Stem Cell Lines Reported Contaminated

WASHINGTON (AP) -- The human embryonic stem cells available for research are contaminated with nonhuman molecules from the culture medium used to grow the cells, researchers report.

The nonhuman cell-surface sialic acid can compromise the potential uses of the stem cells in humans, say scientists at the University of California, San Diego. Their study was published Sunday in the online edition of Nature Medicine.

Stem cells form very early in an embryo's development. They can develop into numerous types of cells to form organs and other parts of the body. Researchers hope to use these cells to repair damaged organs and cure diseases.

The work is controversial because the cells are taken from days-old embryos, which then die.

Opponents say this is unethical. President Bush has limited federal funding to cell lines already in use, but not to newly developed ones.

Currently available stem cell lines have been grown in materials derived from animals. Such materials include connective tissue cells, called feeder layers, from mice and fetal calf serum.

That has raised concerns about potential contamination. Last summer, more than half the members of the Senate urged easing limits on new cell lines, noting that potential contamination could make available lines use for humans uncertain.

"People have always been concerned about the possibility that something deleterious might be transferred from feeder cells to stem cells. This puts a face on that substance," Dr. James Battey, chairman of the stem cell task force at the National Institutes of Health, said about the new report.

This is a safety consideration, along with many others that will need to be addressed, Battey said in a telephone interview.

The paper suggests that growing new stem cell lines in ways that avoid animal contaminants. Battey also suggested that existing cells might be isolated from animal products for a time, allowing the acid to be diluted.

"We eat animal products and drink milk all the time and get this acid into our cells, and yet we are not always suffering from raging autoimmune disease," said Battey, who was not part of the research team.

The study reports that the cell lines currently approved for study under federal funding contain a sialic acid called N-glycolylneuraminic acid, or Neu5Gc.

Human embryonic stem cells are contaminated by this acid "even when grown in special culture conditions with commercially available serum replacements, apparently because these are also derived from animal products," said the lead researcher, Dr. Ajit Varki.

Human cells are unable to make the acid, Varki said. In earlier research he had found that humans have antibodies directed against Neu5Gc.

"We considered that one partial solution to the problem was to use human serum in the growth medium," Varki said in a statement.

The researchers said that when the team grew stem cells in human serum specially selected for low amounts of anti-Neu5Gc antibodies, the immune response was reduced, but not completely eliminated.

The study was funded by the National Institute of General Medical Sciences of the National Institutes of Health, the Lookout Fund and the G. Harold and Leila Y. Mathers Charitable Foundation.

From The Corner at NRO:

“CONTAMINATION” [KJL]
What to make of the LA Times story up last night about “contaminated” stem cell lines (“Study Says All Stem Cell Lines Tainted”)? Here’s the read of a clued in expert I talked with this morning:

Well, fundamentally it's an effort to make an argument for new stem cell lines, by undermining the viability of all the existing lines, including those federally funded. There's not much new to it, except now it's dressed up in a "new" study, when everyone has always known that these lines (not just the Bush-approved ones, but almost all ES cell lines developed past a certain stage) were developed with so-called mouse feeder cells. To call this "contamination" is simply dishonest. A good number of cell products used in humans are developed with feeder cells from animals, and some of these (not embryonic cells, but other cell products) have been successfully developed into medical treatments in the past.

A couple of key points. First, it is not true that all the Bush-approved lines were developed with these mouse feeder cells. There are sixteen lines (not counted in the LA Times's "20 or so" available lines) that have been frozen in an early state, so as to wait for better cell development techniques. These have never been exposed to mouse feeder cells or any other cells, they are frozen and could be used if these folks had a better method to suggest.

Second, the FDA has a lot of experience dealing with cell products (again, not embryonic stem cell, but others) developed with such animal cells. Then-administrator of the FDA Mark McClellan, in testimony before [the president’s bioethics council] in September of 2003 [found here] was asked about the mouse feeder layer issue in embryonic stem cells, and he replied: "We've certainly had experience, successful experience, in thousands of patients in documenting the safety of cells that have been exposed to animal feeder cells, mouse feeder cells, and the like."

This new study strikes me as a partially dishonest repackaging of old worries in an effort to put new pressure on the Bush administration's funding policy. The trouble with it, as with all similar efforts by the researchers, is that the policy is based on a moral conviction, not a scientific assessment. Even if what they are saying were correct, it doesn't change the moral problem with embryonic stem cell research, and so will not change the policy. And from what I can see, it isn't correct either.

Par for the course, alas. What a course!

Stem-cell stocks damaged by study
Researchers see culturing contaminating stem cells

By Val Brickates Kennedy, MarketWatch
Last Update: 6:01 PM ET Jan. 24, 2005

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BOSTON (MarketWatch) -- Shares of three stem cell-related companies fell sharply Monday after a study asserted the bulk of embryonic stem cells used for U.S. research are contaminated and may not be suitable to transplant into humans.

Shares of Aastrom Biosciences (ASTM: news, chart, profile) closed down nearly 20 percent at $3.23.

StemCells Inc. (STEM: news, chart, profile) , meanwhile, fell almost 16 percent to $4.99, and Geron Corp. (GERN: news, chart, profile) lost 6.29 percent to $8.04. Shares of the newly public ViaCell Inc. (VIAC: news, chart, profile) appeared to be unscathed, moving up about 5.01 percent to $9.12.

The study, conducted at the University of California in San Diego and the Salk Institute, blamed the contamination on animal-derived culturing agents that scientists use to grow embryonic stem cells.

Reports of such contamination are not new. Proponents of creating new embryonic-stem-cell lines have often said that the culturing agents, most of which contain mouse cells, have contaminated key stem-cell lines used in basic research.

Yet while the news is of considerable importance to scientists engaged in academic research, it is not likely to have as much of an impact on stem cell companies, few of which are engaged in embryonic stem cell cultivation.

"[The stem-cell-related stocks] are all moving because nobody knows the differences between the companies. They move as a group, rightly or wrongly," said Stephen Dunn, an analyst for Dawson James Securities, who tracks stem-cell companies including Aastrom.

In a report to be published in the February edition of the journal Nature Medicine, the UC-San Diego and Salk researchers posit that most of the nation's embryonic-stem-cell lines, groups of cells culled from human embryos, have been contaminated by foreign genetic material.

Because of this contamination, the researchers believe the embryonic cells could trigger a severe immunological reaction if transplanted into humans for therapeutic purposes.

Fred Gage, a leading researcher for the Salk Institute and a founder of StemCells Inc., was a key member of the research team, according to Nature Medicine's Web site.

Stem cells are primitive cells that have the ability to transform themselves into the more specialized cells that make up the human body. Scientists have been seeking ways to use the cells to repair damage caused by disease or injury.

Embryonic stem cells are culled from days-old embryos donated by fertility clinics. Stem cells can also be derived from tissues in the human body and blood found in umbilical cords.

While StemCells, Aastrom, Geron and ViaCell all are working on stem-cell therapies, the types of cells they have used and how they have been cultured vary greatly.

StemCells, for example, uses fetal stem cells for its leading stem-cell therapy product. That product is currently in Phase I clinical trials for the treatment of Batten disease, a fatal genetic disorder that affects the central nervous system.

The stem cells are derived from donated brain tissue from miscarried, stillborn or aborted babies, according to StemCells Chief Executive Martin McGlynn.

"We're not engaged in embryonic stem-cell research," said McGlynn late Monday. McGlynn added that the stem cells are cultivated in a media that doesn't use any animal or human-derived "feeder" cells to help them grow.

Meanwhile, Aastrom also emphasizes it does not use embryonic stem cells in its products. Aastrom is conducting Phase I clinical trials on a product that takes stem cells from a patient's own bone marrow and replicates them for transplantation to heal severe bone fractures.

A spokeswoman for Aastrom said Monday that the company did not grow its therapeutic stem cells in any media that employs mouse cells.

Dunn said he recently lowered his rating on Aastrom from "buy" to "neutral" due to the stock's high valuation.

Geron Corp., which saw a far narrower swing in its stock, has had a long-standing program engaged in embryonic stem-cell research. The company's work, however, has been more focused on developing cancer drugs based on the enzyme telomerase.

Breaking from the pack on Monday was newcomer ViaCell, which held its initial public offering Friday, offering 7.5 million shares at $7 a share.

While ViaCell has a stem-cell-based therapy in Phase I clinical trials, the company's revenue is mainly derived from storage services for umbilical-cord blood for future therapeutic use. ViaCell's stem-cell products are derived from umbilical-cord blood.

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