HeLa cell

Dividing HeLa cells as seen by scanning electron microscopy

A HeLa cell (also Hela or hela cell) is an immortal cell line used in scientific research. The cell line was derived from cervical cancer cells taken from Henrietta Lacks, who died from her cancer on October 4, 1951.

George Otto Gey and Henrietta Lacks

HeLa cells stained with Hoechst 33258.

The cells were propagated by George Otto Gey without Lacks' knowledge or permission (neither she nor her family gave permission)^[1] and later commercialized, although never patented in their original form. Then, as now, there was no requirement to inform a patient, or their relatives, about such matters because discarded material, or material obtained during surgery, diagnosis or therapy was the property of the physician and/or medical institution. This issue and Ms. Lacks' situation was brought up in the Supreme Court of California case of Moore v. Regents of the University of California. The court ruled that a person's discarded tissue and cells are not their property and can be commercialized.

Initially, the cell line was said to be named after a "Helen Lane" or "Helen Larson", in order to preserve Lacks's anonymity. Despite this attempt, her real name was used by the press within a few years of her death. These cells are treated as cancer cells, as they are descended from a biopsy taken from a visible lesion on the cervix as part of Ms. Lacks' diagnosis of cancer. A debate still continues on the classification of the cells.

HeLa cells are termed "immortal" in that they can divide an unlimited number of times in a laboratory cell culture plate as long as fundamental 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 cultures, but all HeLa cells are descended from the same tumor cells removed from Ms. Lacks. It has been estimated that the total number of HeLa cells that have been propagated in cell culture far exceeds the total number of cells that were in Henrietta Lacks' body.^[2]

According to reporter Michael Rogers, the subsequent development of HeLa by a researcher at the hospital, helped answer the demands of 10,000 who marched for a cure to polio just a few days before. By 1954 HeLa was used by Jonas Salk to develop a vaccine for polio.^[3] As stated by reporter Van Smith in 2002 a demand for HeLa cells "quickly rose ... the cells were put into mass production and traveled around the globe- even into space, on an unmanned satellite to determine whether human tissues could survive zero gravity". Smith continued, "In the half-century since Henrietta Lacks' death, her ... cells ... have continually been used for research into cancer, AIDS, the effects of radiation and toxic substances, gene mapping, and countless other scientific pursuits". HeLa cells have been used to test human sensitivity to tape glue, cosmetics, and many other products.

Telomerase

The HeLa cell line was derived for use in cancer research. These cells proliferate abnormally rapidly, even compared to other cancer cells. HeLa cells have an active version of the enzyme telomerase during cell division, which prevents the incremental shortening of telomeres that is implicated in aging and eventual cell death. In this way, HeLa cells circumvent the Hayflick Limit, which is the limited number of cell divisions that most normal cells can later undergo before dying out in cell culture.

Chromosome number

Horizontal gene transfer from human papillomavirus 18 (HPV18) to human cervical cells created the HeLa genome which is different from either parent genome in various ways including its number of chromosomes. HeLa cells have a modal chromosome number of 82, with four copies of chromosome 12 and three copies of chromosomes 6, 8, and 17.

Human papillomaviruses (HPVs) are frequently integrated into the cellular DNA in cervical cancers. We mapped by FISH five HPV18 integration sites: three on normal chromosomes 8 at 8q24 and two on derivative chromosomes, der(5)t(5;22;8)(q11;q11q13;q24) and der(22)t(8;22)(q24;q13), which have chromosome 8q24 material. An 8q24 copy number increase was detected by CGH. Dual-color FISH with a c-MYC probe mapping to 8q24 revealed colocalization with HPV18 at all integration sites, indicating that dispersion and amplification of the c-MYC gene sequences occurred after and was most likely triggered by the viral insertion at a single integration site. Numerical and structural chromosomal aberrations identified by SKY, genomic imbalances detected by CGH, as well as FISH localization of HPV18 integration at the c-MYC locus in HeLa cells are common and representative for advanced stage cervical cell carcinomas. The HeLa genome has been remarkably stable after years of continuous cultivation; therefore, the genetic alterations detected may have been present in the primary tumor and reflect events that are relevant to the development of cervical cancer.^[4]

Contamination

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Because of their adaptation to growth in tissue culture plates, HeLa cells are sometimes difficult to control. For example, they have proven to be a persistent laboratory "weed" and they can contaminate other cell cultures in the same laboratory, interfering with biological research and forcing researchers to declare many research results invalid because the cells used were later found to be contaminated. The degree of HeLa cell contamination among other cell types is unknown, because few researchers test the identity or purity of already-established cell lines. It has been demonstrated that a substantial fraction of in vitro cell lines — approximately 10%, maybe 20%, are actually contaminated with HeLa cells. Stanley Gartler in 1967 and Walter Nelson-Rees in 1975 were the first to publish on the contamination of various cell lines by HeLa.^[5]

Science writer Michael Gold in his book Conspiracy of Cells: One Woman's Immortal Legacy and the Medical Scandal It Caused (ISBN 0887060994) wrote about the HeLa cell contamination problem. Gold describes Gartler's identification of this problem and many, possibly career-ending, efforts to identify this pervasive worldwide problem, affecting even the laboratories of the best physicians, scientists, and researchers, including Jonas Salk. Gold also states that the HeLa contamination problem almost led to a Cold War incident. The USSR and the USA had started to cooperate in the war on cancer launched by President Richard Nixon and then it was found the cells exchanged were contaminated by HeLa. Gold asks how much time, money and energy was wasted in the war against cancer because of HeLa contamination. In his epilogue, Gold contends that the HeLa problem was amplified by emotions, egos, and a reluctance to admit mistakes, saying "It's all human - an unwillingness to throw away hours and hours of what was thought to be good research...worries about jeopardizing another grant that's being applied for, the hurrying to come out with a paper first. And it isn't limited to biology and cancer research. Scientists in many endeavors all make mistakes, and they all have the same problems".

Rather than recognize or focus on the problem of HeLa cell contamination, or on how to resolve this problem, many scientists, researchers and science writers continue to document this problem as simply a contamination problem, caused not by errors, or shortcomings of scientists, physicians and other personnel in public health, medicine, or science, or researchers, but by the hardiness, tenacity, proliferating or overpowering nature or other characteristic of HeLa.^[6][7].

Recent data suggest that cross contaminations are still a major ongoing problem with modern cell cultures.^[8]

Helacyton gartleri

Due to their ability to replicate indefinitely, and their non-human number of chromosomes, HeLa was described by Leigh Van Valen as an example of the contemporary creation of a new species, Helacyton gartleri, named after Stanley M. Gartler, who Van Valen credits with discovering "the remarkable success of this species." His argument for speciation depends on three points:

• The chromosomal incompatibility of HeLa cells with humans.
• The ecological niche of HeLa cells.
• Their ability to persist and expand well beyond the desires of human cultivators.

It should be noted that this definition has not been followed by others in the scientific community, nor, indeed, has it been widely noted.

As well as proposing a new species for HeLa cells, Van Valen proposes in the same paper the new family Helacytidae and the genus Helacyton.^[9]

See also

• List of contaminated cell lines
• Canine transmissible venereal tumor - infectious cancer in dogs and other canids caused by an immortal cell line
• Devil facial tumour disease - infectious cancer in the Tasmanian devil caused by an immortal cell line

References

• Rebecca Skloot title=The Immortal Life of Henrietta Lacks (2010). New York: Crown/Random House. 

Further reading

• Rebecca Skloot title=The Immortal Life of Henrietta Lacks (2010). New York: Crown/Random House. 
• Hannah Landecker (2000). "Immortality, In Vitro: A History of the HeLa Cell Line". in Brodwin, Paul. Biotechnology and culture: bodies, anxieties, ethics. Bloomington: Indiana University Press. pp. 53–74. ISBN 0-253-21428-9. 

External links

• Rebecca Skloot title=The Immortal Life of Henrietta Lacks (2010). New York: Crown/Random House. 
• Publishers Weekly, Review of The Immortal Life of Henrietta Lacks
• Rebecca Skloot, Henrietta's Dance, Hopkins Magazine:
• Rebecca Skloot, Cells That Save Lives are a Mother's Legacy, New York Times
• "Wonder Woman: The Life, Death, and Life After Death of Henrietta Lacks, Unwitting Heroine of Modern Medical Science" by Van Smith
• "What's Left of Henrietta Lacks?" by Anne Enright
• "Culturing Life: How Cells Became Technologies" a book by Hannah Landecker about HeLa and the history of tissue culture.
• Discussion about the taxonomic effect of creating the new taxon Helacyton.
• Cell Centered Database - HeLa cell