© BRYAN SATALINO
Stem cells require just the right sort of coddling to stay in their pure pluripotent, dividing state. In the lab, the nanny role is often taken on by mouse embryonic fibroblasts (MEFs), lining the culture dish as a “feeder layer.” However, these feeders have their downsides, so scientists are developing other options.
Exactly what makes MEFs or other feeder lines good nannies is a bit uncertain. They seem to offer stem cells two main supports: one is a cozy surface to lie down on, with other cells to contact and the extracellular matrix (ECM) the fibroblast feeders produce; the second consists of growth factors and other molecules secreted by the feeders into the cell-culture medium.
However, feeders also create complications, forcing scientists to culture not ...
