In concept, it is similar to a kidney dialysis machine and its key component is an innovative "bioreactor". Between a network of thin hollow fibre membranes, human hepatocytes or liver cells are kept alive by a constant supply of oxygen and a "culture medium" to feed on. The cells can survive for up to two months in these conditions.
Patients' plasma is separated from their blood in a plasma separator before the plasma is allowed to pass into the bioreactor. As it is flowing over the capillary-like network of fibres, the liver cells function normally, drawing toxins out of the plasma, effectively cleaning and refreshing the patient's blood without actually mixing with it.
Four research centres in Germany, France, Spain, and the United Kingdom are involved in the work, which the European Commission has funded since 1998. Each country has treated different groups of patients in order to test the bioreactor's efficacy and every case has proved successful. So far, eleven patients have been treated. Ten patients had acute liver failure and one had chronic liver failure. All the patients were successfully transferred to liver transplantation.
The bioreactor seems attractive in terms of cost: a liver transplant with life-long treatment costs about 500.000 euro, whereas a bioreactor costs around 2500 euro. However, more trials will be necessary to convince the medical community and, importantly, health insurers that the patients' relatively good health is due to treatment with the bioreactor, according to Dimitrios Kardassis from the University of Berlin.
"We have to show that early treatment with a bioreactor is effectively lower than the cost of liver transplantation. Because if you treat patients early in acute liver failure there is a real chance for the liver to regenerate with the help of this machine."
In particular Dr. Kardassis believes the bioreactor could also provide support for patients who have tumours removed from their livers. Liver cells are able to regenerate in two ways, as he stated: either by increasing in number or by growing bigger. "So if a tumour is removed leaving a patient with just 30 percent of the liver, a bioreactor could help the liver along when it grows back to its original size."
Other research teams are developing similar technologies, but the partners claim that the MELS bioreactor is superior because, rather than using non-human liver cells, it is characteristic for the group to use hepatic cells from humans. "Also, others use conventional filters for plasma separation which are not specifically designed for this task", stated Dr. Kardassis. "But this bioreactor is the result of ten years research."
Currently the MELS team can treat an average of two patients a month, but now the partners have started to disseminate information about their work, they hope to generate interest from other transplant centres. In the future though, Dr. Kardassis and his colleagues believe that gene technology could provide an alternative for patients with liver diseases, which are caused by inherited genetic disorders.
"We could insert missing sections of DNA into patients' cells using a method called transfection and then allow them to multiply in the bioreactor, before being put in the patient. But there is still a long way to go in terms of research and legislation."