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STEM CELLS FOR THE CURIOUS
Stanimir Vuk-Pavlović, College of Medicine, Mayo Clinic, Rochester, United States
20 - 22 September 2012, Opatija, Croatia
Recent evidence for induction of stem cell characteristics in somatic cells by epithelial–mesenchymal transition,
by induced activation of a small number of transcription factors, or by modification of microenvironment has
invalidated the once held notion of differentiation as a strictly unidirectional deterministic process. Together with
the broad interest elicited by current clinical trials testing different cellular preparations dubbed “stem cells,” this
necessitates reconsideration of the very definition of the stem cell. As a result, the focus has shifted from consideration
of “stem cells” as a class of cells to “stemness” as a property that can be acquired, conferred and/or retained
by cells. What is stemness that allows a cell (population) to divide, maintain the size of its pool and differentiatiate
at the same time? How is it defined, induced, maintained? A recent view posits “stemness as a cell default state”
(cf. Casanova, EMBO Reports, 13: 396, 2012). It is based on experimental evidence compatible with a deterministic
model of stemness maintained as long as maintained is the intrinsic/inherent inhibition to differentiation. Another
model invokes stochastic gene and protein expression that drives transitions among deterministic attractors
characterizing stemness and the possible differentiation states (MacArthur et al., Nature Rev. Mol. Cell Biol. 10: 672,
2012). As a further development, one can interrogate the factors that define all levels of cell differentiation (i.e.,
attractors) as properties emergent within complex biological systems.
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