment to hematopoietic/endothelial lineages.
Medicina regenerativa: Células madre embrionarias y adultas Regenerative medicine: Embryonic and adult stem cells  [cached]
Porfirio Hernández Ramírez,Elvira Dorticós Balea
Revista Cubana de Hematolog?-a, Inmunolog?-a y Hemoterapia , 2004,
Abstract: En los últimos a os ha surgido una nueva rama de la medicina denominada medicina regenerativa, basada fundamentalmente en los nuevos conocimientos sobre las células madre y en su capacidad de convertirse en células de diferentes tejidos. Las células madre se clasifican en embrionarias y somáticas o adultas. Durante varios a os se consideró que la célula madre hematopoyética era la única célula en la médula ósea con capacidad generativa. Sin embargo, estudios recientes han mostrado que la composición de la médula ósea es más compleja, pues en ella se ha identificado un grupo heterogéneo de células madre adultas, entre las que se encuentran las: hematopoyéticas, mesenquimales (estromales), población lateral, células progenitoras adultas multipotentes (MAPC). Varios estudios han sugerido que la potencialidad de algunos tipos de células madre adultas es mayor de lo esperado, pues han mostrado en determinadas condiciones capacidad para diferenciarse en células de diferentes linajes, lo que las acercan a la potencialidad de las células embrionarias. Esto ha creado nuevas perspectivas para el tratamiento de diferentes enfermedades con células madre adultas, lo que inicialmente se pensaba solo podía hacerse con las embrionarias In the last few years, there has emerged a new branch of medicine called regenerative medicine based mainly on the new knowledge about stem cells and their capacity to turn into cells of different tissues. Stem cells are classified into embryonic cells and somatic or adult cells. For many years, it was believed that hematopoietic stem cell was the only one with regenerative capacity in the bone-marrow. However, recent studies have shown that the composition of the bone marrow is more complex an heterogeneous group of adult stem cells such as hematopoietic, mesenchymal (stromal), lateral population and multipotent adult progenitor cells have been identified there. Several studies suggested that the potential of some types of adult stem cells is greater than expected since they have shown their capacity to differentiate into cells of various lineages under certain conditions, which means that their potential is very close to that of the embryonic cells. This has given rise to new prospects for the treatment of a number of diseases with adult stem cells that it was thought to be possible only with the embryonic cells
Insulin-Producing Cells Derived from Human Embryonic Stem Cells: Comparison of Definitive Endoderm- and Nestin-Positive Progenitor-Based Differentiation Strategies  [PDF]
Rui Wei, Jin Yang, Wenfang Hou, Guoqiang Liu, Meijuan Gao, Lin Zhang, Haining Wang, Genhong Mao, Hongwei Gao, Guian Chen, Tianpei Hong
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072513
Abstract: Human embryonic stem cells (hESCs) are pluripotent and capable of undergoing multilineage differentiation into highly specialized cells including pancreatic islet cells. Thus, they represent a novel alternative source for targeted therapies and regenerative medicine for diabetes. Significant progress has been made in differentiating hESCs toward pancreatic lineages. One approach is based on the similarities of pancreatic β cell and neuroepithelial development. Nestin-positive cells are selected as pancreatic β cell precursors and further differentiated to secrete insulin. The other approach is based on our knowledge of developmental biology in which the differentiation protocol sequentially reproduces the individual steps that are known in normal β cell ontogenesis during fetal pancreatic development. In the present study, the hESC cell line PKU1.1 was induced to differentiate into insulin-producing cells (IPCs) using both protocols. The differentiation process was dynamically investigated and the similarities and differences between both strategies were explored. Our results show that IPCs can be successfully induced with both differentiation strategies. The resulting IPCs from both protocols shared many similar features with pancreatic islet cells, but not mature, functional β cells. However, these differently-derived IPC cell types displayed specific morphologies and different expression levels of pancreatic islet development-related markers. These data not only broaden our outlook on hESC differentiation into IPCs, but also extend the full potential of these processes for regenerative medicine in diabetes.
The Role of H1 Linker Histone Subtypes in Preserving the Fidelity of Elaboration of Mesendodermal and Neuroectodermal Lineages during Embryonic Development  [PDF]
Giang D. Nguyen, Solen Gokhan, Aldrin E. Molero, Seung-Min Yang, Byung-Ju Kim, Arthur I. Skoultchi, Mark F. Mehler
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096858
Abstract: H1 linker histone proteins are essential for the structural and functional integrity of chromatin and for the fidelity of additional epigenetic modifications. Deletion of H1c, H1d and H1e in mice leads to embryonic lethality by mid-gestation with a broad spectrum of developmental alterations. To elucidate the cellular and molecular mechanisms underlying H1 linker histone developmental functions, we analyzed embryonic stem cells (ESCs) depleted of H1c, H1d and H1e subtypes (H1-KO ESCs) by utilizing established ESC differentiation paradigms. Our study revealed that although H1-KO ESCs continued to express core pluripotency genes and the embryonic stem cell markers, alkaline phosphatase and SSEA1, they exhibited enhanced cell death during embryoid body formation and during specification of mesendoderm and neuroectoderm. In addition, we demonstrated deregulation in the developmental programs of cardiomyocyte, hepatic and pancreatic lineage elaboration. Moreover, ectopic neurogenesis and cardiomyogenesis occurred during endoderm-derived pancreatic but not hepatic differentiation. Furthermore, neural differentiation paradigms revealed selective impairments in the specification and maturation of glutamatergic and dopaminergic neurons with accelerated maturation of glial lineages. These impairments were associated with deregulation in the expression profiles of pro-neural genes in dorsal and ventral forebrain-derived neural stem cell species. Taken together, these experimental observations suggest that H1 linker histone proteins are critical for the specification, maturation and fidelity of organ-specific cellular lineages derived from the three cardinal germ layers.
Epicardial Lineages and Cardiac Repair  [PDF]
Manvendra K. Singh,Jonathan A. Epstein
Journal of Developmental Biology , 2013, DOI: 10.3390/jdb1020141
Abstract: The death of cardiac myocytes resulting from myocardial infarction is a major cause of heart failure worldwide. Effective therapies for regenerating lost cardiac myocytes are lacking. Recently, the epicardium has been implicated as a source of inflammatory cytokines, growth factors and progenitor cells that modulate the response to myocardial injury. During embryonic development, epicardially-derived cells have the potential to differentiate into multiple cardiac lineages, including fibroblasts, vascular smooth muscle and potentially other cell types. In the healthy adult heart, epicardial cells are thought to be generally quiescent. However, injury of the adult heart results in reactivation of a developmental gene program in the epicardium, which leads to increased epicardial cell proliferation and differentiation of epicardium-derived cells (EPDCs) into various cardiac lineages. Recent work suggests that epicardial reactivation after injury is accompanied by, and contributes to, a robust inflammatory response. In this review, we describe the current status of research related to epicardial biology in cardiac development and regeneration, highlighting important recent discoveries and ongoing controversies.
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