Aged stem cells rejuvenated to be functionally younger
May 6, 2012
Scientists have rejuvenated aged hematopoietic stem cells to be functionally younger, offering intriguing clues into how medicine might one day prevent some aspects of old age.
Researchers at Cincinnati Children’s Hospital Medical Center and the Ulm University Medicine in Germany report their findings online in the journal Cell Stem Cell. This study overturns what used to be a broad consensus – that the aging of hematopoietic stem cells (HSCs) was locked in by nature and impossible to reverse.
HSCs are stem cells that originate in the bone marrow and generate all of the body’s red and white blood cells and platelets. They are an essential support mechanism of blood cells and the immune system. As humans and other species age, HSCs become more numerous, but less effective at regenerating blood cells and immune cells. This makes older people more susceptible to infections and disease, including leukemia.
Researchers in the current study determined a protein that regulates cell signaling – Cdc42 – also controls a molecular process that causes HSCs from mice to age. Inhibition of Cdc42 reversed HSC aging and restored function similar to that of young stem cells according to Hartmut Geiger, the study’s lead investigator.
“Aging is interesting, in part because we still don’t understand how we age,” Geiger said. “Our findings suggest a novel and important role for Cdc42 and identify its activity as a target for ameliorating natural HSC aging. We know the aging of HSCs reduces in part the response of the immune system response in older people, which contributes to diseases such as anemia, and may be the cause of tissue attrition in certain systems of the body.”
The findings are early and involve lab manipulation of mouse cells, so it remains to be seen what direct application they may have for human beings. Still, the study expands what is known about the molecular and cellular mechanisms of aging – a necessary step on the long road to defeating the process.
These images of flouresced cells (which illuminate structural and functional components) illustrate the difference between young and aged hematopoietic stem cells. Younger cells have proteins grouped together in a concentrated and organised fashion, while the components of aged cells are more disorganised and scattered.