Placeholder Image

Subtitles section Play video

  • Imagine something small enough to float on a particle of dust

  • that holds the keys to understanding cancer, virology, and genetics.

  • Luckily for us,

  • such a thing exists in the form of trillions upon trillions

  • of human lab-grown cells called HeLa.

  • Let's take a step back for a second.

  • Scientists grow human cells in the lab to study how they function,

  • understand how diseases develop,

  • and test new treatments without endangering patients.

  • To make sure that they can repeat these experiments over and over,

  • and compare the results with other scientists,

  • they need huge populations of identical cells

  • that can duplicate themselves faithfully for years,

  • but until 1951, all human cell lines that researchers tried to grow

  • had died after a few days.

  • Then a John Hopkins scientist named George Gey

  • received a sample of a strange looking tumor:

  • dark purple, shiny, jelly-like.

  • This sample was special.

  • Some of its cells just kept dividing,

  • and dividing,

  • and dividing.

  • When individual cells died,

  • generations of copies took their place and thrived.

  • The result was an endless source of identical cells that's still around today.

  • The very first immortal human cell line.

  • Gey labeled it "HeLa" after the patient with the unusual tumor, Henrietta Lacks.

  • Born on a tobacco farm in Virginia,

  • she lived in Baltimore with her husband and five children.

  • She died of aggressive cervical cancer

  • a few months after her tumorous cells were harvested,

  • and she never knew about them.

  • So what's so special about the cells from Henrietta Lacks

  • that lets them survive when other cell lines die?

  • The short answer is we don't entirely know.

  • Normal human cells have built-in control mechanisms.

  • They can divide about 50 times before they self destruct

  • in a process called apoptosis.

  • This prevents the propagation of genetic errors

  • that creep in after repeated rounds of division.

  • But cancer cells ignore these signals, dividing indefinitely

  • and crowding out normal cells.

  • Still, most cell lines eventually die off, especially outside the human body.

  • Not HeLa, though, and that's the part we can't yet explain.

  • Regardless, when Dr. Gey realized he had the first immortal line of human cells,

  • he sent samples to labs all over the world.

  • Soon the world's first cell production facility

  • was churning out 6 trillion HeLa cells a week,

  • and scientists put them to work in an ethically problematic way,

  • building careers and fortunes off of Henrietta's cells

  • without her or her family's consent, or even knowledge until decades later.

  • The polio epidemic was at its peak in the early 50s.

  • HeLa cells, which easily took up and replicated the virus,

  • allowed Jonas Salk to test his vaccine.

  • They've been used to study diseases,

  • including measles,

  • mumps,

  • HIV,

  • and ebola.

  • We know that human cells have 46 chromosomes

  • because a scientist working with HeLa discovered a chemcial

  • that makes chromosomes visible.

  • HeLa cells themselves actually have around 80 highly mutated chromosomes.

  • HeLa cells were the first to be cloned.

  • They've traveled to outer space.

  • Telomerase,

  • an enzyme that helps cancer cells evade destruction by repairing their DNA,

  • was discovered first in HeLa cells.

  • In an interesting turn of fate,

  • thanks to HeLa, we know that cervical cancer can be caused by a virus called HPV

  • and now there's a vaccine.

  • HeLa-fueled discoveries have filled thousands of scientific papers,

  • and that number is probably even higher than anyone knows.

  • HeLa cells are so resilient that they can travel on almost any surface:

  • a lab worker's hand,

  • a piece of dust,

  • invading cultures of other cells and taking over like weeds,

  • countless cures, patents and discoveries all made thanks to Henrieta Lacks.

Imagine something small enough to float on a particle of dust

Subtitles and vocabulary

Operation of videos Adjust the video here to display the subtitles

B1 INT US TED-Ed hela henrietta dividing human cancer

【TED-Ed】The immortal cells of Henrietta Lacks - Robin Bulleri

  • 1402 151
    Bruce Lan posted on 2016/04/02
Video vocabulary