How the bio-artificial system works

Failure of the liver - a vital organ that performs a variety of tasks including filtering out toxins from the bloodstream - will lead other organs to fail, and an irreversible failure will result in death unless a transplant can be performed.

The bio-artificial liver system developed by United States firm Excorp uses pig liver cells inserted into a cartridge to perform the functions of the liver.

Blood is diverted from a vein in the patient's neck into the machine containing the cartridge, and then passes back into the body through the same point, according to Excorp Medical's chief executive, Dr Daniel Miller.

The device, which will undergo its final clinical tests in Hong Kong, works in a similar way to kidney dialysis.

But dialysis operates by filtration, whereas the bio-artificial liver works by metabolising harmful substances that accumulate in a patient's blood due to diminished liver capacity.

'The liver has remarkable regenerative powers on its own, given enough time,' Miller said.

A fibre membrane in the cartridge will prevent immune reactions between the human blood and pig liver cells. High blood flows are maintained and the therapeutic procedure is designed to last for 12 hours, to be conducted three times over the course of 10 days.

The product will initially be used in patients with severe liver failure, although it will not be useful in helping those suffering to the point of brain damage.

It may also be used in patients after transplants to aid their recovery, Miller said.

Excorp's technology has been patented in both the United States and Europe.