Liver buds grown in a petri dish

Japanese scientists have coaxed stem cells into forming functional liver tissue in the lab. These rudimentary livers were able to metabolize some drugs like real livers.

Japanese scientists have coaxed stem cells into forming functional liver tissue in the lab.

If the results bear out, the advance would help avoid the outcome currently experienced by the many patients who don’t survive long enough to get a new liver. Nature News reports.

Takanori Takebe of Yokohama City University and colleagues grew the organ using induced pluripotent stem (iPS) cells – which are created by reprogramming human skin cells to an embryo-like state.

This is the first time a human functional organ with blood vessel networks was created from pluripotent stem cells.

  1. They placed the cells on growth plates in a specifically designed medium.
  2. After 9 days, the cells contained a biochemical marker of maturing liver cells, or hepatocytes.
  3. At that point, they added 2 more cell types known to help recreate organ-like function in animals: endothelial cells (which line blood vessels, taken from an umbilical cord) and mesenchymal cells (which can differentiate into bone, cartilage or fat, taken from bone marrow).
  4. Two days later, the cells assembled into a 5-millimeter long, 3D tissue that researchers labeled a liver bud, an early stage of liver development.

The tissue lacks bile ducts, and the hepatocytes don’t form neat plates like they would in a real liver. But the tissue does have functional blood vessels and 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. This would make the liver bud useful for toxicity testing in drug screening when bile ducts aren’t needed.

One day, the tissue could be used for long-term replacement or short-term graft while the recipient waits for a suitable liver donor, or in cases in where doctors anticipate that the native liver will eventually regain its function.

The team is collaborating on the project with Tokyo-based biotech Sekisui Medical.

The work was presented at the annual meeting of the International Society for Stem Cell Research in Yokohama last week.

[From Nature News]

Image: Gray’s Anatomy liver via Wiki

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