A way to live with liver disease?
Patients waiting for liver transplants could be given a greater chance of survival by a new liver support system, which has been developed and is now being tested by a European research team. The 'modular extracorporeal liver system' (MELS) is designed to help patients with acute liver failure get through their wait for an organ transplant. 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 (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 it is allowed to pass into the bioreactor. As it flows 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 UK are involved in the work, which the European Commission has funded since 1998. Each country has treated different groups of patients to test the bioreactor's efficacy and every case (11 patients have been treated so far) has proved successful. 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. But 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's 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 can regenerate in two ways, he says: either by increasing in number or growing bigger. 'So if a tumour is removed leaving a patient with just 30 per cent of their liver, a bioreactor could help the liver along as it grows back to its original size.' Other research teams are developing similar technologies, but the MELS team say theirs is superior because, rather than using non-human liver cells, it is one of the group to use hepatic cells from humans. 'Also, others use conventional filters for plasma separation which are not specifically designed for this task,' says 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 they 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's a long way to go - in terms of research and the law.'
Kraje
France