Scientists have sequenced a line of HeLa cells, and found them to be "a mess."
In 1951, scientists at Johns Hopkins Hospital harvested cells from Henrietta Lacks. "With her under anesthesia, they just took this small piece of her tumor -- without her knowing -- and they put it in a dish and sent it down the hall," author Rebecca Skloot told CBS.
Those cells multiplied and multiplied and multiplied, becoming the most-studied human cells in scientific research. The quantity of HeLa cells in the world today is so big that it is said that the only way to measure them would be "in tons," though no one has done this. "A typical lab at the University of California," Richard Dawkins wrote in his book A Devil's Chaplain, "grows 48 liters of HeLa cells per day, as a routine service to researchers in the university."
Though their quantity is unknown, their contributions are anything but: HeLa cells were used to test the polio vaccine and have played an instrumental role in research that has led to two recent Nobel prizes. They went into space to test how human cells would fare in zero gravity. "Scientists who come to my talks come up to me and say, 'You cannot overestimate how important HeLa cells have been,'" Skloot said.
And now researchers in Germany have taken the step of sequencing the HeLa cells' genome, publishing their results in G3. (They used the common "Kyoto" HeLa line.) What they found, Nature writer Ewen Callaway reports, was "a mess." He explains:
[Lars] Steinmetz's team confirmed that HeLa cells contain one extra version of most chromosomes, with up to five copies of some. Many genes were duplicated even more extensively, with four, five or six copies sometimes present, instead of the usual two. Furthermore, large segments of chromosome 11 and several other chromosomes were reshuffled like a deck of cards, drastically altering the arrangement of the genes.
It makes sense that over six decades of replication, errors would have crept in, and researchers do not yet know which of the mutations were originally present in Lacks' tumor and which have developed in the interim, though they'll be able to piece more of the story together as they compare strains from labs around the world.
The mutations, Steinmetz told Nature, complicate the extensive reliance on HeLa cells throughout human cell biology.