<p>ELECTROPORATION ACTION:</p>

Courtesy of James Rae, The Mayo Clinic, Rochester, Minn.

At left, two α-Tn4 cells in the process of completing cell division. Each contains the protein products encoded by ECFP-vimentin and dsRed1-mito plasmids electroporated into one of the cells on consecutive days. At right, an example of successful serial single-cell electroporation on three consecutive days. The plasmids used: dsRed1-mito on day one, EYFP-Golgi on day two, and ECFP-vimentin on day three.

To date, electroporation has largely been a brute-force way to deliver molecules such as DNA, RNA, and drugs into cells. The application of a voltage pulse creates in the cell membrane small, resealable pores whose size varies based on the amplitude and duration of the pulses. Whereas traditional electroporation devices permit only bulk intracellular delivery of molecules, companies are now introducing more sophisticated methods that allow users to manipulate individual cells and even to target specific regions of...

ELECTROPORATION ARRAYS

San Francisco-based Excellin Life Sciences http://www.excellin.com has developed an array-based electroporation device for high-throughput single-cell transfection. Excellin's CellArray™ chip is an electrode-containing silicon chip composed of two chambers separated by a dielectric membrane. The membrane contains a hole in which a single cell can be seated; electrical current passing through the membrane passes only through the cell, inducing electroporation.3

Laura Mazzola, CEO, says that this method works well for high-throughput electroporation of single cells, whereas instruments such as the Axoporator are applied to one cell at a time. "Our technology provides single-cell addressability, but in a high-throughput format. You can plate out, let's say, five to 500 cells at a time, and our electroporation process addresses every cell simultaneously," she says. Mazzola explains that the process is extremely gentle compared to traditional methods, applying only millivolts of electrical field to each cell; it can also be used to probe cell viability. The system continuously detects electrical resistance across cell membranes and can be used to monitor cell health in real time. "It's actually tunable to the cell membrane itself in that we test for viability before, during, and after electroporation. At the single cell level, we can guarantee 100% delivery and cell viability," she says.

According to Mazzola, the CellPort™, a high-volume version of the Excellin system capable of electroporating millions of cells simultaneously, is currently in beta testing; she expects the CellArray system to be released within the next year. Additionally, Cellectricon is currently developing a capillary electroporation array with the technical features of the Axoporator and the throughput of Excellin's instrument.

- Aileen Constans

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