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Researchers Grow Liver Tissue from Pluripotent Stem Cells


Japanese researchers have produced liver-like tissue from induced pluripotent stem cells in the laboratory that can process drugs like a human liver, according to a presentation at the 10th annual meeting of the International Society for Stem Cell Research last week in Yokohama.

As described in a Nature news report, Takanori Takebe from Yokohama City University and colleagues grew the tissue in vitrousing pluripotent stem cells "reprogrammed" from human skin cells. After 9 days, the cell culture contained a biomarker characteristic of maturing hepatocytes. They then added umbilical cord endothelial cells (which line blood vessels) and mesenchymal cells from bone marrow (which differentiate into bone, cartilage, or fat). Within 2 days the cells assembled themselves into a "liver bud" about 5 mm in size. The tricky process "took over a year and hundreds of trials," Takebe told Nature.

The newly produced tissue contained blood vessels, but lacked bile ducts. When it tissue was transplanted under the skin of a mouse, it expressed many of the genes that a complete liver would express, and it produced albumin, an important blood protein synthesized by the liver. Further, the bud graft was able to metabolize some drugs that mouse livers normal cannot metabolize but human livers can.

Though much more research is required before scientists can produce complete organs that can replace damaged livers of people with diseases such as chronic hepatitis B or C -- perhaps substituting for scarce donated livers -- Stuart Forbes from the University of Edinburgh told Naturethat the work "sounds like a genuine advance." In the meantime, liver buds like this could potentially be useful for drug toxicity screening.  



D Cyranoski. Rudimentary liver grown in vitro. Nature. June 20, 2012.