In 1951, a woman named Henrietta Lacks died of cervical cancer. Before she died (but without her knowledge or permission), her doctor took a tiny sample of her cancer cells to see if he could keep them growing artificially outside her body. The cells grew and grew and grew, and he sent them to researchers around the world. Today the HeLa cells, as they are called, exist in nearly every country on the globe, and have even traveled into outer space in experiments–though the woman they come from has been dead for over 60 years! I learned this from The Immortal Life of Henrietta Lacks, by Rebecca Skloot.