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Article by: Waikel, Rebekah L. Department of Biological Sciences, Eastern Kentucky University, Richmond, Kentucky. Last updated: 2016 DOI: https://doi.org/10.1036/1097-8542.311600 (https://doi.org/10.1036/1097-8542.311600)

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Establishment of the first HeLa cells accelerated the discovery and Links to Primary Literature transformed line use of the Salk vaccine Additional Readings Genomic and viral milieu of HeLa cells of HeLa cells

Human cells maintained in tissue culture since 1951, originally excised from the cervical of a patient named . The first immortal human cells to grow successfully outside the human body were labeled HeLa cells (Fig. 1), named for Henrietta Lacks, the 30-year-old cancer patient from whom the cells were derived. HeLa cells are so successful at growing that they have far outlived their person of origin and have contributed to biomedical research since 1951. It is estimated that, collectively, scientists have grown more than 20 tons of these cells. As one example of their importance, used HeLa cells to produce large quantities of the polio , which was a vital step in the development of the first . See also: Biotechnology (/content/biotechnology/084350); Cancer (/content /cancer/105700); Cell (biology) (/content/cell-biology/116000); (/content/cell-biology/116050); Disease (/content/disease/200100); (/content/oncology/469000); Poliomyelitis (/content/poliomyelitis/532900); Public health (/content/public-health/556300); Somatic cell genetics (/content/somatic-cell-genetics/636300); Tissue culture (/content/tissue-culture/698700); Vaccination (/content/vaccination/725200)

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Fig. 1 Multiphoton fluorescence image of HeLa cells stained with the -binding toxin phalloidin (red), (blue), and cell nuclei (purple). (Image courtesy of Tom Deerinck, National Center for Microscopy and Imaging Research, National Institutes of Health)

Establishment of the first human transformed cell line

In 1951, physicians at Johns Hopkins Hospital in Baltimore, Maryland, took a small tissue biopsy from a dime-size tumor located on the cervix of an African-American patient named Henrietta Lacks. The biopsied cancer tissue was divided, and part was sent for pathological analysis. The initial pathology report stated that the was epidermoid (arising from the epithelial cells); however, several years later, it was recognized as a less common and more aggressive form of cervical cancer, an adenocarcinoma (arising from glandular cells). Some of the biopsy tissue was given to George Gey, a cancer working to establish the first continuous (immortal) human cell line, that is, cells capable of growing and dividing an infinite number of times. A normal cell is programmed to divide a defined number of times, typically around 50. Known as the , this is regulated by the gradual shortening of ( ends) with each , leading to either cellular (cell aging and inability to divide) or cell death (). See also: Apoptosis (/content/apoptosis/801560); Cell division (/content/cell-division/116300); Cell senescence (/content/cell- senescence/117250); Chromosome (/content/chromosome/134900); Clinical pathology (/content/clinical-pathology /141100)

In the , the process of growing cells in culture was difficult. George Gey and his laboratory personnel made a concoction of chicken plasma, bovine embryo extract, and human placental cord serum to grow the human cells. George Gey had been trying for years to establish an immortal human cell line, using a variety of malignant tumors, but without success. Therefore, the growth of the HeLa cervical cancer cells was an exciting accomplishment. Why did these cells grow continuously, whereas other cancer cells did not? The answer lies in the genomic information gathered decades later.

Genomic and viral milieu of HeLa cells 2 of 7 7/26/17, 11:42 AM HeLa cells - AccessScience from McGraw-Hill Education http://accessscience.com/content/hela-cells/311600 The human papillomavirus (HPV) is responsible for nearly all cases of cervical cancer. There are about 200 HPV-related , with two strains, HPV-16 and HPV-18, responsible for the majority of cervical . HPV-16 and HPV-18, as well as several other HPV strains, are sexually transmitted viruses. These viral infections are so common that the U.S. Centers for Disease Control and Prevention (CDC) estimates that 90% of sexually active males and 80% of sexually active females will become infected with at least one of HPV. It is estimated that 5% of all cancer worldwide results from an HPV infection. The most common HPV cancers are cervical, penile, and throat. Although condom use reduces the rate of transmission, it does not prevent transmission altogether because HPV can be passed through skin-to-skin contact. Currently, vaccines provide the best protection from HPV infections. See also: Human papillomavirus: impact of cervical cancer vaccine (/content/human-papillomavirus-impact-of-cervical-cancer-vaccine/YB090091); Human papillomaviruses (/content /human-papillomaviruses/900162); Sexually transmitted diseases (/content/sexually-transmitted-diseases/617850); Virus (/content/virus/733500)

HPV is a deoxyribonucleic acid (DNA) virus and is capable of integrating its viral into its host human genome. As with the majority of other cervical cancers, the viral genome of the high-risk HPV-18 strain is integrated into the genome of the HeLa cell lines. Genetic analysis of the HeLa CCL-2 line revealed five HPV-18 integration sites. The HPV viral genome possesses that promote cell division by inhibiting proteins that normally keep the cell cycle in check. Two viral proteins, E6 and E7, inhibit the tumor suppressor genes p53 and Rb, respectively. In addition to the presence of E6 and E7 promoters, one of the HPV-18 viral genes integrates upstream of the cellular Myc. The protein, MYC, is normally involved in regulating the cell cycle. When transcriptionally upregulated by the viral that is upstream, MYC causes the cell to cycle and divide more rapidly. E6, E7, and MYC are all known to increase the levels of , an enzyme that helps the cell to evade a maximum number of cell divisions (the Hayflick limit). Both the presence of several copies of the HPV-18 genome and the upregulation of Myc likely contributed to the development of the original cervical cancer and made the resulting HeLa cells incredibly robust in culture. See also: Cell cycle (/content/cell-cycle/116150); Deoxyribonucleic acid (DNA) (/content /deoxyribonucleic-acid-/186500); Enzyme (/content/enzyme/236000); Gene (/content/gene/284400); Genetic mapping (/content/genetic-mapping/285200); Genomics (/content/genomics/801500); Human genome (/content /human-genome/757575); (/content/oncogenes/468950); Protein (/content/protein/550200); Tumor suppressor genes (/content/tumor-suppressor-genes/800950)

Although the original cervical cancer arose from a single cell or clone, the original cultured HeLa cells were not clonal. Cancer cells have a much higher rate of DNA mutation because they have gained the ability to evade normal cell-cycle checkpoints; thus, in many cases, they divide much more rapidly than do healthy cells. By the time the original several-millimeter-long piece of tissue was placed in culture, there were several variants of the original , with many of the offspring attaining additional mutations, some of which conferred the advantage of a more rapid growth rate. Since 1951, these cancer cells have acquired mutations, chromosomal rearrangements, and aneuploidy (the presence of an abnormal chromosome number), and there are now numerous variants of the original HeLa cell line. See also: Cancer cell metabolism; Cloning (/content/cancer-cell-metabolism-cloning/YB130040); Mutation (/content/mutation/441200)

In 2013, a research group headed by Lars Steinmetz of the European Molecular Biology Laboratory (EMBL) was concerned about the need for a better understanding of the HeLa genome. This group performed an extensive study of the HeLa Kyoto line and revealed 4.5 million single nucleotide variants (SNVs) and 0.5 million insertions, deletions, and interchromosomal translocations. In addition, 80% of the SNVs and insertions/deletions are likely common variations in the general human population. However, the most striking finding was the presence of , the shattering and rebuilding of a chromosome, resulting in thousands of chromosomal rearrangements in a single event. This chromothripsis could have contributed to the initial development of the cervical cancer, or it could have happened during the many years in . See also: Chromosome aberration (/content/chromosome-aberration/135000); Chromothripsis (/content /chromothripsis/YB140292) 3 of 7 7/26/17, 11:42 AM HeLa cells - AccessScience from McGraw-Hill Education http://accessscience.com/content/hela-cells/311600 HeLa cells accelerated the discovery and use of the Salk polio vaccine

The establishment of the HeLa cell culture greatly accelerated the rate of medical advancements (Fig. 2). There have been more than 75,000 scientific publications using HeLa cells. One of the most notable achievements, the development and testing of the first polio vaccine, was only possible in the 1950s with the use of HeLa cells.

Fig. 2 Time line: HeLa cells have facilitated scientific and medical advancements since 1951.

Polio is a debilitating disease that can cause paralysis and death. The first polio epidemic hit the United States in the 1890s. In 1952, at the height of the epidemic in the United States, there were nearly 60,000 new cases and 3000 deaths. Parents were so fearful of this disease that they allowed 1.8 million American children to participate in the largest trial of an experimental vaccine. The first polio vaccine was developed by Jonas Salk, who was already well known in the medical community for his work on the influenza vaccine. Earlier work on polio revealed three types of the virus, which could also easily infect HeLa cells. Viruses, such as polio, infect a cell and use it as a factory to make more viral particles. Given that HeLa cells grew so rapidly and were easily infected, they were an ideal factory to make enough polio virus for a nationwide vaccine. The vaccine developed by Jonas Salk is referred to as an “inactivated” vaccine because virus particles were killed with formaldehyde prior to injection into patients. Although the formaldehyde kills the virus, it minimally affects the viral proteins, thereby eliciting an immune response in the patient and the development of immunity (immunization) against the live virus containing these same proteins. See also: Cellular immunology (/content/cellular-immunology/118100); Immunity (/content/immunity/338100); Immunology (/content/immunology/338700); Polio eradication (/content/polio-eradication /YB130026)

Bioethics of HeLa cells

A discussion of these extraordinary scientific breakthroughs needs to be accompanied by the issue of patient consent. There is no evidence that Henrietta Lacks or a family member provided consent for her tumor to be removed for scientific study. At the time, there were no guidelines or laws in place in the United States that required patient consent. However, it now seems

4 of 7 7/26/17, 11:42 AM HeLa cells - AccessScience from McGraw-Hill Education http://accessscience.com/content/hela-cells/311600 unthinkable that a patient's cells have been bought and sold, used to develop thousands of patents, and made millions of dollars, and that a family's genetic information has been published, without any accountability to the patient and the patient's family. In fact, the Lacks family had no idea that their family member's cells were still alive until they were contacted by a geneticist looking to map HeLa genes in the 1970s. The geneticist had gotten Henrietta's name from a tribute article, following the death of George Gey in 1970. Henrietta's family was contacted repeatedly by writers and news outlets. Members of the Lacks family were not scientists and had very little understanding of biology, and they found themselves quite overwhelmed by the news that Henrietta's cells were still alive. The story of HeLa cells from the family's perspective has been chronicled in a popular book by Rebecca Skloot, The Immortal of Henrietta Lacks, published in 2010.

Moreover, Skloot communicated both her and the Lacks family's disapproval of the publishing of information about the HeLa genome, that is, Henrietta's genome, without the family's consent. This captured the attention of bioethicists and the director of the U.S. National Institutes of Health (NIH). Eventually, the NIH worked with the family and Skloot to negotiate special rules for HeLa cells. The family agreed that information about the HeLa genome sequence would be available to scientists through controlled access. In addition, all future information disseminated about the HeLa genome must be through controlled access. See also: Bioethics (/content/bioethics/YB000141)

Rebekah L. Waikel

Links to Primary Literature

A. Adey et al., The haplotype-resolved genome and epigenome of the aneuploid HeLa cancer cell line, Nature, 500(7461):207–211, 2013 DOI: https://doi.org/10.1038/nature12064 (https://doi.org/10.1038/nature12064)

L. M. Beskow, Lessons from HeLa cells: The ethics and policy of biospecimens, Annu. Rev. Genomics Hum. Genet., 17:395–417, 2016 DOI: https://doi.org/10.1146/annurev-genom-083115-022536 (https://doi.org/10.1146/annurev-genom- 083115-022536)

E. Callaway, Deal done over HeLa cell line, Nature, 500(7461):132–133, 2013 DOI: https://doi.org/10.1038/500132a (https://doi.org/10.1038/500132a)

K. L. Hudson and F. S. Collins, Biospecimen policy: Family matters, Nature, 500(7461):141–142, 2013 DOI: https://doi.org /10.1038/500141a (https://doi.org/10.1038/500141a)

J. J. M. Landry et al., The genomic and transcriptomic landscape of a HeLa cell line, G3 Genes Genet., 3(8):1213–1224, 2013 DOI: https://doi.org/10.1534/g3.113.005777 (https://doi.org/10.1534/g3.113.005777)

W. F. Scherer, J. T. Syverton, and G. O. Gey, Studies on the propagation in vitro of poliomyelitis viruses: IV. Viral multiplication in a stable strain of human malignant epithelial cells (strain HeLa) derived from an epidermoid carcinoma of the cervix, J. Exp. Med., 97(5):695–710, 1953 DOI: https://doi.org/10.1084/jem.97.5.695 (https://doi.org/10.1084/jem.97.5.695)

Additional Readings

R. Skloot, The Immortal Life of Henrietta Lacks, Crown Publishing, 2010

National Institutes of Health: HeLa Cells: A New Chapter in an Enduring Story (http://directorsblog.nih.gov/2013/08/07/hela- cells-a-new-chapter-in-an-enduring-story)

National Public Radio: “Henrietta Lacks”: A Donor's Immortal Legacy (http://www.npr.org/2010/02/02/123232331/henrietta- lacks-a-donors-immortal-legacy)

Smithsonian.com: Henrietta Lacks' “Immortal” Cells (http://www.smithsonianmag.com/science-nature/henrietta-lacks- immortal-cells-6421299/?no-ist)

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