Author: Celine Teh
In 1951, Henrietta Lacks visited the doctor in Maryland for vaginal bleeding and was diagnosed with cervical cancer. Despite undergoing radium treatment, she passed away 10 months later.
The story didn’t end here.
During her treatment, samples of her cancer cells were taken without her acknowledgement, brought to George Otto Gey, a cell biologist who was seeking for a long-lasting cell line, and eventually led to huge advances in medicine.
Normal cancer cells would divide 40-60 times before dying off (this process is called senescence), but Lacks’ cells were different - they seemed to replicate infinitely and double every 24 hours as long as proper nutrients are fed, thus labeled as “immortal” by the scientists. These cells, which would later contribute magnificently to biomedical breakthroughs, were dubbed as HeLa cells. (Henrietta Lacks).
For over 70 years, the HeLa cell line is the oldest cell culture that remains alive in the laboratory independently and mutated to form many subtle strains. However, many of their karyotypes (the number and appearance of chromosomes in a cell) were unusual. Normal somatic cells (body cells other than sex cells) would only have 46 chromosomes (diploid cells), yet Hela cells have between 70 to 90 chromosomes (hypotriploid cells), which includes extra chromosomes inserted by Human Papillomavirus (HPV) that causes cancer.
The discovery of HeLa cells was incidental, but its contributions were dearly wondrous.
Replacing Monkeys in Polio Vaccine Test
Poliomyelitis AKA polio is a contagious, crippling, and potentially lethal disease that is epidemic globally between 1840-1965. Poliovirus, the cause of polio, propagates easily by droplets in air or excretions and attacks the brain and spinal cord. Most people who caught the disease will not have any visible symptoms and act as carriers; some may experience flu-like symptoms such as sore throat and fever; and a minority will develop severe symptoms, mainly paralysis, and eventually result in death.
Polio is prevalent among children under 5 years old. Paralysis usually starts in the lower body and gradually spreads, causing stunted and deformed limbs.
In the 1950s, Jonah Salk, an American virologist and medical researcher, had a possible polio vaccine solution, but the problem is testing. The researchers could have use monkeys, but the trials ceased due to ethical problems and large expenses, so instead, they turned to HeLa cells. These cancerous cells were almost perfect, for not only they could be infected easily by the virus due to similar structure to human cells, but also, they would not be killed quickly as they replicate insanely fast.
In 1954, the first safe and efficient vaccine injection was developed. HeLa cells continued their contribution by mass-producing thousands of vaccines to save thousands of lives. Nowadays, all countries except two have declared polio-free.
This boy is given the Oral Polio Vaccine (OPV), another alternative that vaccinates orally. In spite of being banned in the United State, it serves successfully in other parts of the world.
HeLa Cell Vs. HPV
Human Papillomaviruses (HPV) are ancient viruses that target both humans and animals and cause common sexually transmitted infections. Over 200 types of HPV were identified, most of them will not show any symptoms and many people who had sex caught the virus without knowing it. Unfortunately, some ‘low-risk’ papillomaviruses cause genital warts while other ‘high-risk’ viruses are cancerous.
Since HeLa cells originate from cervical cancer, scientists decided to learn from them. In the 1980s, Harald zur Hausen from Germany observed that not all HPV patients developed cancer, but all patients with cervical cancer had HPV, and consequently established a conclusion that links the cause of cervical cancer to papillomavirus after 10 years of study in 1983. Two years later, the HPV vaccine was developed as one of the first anti-cancer vaccines and he was later rewarded Nobel prize in 2008.
HeLa Cell’s Immortality
You might be asking, how is it possible that HeLa cells divide nonstop tirelessly? And how is this linked to cellular aging? In 1989, Dr. Elizabeth Blackburn, Dr. Carol Greider, and Dr. Jack Szostak gave us the answer.
After comparing HeLa cells and normal cells, the researchers discovered the presence of telomeres. Telomeres are short genes, sequencing in 5'-TTAGGG-3', that repeats 100 to 1000 times at the end of the linear chromosomes. They act as protectives “caps” to prevent the fusion of chromosomes and prevent vital genetic information in the middle of the DNA from being lost during DNA replication. Thus, telomeres get corroded away with each round of cell division, and the cell ages.
The red parts were genes that stored important information that is necessary for the body to function properly. You can think as if the telomeres sacrifice themselves to protect the inner critical genes.
This explains why a normal body cell will obey the Hayflick limit, which is dividing 40-60 times through mitosis (the process of producing two identical daughter cells) before entering cell senescence and subsequently death.
HeLa cells, on the other hand, seem to have something that keeps replenishing the telomeres. After studying deep, telomerase was discovered as enzymes that extend the telomere by using RNA sequences as templates. It was observed that telomerase was active in cancer cells, so by inhibiting the activation of telomerase, doctors may be able to treat those cancers.
Later in 2008, Dr. Elizabeth Blackburn, Dr. Carol Greider, and Dr. Jack Szostak received the Nobel Prize for unshrouding the process of aging and discovering telomerase enzyme.
And Many More...
Besides participating in Nobel Prizes, HeLa cells were also used to study the effects of drugs, toxins, and hormones on cancer cells without human experiment; used to test the effects of radiation by sending them to space; used to identify and isolate HIV and Ebola virus; used to study the human genome, learn how viruses work and also innovate single-cell microscopic imaging method (another Nobel Prize in 2014 for Dr. Eric Betzig, Dr. Stefan W. Hell, and Dr. William E. Moerner).
Henrietta Lacks’ cells acted as catalysts that sped up the pace of biomedical and physiological research. However, it also brings discussion about the importance of consent before using someone's cells in order to conduct ethical research. While the research benefitted many, it is important to get consent before anyone's cells are used for research.
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