Scientists Can Now Grow Functioning Liver From Stem Cells

Scientists have promised a lot of regenerative medicine will come from stem cells, but so far progress has been fairly slow: they can stimualte regrowth of heart tissue, make incredibly expesnive artifical blood, or—at best—construct a short piece of vein. Now, though, scientists are claiming they can grow functional liver.

Nature reports that a team of scientists from Japan has presented its works at a conference, and it's incredible. In fact, George Daley, director of the stem-cell transplantation program at the Boston Children's Hospital in Massachusetts, told Nature that "it blew [his] mind." Wow.

The researchers used stem cells created from human skin cells, then placed the cells on growth plates in a specially designed culture medium. Over the course of nine days, the cells started producing chemicals that a typical liver cell, otherwise known as a hepatocyte, would produce. They then added endothelial and mesenchymal cells—which form parts of blood vessels and other structural tissues within the body—to the mix, in the hope that they would be incorporated and begin to help the cells develop a structure akin to the liver.

The result was amazing: two days later, the researchers found the cells assembled into a 5-millimeter-long, three-dimensional lump. That lump was almost identical to something known as a liver bud—an early stage of liver development. From Nature's report:

"The tissue lacks bile ducts, and the hepatocytes do not form neat plates as they do in a real liver. In that sense, while it does to some degree recapitulate embryonic growth, it does not match the process as faithfully as the optic cup recently reported by another Japanese researcher. But the tissue does have blood vessels that proved functional when it was transplanted under the skin of a mouse. Genetic tests show that the tissue expresses many of the genes expressed in real liver. And, when transferred to the mouse, the tissue was able to metabolize some drugs that human livers metabolize but mouse livers normally cannot. "

While it's not perfect, it's the first time anyone has successfully created part of a functional human organ from stem cells produced from human skin. If scientists hadn't quite managed to deliver on the promise of stem cells so far, they have now. [Nature]

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