New Technology Combines, Fuses Cells for Stem Cell Research

Engineers have developed a new, highly effective way to pair up cells so they can be fused together into a hybrid cell.

The new technique should make it much easier for scientists to study what happens when two cells are combined. For example, fusing an adult cell and an embryonic stem cell allows researchers to study the genetic reprogramming that occurs in such hybrids.

The Massachusetts Institute of Technology (MIT; Cambridge, MA, USA) researchers, led by a collaboration between Dr. Joel Voldman, associate professor of electrical engineering and computer science, and Dr. Rudolf Jaenisch, professor of biology and a member of the Whitehead Institute (Cambridge, MA, USA), reported on the new technique in the January 4, 209, online edition of the journal Nature Methods.

The MIT team's simple but inventive sorting method increases the rate of successful cell fusion from around 10% to roughly 50%, and allows thousands of cell pairings at once. Although cell fusion techniques have been around for a long time, there are many technical limitations, according to Dr. Voldman.

Getting the correct cells to pair up before fusing them is one key hurdle. If scientists are working with a mixture of two cell types, for example A and B, they end up with many AA and BB pairings, as well as the desired AB match. Researchers had earlier trapped cells in tiny cups as they flow across a chip. Each cup can hold only two cells, but there is no way to control whether the cups capture an A and a B, two As or two Bs.

In contrast, the cell-trapping cups on the new sorting device are arranged strategically to capture and pair up cells of different types. First, type A cells are flowed across the chip in one direction and caught in traps that are large enough to hold only one cell. Once the cells are trapped, liquid is flowed across the chip in the opposite direction, pushing the cells out of the small cups and into larger cups across from the small ones. Once one A cell is in each large cup, type B cells are flowed into the large cups. Each cup can only hold two cells, so each ends up with one A and one B. After the cells are paired in the traps, they can be joined together by an electric pulse that fuses the cell membranes.

In addition to helping with studies of stem cell reprogramming, this technique could be used to examine interactions between any types of cells. "It's a very general type of device,” said Dr. Voldman.

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