Human Liver Created From Stem Cells In Mouse

The new research could see human organs such as livers being grown in labs in the future.

Scientists have for the first time created a functional human liver from stem cells derived from skin and blood - suggesting organs could be grown in labs in another 10 years.

The research could alleviate an acute shortage of donor organs across the world for patients with liver, heart, kidney and other organ failure.

Japanese scientists, based at the Yokohama City University Graduate School of Medicine, said they grew tissue "resembling the (human) adult liver" in a lab mouse.

The team used induced pluripotent stem (iPS) cells, which are often taken from blood and skin, to make three different cell types that would normally combine in the natural formation of a human liver.

These were then mixed to see if they would grow into three-dimensional structures called "liver buds" - the precursor clusters that develop into a full liver organ.

Scientist mixed various cells to see if they'd grow into liver buds

The buds were then transplanted onto a mouse brain, where they were observed transforming into a "functional human liver" complete with blood vessels, the scientists wrote in the journal Nature.

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

Takanori Takebe, who led the study, said the liver also performed certain human-specific liver functions - producing proteins and processing specific drugs.

He was so encouraged by the success of this work that he plans similar research on other organs such as the pancreas and lungs.

The technique has yet to be tested in humans, but serves as an important proof of concept, the report added.

Stem cells are infant cells that can develop into any part of the body.

The liver developed blood vessels and performed liver functions

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.

Scientists commenting on the research described it as promising.

"The promise of an off-the-shelf liver seems much closer than one could hope even a year ago," said Dusko Illic, a stem cell expert at King's College London who was not directly involved in the research but praised its success.

He said, however, that while the technique looks "very promising" and represents a huge step forward, "there is much unknown and it will take years before it could be applied in regenerative medicine".

Malcolm Allison, a stem cell expert at Queen Mary University of London, who was not involved in the research, said the study's results offered "the distinct possibility of being able to create mini livers from the skin cells of a patient dying of liver failure" and transplant them to boost the failing organ.

Chris Mason, a regenerative medicine expert at University College London said the greatest impact of iPS cell-liver buds might be in their use in improving drug development.

He said: "Presently to study the metabolism and toxicology of potential new drugs, human cadaveric liver cells are used.

"Unfortunately these are only available in very limited quantities".

A team of American researchers said in April they had created a rat kidney in a lab that was able to function like a natural one, but their method used a "scaffold" structure from a kidney to build a new organ.

And in May last year, British researchers said they had turned skin cells into beating heart tissue that might one day be able to be used to treat heart failure.