4. The First Human Cell Lines: HeLa and WI-38

It should come as no surprise that, given their proclivity for rapid cell division, both cancer cells and fetal stem cells served as excellent starting materials to establish the first human cell lines used in biomedical research.

Derivation, Dissemination, Ownership, Privacy, and Profit¶

The first human cell line, HeLa, was established in 1951 using cells from the cervical cancer tissue biopsy of a young black woman and mother of five. Henrietta Lacks was being treated in the “colored” ward of Johns Hopkins Hospital in Baltimore for a particularly aggressive case of cervical cancer. Her health quickly deteriorated after her cells arrived in the lab of cell culturist George Gey. Although his research team had been trying to establish a stable human cell line for some time, most of these cells stopped dividing after one or two cell divisions. However, when Henrietta’s cells were placed in Gey’s signature growth medium of chicken blood, calf embryos, and human placental blood, they continued to divide. Gey’s assistant, Mary Kubicek, carried out the original culture. She named the cell line “HeLa” using the first two letters of the patient Henrietta Lacks’s first and last name, as was the custom for naming cell lines at the time. Gey distributed the cells at no charge to researchers around the world, creating a new field of cell biological research. To aid researchers in their work, many companies emerged to provide reagents and equipment for cell culture. Human tissue culture led to the birth of an enormous profit-making industry. Henrietta died of her cancer shortly after the biopsy was removed, but her cells live on to this day and a vial of HeLa cells can be purchased through the American Tissue Culture Collection (ATCC) by non-profit researchers for $359 (Skloot, 2010). (Slide 36 & 37: Henrietta Lacks, HeLa as Commodity)

For many years neither Henrietta nor her surviving family received recognition or compensation for use of her ground-breaking cells, but the cell line itself became known to biologists worldwide and led to countless discoveries and breakthroughs in cell biology, genetics, and oncology (the study of cancer) (Slide 38: The Way of All Flesh Film: Curtis, 1996). The cell line was so robust, became so well known and so widely used, that it came to contaminate and overgrow many subsequently created cell lines. Though the family never received financial benefits from derivation of the cell line, they did experience a loss of privacy when Henrietta’s image was released to the public in an article written by journalist Michael Rogers in Rolling Stone magazine, and more recently when researchers released the genomic sequence of the cell line in 2013 without permission from the family (Rogers, 2011; Hayden, 2013; Callaway, 2013).

The derivation of the first non-cancerous human cell line, WI-38, was also mired in ethical issues. Leonard Hayflick established WI-38 in 1962 using fetal lung tissue. The successful line was derived using tissue from a therapeutically aborted fetus obtained from a Swedish hospital, where abortions were legal at that time.

Fetus.Fetal Tissue.In Vitro.ZoomGraphic.

Though the HeLa cell line was named after the person from whom tissue was removed, WI-38 was named after the Wistar Institute in Philadelphia, where Hayflick was employed. Ethical conduct regarding the derivation of the cells has been questioned by the pro-life stance against fetal tissue research, and the distribution of the cells has led to challenges regarding equitable ownership and financial benefits for all stakeholders.

The fetal origin of WI-38 continues to plague pharmaceutical companies that use it to propagate rubella vaccines. Anti-abortion activists have publicized its origin and advocate strongly against the rubella vaccine, which is cultured in these cell lines (Children of God for Life). The 1960s was the height of the rubella epidemic, affecting 1% of all births in Philadelphia General Hospital. Due to the severe developmental defects associated with fetal infection, some women would terminate their pregnancy to avoid this consequence (College of Physicians Philadelphia). Stanley Plotkin, the scientist who developed the rubella vaccine, says “I am fond of saying that the rubella vaccine has prevented thousands more abortions than have ever been prevented by Catholic religionists.” Debbi Vinnedge, the executive director of Children of God for Life, advocates against using a fetal cell line to propagate the vaccine. Her position is in line with the Vatican, which recommends that if no alternative exists it is “lawful” for the parents to have their children immunized with vaccines made using WI-38, in order to avoid health risks to their children and the population. However, the Vatican also encourages that faithful Catholics “employ every lawful means in order to make life difficult for the pharmaceutical industries” that use cell lines derived from fetuses (Wadman, 2013).

With respect to ownership and profit, the WI-38 line has a complicated history that provides lessons for contemporary cell line derivation and banking. Shortly after Hayflick derived the cell line, he accepted a contract by the federal government to disseminate the cells, distributing them to other researchers for a nominal shipping cost ($15). As Hayflick prepared to take a new faculty position, discussion concerning the transport and location of the cell line ensued. The NIH and his home institution, the Wistar Institute, decided to renegotiate the terms of the contract and split the original frozen cell line stocks among the three stakeholders. Hayflick felt pressured to agree, but instead “absconded with the cells” and continued to distribute them to researchers working in the non-profit and commercial sectors, placing any money received in a “Cell Culture Fund” until ownership could be rightfully ascertained. By May 1975, the fund totaled $66,000, and as a consequence of an NIH investigation, Hayflick’s name was released, tarnishing his reputation. Hayflick retaliated and sued the government and ultimately the case was settled out of court (Wadman, 2013; Azvolinsky, 2015).

Video: Providing Researchers with WI-38 Cell Cultures. Web of Stories. Link

Hayflick, in a letter to the editor of the journal Science, reminds the scientific community that ownership of the WI-38 cell line was determined by important legal and social relationships within the biotechnology sector as it relates to government support. He mentions several significant events that contributed to this victory: the Supreme Court ruling that biological material can be patented; passage of the Bayh-Dole Act, which states that federally funded research is not the sole ownership of the government and that royalties can be shared with institutions receiving federal funding; an executive order issued by President Reagan in 1983 that permitted the private sector to hold patent rights on inventions developed under federal contracts and grants; and the emergence of a biotechnology industry that was built on federally funded, basic scientific research (Hayflick, 2013).

That fetal cells and cancer cells were both used to establish the first human cell lines sheds some light on a natural phenomenon as well. In the 1990s, there were some anecdotal evidence that fetal cells could be responsible for extending the lives of women who had been pregnant, and in some cases address diseases of degeneration. Studies in mice have revealed that fetal cells migrate to their mother’s tissues, creating fetal microchimerisms. Because of their high regenerative power, fetal cells can not only promote health in pregnant women, but they could also promote cancer, based on the “immortality” phenotype (Boddy et al., 2015; Zimmer, 2015).

Immortality: Telomerase, HPV, and the Hayflick Limit¶

With two different kinds of human cell lines established, scientists could identify the factors responsible for the immortality property. Prior to establishing WI-38, Hayflick had cultured fetal cells and found that they would divide 50-70 times in cell culture, and adult cells only about 40-60 times, before halting cell division. This cap on the number of times a non-cancerous cell will divides is termed the Hayflick Limit, a theoretical proposition that Hayflick put forth in 1961 based on the hypothesis that something related to aging was responsible for this limit (Slide 39: Hayflick Limit). The term “senescence” is used to describe the molecular processes that contribute to the cessation of cell division, resulting in eventual cell death (Azvolinsky, 2015).

Though there are many molecular processes involved with cell aging, a particularly important one is the protection and maintenance of vital DNA information. Cells protect sequences of DNA from loss by adding a “bumper” of non-coding DNA to the ends of chromosomes (Slide 40: Telomerase Activity). These bumper DNA sequences are referred to as telomeres (the prefix “tele” in Greek means far off or at a distance). Without these non-coding bumpers, cells gradually lose DNA with every round of cell division, due to the nature of DNA replication processes. The existence of such bumper DNA was hypothesized by Hermann Muller and Barbara McClintock in the 1930s, and in 1982, Elizabeth Blackburn and Jack Szostak identified the bumper sequence. In 1984, Blackburn’s student Carole Greider discovered the enzyme responsible for maintaining the bumper DNA sequence and called it “teloVmerase.” In 2009, the three scientists received the Nobel Prize for these discoveries that demonstrated that vital DNA information that codes for proteins is not lost as cells replicate their DNA during multiple cell divisions, as DNA loss only occurs in the telomeric region, which does not code for protein. An illustrated overview of these discoveries and processes can be accessed from the Nobel Prize Website where an Illustrated Presentation reviews molecular steps involved in this fundamental mechanism of DNA maintenance.

Video: Cellular Reprogramming (iPSC). Stem Cells Across Curriculum. Link

Telomerase activity is highly controlled and is only present in cells that need to undergo continual cell division, such as those of the developing embryo, fetus, and adult stem cells in regenerating tissues like bone marrow, gut, skin, and liver. Most cells of the body inactivate telomerase, and this is one reason that our tissues become less efficient as we age, because not all tissues are capable of regenerating cells indefinitely. Telomerase is also active in cancer cells, and its activation is considered one of the hallmarks of cancer progression (Hanahan & Weinberg, 2011. Telomerase activation can be induced by viral infection, as is the case with the HeLa cell line, which is known to be infected with many copies of Human Papilloma Virus 18 (HPV18) (Ambros & Karlic, 1987).

Not surprisingly, the addition of genes such as hTERT that encode molecular components necessary for telomerase function can increase the efficiency of DNA reprogramming ten-fold when creating induced pluripotent stem cell (iPSCs) (Malik, & Mahendra, 2013). hTERT can be used to derive iPSCs from adult body cells that have been reprogrammed to be non-specialized through induction, or exposure to genetic or environmental inducers (Malik, & Mahendra, 2013). iPSCs can undergo rapid cell division providing stem cell researchers with a source of material for regenerative medicine that does not involve the ethically contentious termination of embryos, and can be more immunologically appropriate, as the donor and recipient can be the same person. In more recent research, hTERT has been found to be activated in 73% of cancers and, in some cases, as a result of promoter methylation, suggesting that the promoters can no longer bind to repressor proteins leaving the gene active (Anonymous, 2017, Kakui and Ullman, 2017; Barthel et al., 2017).

As mentioned earlier, activation of telomerase and telomere lengthening is essential for stem cell maintenance, however, macro environmental factors, such as stress, diet, and exercise can influence the rate of telomere shrinking. Based on this work, Blackburn and others have founded a company, Teloyears, that measures telomere length in circulating blood cells. Because hematopoietic stem cells reside in the bone marrow and give rise to a fresh supply of blood cells, telomere length in these cells can serve as biomarker for “biological” age, and by inference the activity of telomerase in this stem cell population. More recent studies have suggested the exercise and meditation can prevent telomere shortening and Teloyears is designed to be used to monitor how life experiences affect telomere length.