Cellule souche embryonnaire

Une cellule souche embryonnaire (CSE) est une cellule souche pluripotente issue de la masse cellulaire interne ou de l'épiblaste d’un embryon préimplantatoire au stade de blastocyste. Un embryon humain atteint le stade de blastocyste 4 à 5 jours après la fécondation et consiste en un amas de 50 à 150 cellules (masse cellulaire interne et trophectoderme). L'isolation de la masse cellulaire interne requiert de détruire le blastocyste. Les cellules souches embryonnaires sont une source quasi parfaite pour les greffes et l'ingénierie tissulaire. La capacité d'une cellule souche à générer l'ensemble des cellules du corps en fait un outil clé pour la recherche sur les maladies humaines, notamment génétique, ou pour tester in vitro la toxicologie de médicaments. Cependant, l'isolation de cellules souches embryonnaires pose un questionnement éthique qui nécessite notamment d'établir si un embryon au stade préimplantatoire possède les mêmes droits légaux et moraux qu'un être humain plus dév

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Cellule souche

vignette|Cellules souches embryonnaires de souris en culture. En biologie cellulaire, une cellule souche est une cellule indifférenciée capable, à la fois, de générer des cellules spécialisées par di

Cell potency

Cell potency is a cell's ability to differentiate into other cell types. The more cell types a cell can differentiate into, the greater its potency. Potency is also described as the gene activation po

Différenciation cellulaire

La différenciation cellulaire est un concept de biologie du développement décrivant le processus par lequel les cellules se spécialisent en un « type » cellulaire avec une structure et une compositi

BIO-447: Stem cells and organoids

This course introduces the fundamentals of stem cell biology, with a particular focus on the role of stem cells during development, tissue homeostasis/regeneration and disease, and the generation of organoids from stem cells

BIOENG-449: Tissue engineering

Tissue engineering is an interdisciplinary field that broadly impacts human health. This course provides students an overview of how engineering approaches can be used to investigate and manipulate cell and tissue functions and enable students to be on the cutting edge of tissue engineering.

BIO-221: Cell and developmental biology for engineers

Students will learn essentials of cell and developmental biology, with an emphasis on animal model systems and quantitative approaches.

Differentiation of human embryonic stem cells to hepatocytes

Noam Beckmann

Many liver diseases involve hepatocyte malfunction. In most cases, transplantation of corrected hepatocytes would correct for disease symptoms. Liver donor shortage and hepatocyte inability to proliferate in vitro accentuate this problem. Embryonic stem and induced pluripotent stem cells proliferate indefinitely and have the capacity to differentiate into every cell type of the body. They could thus represent a solution to this organ donor shortage. In this project, we aim to differentiate ES and iPS cells to hepatocytes. First, we consider an approach to select the ES/iPS cell line showing the best potential to generate liver lineage using teratomas as a selection tool. Then we use lentiviral vectors to transduce this selected cell line with essential liver-‐specific development factors to help differentiation efficiency. Next, we developed an in vitro differentiation protocol based on existing protocols and developmental clues of liver development to generate a pool of hepatocyte precursors. Later on, we injected these differentiated cells in mice liver of Fah-‐, Rag2-‐ and Il-‐2rγ-‐deficient mice to check for engraftment and liver marker expression. Our findings show, after checking for hepatocyte-‐ specific markers in the differentiated cells, that our previous selection for the potentially best cell line seems correct. We also find that the transcription factors involved in liver development appear to have a negative effect in vitro on liver differentiation. Applying our protocol to regular ES cells results on the production of late maturity hepatocyte markers, showing correct differentiation and maturation of newly formed hepatocytes. Finally, mouse in vivo liver transplantation of these differentiated cells gives us human albumin expression detectable in blood serum of said mice

2010

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A satellite DNA array barcodes chromosome 7 and regulates totipotency via ZFP819

Gabriela Ecco, Helen Mary Rowe, Didier Trono

Mammalian genomes are a battleground for genetic conflict between repetitive elements and KRAB-zinc finger proteins (KZFPs). We asked whether KZFPs can regulate cell fate by using ZFP819, which targets a satellite DNA array, ZP3AR. ZP3AR coats megabase regions of chromosome 7 encompassing genes encoding ZSCAN4, a master transcription factor of totipotency. Depleting ZFP819 in mouse embryonic stem cells (mESCs) causes them to transition to a 2-cell (2C)–like state, whereby the ZP3AR array switches from a poised to an active enhancer state. This is accompanied by a global erosion of heterochromatin roadblocks, which we link to decreased SETDB1 stability. These events result in transcription of active LINE-1 elements and impaired differentiation. In summary, ZFP819 and TRIM28 partner up to close chromatin across Zscan4, to promote exit from totipotency. We propose that satellite DNAs may control developmental fate transitions by barcoding and switching off master transcription factor genes.

2022

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MMP-sensitive Hydrogels for Induction of Embryonic Stem Cell Differentiation

Céline Gandar

During embryonic development, the extracellular matrix plays a critical role in regulating the differentiation of embryonic stem cells into specific cell lineages. MMP-sensitive PEG hydrogel is a material that has the ability to be degraded by the cells themselves upon secretion of proteases called MMPs. This synthetic material presents a great potential for mimicking the extracellular matrix due to the numerous bio-active peptides that can be incorporated. The suitability of this gel with mouse embryonic stem cells (ESCs) was studied for the first time in this project and its ability of supporting angiogenesis from embryoid bodies (EBs) was investigated. I encapsulated EBs in MMP-sensitive gel containing RGD and/or Wnt5a peptide and showed that sprouting activity could occurred after 14 days culture in a specific media. Even though the nature of the sprouting cells could not be totally determined, a percentage of them was shown to express the endothelial marker CD31. I also demonstrated the positive effect of RGD on the viability of EBs by analyzing their morphology as well as monitoring the cell proliferation over time. In addition to RGD, Wnt5a-derived peptide was incorporated in the gel to investigate its ability to not only support but also to enhance angiogenic activity. Indeed, in previous studies, this protein was reported as a factor increasing motility and invasion of ESCs-derived endothelial cells. However, due to high variations in EBs responses, the effect of Wnt5a could not be emphasized. Even though those results need to be repeated and further experiments are required to answer many new questions, they point to promising prospects for tissue engineering in terms of designing synthetic material that can encapsulate stem cells and promote desired differentiation thanks to specific incorporated ligands

2009

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