The workhorse liver cells, called hepatocytes, sit next to cells that store fat, immune cells and endothelial cells.

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The hepatocytes produce the enzymes needed to break down toxins, so these little microlivers can be used to test drug toxicity.

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Chen and her group hoped to induce the cancer by activating oncogenes, genes that trigger cancer, in a group of liver cells called hepatocytes.

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Once in their new home, the hepatocytes start to fail immediately.

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With colleagues at the University of Wisconsin, Bhatia is trying to coax hepatocytes from so-called induced pluripotent stem cells--adult cells that can be reprogrammed into stem cells.

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During the next six months, they discovered that up to 2.2% of mature liver cells (hepatocytes) in the female mice were derived from the donated bone marrow.

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It turned out that the cells morphed from being hepatocytes into biliary cells, the kind that line the bile ducts, and then quickly began to form tumors.

FORBES: Cells Get a Makeover, Cancer Follows: A Path to New Therapies (and a Warning to Stem Cell Alchemists)

If hepatocytes and their genomes become disarrayed by disease, Willenbring says, it may activate oncogenes in the same way their experiment did, causing the cells to change identity and form cancers.

FORBES: Cells Get a Makeover, Cancer Follows: A Path to New Therapies (and a Warning to Stem Cell Alchemists)

Among them are neural cells to treat spinal cord injury and degenerative nervous system diseases, cardiomyocytes to treat heart disease, pancreatic islet cells to treat diabetes, dendritic cells for cancer therapy, chondrocytes for arthritis, osteoblasts to rebuild bone and hepatocytes for drug discovery and liver failure.

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