The goal of researchers in the lab of Joel Voldman, PhD, is to physically manipulate cells in order to organize their interactions.  Part of this mission is to create devices capable of isolating cells based on non-traditional phenotypes, such as how cells look under a microscope.  It is currently very difficult to sort cells once they have been imaged.  Strategies involving lasers have been investigated, but until now, these strategies have not proven to be very practical.  Optical “tweezers,” which use multiple laser beams to move particles in three dimensions, can be used to trap and move cells, but this technology is expensive and difficult to use.  Searching for a cheaper and quicker alternative, researchers in Voldman’s lab have created a system that uses an optical “fire hose” instead of “tweezers.”  Cells are placed in wells on a plate, one cell per well, and fluid flows laterally across the tops of the wells.  The plate is viewed under a microscope, and desired cells are pushed upward by a laser, the optical “fire hose.”  Once out of its well, a cell is swept into a collection area by the laterally flowing fluid.  In this manner, cells can be sorted based on any phenotype that is visible under a microscope.  Methods of sorting cells according to their electrical properties are also being investigated.   

In addition to sorting cells, researchers in the Voldman lab are seeking ways to physically control intercellular interactions, particularly those involved in cell reprogramming, the process through which a differentiated cell regains its pluripotency.  Fusing an undifferentiated stem cell with a differentiated cell can accomplish this reprogramming, but studying this fusion is tricky because it occurs relatively quickly, before fusing cells can be separated from other cells.  To get around this problem, researchers have come up with a microfluidic device that uses microscopic “cups” to capture individual cells and to then fuse them with other cells.  Their device is a good example of how microfluidic technology can be used to control the movement of individual cells.

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