Our understanding of how mesodermal tissue is formed, has been limited by the absence of specific and reliable markers of early mesoderm commitment. We report that mesoderm commitment from human embryonic stem cells (hESC) is initiated by Epithelial to Mesenchymal transition (EMT) as shown by gene expression profiling and by reciprocal changes in expression of the cell surface proteins, EpCAM/CD326 and NCAM/CD56. Molecular and functional assays reveal that CD326negCD56+ cells, generated from hESC in the presence of activin A, BMP4, VEGF and FGF2, represent a novel, multi-potent mesoderm-committed progenitor population. CD326negCD56+ progenitors are unique in their ability to generate all mesodermal lineages including hematopoietic, endothelial, mesenchymal (bone, cartilage, fat, fibroblast), smooth muscle and cardiomyocytes, while lacking the pluripotency of hESC. CD326negCD56+ cells are the precursors of previously reported, more lineage-restricted mesodermal progenitors. These findings present a novel approach to study how germ layer specification is regulated, and offer a unique target for tissue engineering.
Mapping the first stages of mesoderm commitment during differentiation of human embryonic stem cells.
Cell line
View SamplesJoint injury and osteoarthritis affect millions of people worldwide, but attempts to generate articular cartilage using adult stem/progenitor cells have been unsuccessful. We hypothesized that recapitulation of the human developmental chondrogenic program using pluripotent stem cells (PSCs) may represent a superior approach for cartilage restoration. Using laser capture microdissection followed by microarray analysis, we first defined a surface phenotype (CD146low/negCD166low/negCD73+CD44lowBMPR1B+) distinguishing the earliest cartilage committed cells (pre-chondrocytes) at 5-6 weeks of development; pellet assays confirmed these cells as functional, chondrocyte-restricted progenitors. Flow cytometry, qPCR and immunohistochemistry at 17 weeks revealed that the superficial layer of peri-articular chondrocytes was enriched in cells with this surface phenotype. Isolation of cells with a similar immunophenotype from differentiating human PSCs revealed a population of CD166negBMPR1B+ putative pre-chondrocytes. Functional characterization confirmed these cells as cartilage-committed, chondrocyte progenitors. The identification of a specific molecular signature for primary cartilagecommitted progenitors may provide essential knowledge for the generation of purified, clinically relevant cartilage cells from PSCs.
Human developmental chondrogenesis as a basis for engineering chondrocytes from pluripotent stem cells.
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View SamplesHuman cell line HCT116 incubated with Myxothiazol for 5 or 17 hours
A sustained deficiency of mitochondrial respiratory complex III induces an apoptotic cell death through the p53-mediated inhibition of pro-survival activities of the activating transcription factor 4.
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