SCIENCE: 13. 9. 2013

SCIENCE: Cells reprogrammed in living mice

"Researchers have discovered a surprisingly effective way to “reprogram” mature mouse cells into an embryolike state, able to become any of the body’s cell types. Their recipe: Let the transformation happen in a living animal instead of a petri dish. The finding could help scientists better understand how reprogramming works and it may one day help breed replacement tissues or organs in the lab—or in patients. In culture dishes, ramping up the expression of just four genes can turn skin and other cells into so-called induced pluripotent stem (iPS) cells. Pluripotent cells can become any of the cell types usually found in the body—although there are certain special types of tissue, such as placenta, that they can't form. (Stem cells extracted from embryos, called embryonic stem [ES] cells, are also pluripotent.). Many scientists had assumed, however, that the cellular environment in living tissues would interfere with the reprogramming process, especially because natural development is usually a one-way street, from stem cells to differentiated and mature tissue cells. “The assumption is that everything in our body is promoting differentiation,” says Manuel Serrano of the Spanish National Cancer Research Center in Madrid. (...)"

http://news.sciencemag.org/biology/2013/09/cells-reprogrammed-living-mice

STEM CELL REPORTS: Transcriptome analysis identifies regulators of hematopoietic stem and progenitor cells

"Hematopoietic stem cells (HSCs) maintain blood homeostasis and are the functional units of bone marrow transplantation. To improve the molecular understanding of HSCs and their proximal progenitors, we performed transcriptome analysis within the context of the ImmGen Consortium data set. Gene sets that define steady-state and mobilized HSCs, as well as hematopoietic stem and progenitor cells (HSPCs), were determined. Genes involved in transcriptional regulation, including a group of putative transcriptional repressors, were identified in multipotent progenitors and HSCs. Proximal promoter analyses combined with ImmGen module analysis identified candidate regulators of HSCs. Enforced expression of one predicted regulator, Hlf, in diverse HSPC subsets led to extensive self-renewal activity ex vivo. These analyses reveal unique insights into the mechanisms that control the core properties of HSPCs. (...)"

http://www.cell.com/stem-cell-reports/abstract/S2213-6711(13)00053-2