Information

Is it safe to work with HeLa cells?

Is it safe to work with HeLa cells?


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

Hela cells are infected with HPV. So is it safe to work with them? What are the safety precautions?


Most guidelines for HeLa (and most cells of human origin) say they should be kept at a BSL2 level. For example, from a 2007 publication in Applied Biosafety:

Work with cell cultures from human or primate origin should generally be performed under BSL2 conditions. Containment level 1 may be considered if all manipulations occur in a Type II biosafety cabinet…

--Animal Cell Cultures: Risk Assessment and Biosafety Recommendations

ATCC general guidelines recommend BSL2 containment for the broad category covering HeLa:

  • Biosafety Level 2
    • Cell lines that harbor mycoplasma or any other BSL 2 agent (See: NOTE)
    • Cell lines exposed to or transformed by a primate oncogenic virus
    • Primate cell lines that contain viruses
    • Cell lines carrying a part of certain viral genomes, even if whole virus is not released from the cell

--ATCC® ANIMAL CELL CULTURE GUIDE: tips and techniques for continuous cell lines

Their specific page for HeLa also recommends BSL2, with the note "[Cells contain human papilloma virus]".

That said, HeLa cells have been very widely used, including for decades before modern lab safety practices were agreed on, and I'm not aware of any actual problem ever arising (including such amazing practices as injecting live HeLa cells into convict "volunteers" to see if cancers would appear - They did not).

So the answer to the question is that it is safe to work with HeLa cells, but that proper BSL2 lab practices should be followed.


Cell line selection? - suggestions (May/05/2006 )

I'm looking to work with a mammalian cell line that's easy to deal with and divides quickly. The purpose is for optimizing a protocol that ultimately could be performed in any cell type. Initially I want something easy to use before trying more difficult cases. The natural choice is HeLa cells, but I don't want the trouble of potential contamination in my other cells.

Any suggestions would be great.

Ya, I realize cells don't fly. But I'd rather be safe. When one cell can contaminate and ruin another culture, why work with it if you don't have to? It's common sense.

You mean you fear you would maybe end up contaminating your other cells with e.g. Hela's?

I'm working with a lot of cell lines these days (as do other people in our lab) and no one has ever encountered this problem. (to give you an example: for the moment I have Hela, 293-T, 3 different stably selected U87 cells, C8166, MT-4, MT-2, Jurkat, Hut-78, CEM and SupT1, and there are severall others in the same incubator/treated in the same laminar flow cabin and we had no contamination so far)

Jaknight, what do you mean by "easy to work with"? In terms of easy to transfect, I would definitely use 293 as they can be easily transfected with CaPO4 (which is also very cheap. ). However, they don't appear "nice", and some subtypes needs to be grown on collagen coated plates. NIH3T3 are very easy to grow and appear nicer. CHO are also nice - they are perfect for microscopy photos.
The bottom line is - specifiy the purpose of your work.

Vairus, that is my fear. I don't know how real it is, but a lot is made of the potential for hela contamination. Maybe I'm too paranoid.

What I need cells for is protein. I need lysate from a mammalian system. Don't need to transfect or do microscropy, just lysate. I suppose by easy to work with I mean not having to spend much time working on them. A simple protocol I guess, along with rapid and reliable growth.

Is there any reason why Hela cells would contaminate your other cells easier than NIH3T3, CHO, 293, any other cell line? If you follow basic cell culture procedures, there shouldn't be a problem. If you don't trust it, split your hela cells, or work with them, and afterwards, spray 70% EtOH in the flow cabin, shut it down, come back an hour later and start working with your other cells (though I don't think this is necessary at all).


1. Polio eradication

Jonas Salk had developed a polio vaccine in the early 1950’s but was struggling to find a way to test it in field trials as traditionally used rhesus monkey cells were too expensive for such a large-scale study. In 1952, HeLa cells were found to be both susceptible to, but not killed by polio, making them an ideal source of host cells. A HeLa cell culture production laboratory was set up at Tuskegee University, which at its peak was shipping in the region of 20,000 tube cultures per week. We are currently 99% of the way to eradicating polio globally.


How making a COVID-19 vaccine confronts thorny ethical issues

A COVID-19 vaccine comes with many ethical questions. Even before we ask who should get it, some are questioning how they should be developed.

Manjurul/iStock/Getty Images Plus

Share this:

Ethical concerns abound in the race to develop a COVID-19 vaccine. How do we ethically test it in people? Can people be forced to get the vaccine if they don’t want it? Who should get it first?

Tackling those questions demands that a vaccine exist. But a slew of other ethical questions arise long before anything is loaded into a syringe. In particular, some Catholic leaders in the United States and Canada are concerned about COVID-19 vaccine candidates made using cells derived from human fetuses aborted electively in the 1970s and 1980s. The group wrote a letter to the commissioner of the U.S. Food and Drug Administration in April, expressing concern that several vaccines involving these cell lines were selected for Operation Warp Speed — a multibillion-dollar U.S. government partnership aimed at delivering a COVID-19 vaccine by January 2021.

Sign up for e-mail updates on the latest coronavirus news and research

The group urged the FDA to instead provide incentives for COVID-19 vaccines that do not use fetal cell lines. But, as virologist Angela Rasmussen of Columbia University pointed out on Twitter, those other vaccines are being developed with scientific input from research using HeLA cells — which come with their own thorny ethical issues of consent.

Here’s how scientists and bioethicists are thinking about the cell lines they use as they develop COVID-19 vaccines.

What are cell lines, and what is their connection to vaccine research and development?

Cell lines are cultures of human or other animal cells that can be grown for long periods of time in the lab. Some of these cultures are known as immortalized cell lines because the cells never stop dividing. Most cells can’t perform this trick — they eventually stop splitting and die. Immortal cell lines have cheated death. Some are more than 50 years old.

Cell lines can be manipulated to become immortal. Or sometimes, immortality arises by chance. “Whenever people make primary cell cultures from different organs of different animals, every so often you just get … lucky, and some cultures just won’t die,” explains Matthew Koci, a viral immunologist at North Carolina State University in Raleigh. Such long-lasting cell lines go on to get studied, and studied some more. Some end up being used in labs around the world.

Immortalized cell lines are crucial for many different types of biomedical research, not just vaccines. They’ve been used to study diabetes, hypertension, Alzheimer’s and much more. Some are human cells, but many also come from animal models. For example, many COVID-19 studies — beyond just those related to vaccines — are using Vero cells, a cell line derived from the kidney of an African green monkey, Rasmussen says.

Two common immortalized cell lines go by the monikers HEK-293 and HeLa. HEK-293 is a cell line isolated from a human embryo that was electively aborted in the Netherlands in 1973. Catholic leaders and other antiabortion groups have objected to the use of HEK-293 in the development of some COVID-19 vaccine candidates. Cells derived from elective abortions, including HEK-293, have been used to develop vaccines, including rubella, hepatitis A, chickenpox and more. Other fetal cell lines, such as the proprietary cell line PER.C6, are also used in vaccine development, including for COVID-19.

These are HEK-293 cells, isolated from a human embryonic kidney sample in 1973. The sample was taken from a legal abortion in the Netherlands. Genes inserted into the cells then made them immortal, meaning they are able to divide forever. GerMan101/iStock/Getty Images Plus

HeLa cells are named after Henrietta Lacks, a Black tobacco farmer and mother of five from Virginia who was diagnosed with cervical cancer in 1951. That cell line comes from a sample taken from her cervix by researchers at Johns Hopkins University when she was undergoing treatment there. These cells have been used in development of vaccines including the polio and human papilloma virus, or HPV, vaccines. They’ve even contributed to our understanding of the human genome.

Are human immortalized cell lines necessary to make COVID-19 vaccines?

More than 125 candidate vaccines against COVID-19 are under development around the world. As of July 2, 14 were in human trials.

Those vaccines can be divided into a few different types. Some, such as RNA vaccines made by companies like Moderna (SN: 5/18/20), do not require a live cell, and thus, no cell line. But other types do require live cells during their production. That includes candidates that use the old-school method for developing vaccines: attenuation. This is “what Pasteur did” when he made the first vaccines against anthrax and rabies, explains Mark Davis, a virologist at Stanford University. “You grow a virus,” and over time the virus loses potency. “It’s still alive, but for some reason, it typically loses its more dramatic clinical effects.”

See all our coverage of the coronavirus outbreak

In another type of vaccine under development called viral-vector, the viral genes to produce immunity to the coronavirus are placed in another, harmless virus. That new combined virus is then grown in cells.

In vaccine development in general, “if we’ve got a virus that has to go through its life cycle, that happens in cell lines,” Koci says.

Many current vaccines, such as those for influenza, hepatitis B and HPV, are grown in nonhuman cell lines and even chicken eggs, bacteria or yeast. But human cell lines are especially useful when working with a new virus, Koci explains. “We don’t know what’s really important” yet in how the coronavirus replicates, he says. There’s no guarantee that a nonhuman cell line will work immediately. Over a few years of work, Koci says, a COVID-19 vaccine might be developed that could be grown in yeast or chicken eggs. But we don’t have years. “We want to make [the system] look as [much like] a human cell as we can.”

This is where immortal cell lines come in.

HEK-293 cells, for example, are especially useful for vaccine work, Rasmussen explains. It’s easy to put new viral genes in them, she says, and once they have the genes inside, HEK-293 cells can pump out large amounts of viral protein — exactly what’s needed to help people develop an immune response.

HeLa are also relatively easy to work with. They can be used to analyze how the coronavirus enters cells to hijack their machinery, for example. “It’s great to have them in the arsenal,” Rasmussen says. But, she says, it’s important to “think about their origins.”

What are some of the moral or ethical issues associated with cell lines such as HEK-293 and HeLa?

No matter what cell line is used, ethical questions will need to be answered. Cell lines derived from animals have all the ethical complications associated with animal research. But in the case of fetal cells, some anti-abortion groups are opposed to using anything that involves fetal cell lines anywhere in its development. The basis for the objection comes down to the idea that if you use anything derived from an abortion, you are in some small way complicit in the abortion itself.

Fetal cell lines have been widely used in basic science and clinical medicine for decades, says Nicholas Evans, a bioethicist at the University of Massachusetts Lowell. “Chances are if you have had a medical intervention in this country or pretty much any other country, you have benefited from the use of these cell lines in some way.”

Catholics got permission in 2005 and 2017 from the Vatican’s Pontifical Academy for Life to get vaccines that use historical fetal cell lines, if no alternatives are available. “The reason is that the risk to public health, if one chooses not to vaccinate, outweighs the legitimate concerns about the origins of the vaccine,” Evans explains. Of course, many people who are anti-abortion are not Catholic, and not all Catholics agree.

Henrietta Lacks (pictured) had cancer cells taken from her cervix in the early 1950s. Those cells went to a laboratory, without her knowledge or consent, and proved to have stunning powers of replication. Oregon State University/Crown Books/Flickr (CC BY-SA 2.0)

In the case of HeLa cells, the ethical problems began the day the cells were taken from Lacks, who was never told that her cells might be used for experimentation. “There was no informed consent. She wasn’t aware, and her family wasn’t aware,” says Yolonda Wilson, a bioethicist at Howard University in Washington, D.C. “The use of this Black woman’s body has I think contributed to a kind of cultural memory of mistrusting health institutions among Black folks,” she says. “It’s not this one-off … it’s a larger narrative of disrespecting Black patients, using Black people and Black bodies in experiments.”

In 2010, science writer Rebecca Skloot wrote a book about Lacks’ story. Since then, Wilson says, “Johns Hopkins University, at least, seems to recognize the ethical issues involved and [is] taking steps to repair some of the damage that has been done.” The university has worked closely with members of Lacks’ family to create scholarships, awards and symposiums about medical ethics. The university will also be constructing a building to be named in Lacks’ honor. But Wilson notes that damage still remains in the broader Black community.

How should those ethical issues be taken into account in COVID-19 vaccine development?

There’s no avoiding immortal cell lines. “Certainly I would expect they would be involved in some of the work, directly or not” in any vaccine that comes out, Rasmussen says. Even though HeLa cells or HEK-293 cells might not be used in the production of a particular COVID-19 vaccine, they are being used as scientists work to understand the virus. Some knowledge gained from those cell lines will go into a vaccine, at the very least.

But for HeLa cells in particular, Wilson says, there’s an opportunity for restorative justice. Given the disproportionate effects of the virus among Black people in the United States due to underlying health conditions and jobs that may expose them more to the virus (SN: 4/10/20), “special effort should be made to ensure that Black people are vaccinated once we know that this is safe,” she says. Latino people have been similarly hard-hit by COVID-19.

Wilson also notes that it’s an opportunity to help researchers think more about the history and context of their work. “It’s important not to act as though the science that happens is divorced from the communities in which it happens.”

The world is waiting anxiously for a COVID-19 vaccine. But as work to make a vaccine goes on, scientists need to think about the materials they use and why, Rasmussen says. “I think probably more [scientists] think about HeLa cells in this way,” she explains. “Many of us have read Skloot’s excellent book.” But that doesn’t mean that scientists could, or should, stop using HeLa cells entirely. In the end, she says, “you’re going to use the cell type that’s right for the experiment.”

Wilson agrees. Ethical considerations are not about weighing an ethical approach against the need to save lives. “That’s false framing,” she says. “It’s not: Be ethical or save lives. Ethics should guide us in thinking how to save lives.”

Trustworthy journalism comes at a price.

Scientists and journalists share a core belief in questioning, observing and verifying to reach the truth. Science News reports on crucial research and discovery across science disciplines. We need your financial support to make it happen – every contribution makes a difference.


A Family Consents to a Medical Gift, 62 Years Later

Henrietta Lacks was only 31 when she died of cervical cancer in 1951 in a Baltimore hospital. Not long before her death, doctors removed some of her tumor cells. They later discovered that the cells could thrive in a lab, a feat no human cells had achieved before.

Soon the cells, called HeLa cells, were being shipped from Baltimore around the world. In the 62 years since — twice as long as Ms. Lacks’s own life — her cells have been the subject of more than 74,000 studies, many of which have yielded profound insights into cell biology, vaccines, in vitro fertilization and cancer.

But Henrietta Lacks, who was poor, black and uneducated, never consented to her cells’ being studied. For 62 years, her family has been left out of the decision-making about that research. Now, over the past four months, the National Institutes of Health has come to an agreement with the Lacks family to grant them some control over how Henrietta Lacks’s genome is used.

“In 20 years at N.I.H., I can’t remember something like this,” Dr. Francis S. Collins, the institute’s director, said in an interview.

The agreement, which does not provide the family with the right to potential earnings from future research on Ms. Lacks’s genome, was prompted by two projects to sequence the genome of HeLa cells, the second of which was published Wednesday in the journal Nature.

Though the agreement, which was announced Wednesday, is a milestone in the saga of Ms. Lacks, it also draws attention to a lack of policies to balance the benefits of studying genomes with the risks to the privacy of people whose genomes are studied — as well as their relatives.

As the journalist Rebecca Skloot recounted in her 2010 best-seller, “The Immortal Life of Henrietta Lacks,” it was not until 1973, when a scientist called to ask for blood samples to study the genes her children had inherited from her, that Ms. Lacks’s family learned that their mother’s cells were, in effect, scattered across the planet.

Some members of the family tried to find more information. Some wanted a portion of the profits that companies were earning from research on HeLa cells. They were largely ignored for years.

Image

Ms. Lacks is survived by children, grandchildren and great-grandchildren, many still living in or around Baltimore.

And this March they experienced an intense feeling of déjà vu.

Scientists at the European Molecular Biology Laboratory published the genome of a line of HeLa cells, making it publicly available for downloading. Another study, sponsored by the National Institutes of Health at the University of Washington, was about to be published in Nature. The Lacks family was made aware of neither project.

“I said, ‘No, this is not right,’ ” Jeri Lacks Whye, one of Henrietta Lacks’s grandchildren, said in an interview. “They should not have this up unless they have consent from the family.”

Officials at the National Institutes of Health now acknowledge that they should have contacted the Lacks family when researchers first applied for a grant to sequence the HeLa genome. They belatedly addressed the problem after the family raised its objections.

The European researchers took down their public data, and the publication of the University of Washington paper was stopped. Dr. Collins and Kathy L. Hudson, the National Institutes of Health deputy director for science, outreach and policy, made three trips to Baltimore to meet with the Lacks family to discuss the research and what to do about it.

“The biggest concern was privacy — what information was actually going to be out there about our grandmother, and what information they can obtain from her sequencing that will tell them about her children and grandchildren and going down the line,” Ms. Lacks Whye said.

The Lacks family and the N.I.H. settled on an agreement: the data from both studies should be stored in the institutes’ database of genotypes and phenotypes. Researchers who want to use the data can apply for access and will have to submit annual reports about their research. A so-called HeLa Genome Data Access working group at the N.I.H. will review the applications. Two members of the Lacks family will be members. The agreement does not provide the Lacks family with proceeds from any commercial products that may be developed from research on the HeLa genome.

With this agreement in place, the University of Washington researchers were then able to publish their results. Their analysis goes beyond the European study in several ways. Most important, they show precisely where each gene is situated in HeLa DNA.

A human genome is actually two genomes, each passed down from a parent. The two versions of a gene may be identical, or they may carry genetic variations setting them apart.

“If you think of the variations as beads on a string, you really have two strings,” said Dr. Jay Shendure, who led the Washington genome study. “The way we sequence genomes today, for the most part we just get a list of where the genes are located, but no information about which ones are on which string.”

Dr. Shendure and his colleagues have developed new methods that allow them to gather that information. By reconstructing both strings of the HeLa genome, they could better understand how Ms. Lacks’s healthy cells had been transformed over the past 60 years.

For example, they could see how Ms. Lacks got cancer. Cervical cancer is caused by human papillomavirus infections. The virus accelerates the growth of infected cells, which may go on to become tumors.

Dr. Shendure and his colleagues discovered the DNA of a human papillomavirus embedded in Ms. Lacks’s genome. By landing at a particular spot, Ms. Lacks’s virus may have given her cancer cells their remarkable endurance.

“That’s one of the frequent questions that I and the Lacks family get whenever we talk about this stuff,” Ms. Skloot said. “The answer was always, ‘We don’t know.’ Now, there’s at least somewhat of an answer: because it happened to land right there.”

Richard Sharp, the director of biomedical ethics at the Mayo Clinic, said he thought the agreement “was pretty well handled.” But he warned that it was only a “one-off solution,” rather than a broad policy to address the tension between genome research and the privacy of relatives, now that recent research has demonstrated that it is possible to reveal a person’s identity through sequencing.

Dr. Sharp considered it impractical to set up a working group of scientists and relatives for every genome with these issues. “There’s absolutely a need for a new policy,” he said.

Eric S. Lander, the founding director of the Broad Institute, a science research center at Harvard and M.I.T., said resolving these issues was crucial to taking advantage of the knowledge hidden in our genomes.

“If we are going to solve cancer, it’s going to take a movement of tens of thousands, or hundreds of thousands, of patients willing to contribute information from their cancer genomes towards a common good,” Dr. Lander said. “We are going to need to have ways to have patients feel comfortable doing that. We can’t do it without a foundation of respect and trust.”


The Importance of HeLa Cells

Among the important scientific discoveries of the last century was the first immortal human cell line known as “HeLa”  — a remarkably durable and prolific line of cells obtained during the treatment of Henrietta’s cancer by Johns Hopkins researcher Dr. George Gey in 1951.

Although these were the first cells that could be easily shared and multiplied in a lab setting, Johns Hopkins has never sold or profited from the discovery or distribution of HeLa cells and does not own the rights to the HeLa cell line. Rather, Johns Hopkins offered HeLa cells freely and widely for scientific research.

Over the past several decades, this cell line has contributed to many medical breakthroughs, from research on the effects of zero gravity in outer space and the development of the polio vaccine, to the study of leukemia, the AIDS virus and cancer worldwide.

Although many other cell lines are in use today, HeLa cells have supported advances in most fields of medical research in the years since HeLa cells were isolated.


Cell Culture Contamination

Biological contamination is the dread of every person working with cell culture. When cultures become infected with microorganisms, or cross-contaminated by foreign cells, these cultures usually must be destroyed. Since the sources of culture contamination are ubiquitous as well as difficult to identify and eliminate, no cell culture laboratory remains unaffected by this concern. With the continuing increase in the use of cell culture for biological research, vaccine production, and production of therapeutic proteins for personalized medicine and emerging regenerative medicine applications, culture contamination remains a highly important issue.

Introduction

Cell culture is continuing a 60-year trend of increasing use and importance in academic research, therapeutic medicine, and drug discovery, accompanied by an amplified economic impact. 1,2 New therapies, vaccines, and drugs, as well as regenerated and synthetic organs, will increasingly come from cultured mammalian cells. With greater usage and proficiency of cell culture techniques comes a better understanding of the perils and problems associated with cell culture contamination. In the 21st century, there are better testing methods and preventive tools, and an awareness of the risk and effects of contamination requires that cell culturists remain vigilant undetected contamination can have widespread downstream effects.

Biological contamination: a common companion

The chance discovery of penicillin back in 1928 was one of those rare occurrences that most researchers can only dream about. After returning from a summer vacation during which he carelessly left a set of Petri dishes stacked up in a corner of his lab, Alexander Fleming discovered one of the 20th century&rsquos most powerful drugs. Fleming noticed that one of his bacterial cultures was contaminated with a fungus, but the colonies of Staphylococci immediately surrounding the fungus had been destroyed. The fungus was, of course, Penicillium notatum, and Fleming went on to discover antibiotics. This is, however, a very rare example of contamination actually advancing the path of scientific research. For the most part, the contamination of cultures remains every scientist&rsquos worst nightmare. Carolyn Kay Lincoln and Michael Gabridge summed up the problem in 1998: &ldquoCell culture contamination continues to be a major problem at the basic research bench as well as for bioproduct manufacturers. Contamination is what truly endangers the use of cell cultures as reliable reagents and tools.&rdquo 3

The biological contamination of mammalian cell cultures is more common than you might think. Statistics reported in the mid-1990s show that between 11 percent and 15 percent of cultures in U.S laboratories were infected with Mycoplasma species. 4 Even with better recognition of the problem and more stringent testing of commercially prepared reagents and media, the incidence of mycoplasma growth in research laboratory cultures was 23 percent in one recent study, 5 and in 2010 an astonishing 8.45 percent of cultures commercially tested from biopharmaceutical sources were contaminated with fungi and bacteria, including mycoplasma. 6

In the research laboratory, contamination is not just an occasional irritation, but it can cost valuable resources including time and money. Ultimately, contamination can affect the credibility of a research group or particular scientist publications sometimes must be withdrawn due to fears about retrospective sample contamination or reported results that turn out to be artifacts. In biopharmaceutical manufacturing, contamination can have an even more dramatic effect when entire production runs must be discarded. It is extremely important, therefore, to understand how sample contamination can occur and what methods are available to limit and, ultimately, prevent it.

What causes biological contamination?

Biological contaminants can be divided into two subgroups depending on the ease of detecting them in cultures, with the easiest being most bacteria and fungi. Those that are more difficult to detect, and thus present potentially more serious problems, include Mycoplasmas, viruses, and cross-contamination by other mammalian cells.

Bacteria and fungi

Bacteria and fungi, including molds and yeasts, are ubiquitous in the environment and are able to quickly colonize and flourish in the rich cell culture milieu. Their small size and fast growth rates make these microbes the most commonly encountered cell culture contaminants. In the absence of antibiotics, bacteria can usually be detected in a culture within a few days of contamination, either by microscopic observation or by their direct effects on the culture (pH shifts, turbidity, and cell death). Yeasts generally cause the growth medium to become very cloudy or turbid, whereas molds will produce branched mycelium, which eventually appear as furry clumps floating in the medium.

Mycoplasmas

Mycoplasmas are certainly the most serious and widespread of all the biological contaminants, due to their low detection rates and their effect on mammalian cells. Although mycoplasmas are technically bacteria, they possess certain characteristics that make them unique. They are much smaller than most bacteria (0.15 to 0.3 &mum), so they can grow to very high densities without any visible signs. They also lack a cell wall, and that, combined with their small size, means that they can sometimes slip through the pores of filter membranes used in sterilization. Since the most common antibiotics target bacterial cell walls, mycoplasmas are resistant.

Mycoplasmas are extremely detrimental to any cell culture: they affect the host cells&rsquo metabolism and morphology, cause chromosomal aberrations and damage, and can provoke cytopathic responses, rendering any data from contaminated cultures unreliable. In Europe, mycoplasma contamination levels have been found to be extremely high&mdashbetween 25 percent and 40 percent&mdashand reported rates in Japan have been as high as 80 percent.4 The discrepancy between the U.S. and the rest of the world is likely due to the use of testing programs. Statistics show that laboratories that routinely test for mycoplasma contamination have much lower incidence once detected, contamination can be contained and eliminated. Testing for mycoplasma should be performed at least once per month, and there is a wide range of commercially available kits. The only way to ensure detection of species is to use at least two different testing methods, such as DAPI staining and PCR. 5

Like mycoplasmas, viruses do not provide visual cues to their presence they do not change the pH of the culture medium or result in turbidity. Since viruses use their host for replication, drugs used to block viruses can also be highly toxic for the cells being cultured. Viruses that cause damage to the host cell do, however, tend to be self-limiting, so the major concern for viral contamination is their potential for infecting laboratory personnel. Those working with human or other primate cells must use extra safety precautions.

Other mammalian cell types

Cross-contamination of a cell culture with other cell types is a serious problem that has only recently been considered alarming. 7,8 An estimated 15 percent to 20 percent of cell lines currently in use are misidentified 9,10 , a problem that began with the first human cell line, HeLa, an unusually aggressive cervical adenocarcinoma isolated from Henrietta Lacks in 1952. HeLa cells are so aggressive that, once accidentally introduced into a culture, they quickly overgrow the original cells. But the problem is not limited to HeLa there are many examples of cell lines that are characterized as endothelial cells or prostate cancer cells but are actually bladder cancer cells, and characterized as breast cancer cells but are in fact ovarian cancer cells. In these cases, the problem occurs when the foreign cell type is better adapted to the culture conditions, and thus replaces the original cells in the culture. Such contamination clearly poses a problem for the quality of research produced, and the use of cultures containing the wrong cell types can lead to retraction of published results.

Sources of biological contaminants in the lab

In order to reduce the frequency of biological contamination, it is important to understand how biological contaminants can enter culture dishes. In most laboratories, the greatest sources of microbes are those that accompany laboratory personnel. These are circulated as airborne particles and aerosols during normal lab work. Talking, sneezing, and coughing can generate significant amounts of aerosols. Clothing can also harbor and transport a range of microorganisms from outside the lab, so it is crucial to wear lab coats when working in the cell culture lab. Even simply moving around the lab can create air movement, so the room must be cleaned often to reduce dust particles.

Certain laboratory equipment, such as pipetting devices, vortexers, or centrifuges without biocontainment vessels, can generate large amounts of microbial-laden particulates and aerosols. Frequently used laboratory equipment, including water baths, refrigerators, microscopes, and cold storage rooms, are also reservoirs for microbes and fungi. Improperly cleaned and maintained incubators can serve as an acceptable home for fungi and bacteria. Overcrowding of materials in the autoclave during sterilization can also result in incomplete elimination of microbes.

Culture media, bovine sera, reagents, and plasticware can also be major sources of biological contaminants. While commercial testing methods are much improved over those of earlier decades, it is paramount to use materials that are certified for cell culture use. Cross-contamination can occur when working with multiple cell lines at the same time. Each cell type should have its own solutions and supplies and should be manipulated separately from other cells. Unintentional use of nonsterile supplies, media, or solutions during routine cell culture procedures is the major source of microbial spread.

Contamination is a prevalent issue in the culturing of cells, and it is essential that any risks are managed effectively so that experiment integrity is maintained. Antibiotics can be used for a few weeks to ensure resolution of a known microbial contamination however, routine use should be avoided. Regular inclusion of antibiotics not only selects for resistant organisms, but also masks any low-level infection and habitual mistakes in aseptic technique.

The best approach to fighting contamination is for each person to keep records of all cell culture work including each passage, general cell appearance, and manipulations including feeding, splitting, and counting of cells. If contamination does occur, make a note of the characteristics and the time and date. In this way, any contamination can be pinpointed at the time it occurs and improvements can be made to aseptic techniques or lab protocols. In the next article of this series, we explore in more detail effective measures for contamination prevention, in particular the key role of the CO2 incubator.


The Incredible True Story of Henrietta Lacks &mdash the Most Important Woman in Modern Medicine

Henrietta Lacks was just 30 years old when she discovered a lump on her cervix while in her bathtub at home.

A private-care doctor referred her to Johns Hopkins Hospital for further testing and she was diagnosed with cancer in January 1951. Lacks, the wife of a steelworker and a mother of five, was treated with radiation and sent home, but she was hospitalized the following August. She died at the age of 31 two months later.

But that’s not where her story ends.

Without her knowledge or permission, doctors harvested samples of Lacks’ cervical tissue during her treatments and discovered her cancerous cells were not like any other they𠆝 seen — they were able to duplicate in labs and stay alive. This meant that the same sample of tissue could be tested multiple times for research, making her cell line immortal.

Research using Lacks’ cells helped spur numerous medical breakthroughs, include vaccines, cancer treatments and in vitro fertilization. But, for decades, her family was kept in the dark about her second life — and were never compensated for her contributions.

Henrietta Lacks

Now, Oprah Winfrey is executive-producing and starring in an HBO movie adaptation of The Immortal Life of Henrietta Lacks — the New York Times best seller by Rebecca Skloot that detailed how Lacks’ cells came to be known as the HeLa line, and how its existence has impacted the family she left behind.

“They did what they𠆝 never had another human cell do — duplicate itself and then duplicate itself and then duplicate itself,” Winfrey, who plays Lacks’ daughter Deborah in the movie, tells PEOPLE during the latest edition of The Jess Cagle Interview, excerpted in this week’s issue. (You can watch a video clip of it above.) “That’s why it’s called the Immortal Life of Henrietta Lacks, because her cells even now as we speak are still replicating somewhere in some tube.”

HeLa cells have contributed to medical advancements like the polio vaccine and have been used in gene mapping and AIDS and cancer research. And although Lacks died in 1951, her family didn’t know that her cells were still alive in labs all over the country. That all changed in 1973, when doctors requested blood samples from them after HeLa inadvertently contaminated other samples.

“Her family didn’t know that anyone had taken her cells until much later on. Once they discovered it, trying to figure out how it all happened — and how it unraveled and multi-millions of dollars, now billions of dollars, have been made off of the cells — is the story of the Immortal Life of Henrietta Lacks,” Winfrey says during the interview, which took place at The London West Hollywood in Beverly Hills.


Rabin Martin

Henrietta Lacks.

Most people have never heard of Henrietta Lacks. Yet, for more than 60 years, her cells have been used to help save countless lives.

Henrietta’s cells (more commonly known as HeLa cells), were taken without her consent when she was being treated for cervical cancer and were considered to be immortal unlike most other cells, they lived and grew continuously in culture. Henrietta Lacks is the woman behind the cells that revolutionized the medical field – helping develop the polio vaccine, cloning and numerous cancer treatments.

Last week, the Rabin Martin Book Club discussed the impact of HeLa cells and the ethical issues related to informed consent in medical practice. As a striking contrast to the immeasurable good made possible through research on HeLa cells, The Immortal Life of Henrietta Lacks offers a poignant depiction of the deep injustices she and her family experienced.

Since the discovery of HeLa cells, they have been bought and sold for incalculable profit, yet Henrietta’s family could never afford consistent health insurance despite suffering from chronic illnesses. While Henrietta Lacks’ cells were taken without her informed consent when she died in 1951, it wasn’t until 1971 that her family even became aware that her cells existed, and not until very recently that they were granted any real say as to how researchers used her cells.

The story of Henrietta Lacks is a prime example of the ethical tradeoffs the scientific community grapples with in pursuit of the common good, but it also signaled a turning point. It revealed a tangible opportunity for the public to voice concerns and demand appropriate measures be taken to learn from past mistakes.

In an act of uncanny timeliness, during the week of our discussion, three articles were published in top-tier news outlets about Henrietta’s cells. The rights and privacy of the Lacks family were formally addressed after German researchers published the full genome sequence of a HeLa cell line (which reveals all genetic predispositions) on a public database, without consulting the family. While their actions were not illegal, the controversy resulting from this breach of privacy prompted long overdue action on behalf of the National Institutes of Health (NIH). For the first time, it was decided that before any NIH-funded research on HeLa cells can be published, it needs to be approved by a board that includes two Lacks family members.

Although it took more than 60 years to fully acknowledge the origin and history of Henrietta’s cells, it is reassuring to see that efforts are now being made to ensure that her family’s best interest remains at the forefront of future research. To learn more about the incredible legacy of Henrietta Lacks and the ongoing efforts to safeguard her family’s privacy, read these recently-published pieces in The New York Times, The Guardian and NPR.


Prerequisites

Before beginning the lab investigation with my students I give a brief lecture on why cancer is not contagious. I introduce the concept of major histocompatibility markers (MHC) on the surface of cells and how the immune system uses these markers to recognize self from nonself. This is so that students (and their parents) don't feel nervous about our use of living cancer cells in the lab. In addition, I cover mitosis before the lab and use the lab to reinforce the concepts students have already learned about the cell cycle.

Next, I discuss how cancer is uncontrolled cell division and how tumors are formed from a mass of rapidly diving cancerous cells. I describe the chromosomal differences between a normal diploid cell and a cancerous cell. Cancer cells are aneuploid they have an incorrect number of chromosomes. HeLa cells have mutated so much in the past 60 years that they contain 82 chromosomes per cell (Macville et al., 1999). Because the cells are so different from normal human cervical cells and can survive and multiply outside the human body, some scientists have even proposed identifying the cells as a species, Helacyton gartleri (Van Valen & Maiorana, 1991).

Informing students how the HeLa cells were prepared prior to shipment will also help improve their understanding of mitosis. The cells are exposed to a colchicine, a plant-based toxin that inhibits microtubule function. Therefore, this toxin stops the cells in the middle of mitosis after the DNA has already been condensed into visible chromosomes.


The majority of the cells derived from vertebrates, with the exception of hematopoietic cell lines and a few others, are anchorage-dependent and have to be cultured on a suitable substrate that is specifically treated to allow cell adhesion and spreading (i.e., tissue-culture treated). However, many cell lines can also be adapted for suspension culture. Similarly, most of the commercially available insect cell lines grow well in monolayer or suspension culture.

Cells that are cultured in suspension can be maintained in culture flasks that are not tissue-culture treated, but as the culture volume to surface area is increased beyond which adequate gas exchange is hindered (usually 0.2 – 0.5 mL/cm 2 ), the medium requires agitation. This agitation is usually achieved with a magnetic stirrer or rotating spinner flasks.


Watch the video: Τι είναι τα βλαστοκύτταρα; (September 2022).


Comments:

  1. Shereef

    I apologise, but, in my opinion, you commit an error. I suggest it to discuss. Write to me in PM, we will communicate.

  2. Earle

    Wait for.

  3. Clay

    I advice you.

  4. Simba

    There is something in this. Thank you so much for your help in this matter, now I will not make such a mistake.



Write a message