Scientists in Japan today said they had grown human liver tissue from stem cells in a first that holds promise for alleviating the critical shortage of donor organs.
Creating lab-grown tissue to replenish organs damaged by accident or disease is a Holy Grail for the pioneering field of research into the premature cells known as stem cells.
Now Takanori Takebe of the Yokohama City University Graduate School of Medicine and team report in the journal Nature that they grew tissue "resembling the (human) adult liver" in a lab mouse.
"To our knowledge, this is the first report demonstrating the generation of a functional human organ from pluripotent stem (iPS) cells," said the report.
The technique has yet to be tested in humans, but serves as an important proof of concept, it added.
Stem cells are infant cells that can develop into any part of the body.
Until a few years ago, when iPS cells were created, the only way to obtain stem cells was to harvest them from human embryos.
This is controversial because it requires the destruction of the embryo, a process to which religious conservatives and others object.
IPS cells are easily-obtainable mature cells that are "reprogrammed" into a versatile, primitive state from where they can develop into any kind of cell in the body.
According to Takebe, the liver developed blood vessels which fused with those of the animal. It also performed certain human-specific liver functions - producing proteins and processing certain drugs.
"We have concluded that this liver is functioning," the scientist said. "We think this is enough for improving survival after liver failure."
Scientists commenting on the research described it as promising.
"This science opens up the distinct possibility of being able to create mini-livers from the skin cells of a patient dying of liver failure," said Malcolm Alison, professor of stem cell biology at the Queen Mary University of London.
Takebe said the method may also work in organs like the pancreas, kidneys or lungs, but it would be another 10 years before trials are done in humans.
