[Human embryonic stem cells: from the human embryo transgressed to the regenerative medicine of tomorrow].

Human embryonic stem cells (hESC) are derived from the inner cell mass (ICM) of the human blastocyst at day 5 or 6 of the early embryo development. These cells display two cardinal features: they are able to differentiate into cell types from many if not all human tissue (pluripotency) and they proliferate strongly and indefinitely without senescence in vitro. Therefore, hESC are a source of choice for stem cells for regenerative medicine and are a reference model to study the biology of pluripotency.

Stage specific over-expression of the dominant negative Ikaros 6 reveals distinct role of Ikaros throughout human B-cell differentiation.

Ikaros is a transcription factor that acts both as an activator and as an inhibitor of gene expression in several hematopoietic lineages. Ikaros functions in hematopoiesis have mostly been studied in mice, and are notably crucial for lymphopoiesis. Deregulation of Ikaros expression was evidenced in several leukemia subtypes, including pre-B-ALL.

[Ikaros and erythropoiesis].

Mostly studied in murine models, Ikaros--a factor that positively or negatively controls gene transcription--was first described as essential to lymphopoiesis until its involvement in numerous hematopoietic lineages was documented. Indeed, Ikaros is also active in murine erythropoiesis and more precisely during fetal to adult globin switching. Recently, these observations were confirmed by our team in a human context.

The role of Ikaros in human erythroid differentiation.

Ikaros--a factor that positively or negatively controls gene transcription--is active in murine adult erythroid cells, and involved in fetal to adult globin switching. Mice with Ikaros mutations have defects in erythropoiesis and anemia. In this paper, we have studied the role of Ikaros in human erythroid development for the first time.

Expression and recombination of the EGFP and EYFP genes in lentiviral vectors carrying two heterologous promoters.

Background: Expressing two genes in the progeny of stem and progenitor cells that are transduced with a unique viral vector is desirable in certain situations. We tested the ability of two lentiviral vectors to transduce human cells of hematopoietic origin and concomitantly express two reporter genes, either EGFP (enhanced green fluorescent protein) and DsRed2, or EGFP and EYFP (enhanced yellow fluorescent protein), from two internal promoters.

Methods: The vectors were generated from the pTRIP deltaU3 EF1alpha EGFP lentiviral vector.