In directing stem cells, study shows context matters

Figuring out how blank slate stem cells decide which kind of cell they want to be when they grow up - a muscle cell, a bone cell, a neuron - has been no small task for science. Human pluripotent stem cells, the undifferentiated cells that have the potential to become any of the 220 types of cells in the body, are influenced in the lab dish by the cocktail of chemical factors and proteins upon which they are grown and nurtured. Depending on the combination of factors used in a culture, the cells can be coaxed to become specific types of cells. When blank slate stem cells are exposed to a soft rather than hard surface on which to grow, they begin to transform into neurons. Photo: Kiessling Lab Now, in a new study published today, Sept. 8, in the Proceedings of the National Academy of Sciences, a team of researchers from the University of Wisconsin-Madison has added a new wrinkle to the cell differentiation equation, showing that the stiffness of the surfaces on which stem cells are grown can exert a profound influence on cell fate. "To derive lineages, people use soluble growth factors to get the cells to differentiate," explains Laura Kiessling , a UW-Madison professor of chemistry and biochemistry and stem cell expert.