HeLa cells are the first and only immortal human cells ever cultured. It has been continuously cultured since 1951. HeLa cells are the only cells to survive in vitro.
Image:EnCor Biotechnology Inc./GerryShaw[CC BY-SA 3.0
History:
In 1951, a 31-year-old African-American woman by the name of Henrietta Lacks was brought to John Hopkins Hospital in Baltimore regarding a lump in her abdomen. Henrietta Lacks was a 31-year-old mother of five, but her name lives on in the form of a remarkable lineage of continually dividing cells that have achieved, to all intents and purposes, “immortality”. The diagnosis revealed that Lacks was suffering from a severely aggressive type of cancer i.e. adenocarcinoma of the cervix or adenoepidermoid tumor. During treatment, her doctor also removed a piece of her cancer tumor for culture studies without her knowledge or consent. The name 'HeLa" was derived from the first two letters of her first and last names.
Henrietta Lacks (1920-1951)Her identity was revealed in the 1970s.
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Three Major Characteristics:
(1)Cancerous:
HeLa cells were obtained from cancerous tissue, hence they are also cancerous cells and have different genetic characteristics as compared to normal human cells.
Just like other tumor cells, the HeLa cell contains many errors in its genetic material. Chromosome copies of the cell (HeLa) were shown to contain between 76 and 80 chromosomes with a good number of these being highly mutated as compared to the normal cell with 46 chromosomes.
According to recent studies, HeLa cells contain DNA of the Human Papillomavirus(HPV). HPV causes cervical cancer which acts by transferring its DNA into the host cells.
The resulting DNA produces a p53-binding protein that prevents p53 from mutation repair and tumor suppression. This was shown to contribute to changes in microRNA expression and ultimately to the prolific growth of the cells in culture.
(2) High Growth Rate:
Compared to normal cells, HeLa cells grow unusually fast even considering their cancerous state. In addition, they have proven easy to grow which in addition to their rapid growth (double in a 24 hour period), has made them ideal for large-scale research studies.
HeLa cells are also capable of easily contaminating and outgrowing other cell lines in culture because of their ability to multiply rapidly.
The unusual fast growth of HeLa cells has been attributed to the fact that Lacks had syphilis and HPV. The presence of the HPV genome causes suppression of the immune system thus allowing for the proliferation of the cells.
(3) Immortal:
Repetitive division of "immortal HeLa cells" has allowed researchers to cultivate them for the past 6 decades. This point of the cells has been provided for the expression of overactive telomerase that allows the rebuilding of telomeres in each division.
This has prevented cellular senescence which in turn has allowed cell division to continue for so long.
Cell culture (HeLa cells) - metaphase, prophase. Optical microscopy Doc. RNDr. Josef Reischig, CSc. [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]
Uses and Medical Breakthroughs:
(1) Study the Impact of Zero Gravity on Human Cells:
NASA placed HeLa cells in the Discoverer XVIII satellite on a mission to space.
In the year 1960, HeLa cells were also sent to space with the Korabl-Sputnik(Soviet Satellite).
The main rationale behind this was to observe the impact that zero gravity has on human cells. As a result, cells divided even faster in zero gravity. Hence, HeLa cells have played an important role in learning about space biology.
(2) Gene Mapping:
The technique by which researchers identify a given locus and distance between genes is known as Gene Mapping.
In the year 1965, HeLa cells were fused with mouse cells. In the process, researchers created the first human-animal hybrid cell which in turn set the stage for gene mapping.
Through this, scientists were able to observe the impact of different genes added to the DNA. Hence, the HeLa cell can be said to have assisted in the stage for mapping of the human genome.
(3) HPV Vaccination:
In 1984, the original sample of Lacks' biopsy revealed the presence of human papillomavirus, which allowed scientists to identify the virus as the cause of cervical cancer.
From the research, the scientists found out that by forcing its DNA into normal human cells, the virus took control of the cell forcing them to produce various proteins associated with cancer. This proved to be one of the most important discoveries in that it allowed other scientists to use the knowledge to develop vaccines against the virus.
Today, HPV vaccines are available in every country and protect young girls from the potential risk of getting HPV infections.
(4) Eradication of Polio:
HeLa cells also played a significant role in the eradication of polio. Polio was one of the most serious viral diseases that affected many people in the 1950s
As the HeLa cells were discovered at approximately the same period of time, they played a major role in the test as they were susceptible to infection, but could not be killed by the poliovirus.
Using HeLa cells, Salk was able to test the vaccine on a large scale and check its effectiveness and efficiency.
It was put forth that the vaccine was safe to use. Now, the polio vaccine is being to used all over the globe with excellent results.
(5) Chromosome counting:
In 1953, a small laboratory mix-up resulted in the HeLa cells being mixed with a liquid that caused chromosomes of the cell DNA to unwind. Because of this small accident, scientists👨🔬 were able to observe and count the number of chromosomes of the cell. This provided for the development of a staining technique that made it possible to efficiently count the number of chromosomes in human cells.
(6) Virology:
Different types of viruses have been tested to determine their action on human cells by using HeLa cells as test subjects.
(7) Improved laboratory practices:
The contamination of other cell lines because of HeLa cells demanded a need for better laboratory protocol internationally.
(8) Extended cell lifespan:
Researchers by studying HeLa cells are able to understand why some cells remain young and healthy over time.
Importance of HeLa Cells:
HeLa cells have a number of unique traits that make them very important for medical and biological studies.
Approximately 70,000 studies have been published that involved the use of HeLa cells and they are in wide use throughout the field of immunology and biotechnology.
As they are immortal cells, experiments can be conducted on clones of the original HeLa cells. This is lacking in normal, healthy human cells.
Disadvantages:
HeLa cells lack the normal human karyotype.
They can aggressively contaminate other cell lines.
As mentioned above the genome of these cells can contain as many as 80 chromosomes. Because of this, there are limitations as to the limit to which the cells can be used.
Despite this, the HeLa cells have been successfully used for several biological breakthroughs over the past 70 years.
Controversies related to Hela Cells:
The HeLa cell and research studies on the cells have raised an important issue regarding consent and privacy. This is because of the fact that Henrietta Lacks did not give consent or permission for her cells to be isolated and used for research studies. It also raised questions about the patient's privacy and confidentiality: Protecting the privacy of the patient and their medical information.
Conclusion :
Millions of HeLa cells, are still alive today. HeLa cells have continued to live healthy beyond her death in labs around the world. |
Even though these cells were the first cells that could be easily shared between Labs and multiplied in a lab setting, Johns Hopkins has never profited from the discovery or distribution of HeLa cells. They even do not own the rights to the HeLa cell line. Notably, they offered HeLa cells freely for scientific research.
In normal circumstances, cancer cells would divide a few times and die off before any notable studies could be done with them. But Hela cells just kept on dividing and dividing, just as long as they were fed with the right nutrients for them to grow.
The story of Lack’s life and the afterlife is explained in “The immortal life of Henrietta Lacks”, a novel was written by Rebecca Skloot.
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