1984–1995

In 1984, a scientist finally found a probable cause for Henrietta’s cancer. He discovered a new strain of a sexually transmitted disease called Human Papilloma Virus (HPV) and found that HeLa cells tested positive for it. This strain of HPV switched off a gene in Henrietta’s chromosomes that normally suppresses tumor growth. Research into this and other strains of HPV, which affects about 90 percent of all adults who are sexually active, increased understanding of cervical cancer and also led to the development of an HPV vaccine.

However, no scientist has ever been able to explain why Henrietta’s cancer was so virulent, nor why it grew so well in culture. Since the 1950s, scientific advances have made it easier to grow human cells in a laboratory, but Henrietta’s somehow grew well without much help. Henrietta’s family members tend to explain this phenomenon as the work of God or the intervention of spirits. Her cousin Sadie once even suggested that it was caused by some force from outer space. She laughed at herself for saying something so ridiculous, but she added:

Everything just go through your mind, you know? How else you gonna explain them cells growin like they do?

The 1980s brought new discoveries and ethical fights involving HeLa. Researchers made changes to the DNA of some of Henrietta’s cells in order to infect them with HIV, which normally infects only blood cells. This effort helped the fight against AIDS but also led to a lawsuit by activists who considered it immoral and irresponsible to change the DNA structure of any human cell.

In a strange twist of the HeLa cells’ story, two researchers at the University of Chicago noted that HeLa had undergone changes while reproducing in culture. All cells undergo changes over time, so these researchers suggested that HeLa cells were not human anymore. However, few scientists took this point seriously. One prominent researcher, Robert Stevenson, mocked the suggestion:

Scientists don’t like to think of HeLa cells as being little bits of Henrietta because it’s much easier to do science when you disassociate your materials from the people they came from.

Scientists also discovered why cancer cells can keep growing and replicating so much longer than normal cells. For decades, they had known that normal cells contained strings of DNA called telomeres which grew shorter each time they replicated. When an ordinary cell replicates about fifty times, the telomeres become extremely short, and the cells stop replicating and die. By the early 1990s, researchers discovered that cancer cells contained a chemical called telomerase that allowed the telomeres to rebuild themselves. Telomerase was the key to cancer cell immortality.