Telomeres are the protective caps at the ends of our chromosomes that keep them from fraying or sticking to each other, like the plastic tips at the end of shoelaces. Every time a cell copies itself during cell division, the telomeres get shorter. Eventually, they get so short that the cell can no longer divide—this is how we age.
But there’s an enzyme called telomerase that can rebuild telomeres. This “immortalizing” enzyme is found in cells throughout our bodies, but it’s most active in embryonic cells and cancer cells. That’s why cancer cells can divide endlessly (and why embryos can grow into babies).
Scientists are working on ways to harness telomerase to treat age-related diseases and cancer. For example, they’re trying to develop drugs that stimulate telomerase activity in healthy cells while keeping it under control in cancer cells. They’re also exploring whether it might be possible to genetically engineer immune cells with long telomeres so they could better fight infection and disease.