A new study published in Cell has found a previously unknown group of cells that have a greater ability to regenerate liver tissue in mice without forming tumors compared to ordinary liver cells, known as hepatocytes.
Researchers examined liver cells involved in regenerating tissue following injuries that were caused by carbon tetrachlorideexposure, an environmental toxin. The team discovered this new group of cells, called hybrid hepatocytes, in the portal triad of the liver.
For chronic liver injuries, hybrid hepatocyte cells reproduce efficiently and replenish tissue in the liver. While they are very similar to hepatocytes, hybrid hepatocytes were found to have much lower levels of bile duct cell-specific genes.
The study’s first author, Joan Font-Burgada, notes that “Although hybrid hepatocytes are not stem cells, thus far they seem to be the most effective in rescuing a diseased liver from complete failure.”
Currently, induced pluripotent stem cells (iPSCs) are being tested for the reparation of damaged livers and the treatment of liver failure. In studies, these cells are known for being difficult to stop once they’ve started proliferating—a concern that raises the risk of cancerous tumor formations.
Through this study, researchers wanted to test to see if these new hybrid hepatocytes would show similar tumor-forming properties. Researchers tested the tumors in three different mouse models of liver cancer to look for the presence of hybrid hepatocytes. No evidence of hybrid hepatocytes was found in any of the three tumors. Study authors thereby concluded that the cells did not contribute to the formation of cancerous liver tumors.
It should be noted that while the study was principally performed using mice models, researchers have found cells similar to the mouse hybrid hepatocytes in human livers.
The study’s lead author, Michael Karin, suggests, “Hybrid hepatocytes represent not only the most effective way to repair a diseased liver, but also the safest way to prevent fatal liver failure by cell transplantation.”
The researchers hope this study will lead the way to cell-based therapies that could replace the need for liver transplants in the future.
Sources for Today’s Article:
Karin, M., et al., “Hybrid Periportal Hepatocytes Regenerate the Injured Liver without Giving Rise to Cancer,” Cell August 13, 2015; http://www.cell.com/cell/abstract/S0092-8674%2815%2900903-4, 162(4): 766–779, doi: 10.1016/j.cell.2015.07.026.
McIntosh, J. “Scientists discover new liver-regenerating cells,” Medical News Today web site, August 14, 2015; http://www.medicalnewstoday.com/articles/298087.php.