Jack Blackburn Quotes

one of the key hallmarks of aging is the accumulation of senescent cells. These are cells that have permanently ceased reproduction. Young human cells taken out of the body and grown in a petri dish divide about forty to sixty times until their telomeres become critically short, a point discovered by the anatomist Leonard Hayflick that we now call the Hayflick limit. Although the enzyme known as telomerase can extend telomeres—the discovery of which afforded Elizabeth Blackburn, Carol Greider, and Jack Szostak a Nobel Prize in 2009—it is switched off to protect us from cancer, except in stem cells. In 1997, it was a remarkable finding that if you put telomerase into cultured skin cells, they don’t ever senesce.