Skloot's title intends to make us think about what Henrietta's immortality really means—for her, for her family, and for the scientific community. It's clear from the book that "immortality" means something different to each group involved in Henrietta's story.
For the scientific community, it means everlasting cell life. But her family knows that behind the science lies a real person. And that person suffered and left behind a family, the legacy of her heart as well as her genes. In this title, Skloot challenges us to think about which version we value most: Henrietta Lacks or HeLa?