Stem Cells and the Liver. Stem cells with high levels of telomerase regenerate the liver. These are hepatic stem cells that express high levels of telomerase, a protein often associated with anti-aging properties.
They act in mice to regenerate the organ during normal cell turnover or tissue damage. This was discovered in a study conducted by researchers from the School of Medicine at Stanford University. Palo Alto, California, United States.
The liver distributes the cells throughout its lobes. This allows them to quickly repair themselves regardless of the location of the damage. Understanding the remarkable repair and regeneration capacity of the liver is crucial in comprehending the consequences of its malfunction. This occurs in cases of cirrhosis or liver cancer.
Professor Steven Artandi, the study’s lead author, says, “The liver is a significant source of human disease.” They published the study this Wednesday in the digital edition of Nature. “It is crucial to understand the cellular mechanism by which the liver renews itself. We have discovered that the liver disperses these rare and proliferative cells throughout the organ, and the liver needs them to replace damaged cells. It is also likely that these cells can give rise to liver cancers when their regulation fails.”
Telomerase
Telomerase is a protein complex that “caps” the ends of chromosomes after DNA replication. Without its activity, protective chromosome caps called telomeres would gradually shorten with each cell division. Most adult cells have low or no telomerase activity. The progressive shortening of telomeres serves as a kind of molecular clock that limits the lifespan of cells.
However, stem cells and some cancer cells produce enough telomerase to prevent telomere shortening. This effectively stops the aging clock and allows seemingly unlimited cell divisions. Mutations that block telomerase activity cause cirrhosis in mice and humans. On the other hand, liver cancers often have mutations that activate telomerase at a high rate.
Discoveries
The study found that in mice, between 3 and 5 percent of all liver cells express unusually high levels of telomerase. These cells, which also expressed lower levels of genes involved in normal cellular metabolism, were evenly distributed throughout the liver lobes. During normal cell turnover or after liver damage, these cells proliferate in place to form clusters of new liver cells.
“These rare cells can be activated to divide and form clones throughout the liver,” notes Dr. Artandi. “As mature hepatocytes die, these clones replace the liver mass. However, they are functioning, they are not recruited from other areas of the liver. This may explain how the liver can repair the damage quickly, regardless of its location within the organ.”
Conclusions
The fact that these stem cells express fewer metabolic genes could be a way to protect the cells from the daily routine faced by their counterparts. This can limit the production of metabolic byproducts that can damage DNA. “This may be a way to protect these important cells and allow them to pass on a more pristine genome to their daughter cells,” says Artandi. “They are not performing all the worker bee functions of normal hepatocytes.”
Stem Cells and the Liver. When Dr. Lin (a research team member) designed telomerase-expressing hepatocytes to come to life in response to a chemical signal. He gave mice a harmful chemical for the liver. “He discovered that the destruction of telomerase cells in animals resulted in much more severe liver scarring.” This was in contrast to those in which the cells were functional.
The future looks promising in the study of stem cells and the liver. If you suffer from liver conditions and want to learn about therapeutic options available in the field of regenerative medicine, we invite you to contact us right now and schedule your appointment.
If you would like to learn more about the topic, we invite you to read our article. The article is titled “What are Stem Cells?”
