Stem cell hope for liver damage

A clinical trial using bone marrow stem cells to treat irreversible liver damage has started in Japan, New Scientist magazine reports. Scientists at Yamaguchi University began the trial after showing that bone marrow stem cell transplants can partly reverse serious liver damage in mice. A similar trial using bone marrow stem cells to treat cirrhosis of the liver is about to begin at the Hammersmith Hospital in London, according to BBC News Online.

Currently, the only treatment for permanent liver damage is a transplant operation, but there is a severe shortage of available organs. Recent research suggests that bone marrow stem cells, which normally make different types of blood cell, can also turn into other types of body cell - including liver cells. This means it could be possible to treat liver damage using a patient's own bone marrow, avoiding the need for a transplant and also the problem of tissue rejection by the body.

In their mouse experiments, the Japanese team first damaged the animals' livers by injecting them with carbon tetrachloride, triggering liver fibrosis. This condition, in which patches of dead and dying tissue appear in the liver, eventually develops into cirrhosis. After four weeks, the scientists injected bone marrow cells tagged with a fluorescent marker, into the tail veins of half the mice. The proportion of fibrous liver tissue in the treated mice fell from around 5.4 per cent in the fifth week to less than 4.2 per cent three weeks later. There was no change in the amount of fibrous tissue in the untreated mice, which were injected with a salt solution.

'Our results showed that even if chronic liver injury exists, transplantation of bone marrow cells can reverse this', said team leader Isao Sakaida. However, he said that it was 'too soon' to know if people in the trial were responding to the treatment.

At the Hammersmith Hospital, a team lead by Nagy Habib is planning to use stem cells isolated from their patients' own blood to treat cirrhosis. In the UK, around 239 people are currently waiting for a liver transplant. 'If this research is successful, it would be a very good option for those people', said Habib.

Using bone marrow stem cells to heal damaged or diseased tissues is a poorly understood approach at present. Some scientists claim that bone marrow cells can only produce blood cells, and that in other body tissues they fuse with existing cells, rather than forming new cells. Other researchers think that cell fusion may be peculiar to the liver, and that bone marrow cells can produce genuine new muscle and heart cells. In a previous US study using bone marrow cells to treat liver damage, the authors concluded that 'bone marrow derived cells cannot generally lead to a cure of liver damage. The group published their findings in the Proceedings of the National Academy of Sciences last year.