Laboratory-grown human cell cultures are often used in biomedical research and in the development of new treatments. Among the many cell lines, one of the most famous is HeLa. These cells, imitating the human body in vitro (“in vitro”), are “eternal” - they can endlessly divide, the results of research using them are reliably reproduced in different laboratories. On their surface, they carry a fairly universal set of receptors, which allows them to be used to study the action of various substances, from simple inorganic ones to proteins and nucleic acids; they are unpretentious in cultivation and tolerate freezing and conservation well.
These cells got into big science quite unexpectedly. They were taken from a woman named HEnrietta LAcks, who died shortly thereafter. But the cell culture of the tumor that killed her turned out to be an indispensable tool for scientists.
Let's find out more about this …
Henrietta Lacks
Henrietta Lacks was a beautiful black American woman. She lived in the small town of Turner in South Virginia with her husband and five children. On February 1, 1951, Henrietta went to Johns Hopkins Hospital - she was worried about the strange discharge that she periodically found on her underwear. The medical diagnosis was terrible and merciless - cervical cancer. Eight months later, despite surgery and radiation therapy, she died. She was 31 years old.
While Henrietta was in Hopkins Hospital, the attending physician sent the tumor cells obtained with the help of a biopsy for analysis to George Gay, head of the tissue cell research laboratory at Hopkins Hospital. At that time, the cultivation of cells outside the body was only at the stage of formation, and the main problem was the inevitable cell death - after a certain number of divisions, the entire cell line died.
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It turned out that the cells designated "HeLa" (an acronym for Henrietta Lax's first and last name) multiplied much faster than cells from normal tissues. In addition, malignant transformation made these cells immortal - their growth suppression program was turned off after a certain number of divisions. This has never happened before in vitro with any other cells. This opened up unprecedented perspectives in biology.
Indeed, never before that moment could researchers consider the results obtained in cell cultures to be completely reliable: all experiments were carried out on dissimilar cell lines, which eventually died - sometimes even before they could get any results. And then scientists became the owners of the first stable and even eternal (!) Cell line, which adequately mimics the properties of the organism. And when it was discovered that HeLa cells could even survive mailing, Gay sent them out to colleagues across the country. Very soon, the demand for HeLa cells grew and they were replicated in laboratories around the world. They became the first "template" cell line.
It so happened that Henrietta died on the very day when George Gay spoke in front of television cameras, holding a test tube with her cells. He stated that an era of new perspectives in drug discovery and biomedical research has begun.
Why are her cells so important?
And he was right. The cell line, identical in all laboratories of the world, made it possible to quickly obtain and independently confirm more and more new data. We can safely say that the giant leap in molecular biology at the end of the last century was due to the ability to cultivate cells in vitro. Henrietta Lacks' cells were the first immortal human cells ever grown in artificial culture media. HeLa trained researchers to cultivate hundreds of other cancer cell lines. And although in recent years the priority in this area has shifted towards cultures of cells of normal tissues and induced pluripotent stem cells (Japanese scientist Shinya Yamanaka received the Nobel Prize in Physiology or Medicine 2012 for the discovery of a method for returning cells of an adult organism to an embryonic state),nevertheless, cancer cells remain the accepted standard in biomedical research. The main advantage of HeLa is uncontrollable growth on simple nutrient media, which allows large-scale research at a minimum cost.
Since the death of Henrietta Lacks, her tumor cells have been continuously used to study the molecular patterns of the development of various diseases, including cancer and AIDS, to study the effects of radiation and toxic substances, to draw up genetic maps and a huge number of other scientific problems. In the biomedical world, HeLa cells have become as famous as laboratory rats and petri dishes. In December 1960, HeLa cells were the first to fly into space in a Soviet satellite. Even today, the scope of the experiments carried out then by Soviet geneticists in space is striking. The results showed that HeLa do well not only in terrestrial conditions, but also in zero gravity.
Without HeLa cells, the development of the polio vaccine developed by Jonas Salk would have been impossible. By the way, Salk was so confident in the safety of the vaccine he received (weakened polio virus) that, as proof of the reliability of his medicine, he injected himself, his wife and three children.
Since then, HeLa has been used for cloning (preliminary experiments on transplanting cell nuclei before cloning the famous Dolly sheep were carried out on HeLa), for testing methods of artificial insemination and thousands of other studies (some of them are shown in the table).
Besides science …
The personality of Henrietta Lacks herself was not advertised for a long time. For Dr. Gay, of course, the origin of HeLa cells was not a secret, but he believed that privacy was a priority, and for many years the Lacks family did not know that Henrietta's cells were famous throughout the world. The mystery was revealed only after the death of Dr. Gay in 1970.
Recall that the standards of sterility and techniques for working with cell lines were in their infancy at that time, and some errors surfaced only years later. So in the case of HeLa cells - after 25 years, scientists found that many of the cell cultures used in research, originating from other types of tissues, including breast and prostate cancer cells, were infected with more aggressive and tenacious HeLa cells. It turned out that HeLa can move with dust particles in the air or on insufficiently washed hands and take root in cultures of other cells. This caused a big scandal. Hoping to solve the problem by genotyping (sequencing - a complete reading of the genome - at that time was still only planned as a grandiose international project),one group of scientists tracked down Henrietta's relatives and asked for DNA samples from the family in order to map the genes. Thus, the secret was revealed.
By the way, the Americans are still more worried about the fact that Henrietta's family never received compensation for using HeLa cells without the consent of the donor. To this day, the family lives in not very good prosperity, and financial assistance would be very useful. But all inquiries run into a blank wall - there have been no respondents for a long time, and the Medical Academy and other scientific structures predictably do not want to discuss this topic.
On March 11, 2013, a new publication added fuel to the fire, where the results of the complete genome sequence of the HeLa cell line were presented. Again, the experiment was conducted without the consent of Henrietta's descendants, and after a brief ethical controversy, full access to genomic information was only allowed to professionals. Nevertheless, the complete genomic sequence of HeLa is of great importance for subsequent work, allowing the use of the cell line in future genomic projects.
Real immortality?
The malignant tumor that killed Henrietta made her cells potentially immortal. Did this woman want immortality? And did she get it? If you think about it, a fantastic sensation arises - a part of a living person, artificially multiplied, endures millions of tests, “tastes” all drugs before they are tested on animals, is racked to the core by molecular biologists all over the world …
Of course, all this has nothing to do with "life after life." It is foolish to believe that in the cells of HeLa, incessantly tormented by insatiable scientists, there is at least some part of the soul of an unhappy young woman. Moreover, these cells can be considered human only in part. In the nucleus of each HeLa cell, there are 76 to 82 chromosomes due to the transformation that took place in the process of malignancy (normal human cells contain 46 chromosomes), and this polyploidy periodically raises debates about the suitability of HeLa cells as a model of human physiology. It was even proposed to isolate these cells into a separate, close to human species, called Helacyton gartleri, in honor of Stanley Gartler, who studied these cells, but this is not seriously discussed today.
However, researchers are always mindful of the limitations that need to be borne in mind. First, HeLa, despite all the changes, still remain human cells: all their genes and biological molecules correspond to human ones, and molecular interactions in the vast majority of cases are identical to the biochemical pathways of healthy cells. Secondly, polyploidy makes this line more convenient for genomic studies, since the amount of genetic material in one cell is increased, and the results are clearer and more contrasting. Thirdly, the wide distribution of cell lines around the world allows you to easily repeat the experiments of colleagues and use the published data as a basis for your own research. Having established the basic facts on the HeLa model (and everyone remembers that this is even a convenient, but only a model of the body),scientists are trying to replicate them on more adequate model systems. As you can see, HeLa and similar cells represent the foundation for all science today. And, despite the ethical and moral disputes, today I want to honor the memory of this woman, since her involuntary contribution to medicine is invaluable: the cells left after her saved and continue to save more lives than any doctor can do.
Cellular record holders
The immortality of HeLa cells is associated with the consequences of infection with the human papillomavirus HPV18. The infection caused triplodia of many chromosomes (the formation of three copies instead of the usual pair) and the splitting of some of them into fragments. In addition, the infection increased the activity of a number of cell growth regulators, such as the genes telomerase (a regulator of cell death) and c-Myc (a regulator of the activity of synthesis of many proteins). Such unique (and random) changes have made HeLa cells the record for growth rate and resistance even among other cancer cell lines, of which there are several hundred today. In addition, the obtained changes in the genome turned out to be very stable and in laboratory conditions remain unchanged throughout the past years.
Soon after Henrietta's death, the HeLa factory began to be created, a large-scale enterprise that would make it possible to grow trillions of HeLa cells weekly. The factory was built for one single reason - to stop polio.
By the end of 1951, the world's largest polio epidemic in history. Schools were closed, parents were in a panic. A vaccine was urgently needed. In February 1952, Jonas Salk of the University of Pittsburgh announced that he had developed the world's first polio vaccine, but could not offer it to children until he had thoroughly tested its safety and effectiveness. This required cultured cells in such huge industrial volumes that they had never been produced before.
The National Endowment for Infant Paralysis (NFIP), a charity founded by President Franklin Delano Roosevelt, who was himself paralyzed by polio, was preparing the largest field trial of a polio vaccine in medical history. It was planned that Salk will vaccinate two million children, and the NFIP will take blood from them to test if they are immune. However, millions of neutralization tests will have to be carried out when the serum of vaccinated children is mixed with live polio viruses and cultured cells. If the vaccine works, then the serum of the vaccinated children should block the polio virus and protect the cells. Otherwise, the virus infects cells and causes damage that scientists can see under a microscope.
The difficulty was that monkey cells were used for neutralization tests, which died during this reaction. This was a problem - not because they took care of animals (this was not discussed then, unlike our time), but because monkeys were expensive. Millions of neutralization reactions with monkey cells would cost millions of dollars, so the NFIP frantically looked for a cell to cultivate that could multiply en masse and cost less than monkey cells.
The NFIP turned to Guy and several other cell culture specialists for help, and Guy realized that this was truly a gold mine. As a result of the charity, the NFIP received an average of $ 50 million annually in donations, and his director wanted to donate most of this amount to cell cultivators so that they could find the way to mass produce cells that everyone has dreamed of for many years.
The offer came at the right time: by a happy coincidence, shortly after the call from NFIP asking for help, Guy realized that Henrietta's cells did not grow like any human cells he had met so far.
Most cells in culture grow in a single layer in the form of a clot on the surface of the glass, which means that the free space quickly runs out. Increasing the number of cells is labor intensive: Scientists have to scrape the cells out of the test tube over and over again and distribute them in several new containers to give the cells new space to grow. As it turned out, HeLa cells are very unpretentious: they did not need a glass surface to grow, they could grow by floating in a culture medium that was continuously stirred by a "magic device" - an important technology developed by Guy, today it is called suspension cultivation. This meant that HeLa cells were not limited by space like everyone else; they could share as long as the culture medium remained. The larger the container with the culture medium,the more cells grew. This discovery meant that if HeLa cells are susceptible to the polio virus (because some cells are insensitive to it), it would solve the problem of mass production of cells and help avoid testing the vaccine on millions of monkey cells.
And so in April 1952, Guy and his colleague on the NFIP Advisory Committee, William Scherer - a young research fellow at the University of Minnesota who recently defended his thesis - tried to infect Henrietta's cells with the polio virus. A few days later, they discovered that HeLa was actually more susceptible to the virus than any other cultured cells so far. And they realized they had found exactly what the NFIP needed.
They also realized that before they could start mass-producing any cells, they needed to find a new way to transport them. The airplane drop-off that Guy used was great for sending multiple vials to colleagues, but too costly for large volumes. Billions of cells grown will be useless if those cells cannot be delivered to the right place. And scientists started experimenting.
In 1952, on Memorial Day, Guy took several tubes of HeLa and enough culture medium to last several days for the cells to live, and placed them in a tin container lined with a cork and filled with ice to avoid overheating. Providing all this with detailed care instructions, he sent Mary to the post office to send a parcel with test tubes to Scherer in Minnesota. Due to the holiday, all post offices in Baltimore were closed, except for the central office in the downtown area. To get there, Mary had to change several trams, but in the end she got there. So did the cages: four days later, the package arrived in Minneapolis. Scherer placed the cells in an incubator and began to grow. For the first time, living cells have successfully postponed dispatch.
In the months that followed, to make sure the cells could withstand the long journey in any climate, Guy and Scherer sent HeLa tubes by plane, train, and truck across the country, from Minneapolis to Norwich, New York, and back. The cells died in only one test tube.
When the NFIP learned that HeLa was susceptible to the polio virus and could be grown in large quantities at low cost, an agreement was immediately made with William Scherer to oversee the development of the HeLa Distribution Center at Tuskegee University, one of the country's most prestigious universities for black. The NFIP chose Tuskegee University for this project because of Charles Bynum, director of the foundation's Negro Activities. Bainum - a science teacher and civil rights activist and the nation's first black foundation director - wanted to host the center in Tuskegee for hundreds of thousands of dollars in funding, many jobs, and training opportunities for young black scientists.
Within a few months, a team of six black scientists and laboratory technicians had built a factory in Tuskegee never seen before: industrial steel autoclaves for steam sterilization lined the walls, huge vats of mechanically stirred culture media stood in rows, incubators full of glass bottles for cell cultures, and automatic cell dispensers are tall, with long, thin metal handles that inject HeLa cells into one tube after another. Each week, the team in Tuskegee prepared thousands of liters of Guy's recipe culture medium, mixing salts, minerals and blood serum from the scores of students, soldiers and cotton farmers who responded to advertisements in the local newspaper for donating blood for money.
Several technicians served as a quality control pipeline and viewed hundreds of thousands of HeLa cell cultures every week to ensure they were viable and healthy. Others sent cells to researchers across the country on a strict schedule at 23 polio vaccine testing centers.
Ultimately, the Tuskegee team grew to 35 scientists and lab technicians who produced 20,000 HeLa tubes a week - about 6 trillion cells. It was the very first cell factory, and started with a single HeLa tube that Guy sent to Scherer in a first test package shortly after Henrietta's death.
Using these cells, scientists were able to prove the effectiveness of the Salk vaccine. Soon, the New York Times published photographs of black women bent over microscopes, examining cells and holding HeLa tubes in their black hands. The headline read:
Black scientists and laboratory technicians, many of them women, used the cells of a black woman to save the lives of millions of Americans - most of whom were white. And it was at the same university and at the same time that government officials were conducting the infamous syphilis study.
Initially, the Tuskegee center only supplied HeLa cells to laboratories that tested polio vaccines. However, when it became clear that there were enough HeLa cells for everyone, they began to be sent to all scientists who were ready to purchase them for ten dollars plus the cost of airmail. If scientists wanted to find out how cells would behave in a particular environment, how they would react to a certain chemical, or how they build a certain protein, they turned to HeLa cells. Although they were cancerous, they had all the fundamental characteristics of normal cells: they built protein and communicated with each other like normal cells, dividing and producing energy, ferrying and regulating genetic material, and were susceptible to infections, which made them an optimal tool. to synthesize and study everythingwhat is possible - including bacteria, hormones, proteins and especially viruses.
Viruses multiply by injecting particles of their genetic material into a living cell. The cell radically changes its program and begins to reproduce the virus instead of itself. When it came to growing viruses, as in many other cases, the malignant nature of HeLa only made them more useful. HeLa cells grew much faster than normal cells and therefore brought results faster. HeLa cells were the workhorse - hardy, inexpensive, and ubiquitous.
The timing was right. In the early 1950s, scientists were just beginning to understand the nature of viruses, and when Henrietta's cells appeared in laboratories around the country, researchers began to infect them with all kinds of viruses - herpes, measles, mumps, chickenpox, equine encephalitis - to study how the virus penetrates into cells, multiplies in them and spreads.
Henrietta's cells helped lay the foundations of virology, but that was just the beginning. In the first years after Henrietta's death, having received the first test tubes with her cells, researchers around the world were able to make several important scientific discoveries. First, a team of scientists used HeLa to develop methods to freeze cells without damaging or altering them. Through these methods, cells began to be shipped around the world in a proven and standardized way that was used to transport frozen food and frozen semen for livestock production. It also meant that scientists could keep cells in between experiments without worrying about nutrition and sterility. However, most of all scientists were pleased with the fact that freezing made it possible to "fix" cells in their most diverse states.
The cell was frozen like pressing the pause button: division, metabolism and all other processes stopped and resumed after defrosting, as if you simply pressed the start button. Scientists could now pause cell development at any frequency during the experiment to compare the response of certain cells to a drug after one, two or six weeks. They could observe the state of the same cells at different stages of development: the scientists hoped to see exactly at what point a normal cell growing in culture becomes malignant - a phenomenon called spontaneous transformation.
Freezing is the first in a list of amazing improvements in tissue culture thanks to HeLa. Another breakthrough is the standardization of the cell culture process, an area that until then had been a mess. Guy and his colleagues complained that they spent too much time preparing the culture medium and keeping the cells alive. What worried them most, however, was that because everyone used different ingredients to form the culture medium, different recipes, different cells and different techniques, and few knew about their colleagues' methods, it was difficult or nearly impossible to replicate anyone’s experiment. And repetition is a necessary part of science: a discovery is not considered valid if others cannot repeat and get the same results. Guy and others feared that without standardization of methods and materials, tissue culture could stagnate.
For a long time, scientists believed that human cells contain forty-eight chromosomes - strands of DNA inside cells that contain all of our genetic information. However, the chromosomes stuck together, and it was not possible to accurately count them. In 1953, a Texas geneticist mistakenly mixed the wrong liquid with HeLa and some other cells. This accident was lucky. The chromosomes in the cells swelled and separated from each other, and for the first time scientists were able to examine each of them in detail. This accidental discovery was the first in a string of discoveries that allowed two researchers from Spain and Sweden to discover that a normal human cell contains forty-six chromosomes.
Now, knowing how many chromosomes a person should have, scientists could tell that someone has more or less, and with the help of this information, diagnose genetic diseases. Soon enough, researchers around the world began to identify chromosomal abnormalities. So, it was found that patients with Down syndrome had an extra chromosome in the twenty-first pair, those suffering from Klinefelter syndrome had an extra sex x chromosome, and in patients with Shereshevsky-Turner syndrome, this chromosome was absent or was defective.
With all these new developments, the demand for HeLa cells increased and the Tuskegee center was no longer able to meet it. The owner of Microbiological Associates - a military man named Samuel Reeder - was not knowledgeable, but his business partner Monroe Vincent was himself a researcher and understood how big the potential market for cells was. Cells were needed by many scientists, and few of them had the time or opportunity to grow them in sufficient quantities on their own. The researchers just wanted to buy the cells, so Reeder and Vincent decided to use HeLa as a springboard to launch the first industrial commercial center to supply cells.
It all started with a cell factory - as Reeder called it. In Bethesda, Maryland, in the middle of a spacious warehouse that was once a factory for the production of Fritos chips, he erected a glass enclosed space and installed a moving conveyor belt with hundreds of built-in test tube racks. Outside the glass room, everything was organized almost like in Tuskegee - huge vats of culture medium, only even larger. When the cages were ready for shipment, a loud bell rang and all the factory workers, including the mailing department employees, interrupted current business, washed properly in the sterilization room, put on a robe and cap, and lined up at the conveyor belt. Some filled test tubes, others closed them with rubber stoppers, sealed them or placed them in a portable incubator,where they were stored until packing for shipment.
Laboratories like the National Institutes of Health were Microbiological Associates' largest customers, and they continually ordered millions of HeLa cells on a set schedule. However, scientists from anywhere in the world could place an order, pay less than fifty dollars, and Microbiological Associates immediately sent them tubes of HeLa cells. Reader signed an agreement with several major airlines, and therefore, wherever the order came, the courier sent the cells on the next flight, they were picked up at the airport and delivered to the laboratories by taxi. This is how the multi-billion dollar industry of human biomaterials was born step by step.
Henrietta's cells could not restore youthfulness to women's necks, but cosmetic and pharmaceutical companies in Europe and the United States began to use them instead of laboratory animals to test new products and drugs that caused cell destruction or damage. Scientists cut HeLa cells in half, and proved that cells can live after removing the nucleus, they used them to develop methods of injecting substances into the cell without killing it. HeLa was used to understand the effects of steroids, drug chemotherapy, hormones, vitamins, and environmental stress; they were infected with tuberculosis, salmonella and the bacteria that cause vaginitis.
In 1953, at the request of the US government, Guy took Henrietta's cells with him to the Far East to study the hemorrhagic fever that was killing American soldiers. He would inject HeLa into rats and see if they got cancer. For the most part, however, he was trying to move from HeLa to growing normal and cancer cells from one patient in order to compare them with each other. He could not escape the seemingly endless questions about HeLa and cell culture from other scientists. Every week, scientists repeatedly visited his laboratory with requests to teach them the technique, and he often had to travel around the world, helping to establish work on cell multiplication.
Many of Guy's colleagues insisted that he publish the research data and receive the recognition it deserves, but he was always discouraged from being busy. He worked at home all night long. He was late with the deadline for preparing documents for a grant, often delayed for months with replies to letters, and once paid the salary of a deceased employee for three months before someone noticed it. Mary and Margaret grumbled for a year to get George to publish anything about growing HeLa; in the end he wrote a short paragraph for the conference. After that, Margaret herself wrote about his work in his place and fussed about publication.
By the mid-1950s, many scientists were already working with cell cultures, and Guy was tired. He wrote to friends and colleagues: "Someone has to figure out how to call what is happening now, say, 'The world has gone crazy with this tissue growing and its possibilities." I hope that at least some of this chatter about tissue cultivation has a foundation and has benefited people … and most of all I want this hype to subside a little …"
Guy was annoyed by the hype around HeLa. After all, there were other cells, including those he himself had grown: A. Fi. and D-1 Re, named for the patients from whom the original sample was taken. Guy offered them to scientists all the time, but these cells were more difficult to grow and therefore they never enjoyed the popularity of Henrietta's cells. Guy no longer distributed HeLa as the companies took over the task, however he did not like the fact that HeLa cultivation was completely out of his control.
Ever since the Tuskegee manufacturing plant went into operation, Guy has sent letters to scientists in an attempt to limit the uses of HeLa cells. He once complained in a letter to his old friend Charles Pomerat that everyone around, including the staff of Pomerat's laboratory, used HeLa for research, which Guy was "more capable" of, and some had already been done, but had not yet published the results … Pomerat wrote in response:
As for your… disapproval of the widespread study of the HeLa strain, I don't see how you can hope to slow things down, for you yourself have spread this strain so widely that it can now be purchased for money. This is almost the same as asking people not to experiment on golden hamsters!.. I understand that it was only thanks to your kindness that HeLa cells became available to the public. So why, in fact, now you think that everyone wants to grab a piece for themselves?
Pomerat believed that Guy should have completed his own research on HeLa before "releasing [HeLa] to the general public, for after that culture becomes a universal scientific property."
However, Guy did not. As soon as HeLa cells became "universal scientific property", people began to wonder who was their donor.
