The Origins and Importance of HeLa Cells

This woman may have helped to save your life – yet you probably don’t even know her name.

Henrietta Lacks was an African-American woman who lived with her husband and five children in Baltimore County, USA. In 1951, at just 31 years of age, she was diagnosed with a highly aggressive form of cancer called cervical adenocarcinoma. Lacks was immediately admitted into John Hopkins Hospital. Unbeknownst to her, however, her doctor collected samples of her healthy and cancerous cervical tissue while she was under anaesthesia for a cancer treatment. He then sent them to a research laboratory in the hospital. No permission was ever asked from either her or her family. They had been kept in the dark.

This research laboratory was run by Dr. George Otto Gey, a cell biologist working at John Hopkins. At the time, Dr. Gey wanted to create an immortal human cell line, which could be used for scientific research in the future. A cell line is a population of cells from a multicellular organism which is derived from a single ancestral cell. Cell lines can grow and replicate indefinitely in vitro, as long as it is provided with sufficient space and nutrients. This is extremely useful for medical research as scientists have a large supply of clonal cells, allowing them to test the effects of different medications on cells with the exact same genotype. This would ensure that this variable remains constant throughout experiments, ensuring that the results are reliable and accurate.

Although an immortal cell line may seem easy to culture, scientists had been struggling to achieve this for years up until the 1950s, due to a biological constraint known as the Hayflick limit. While it appears that a cell population would replicate indefinitely in the presence of unlimited nutrients, most human cells in the lab actually stop replicating after approximately 40 to 60 cycles, which is known as senescence. To understand why the Hayflick limit exists, we have to take a closer look at the cell cycle and how a cell undergoes division.

Before a cell undergoes mitosis, its DNA must first replicate in order to ensure that its daughter cells have the same genetic information as the parent cell. Due to the nature of DNA replication, every time a DNA strand is duplicated, small segments at the end of each strand cannot be replicated along with the rest of the molecule. This is because an enzyme called DNA polymerase is unable to add deoxyribonucleotides after the RNA primer is excised. Thus, every time a cell divides, its DNA strands become shorter and shorter. Scientists call this the end replication problem. Obviously, this is a major concern, because if our DNA continues to shorten without stopping, then vital genetic sequences would not be replicated, leading to the collapse of our bodily functions. To counteract this, our DNA has long, repetitive sequences at either end called telomeres. These telomeres are non-coding, which means that they do not code for anything. Instead, they act as buffer regions by protecting vital genetic sequences of the DNA from being cut away as chromosomes shorten, preventing any disruption to cellular functions. Basically, telomeres ‘shield’ our genes from being eroded due to the shortening of chromosomes after every mitotic division, similar to how the aglet of a shoelace prevents it from unravelling.

However, these telomeres have a limited length, and regular human cells don’t express the enzymes required to regenerate them, known as telomerases. Therefore, once the telomeres are entirely removed from DNA molecules, they cannot be replaced anymore. Mitosis would thus become deadly for our cells, as further rounds of DNA replication could cause vital genes to be eroded, to irregular cellular functions. As a result, the cell enters a state of senescence, where it is still alive and performing its functions, but it stops actively dividing. This is what causes cells to stop replicating after 40-60 cycles in the lab. In fact, it is the shortening of telomeres, along with the accumulation of genetic mutations within somatic cells, that causes aging within humans.

Due to the Hayflick limit, Dr. George Otto Gey was also struggling to create an immortal cell line. However, there was something… different about Henrietta Lacks’s cells. Dr. Gey and his assistants noticed that unlike other cell cultures, which eventually died out after a while, Lacks’ cells divided continuously at an unprecedented rate, doubling every 20-24 hours. This is because her cells were infected with a human papillomavirus (HPV), which was the cause of her cancer. HPV is a disease which can cause cancer in various parts of the body upon infection. It is caused by viruses belonging to the family Papillomaviridae, which consists of over 200 unique species. When the virus entered Lacks’ cervical cells, it integrated its genome into the nuclear DNA of her cells. Some of its genes coded for E6 and E7 proteins, which not only degraded two major tumour-suppressor proteins, p53 and retinoblastoma, but also activated the hTERT gene, which codes for telomerase. Due to their high levels of telomerase, Lacks’ cells were thus able to replicate telomeric DNA. This counteracted the shortening of chromosomes after each cell division, allowing them to effectively bypass the Hayflick limit and divide indefinitely. Furthermore, the inactivation of tumour-suppressor proteins, which normally prevent excessive cell division, caused a dysregulation of the cell cycle’s checkpoints. As a result, the cells were able to divide uncontrollably. Thus, Dr. Gey managed to create the first ever immortal human cell line. He named it HeLa; naming it after the first two letters of Henrietta Lacks’s first and last names.

Even though Henrietta Lacks died in 1951 due to cervical cancer, her cells live on to this day, and are still extensively used in biomedical research. When Dr. George Otto Gey created the HeLa cell line, he realised its potential for research and medicine, and thus freely donated vials of HeLa cells to his scientific peers, purely for the benefit of science. HeLa cells are excellent for research, since they are robust, easy to grow, and replicate continuously. For instance, they have been used to investigate physiological conditions and the impact of medications on human cells. Due to their rapid proliferation, scientists can easily obtain a large sample size, thus being able to quickly obtain new cells when needed. Furthermore, since HeLa cells are of human origin, they are able to more accurately reflect how our own cells would react to different medicines or diseases, as compared to animal cell lines. Given how optimal these cells are for scientific research, the HeLa cell line has been used for countless experiments, leading to an astounding amount of discoveries. By infecting HeLa cells with different viruses, for example scientists are able to see the effects of viral infections, vaccines, and other types of treatments on human cells. This has not only led to the invention of the polio vaccine, but also to many groundbreaking discoveries about how viruses like HIVs, HPVs and the Zika virus reproduce. HeLa cells have even been sent to space in order to investigate the impact of space travel on living cells and tissues! They have even enabled advancements in gene mapping, enabling us to discover the physical locations of various genes on chromosomes. In fact, ever since their discovery, HeLa cells have been used in over 100,000 scientific publications.

However, even though the creation of the HeLa cell line has been integral for medical research, it has been shrouded in controversy and has sparked many bioethical debates. This is because Henrietta Lacks never gave consent for samples of her cervical tissue to be collected, nor did she have any knowledge of this. Furthermore, her family received no form of financial compensation whatsoever, even as HeLa cells and their discoveries became increasingly popular and commercialized. In fact, Henrietta Lacks’s story highlights the unfortunate lack of informed consent in medicine during the 1950s. At that time, it was very common for doctors to collect samples from their patients and use it for research purposes without their patients’ knowledge or consent, especially since there was very little communication between doctors and patients about their treatment plans. This was especially prevalent in wards for colored patients. Henrietta Lacks was treated in the colored ward of the John Hopkins Hospital, as that was the only place where she could receive treatment for free. The effects of racial discrimination were apparent in medicine; African-Americans were often treated as second-class citizens and their rights were often diminished. This painful history is best exemplified by the barbaric Tuskegee Experiment, in which African-American men with syphilis were left untreated as a control group in order to study the disease’s effects. This study was conducted despite the fact that penicillin already had been demonstrated to be a completely safe and effective treatment. Over 100 men died as a result of this experiment.

Due to the controversy surrounding Lacks’ case, many new laws and ethical frameworks have been established regarding the rights of patients. The Common Rule, for example, is an American federal policy that was established in 1991 and remains as an important part of medical ethics. It stipulates that doctors must inform patients if they plan to use any details of the patient's case for research, thus ensuring informed consent. Furthermore, institutional review boards must evaluate the research project before its inception to ensure that it is ethical, and research participants must be informed of all the risks and benefits before participating in these experiments, so that they can make informed decisions.

Ultimately, there is no doubt that Henrietta Lacks and her cells have made a massive contribution to research, both in terms of scientific advancement and bioethics. The creation of the HeLa cell line was one of the most notable inventions of the 20th century, since it laid the foundation for countless other discoveries that have greatly benefitted humanity. Moreover, Henrietta Lacks’ story has brought a lot of attention to the topic of informed consent in healthcare. It has sparked informative and meaningful conversations on topics that had previously been neglected, and it has raised questions that people had been too afraid to address. This has led to a sociocultural shift in society where there is a greater emphasis on patient ethics and rights. Not only have researchers ensured that their experiments are ethical, but the general public has also stood up to protect their rights. This has helped to foster a safer and more egalitarian society. (1745 words)

References:

1. HELA Cell Line | Embryo Project Encyclopedia. (2020). https://embryo.asu.edu/pages/hela-cell-line

2. Jarry, J. (2022). Immortality in the lab: How one woman’s cells changed medicine and ethics. McGill University Office for Science and Society. https://www.mcgill.ca/oss/article/history/immortality-lab-how-one-womans-cells-changed-medicine-and-ethics

3. Scientific, T. F. (2026). EXPI293TM PRO Expression System: higher yields across a wider variety of proteins. The Scientist. https://www.the-scientist.com/expi293-pro-expression-system-higher-yields-across-a-wider-variety-of-proteins-73981

4. MacDonald, A., & MacDonald, A. (2024). HELA cells: key discoveries and the science of their immortality. Cell Science From Technology Networks. https://www.technologynetworks.com/cell-science/lists/hela-cells-key-discoveries-and-the-science-of-their-immortality-305036