Pryhelm science & society Why Are HeLa Cells “Immortal”? The remarkable science behind a cell line that transformed medicine—and the human story and consent questions that must never be left out. cells in a lab dish The short answer: HeLa cells are cancer cells taken from Henrietta Lacks’s cervical tumour in 1951. In laboratory conditions they can continue dividing for an exceptionally long time. They are called an “immortal cell line,” but that term describes the cells—not a person, and not human immortality. HeLa cells explained for students and curious adults Most healthy human cells cannot divide forever. With repeated division, protective chromosome ends called telomeres tend to shorten, and cells eventually stop dividing. Cancer cells can acquire changes that help them bypass this limit. HeLa cells are unusual because they grow vigorously and can be maintained and shared between laboratories, allowing researchers to...