Japanese scientists have been able to induce stem cells to create liver-like tissue in a dish. The new findings were reported online by the journal Nature, but the scientists have yet to publish their findings. Once the achievement is accomplished, there could be several big clinical implications. This could mean that it would be possible to coax stem cells to organize into functional organs for transplantation.
Takanori Takebe, a stem-cell biologist at Yokohoma City University in Japan, presented his team’s research at the annual meeting of the International Society for Stem Cell Research in Yokohoma last week.
The proto-liver still has a long way to go before it can be transplanted. Induced pluripotent stem cells (iPS), which were created by reprogramming human skin cells to an embryo-like state, were placed in growth plates in a specifically designed medium. After nine days, an analysis showed that these cells contained the biochemical markers of hepatocytes, maturing liver cells.
Two more types of cells were added, endothelial and mesenchymal cells. Two days later, the cells assembled themselves into a 5mm long, three-dimensional tissue, that the researchers labeled a liver bud.
The tissue lacks bile ducts, but has functional blood vessels. The tissue was transplanted into a mouse, where it was able to metabolize certain drugs that mouse livers normally wouldn’t be able to. Takebe states that the success depended on the proper timing of the addition of the two other cell types. It took over a year and hundreds of trials to fine-tune the process.
The next step would be to try and make the liver bud more like a real liver, by finding a way to include structures like bile ducts.
Reference: “Rudimentary liver grown in vitro” by David Cyranoski, 20 June 2012, Nature.