News of Progress in Growing Liver Tissue from Stem Cells

Last year Japanese scientists published on their work in growing small amounts of liver tissue from stem cells. Here is more on this line of research:

The researchers found that a mixture of human liver precursor cells and two other cell types can spontaneously form three-dimensional structures dubbed "liver buds." In the mice, these liver buds formed functional connections with natural blood vessels and perform some liver-specific functions such as breaking down drugs in the bloodstream. It's possible the technique will work with other organ types, including the pancreas, kidney, or lungs. The study is the first demonstration that a rudimentary human organ can be produced using induced pluripotent stem (iPS) cells. These iPS cells are made by converting mature cells such as skin cells into a state from which they can develop into many other cell types.

The researchers took a creative approach to building the proto-liver [by] co-mingling three different cell types: liver cell precursors derived from human iPS cells, blood vessel precursors called endothelial cells, and connective tissue precursor cells called mesenchymal stem cells. Both the blood vessel and connective tissue precursor cells were harvested from umbilical cords.

To demonstrate the therapeutic potential of the liver bud method, [the researchers] transplanted a dozen liver buds into the abdomen of mice whose natural liver function was shut down with a drug. The liver bud transplants kept these mice alive for the month they were watched. The liver buds did not achieve all the functions of a mature liver. For instance, the buds did not form a bile duct system. However, in ongoing research, the team has found that by transplanting the buds into an existing liver, the body seems to make use of the existing bile system.

One potential therapeutic use of the method could involve delivering microscopic liver buds to human patients through a large vein that connects to the liver to improve survival after liver failure. [The researchers are] optimistic that as much as 30 percent of liver function could be restored through this method, [but] estimated that such a treatment is at least 10 years away. In the meantime, the method must be improved so that the liver buds can be produced much more efficiently.



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