It's a unique and ingenious way of approaching the problem

Alfred Strachan Drug Delivery

Lee Russell, who runs Gendel, in Coleraine, Northern Ireland, the company behind the technology, said that in the past using the red blood cells to deliver drugs or enzymes had met with limited success.

"What could be better for delivering drugs than a patient's own cells?

"You can put things into red blood cells, but the limitation has always been how to get them out."

The technique exploits an effect discovered by Dr Tony McHale at the University of Ulster, in Coleraine.

Cancer drugs would be able to be sent round the blood

Dr McHale, a co-founder of Gendel, found that an electric field can "sensitise" red blood cells so that they burst open when exposed to ultrasound.

Now the company is developing an automated device which accepts around 20 millilitres of a patient's red cells.

The blood is then sensitised to ultrasound and loaded with a drug. Two or three hours later doctors take the treated blood, re-inject it, then release the drug by exposing the diseased tissue to ultrasound.

Testing technique

Depending on how long the ultrasound pulse is applied the drug could be released in bursts or all at once.

Gendel has already tested the technique in mice and pigs without any adverse effects.

Instead of using drugs, the red cells were loaded with proteins which were tagged with fluorescent labels, allowing the researchers to check that the cells released the drugs in to the right places.

Pigs were chosen because they have similar blood cells and circulatory system to humans.

Gendel hopes that it will eventually be able to use the system to treat cancer and cardiovascular diseases by loading the blood cells with agents such as antibodies, gene treatments and designer proteins.

Alfred Stracher, editor-in-chief of the journal Drug Delivery, said Gendel seemed to have solved the problems other researchers had experienced.

"This company seems to have a way of delivering it to a specific site, which would make it much more valuable.

"It's a unique and ingenious way of approaching the problem."

A spokesman for the Cancer Research Campaign said that scientists are moving towards targeting therapies which would spare healthy tissues and reduce side-effects.

"This technique is interesting as it works along these principals.

"However, it is early days as the technique is yet to be tested in humans. If it is effective in humans it should have much potential on improving the delivery of anticancer treatments."

The research is reported in New Scientist.