[Wired]

In the 1950’s, Henrietta Lacks got cervical cancer, which evolved into a new species.

A HeLa cell (also Hela or hela cell) is both an immortal cell used in medical research and a new single cell species (Helacyton gartleri) created via horizontal gene transfer. The cell line was derived from cervical cancer cells taken from Henrietta Lacks, who died from her cancer in 1951. The species has evolved so that it does not age.

The cells were propagated without Lacks' knowledge or permission by George Otto Gey. Initially, the cell line was said to be named after a "Helen Lane" or "Helen Larson", in order to preserve Lacks' anonymity. These cells are treated as cancer cells, as they are believed to have stemmed from Ms. Lacks' cervical cancer, but a debate still continues on the classification of these cells.

HeLa are considered "immortal". They do not die of old age and can divide an unlimited number of times as long as basic cell survival conditions are met (i.e. being maintained and sustained in a suitable environment). There are many strains of HeLa cells as they continue to evolve by being grown in cell culture, but all HeLa cells are derived from the same tumour cells removed from Lacks. It has been estimated that the total mass of HeLa cells today far exceeds that of the rest of Henrietta Lacks' body.

HeLa cells have proven difficult to control. They sometimes contaminate other cell cultures growing in the same laboratory, interfering with biological research. The degree of contamination is unknown, because few researchers test the identity or purity of already-established cell lines. It has been claimed that a substantial fraction of in vitro cell lines are actually HeLa, their original cells having been overwhelmed by a rapidly growing population derived from HeLa contaminant cells. Stanley Gartler in 1967, and Walter Nelson-Rees in 1975 were the first to publish on the contamination of cell lines by HeLa.