Casanova's notion is that stem cells emerge not because of the presence of factors that confer capacity to the stem cell but because of factors that repress the cellular signals for differentiation and specialization. Casanova believes that somehow all non-differentiated cells intrinsically carry the qualities of the stem cell by default and that there are factors at work that remove these capacities. Said another way: a stem cell is a stem cell because it has evaded differentiation. According to Casanova, if the idea of "a stem cell by default" is considered, research should focus not on what a cell requires to become a stem cell but what it must escape from.
To support his notion, Jordi Casanova analyzes from this new perspective the properties and characteristics currently known about stem cells and tests whether they generally fit the hypothesis. The author of this article hopes that this new angle stimulates research in the international scientific community working on stem cells and cell differentiation in order to confirm or reject the hypothesis. The generation of new knowledge in this field is of enormous interest given the potential of therapeutic applications based on stem cells.
EMBO reports advance online publication 10 April 2012; doi:10.1038/embor.2012.47
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