72 research outputs found
Les cellules souches embryonnaires : Du développement myocardique à la médecine régénératrice
Les cellules souches embryonnaires (ES) pluripotentes offrent un modĂšle de dĂ©veloppement prĂ©coce du myocarde et apportent de nouveaux espoirs de thĂ©rapie cellulaire des maladies dĂ©gĂ©nĂ©ratives. Les potentialitĂ©s cardiogĂ©niques des cellules ES permettent une recherche cognitive sur les rĂ©seaux transcriptionnels activĂ©s par les morphogĂšnes et qui gouvernent la diffĂ©renciation cellulaire cardiaque. Bien que les cellules ES humaines soient, comme les cellules de souris, isolĂ©es Ă partir du stade blastocyste de lâembryon, des diffĂ©rences dans le dĂ©veloppement embryonnaire des deux espĂšces entraĂźnent des phĂ©notypes cellulaires et des propriĂ©tĂ©s spĂ©cifiques Ă chaque espĂšce. Les enjeux actuels sont donc de comprendre les mĂ©canismes molĂ©culaires des processus de spĂ©cification et de diffĂ©renciation cardiaque des cellules ES humaines afin dâaccroĂźtre leur potentiel cardiogĂ©nique. Ce but atteint, ces cellules permettront lâĂ©tude du dĂ©veloppement cardiaque prĂ©coce, nĂ©cessaire Ă une meilleure comprĂ©hension des maladies cardiaques congĂ©nitales et ouvriront les perspectives de thĂ©rapie rĂ©gĂ©nĂ©ratrice du myocarde.Embryonic stem cells are capable to recapitulate the first stages of myocardial development. Using mouse embryonic stem cells, transcriptional networks specifying the cardiac fate can be delineated. Furthermore, using members of the TGFÎČ superfamily to commit mouse ES cells toward a cardiac lineage, recent studies showed that ESC-derived cardiomyocytes were capable to repair post-infarcted myocardium of small and large animals. The next challenges are to validate such results using human ESCs in order to better comprehend cardiac congenital diseases and to foresee a cell therapy of heart failure
"I6 passages: on the reproduction of a human embryonic stem cell line from Israel to France".
The first French clinical trial using human embryonic stem cells for regenerative purposes was launched in 2014, using the I6 stem cell line that was imported from Israel. From Israel to France, national reproductive policies and practices inform how basic scientists produce, manage and circulate cells across countries. Building on an interdisciplinary co-production involving two social scientists and a life scientist, this article suggests that biobanks passage cells from in vitro fertilization to stem cell science and from country to country by modifying their reproductive meaning. Four passages are described: the absence of cells in 2005 when the research started in France; the presence of supernumerary embryos available for research in Israeli IVF biobanks; the production of the I6 stem cell bank in Israel; the importation and laboratory biobanking of the cells in France. Human embryonic stem cell lines can never be completely disentangled from reproduction.Wellcome Trust Grant no. 100606
H2020 Marie SkĆodowska-Curie Actions
Fondation Fysse
Calreticulin reveals a critical Ca2+ checkpoint in cardiac myofibrillogenesis
Calreticulin (crt) is an ubiquitously expressed and multifunctional Ca2+-binding protein that regulates diverse vital cell functions, including Ca2+ storage in the ER and protein folding. Calreticulin deficiency in mice is lethal in utero due to defects in heart development and function. Herein, we used crtâ/â embryonic stem (ES) cells differentiated in vitro into cardiac cells to investigate the molecular mechanisms underlying heart failure of knockout embryos. After 8 d of differentiation, beating areas were prominent in ES-derived wild-type (wt) embryoid bodies (EBs), but not in ES-derived crtâ/â EBs, despite normal expression levels of cardiac transcription factors. Crtâ/â EBs exhibited a severe decrease in expression and a lack of phosphorylation of ventricular myosin light chain 2 (MLC2v), resulting in an impaired organization of myofibrils. Crtâ/â phenotype could be recreated in wt cells by chelating extracellular or cytoplasmic Ca2+ with EGTA or BAPTA, or by inhibiting Ca2+/calmodulin-dependent kinases (CaMKs). An imposed ionomycin-triggered cystolic-free Ca2+ concentration ([Ca2+]c) elevation restored the expression, phosphorylation, and insertion of MLC2v into sarcomeric structures and in turn the myofibrillogenesis. The transcription factor myocyte enhancer factor C2 failed to accumulate into nuclei of crtâ/â cardiac cells in the absence of ionomycin-triggered [Ca2+]c increase. We conclude that the absence of calreticulin interferes with myofibril formation. Most importantly, calreticulin deficiency revealed the importance of a Ca2+-dependent checkpoint critical for early events during cardiac myofibrillogenesis
Interplay of Oct4 with Sox2 and Sox17: a molecular switch from stem cell pluripotency to specifying a cardiac fate
Embryonic stem cell pluripotency, once achieved, triggers a switch in promoter affinity for Oct4, which leads to cardiogenesis
Human pre-valvular endocardial cells derived from pluripotent stem cells recapitulate cardiac pathophysiological valvulogenesis
Genetically modified mice have advanced our understanding of valve development and disease. Yet, human pathophysiological valvulogenesis remains poorly understood. Here we report that, by combining single cell sequencing and in vivo approaches, a population of human pre-valvular endocardial cells (HPVCs) can be derived from pluripotent stem cells. HPVCs express gene patterns conforming to the E9.0 mouse atrio-ventricular canal (AVC) endocardium signature. HPVCs treated with BMP2, cultured on mouse AVC cushions, or transplanted into the AVC of embryonic mouse hearts, undergo endothelial-to-mesenchymal transition and express markers of valve interstitial cells of different valvular layers, demonstrating cell specificity. Extending this model to patient-specific induced pluripotent stem cells recapitulates features of mitral valve prolapse and identified dysregulation of the SHH pathway. Concurrently increased ECM secretion can be rescued by SHH inhibition, thus providing a putative therapeutic target. In summary, we report a human cell model of valvulogenesis that faithfully recapitulates valve disease in a dish.We thank the Leducq Fondation for supporting Tui Neri, and funding this research under the framework of the MITRAL network and for generously awarding us for the equipment of our cell imaging facility in the frame of their program âEquipement de Recherche et Plateformes Technologiquesâ (ERPT to M.P.), the Genopole at Evry and the Fondation de la recherche Medicale (grant DEQ20100318280) for supporting the laboratory of Michel Puceat. Part of this work in South Carolina University was conducted in a facility constructed with support from the National Institutes of Health, Grant Number C06 RR018823 from the Extramural Research Facilities Program of the National Center for Research Resources. Other funding sources: National Heart Lung and Blood Institute: RO1-HL33756 (R.R.M.), COBRE P20RR016434â07 (R.R.M., R.A. N.), P20RR016434â09S1 (R.R.M. and R.A.N.); American Heart Association: 11SDG5270006 (R.A.N.); National Science Foundation: EPS-0902795 (R.R.M. and R.A. N.); American Heart Association: 10SDG2630130 (A.C.Z.), NIH: P01HD032573 (A.C. Z.), NIH: U54 HL108460 (A.C.Z), NCATS: UL1TR000100 (A.C.Z.); EH was supported by a fellowship of the Ministere de la recherche et de lâĂ©ducation in France.TM-M was supported by a fellowship from the Fondation Foulon Delalande and the Leducq Foundation. P.v.V. was sponsored by a UC San Diego Cardiovascular Scholarship Award and a Postdoctoral Fellowship from the California Institute for Regenerative Medicine (CIRM) Interdisciplinary Stem Cell Training Program II. S.M.E. was funded by a grant from the National Heart, Lung, and Blood Institute (HL-117649). A.T. is supported by the National Heart, Lung, and Blood Institute (R01-HL134664).S
Cellules souches pluripotentes : un modÚle cellulaire de développement cardiaque précoce
Les cellules souches embryonnaires murines dérivées
il y a trois décennies ont permis la transgenÚse et la génération
de souris gĂ©nĂ©tiquement modifiĂ©es. Ces animaux et dâautres organismes
plus primitifs, dans le passĂ© comme encore aujourdâhui, ont permis lâĂ©tude
des premiĂšres dĂ©cisions cellulaires dans lâembryon. La dĂ©rivation
de lignées de cellules souches embryonnaires humaines a apporté
un modĂšle de dĂ©veloppement dans un contexte oĂč lâĂ©thique nâautorise
pas lâutilisation dâembryon. Il est alors devenu possible dâĂ©tudier
les mécanismes génétiques et épigénétiques de ces décisions cellulaires
humaines. Cette synthĂšse prend lâexemple de la cardiogĂ©nĂšse, un
des premiers Ă©vĂšnements cellulaires au cours de lâembryogenĂšse et
montre lâapport des cellules souches dans la biologie du dĂ©veloppement
cardiaque humain
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