August 24, 2001

Lives of the Stem Cell
Overcoming Alchemy
Migration from Mad Town

Lives of the Stem Cell

Last Christmas, I received a feedback message on one of my earlier columns, "Connecting Points: A Pilot and a Surgeon" about the collaboration between aviator Charles Lindbergh and surgeon Alexis Carrel. In the 1930s Lindbergh and Carrel built a glass perfusion pump that was able to prolong the life of animal organs in culture.

The message was from a professor emeritus of pharmacy at Georgetown University. He wrote to take issue with my understanding of the famous cell line that Carrel created. In addition to being a Nobel Prize-winning surgeon, Carrel was the father of tissue culture science. Here is what I wrote:

"On January 17, 1912 Carrel placed a slice of heart muscle from a chick embryo in a culture medium. The cells lived until 1946.... They stopped pulsating two years after Carrel himself died of a heart attack after being associated with the collaborationist Vichy government in France.

"For many years, Carrel's laboratory hosted a birthday party for the historic heart cells on January 17th, celebrating over the pulsating culture."

What a wonderful story about the foundation of experimental biology in the 20th century: The cell line.

But apparently I bought into a fiction rather than a fact. "The immortality of Carrel's chick embryo heart cells has long since been recognized to be legend, at best, and fraud, at worst," the professor wrote, listing several references for me to check for myself. "The story can be one of simple laboratory error or political intrigue -- the latter referring to the relatively unsubstantiated proposition that one of his lab techs was trying to do him in because of his politics."

I investigated and responded a bit sheepishly: "Thanks for setting me straight about Carrel and the chick embryonic heart cells. Thirty-four years does seem a bit long to keep a cell line going."

I knew something about cell lines from my close association with chromosome scientist Jorge J. Yunis. I knew about the pioneering work of Leonard Hayflick in the early 1960s. Hayflick is known world wide for his studies of cells in culture, first at the Wistar Institute at the University of Pennsylvania and later at the University of California in San Francisco [UCSF]. Try as he might, he could not reproduce Carrel's experiment.

"What about Carrel's immortal chicken cells?" asked Boyce Rensberger of the Washington Post in a story published in 1998. The article was adapted from Rensberger's book Life Itself: Exploring the Realm of the Living Cell [Oxford University Press, 1997]. "Hayflick could not confirm Carrel's result. His own cultured chicken cell lines invariably became extinct after 15 to 35 rounds of cell division. Scientists now generally believe that Carrel's cell line was not really continuous. His method of feeding cells used serum prepared from chicken blood in a way that inadvertently included fresh chicken cells. The old cells, it now seems obvious, must have been dying but, unbeknownst to Carrel, were being replaced repeatedly with new cells."

Most human cell lines, unless they are tumor lines, begin to die off after about 50 cell divisions. The 50-division threshold is known today as the "Hayflick limit" after the discoverer of the aging process in human cells. Today their lifespan can be maximized by growing them on "feeder layers" of mouse embryonic cells. The mouse cells have some unknown substances that the human cells like.

"We showed [in 1961] that when normal human embryonic cells are grown under the most favorable conditions, aging and death is the inevitable consequence after about fifty population doublings," Hayflick wrote in a review published in 1997. "We showed that the death of cultured normal human cells was not due to some trivial cause involving medium components or culture conditions but was an inherent property of the cells themselves."

All this came to mind in the wake of President Bush's announcement August 9th that federal funds would be made available for research on human embryonic stem cells but only on cells from cell lines that already exist. In a quick search before his announcement, National Institutes of Health policy official Lana Skirboll found 60 cell lines derived from human embryos.

Researchers were surprised at the number of existing embryonic stem cell lines NIH identified as available for research. One of the surprised is Catherine Verfaillie, professor of medicine and director of the University of Minnesota's Stem Cell Institute where she works on adult stem cells. "I thought there were only about a dozen out there,'' she told the Associated Press.

Her colleague John Gearhart, a professor of medicine at the Johns Hopkins University Medical School in Baltimore, questioned whether 60 embryonic stem cell lines is enough.

"We know that there is a shelf life to these, and we are very concerned when we will need more lines, what happens then?'' Gearhart said on the CBS Sunday interview program "Face the Nation.'' "And I do think it will be sooner rather than later.''

Another stem cell researcher, Douglas Melton, chairman of the department of molecular and cellular biology at Harvard University, told the New York Times in June that human embryonic cell lines "are immortal. They can be propagate forever."

But Melton himself has had problems with the half-dozen lines he has access to, lines developed by an Israeli research team. "Only one works well," he told the Washington Post after Bush's announcement. "The others, they have all kinds of different problems. They either don't grow well, or they differentiate spontaneously, kind of like popcorn popping before you've added heat."

Melton has been working behind the scenes for several years to expand the supply of embryonic stem cells for research, and his efforts are bearing fruit. Today, Melton announced that Boston IVF, the nation's largest fertility clinic, will provide leftover human embryos to Harvard University, which in turn will provide stem cells extracted from the embryos to researchers at other institutions free of charge. The private Howard Hughes Medical Institute will finance the arrangement, according to a story in the Boston Globe.

In light of Bush's announcement, federal funds will not be available to researchers working on these cells.

Overcoming Alchemy

David Anderson, a biology professor at the California Institute of Technology, wrote in the New York Times in July that it is one thing to say that stem cells have the potential to do something. "It is quite another to figure out how to reveal that potential and control it. What seems lost in the current debates is a sense of how difficult it really is, in practice, to get stem cells to do what you want them to do."

Much of stem cell research "is still basically alchemy," he wrote.

Alchemy! But consider that one of the main goals of alchemy, which holds a hallowed place in the annals of occult art and pseudoscience, was to discover an agent that would lead to immortality, the "transcendence motif."

Whether stem cells carry such a motif, even for extending life through new treatments and cures, may depend on their viability and performance in a petri dish. And that may depend on the repetitive DNA sequence TTAGGG [thymine, thymine, adenine, guanine, guanine, guanine].

A nondescript sequence of letters to us is a magical cap to human chromosomes, the string-like bodies in the cell nucleus that carry the genes. In a earlier column, "Shoestrings, Telomeres, and the Great Chain of Being" [August 31, 1999], I used the metaphor of shoestrings (specifically those in my daughter's shoes) to illustrate the point:

"The shoestring, you see, has come to symbolize certain features of our biological destiny.... One of the reasons is that the shoestring comes outfitted with little plastic sleeve around its ends to prevent its unraveling and to facilitate lacing. The chromosomal equivalent of the plastic sleeve is its 'telomere' at each tip (from the Greek telos meaning 'end' and meros meaning 'part').

The 'unraveling' effect I experienced waiting for my daughter to tie her shoes is the sequential loss of telomeric DNA, a normal consequence of the aging of cells. With each cell division, the cell's chromosomal telomeres become shorter -- until the cell dies."

The mystery of chromosomal telomeres was unraveled in the 1980s by, among others, Elizabeth Blackburn, a colleague of Hayflick's at UCSF. She discovered the RNA-protein enzyme telomerase which rebuilds telomeres by adding the repetitive sequence TTAGGG, allowing cells to keep on dividing.

The chromosomal recapping action of telomerase is one of the factors that scientists are presumably leaning on when they refer to embryonic stem cell lines as "immortal." The lines include five cell lines at the University of Wisconsin in Madison. UW stem cell scientist James Thomson developed the lines in 1998 and then collaborated with the Geron Corporation of Menlo Park, California, which makes telomerase. Geron is also collaborating with stem cell researchers at John Hopkins, Cornell and other universities.

According to Geron, embryonic stem cells, unlike adult stem cells, make plenty of their own telomerase and thus have the capacity for "self-renewal." Their chromosomes get a regular recapping. Plus their chromosomes, up until now at least, appear normal under the microscope. The chromosomes in some cell lines develop all sorts of problems, including deletions and additions of genetic material and bizarre configurations.

But human embryonic stem cell lines are only a few years old, and their mysteries reign. Thomson's cells, for example, begin to differentiate or commit to certain cell-type pathways if the feeder layer of mouse embryonic cells is withdrawn. Yet no one knows what is in the mouse cells that keeps the human cells growing and dividing in their most primitive state.

Even if the cells were to stop making telomerase and Geron furnished it from its own supplies, no one knows if the cells will remain, in Bush's words, "robust and viable for research."

No one knows if they will get along swimmingly in a cellular "Fountain of Youth" and if they are willing to cooperate with curious people in white coats.

Migration from Mad Town

Last May, I spent two days at the State Historical Society of Wisconsin. I was there to investigate the migration of my family from Fond du Lac to south central Minnesota after the Civil War.

Wisconsin's historical society is on the University of Wisconsin campus in Madison. It is charged by statute with "collecting, advancing, and disseminating knowledge of Wisconsin and of the trans-Allegheny West."

In brief, the society is one of the nation's leading archives for the Great Migration to the American West during the 19th century.

While in Madison, I was the dinner guest of a former dean of the University of Wisconsin Medical School. I naively asked him what it was in Madison that produced the likes of Donna Shalala and Tommy Thompson, the former and the current U.S. Secretary of Health and Human Services. Shalala was chancellor of the University of Wisconsin System when he was dean; Thompson was governor.

Though he raised his family in Rochester, Minnesota where he was chief of pathology at the Mayo Clinic, he has made Madison his retirement home. I detected a tincture of boosterism in his response of the sort that you might expect from a Wisconsin Badger fan, and I dropped the line of inquiry.

A few weeks ago Washington Post columnist David Broder wondered as well in "There's something about Mad City that generates superlative public servants."

"Maybe it's something in the waters of Lake Mendota. Maybe it's just their personal makeup. But the two folks who migrated from Madison, Wis., to the top job at the Department of Health and Human Services...have set a remarkable standard for leadership in that largest of all civilian agencies."

Today, the city's university on the shore of Lake Mendota is the center of another hoped-for migration: The migration of intellectual property embodied in human embryonic stem cells lines. But how and under what circumstances will that migration take place to researchers in the U.S.? At what cost? And to what effect on the future of medicine?

The Wisconsin Alumni Research Foundation (WARF) owns United States patent 6,200,806, a claim to the human embryonic stem cell. The patent covers both the method of isolating the cells and the cells themselves, putting the university, some say, in the driver's seat when it comes to embryonic stem cell research and resulting therapies.

WARF may have rights not yet specified on most or all of the 60 lines NIH has located, according to a story in the New York Times ["Patent Laws May Determine Shape of Stem Cell Research," Aug. 17, 2001].

Less than a week after Bush's momentous announcement, WARF filed suite against the Geron Corporation.

WARF sued Geron Corp. in U.S. District Court in Madison, asking the court "to prevent Geron from interfering with its ability to contract with other firms to develop new types of stem cells," according to a report published in the Milwaukee Journal Sentinel.

UW-Madison Chancellor John Wiley said in a statement: "This action will ensure that future research is conducted in the public interest by preserving the broadest access to these original stem cell lines." A WARF spokesman said: "This is not about money. We are not asking for any money. It is about access."

It was as if WARF officials had read and taken to heart a passage in Jeremy Rifkin's latest book The Age of Access subtitled "the new culture of hypercapitalism where all life is a paid-for experience." [Jeremy P. Tarcher/Putnam 2000] On page 71 he writes:

"In 1998, researchers at Johns Hopkins University and the University of Wisconsin, under licensing agreements with the Geron Corporation, a California-based biotech company, announced that they had succeeded in isolating and perpetuating human stem cells, the primordial cells from which each individual develops into a human being. Patent applications are pending at the PTO [U.S. Patent and Trademark Office]. If the patent is granted, Geron will control the basic cell of human life for twenty years, giving the company unprecedented power to dictate the terms of future medical research and even the future evolutionary direction of the human race.... In the future, anyone who might need to avail him- or herself of medical therapies arising from the stem cell research would have to pay for access to the procedures."

Was WARF's action a pre-emptive strike in an upcoming patent war? WARF and Geron suggest not, that ongoing talks will settle the matter.

WARF has separate patents on five embryonic stem cell lines, each of which is potentially capable of generating some 200 different types of cells found in the body. WARF officials contend that Geron has licensed rights to just six types of cells that can be grown from the five lines: liver, muscle, nerve, pancreas, blood and bone. It sued to prevent Geron from exercising an option to add 12 more cell types to its license agreement and "to enable more academic researchers and private companies to join the search for new therapies and cures for some of the world's most debilitating diseases," a WARF spokesman told the Journal Sentinel.

Cells not licensed to Geron are available to academic or non-profit researchers for a standard $5,000 fee. Fees from licensing cells to private companies are needed to offset the more than $1 million spent by WARF to establish a lab and finance the research, which occurred in a separate facility set up specifically for work on the cell lines. The WiCell Research Institute, Inc., a nonprofit subsidiary of WARF, licenses and distributes the cells.

High-level negotiations are being held in Madison and Washington, DC to establish the conditions under which Thomson's human embryonic stem cells will be permitted to migrate.

The "mother cells" have to migrate from somewhere, I suppose. From my vantage point some miles to the northwest, I'm growing more comfortable with the idea that the most valuable stem cells, cells scientists supported by federal funds are allowed to work on, reside in Madison. Perhaps the wisdom of James Madison, fourth president of the United States and father of the Constitution after whom the city was named, will seep into the deliberations between WARF, NIH, universities and private enterprise.

The city's contributions are already numerous: to medical research; to our social history of migration; to our natural history of glacial landscaping; to the artistic landscaping of the Woodland Indian mound-builders with their effigies of bear, bison, deer, and birds, expressions of their oneness with Mother Earth.

In an era of high science, medical miracles and miracles-in-waiting, Madison is a good home for the mother cells.

    --William Hoffman    hoffm003@umn.edu