Stories about: cellular aging

The costs of quiescence, for cars and blood cells

Old car aging blood cell hematopoietic stem cell blood disorder Derrick Rossi
Like an old, unused car, our aging blood stem cells can accumulate damage over time that they can't fully repair.

My first car was my grandfather’s 1980 Chevrolet Malibu. For about two years before my family gave it to me, it sat unused in Grandpa’s garage—just enough time for all of the belts and hoses to rot and the battery to trickle down to nothing.

Why am I telling this story? Because it’s much like what happens to the DNA in our blood-forming stem cells as we age.

Hematopoietic stem cells (HSCs) spend very little of their lives in an active, cycling state. Much of the time they’re quiescent or dormant, keeping their molecular and metabolic processes dialed down. These quiet periods allow the cells to conserve resources, but also give time an opportunity to wear away at their genes.

“DNA damage doesn’t just arise from mistakes during replication,” explains Derrick Rossi, PhD, a stem cell biology researcher with Boston Children’s Hospital’s Program in Cellular and Molecular Medicine. “There are many ways for damage to occur during periods of inactivity, such as reactions with byproducts of our oxidative metabolism.”

The canonical view has been that HSCs always keep one eye open for DNA damage and repair it, even when dormant. But in a study recently published in Cell Stem Cell, Rossi and his team found evidence to the contrary­­—which might tell us something about age-related blood cancers and blood disorders.

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Lesson from Romania: Neglect and deprivation are bad for children’s DNA

Romanian orphan-Angela Catlin_Wikimedia Commons
Photo: Angela Catlin/Wikimedia Commons

The infamous orphanages of Romania have become laboratories for studying the effects of profound child neglect. We already know from this sad situation that depriving children of normal emotional and social interaction leads to lower IQ scores, high rates of mental illness and stunted physical growth.

Now there’s evidence that early adversity goes to the core of children’s DNA – prematurely shortening their chromosome tips, known as telomeres, and hastening how quickly their cells “age.”

“Orphanages” is a misnomer, because these state-run institutions mostly house children who were abandoned by their families. They are a legacy of the 1960s, when Romania’s Communist dictator Nicolae Ceausescu taxed all families with fewer than five children, and then built child placement centers to house the children whose families couldn’t support them.

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