NATURE: 14. 11. 2013

NATURE: Dedifferentiation of committed epithelial cells into stem cells in vivo

"Cellular plasticity contributes to the regenerative capacity of plants, invertebrates, teleost fishes and amphibians. In vertebrates, differentiated cells are known to revert into replicating progenitors, but these cells do not persist as stable stem cells. Here we present evidence that differentiated airway epithelial cells can revert into stable and functional stem cells in vivo. After the ablation of airway stem cells, we observed a surprising increase in the proliferation of committed secretory cells. Subsequent lineage tracing demonstrated that the luminal secretory cells had dedifferentiated into basal stem cells. Dedifferentiated cells were morphologically indistinguishable from stem cells and they functioned as well as their endogenous counterparts in repairing epithelial injury. Single secretory cells clonally dedifferentiated into multipotent stem cells when they were cultured ex vivo without basal stem cells. By contrast, direct contact with a single basal stem cell was sufficient to prevent secretory cell dedifferentiation. In analogy to classical descriptions of amphibian nuclear reprogramming, the propensity of committed cells to dedifferentiate is inversely correlated to their state of maturity. This capacity of committed cells to dedifferentiate into stem cells may have a more general role in the regeneration of many tissues and in multiple disease states, notably cancer."

http://www.nature.com/nature/journal/v503/n7475/full/nature12777.html

 

NATURE: Stem cells: A time to heal

"The millions of nerve cells that compose the spinal cord form bundles that convey electrical signals between the brain and the rest of the body. A sudden blow can damage the vertebrae and bruise the spinal cord, killing neurons and the glial cells that support them and severing connections between nerves. Once the dead cells are cleared away by the immune system, a cavity remains. No signals can bridge this gap and the scar tissue that forms around it impedes the growth of new neurons. Inflammation can also spark further damage to the cord. “The highest hope for a stem-cell therapy would be that [it] could actually replace neurons that were lost,” Tansey says. (...)"

http://www.nature.com/nature/journal/v503/n7475_supp/full/503S4a.html