The researchers used an electric field to pull stem cells through a fluid in a process called dielectrophoresis. They varied the frequency of the voltage used to generate the electric field and studied how the cells moved, a response that was affected by the cell's electrical properties.
The researchers found that differentiated stem cells could store a significantly greater charge on their outer membranes, a characteristic that might be used to effectively identify and separate them from undifferentiated cells. The researchers write that the wrinkling, folding, and thinning of a cell's membrane as it differentiates may explain why the later-stage cells can store more charge.
The sorting method may prove useful in separating cells for biomedical research or ultimately for treatments of diseases such as Parkinson's.