Individual liver stem cells can grow into liver tissue. This cultured tissue can repair liver damage in lab animals.
Prof. Hans Clevers and colleagues at the Hubrecht Institute describe this in an article in Nature (27 January 2013).
The liver responds to damage by producing new liver cells and bile ducts. The researchers located the stem cells responsible for this regeneration. Just like in the intestine, the stomach and hair follicles, the stem cells can be identified by their Lgr5 protein. Liver stem cells are unusual became they only become active in response to tissue damage.
Next, the researchers grew small pieces of liver tissue from the individual stem cells. These organoids or mini-livers can grow for more than a year in a laboratory environment. Crucial is the addition of Rspondin, a culture medium that keeps the stem cells active.
The researchers then tested this liver tissue on mice with a liver disorder that prevents them from producing a particular liver enzyme, resulting in a lethal accumulation of toxic substances. By transplanting the cultured liver tissues, the researchers hoped to cure the disorder. And indeed, in the next few months active liver tissue grew in the transplanted mice, resulting in an improved liver function.
These results may be important for billions of people suffering from chronic liver failure due to viruses, alcohol or other toxic substances, according to Prof. Clevers. 'Because the same cells can be grown from human liver tissue, these results show that it will be possible someday to grow new liver tissue for patients suffering liver failure from a small amount of healthy tissue taken from either the patient or a donor.'