Diabetes Study Fuels Stem Cell Funding War

WASHINGTON — Offering new hope for diabetics, scientists on Thursday reported the latest marvel from stem cell research: mouse embryo cells that can develop into the insulin-producing portion of the pancreas. The report from researchers at the National Institutes of Health appears today in the journal Science and raises the remarkable prospect that scientists may someday be able to grow human organs in a lab that can be transplanted into patients.

But the latest news about stem cells is more than a dispatch from the lab. It is a cause for new skirmishes in the widening political war over whether to federally fund potentially lifesaving stem cell research.

Other teams have induced embryo cells to become simple structures, but the NIH team has shown that a single embryo cell can grow into a more complex organ involving four different cell types, scientists who reviewed the study said.

“In trying to make replacement tissues for diabetics, this is the most important paper that has appeared in a decade,” said Douglas Melton, chairman of Harvard University’s department of molecular and cellular biology.

Stem cells are powerful cells that give rise to more specialized types of cells in the body. Scientists hope to grow stem cells into replacement parts for patients: heart tissue for cardiac patients, brain cells for people with Parkinson’s disease and insulin-producing cells for the nation’s 16 million diabetics.

The NIH wants to offer its first-ever funding for experiments using stem cells from human embryos, which many scientists say are the most potent and versatile. Abortion opponents, however, are lobbying President Bush to block the money on grounds that destroying human embryos is immoral and unnecessary. They say that somewhat different types of stem cells found in adults are proving to be as versatile as cells from embryos.

“This comes up every time in conversations with members of Congress and staff--that adult cells could be a suitable alternative to embryo cells,” said Lawrence Soler, director of government relations for the Juvenile Diabetes Assn. “But we just don’t think that’s right.”

With a decision from Bush on funding embryo research due this summer, each new scientific report is triggering a flurry of news releases in the funding fight.

Lately, scientists have given Washington interest groups a lot to comment on.

When scientists this month reported isolating stem cells in human fat, the American Life League, an anti-abortion group, said the finding gave Bush another reason “to leave behind the horrors of embryonic stem cell experimentation, which always involves the killing of human persons.”

But advocates of embryo research said the study may not have truly proved that fat contains stem cells. Moreover, critics said that while the researchers may have generated bone, cartilage and muscle from certain fat cells, they had not grown other medically valuable material that embryo cells can produce, such as brain, blood or pancreas cells.

Both sides in the debate have offered their spin on the science to Bush. “It is premature to conclude that adult stem cells have the same potential as embryonic stem cells,” wrote 80 Nobel laureates to Bush in February. As if answering the Nobelists, at least 23 Congress members signed a letter in March that highlighted new findings about adult stem cells.

“Mr. President, we wanted to alert you to the fact that successful stem cell research does not necessitate the use of human embryos,” the lawmakers wrote.

Bush himself has suggested that he opposes using embryo cells. Amid the funding uncertainties, only three researchers have submitted proposals to the NIH for embryonic stem cell grants, and the Bush administration this month postponed the first meeting of a committee to assess those applications, citing its own review of legal underpinnings of the funding plan.

There is one thing everyone agrees on: Adult stem cells are proving to be far more versatile than originally thought.

Until recently, scientists believed that adult bone marrow stem cells could produce various blood cells, but not brain or muscle cells. They thought neural stem cells could produce material for the nervous system, but nothing else.

But to widespread delight, scientists are finding that this is not true. In revolutionary animal studies, for example, two teams reported last month that bone marrow cells could be turned into heart muscle and heart blood vessels in rats, helping to repair the damage from heart attacks.

In the diabetes paper, NIH researchers Ron McKay, Nadya Lumelsy and their colleagues caused mouse embryonic cells to evolve into four types of pancreas cells, which then self-assembled into structures similar to those known as islets of Langerhans.

Islets exist naturally in the pancreas and produce insulin and other hormones that regulate blood sugar. In an important finding, the researchers’ islets produced insulin in response to sugar, suggesting that they can regulate blood sugar as do islets in the body. However, the islets produced only 2% as much insulin as normal islets do. When placed in the shoulders of diabetic mice, the cells survived but did not produce enough insulin to affect the health of the rodents.

Dr. Robert Goldstein, chief scientific officer for the Juvenile Diabetes Research Foundation, called the report “fabulously interesting” and “very significant” because the islets created in the lab were close in structure and function to those found in the body. “This is very exciting . . . but it is not ready for prime time yet. It’s not cell therapy.”

Some researchers said this work should move from animals to experiments using human embryo stem cells--the kind of research that could soon be barred from receiving federal funds.

But David Prentice, a biology professor at Indiana State University and opponent of embryo cell research, said that adult stem cells also might be used to treat diabetes. He noted that researchers at the University of Florida reported last year that they had reversed diabetes in mice using stem cells found in the pancreas of adult mice.

In a separate paper in Science published today, researchers added to the evidence that stem cell science, combined with cloning, might allow patients to use their own cells to generate new body parts.

Often, transplant patients reject a new organ or tissue, as their bodies perceive it as a type of foreign invader. In theory, cloning could produce tissues and organs that match a patient’s genes exactly, bypassing the problem of rejection.

In the paper, Teruhiko Wakayama of Rockefeller University in New York and colleagues cloned adult mice to produce mouse embryos. They then extracted stem cells from the embryos and used them to produce a variety of different cell types.

The researchers said this showed that the cloning process does not diminish the versatility of embryo stem cells.