A University of Osaka team said it has become the world's first to make elaborate miniature livers from human induced pluripotent stem, or iPS, cells.
The small livers, called liver organoids, each about 0.5 millimeters in size, can function as well as the liver of a human newborn. The team expects that the organoids can be used to treat patients with end-stage liver disease.
The research results were published in the online edition of the British journal Nature on Thursday.
Regions in the liver have their own functions, such as synthesizing and breaking down sugar and fat, making it difficult to reproduce such a complex structure when creating a liver from iPS cells.
To make the organoids, the team — including professor Takanori Takebe of the university's Graduate School of Medicine — decided to use bilirubin, produced when red blood cells are broken down, and vitamin C because both substances control liver functions.
When iPS cells and the two substances were put in a container under certain conditions and cultured, an organoid with a complex structure of about 0.5 millimeters was formed.
In experiments on rats with severe liver failure, more than 50% of rats implanted with several thousand liver organoids were still alive after 30 days, far higher than the survival rate of less than 30% for rats without such treatment.
The team expects that the liver organoid production technology can be applied to the development of bioartificial liver devices, such as for dialysis.
"Treatment using organoids has become quite realistic," Takebe said.
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