Scientists create 'human liver' from stem cells

Scientists in Japan 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 a team reported Wednesday in the journal Nature that they grew tissue "resembling the (human) adult liver" in a lab mouse.

They first created induced pluripotent stem (iPS) cells which they mixed with other cell types and coaxed into "liver buds" -- the precursor clusters that develop into a liver.

The buds, each about five millimetres (0.2 inches) big, were then transplanted onto a mouse brain, where they were observed transforming into a "functional human liver" complete with blood vessels, the scientists wrote.

"To our knowledge, this is the first report demonstrating the generation of a functional human organ from pluripotent stem 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.

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Scientists create 'human liver' from stem cells