Aging of blood–forming stem cells is linked to defect in cellular recycling process.
A molecular key to aging of the blood and immune system has been discovered in new research conducted at UC San Francisco, raising hope that it may be possible to find a way to slow or reverse the growing risk for aging–associated chronic inflammatory diseases, anemia, blood cancers, and life–threatening infections.

The key is a link between the health of a rare population of adult stem cells that arise early in development and are responsible for replenishing all blood cell types throughout a lifetime, and a newly identified role for autophagy, an important cellular cleanup and recycling process that was the focus of the 2016 Nobel Prize in Physiology or Medicine.

In their new study, published online March 1 in the journal Nature, the UCSF team discovered that in addition to its normal role in cellular waste–processing, autophagy also is needed for the orderly maintenance of blood–forming hematopoietic stem cells (HSCs), the adult stem cells that give rise to red blood cells, which carry oxygen, and to platelets, which prevent bleeding, as well as the entire immune system, which fights infections and disposes of pathogens.

The researchers found that autophagy keeps HSCs in check by allowing metabolically active HSCs to return to a resting, quiescent state akin to hibernation. This is the default state of adult HSCs, allowing their maintenance for a lifetime.

According to Emmanuelle Passegué, PhD, the senior scientist for the study, “This is a previously unknown role for autophagy in stem cell biology.”