(RxWiki News) Everything ages over time. And human stem cells are no exception. Understanding this aging process may help explain why the elderly are more susceptible to infections and certain cancers.
Scientists have realized that as we age, our bodies make fewer blood and immune system stem cells that are critical for battling viruses and bacteria. This may, in part, explain why bacterial and viral infections, along with cancers of the blood are more prevalent in older individuals.
"Science is gaining understanding on how the aging process promotes illness."
A team of researchers from the Stanford University School of Medicine have studied what's known as hematopoietic stem cells (HSC) which create cells that make up the blood and immune system.
People over the age of 65 make fewer HSC, which produce lymphocytes - a type of white blood cell that fights off foreign invaders. The HSC that are made tend to have a bias toward making a kind of white blood cell that promotes certain cancers.
The study's first author, Wendy Pang, M.D., who is in the Medical Science Training Program at Stanford, first learned that human HSC behave like stem cells in mice.
In this study, she gathered, analyzed and compared the characteristics of HSC from 15 healthy elderly people and 28 healthy young people. Dr. Pang found that the cells from elderly individuals worked harder and less successfully just to keep up with everyday demands.
This struggle can result in less efficient immune responses, leading to more infections. The aging, faltering stem cells can also have unstable growth and certain types of blood cancers, such as acute myeloid leukemia (AML).
Dr. Pang worked with Irving Weissman, M.D., the director of Stanford's Institute for Stem Cell Biology and Regenerative Medicine.
Dr. Pang concludes this study will help scientists "tease out disease-associated changes from normal age-associated phenomena,"
The study was published online Nov. 28, 2011 in the Proceedings of the National Academy of Sciences.