A microchip that allows controlled delivery of genetic material to cell cultures will be a major advance for the life sciences, say US bioengineers.

The chip, a microelectrode array developed by Tilak Jain and Jit Muthuswamy of the Arizona State University in Tempe, delivers electronic pulses to specific areas of a cell culture grown on top. The cell membranes in those areas become porous and the cells absorb any genetic material present in the surrounding medium.

Cells exposed to higher voltage pulses from the microchip (right) show higher uptakes of genetic material and show up green (left)

Delivering genetic material to cells, known as transfection, is an important process in understanding gene function and drug discovery. The transfected material is designed to either overexpress or silence genes in target cells and the effect of the change in gene activity on the cells is then studied.

Muthuswamy explained that a big advantage of his array is that multiple types of genetic material can be transfected sequentially and in different areas of the cell culture. In this way, combinations of overexpressed or silenced genes can be studied. Doing this in one culture is important: 'inter-culture variabilities are eliminated,' said Muthuswamy. 'Also, you can assess interactions between transfected cells and control cells.'

'This method is easier to use and quicker than previous methods,' Muthuswamy said. But, a drawback is that different RNAs or DNAs to be transfected would have to be sequentially applied to the cells and washed off again following transfection - a time-consuming process. To make the array more suitable for high-throughput studies, Muthuswamy plans to include a microfluidic system to deliver the genetic material to the cell culture.

Muthuswamy intends to use his technology in his own research area of brain injury. 'We can test the role of specific genes in repair of damaged neurons,' he said. He is currently taking the first step, applying his method to transfect neuron cells.

Danièle Gibney