Unlocking mystery of human cells Research: Two teams of scientists report growing embryonic stem cells -- the parent cells from which all human tissue is produced.

November 06, 1998|By Jonathan Bor | Jonathan Bor,SUN STAFF

Scientists at the Johns Hopkins School of Medicine and the University of Wisconsin said yesterday that they had separately reached a potential milestone toward growing human tissue for transplantation.

The researchers, reporting in two journals, said they had used different methods to grow colonies of embryonic stem cells -- parent cells for every tissue in the human body. Both teams acknowledged that the work, although exciting, is likely to ignite a debate over the source of the cells: aborted fetuses in Baltimore and unused embryos in Wisconsin.

Though they face technical hurdles as well, the researchers speculated broadly that the culturing techniques could be used to grow healthy tissues for transplant into people suffering from Parkinson's disease, heart disease, spinal injuries, diabetes and other disorders where key cells have gone awry.

"The potential of these unique, versatile cells for human biologic studies and medicine is enormous," said Dr. John Gearhart, a professor of obstetrics and gynecology who led the Hopkins effort. "We assume that they can form virtually every cell in the body."

Dr. James A. Thomson, who led the Wisconsin team, said scientists must find ways to transform the stem cells, which have no specialized function, into cells that fill a particular niche in bone, blood, muscle or nerve.

"It's a big deal, but it's really just a first step," Thomson said.

At Hopkins, scientists isolated stem cells from aborted fetuses and successfully grew them in laboratory cultures. In Wisconsin, researchers obtained stem cells from embryos that had gone unused in fertility clinics. In both cases, scientists said they obtained appropriate consents.

In 1995, Congress banned the use of federal funds for research involving human embryos that are destroyed or discarded. For this reason, the Wisconsin group used private money from Geron Inc., a biotechnology firm in Menlo Park, Calif. The Hopkins team received its funding from the same company, though Gearhart said his work should be eligible for federal money because it does not make use of embryos.

Yesterday, an official with the National Institutes of Health said federal law "absolutely bans" the use of federal money for Thomson's work. "He sought the advice of the NIH, and we gave him clear indication of the fact that [federal money] was not allowed," said Lana Skirboll, director of science policy.

But she left open the possibility that research on the cell lines derived from the embryos might fall outside the federal ban. "We're seeking advice from our lawyers," she said. Skirboll said she was not familiar with the Hopkins research.

The Hopkins study is described in Proceedings of the National Academy of Science; the Wisconsin finding in the journal Science.

If left alone, stem cells will spontaneously grow and take on the character of bone, blood or some other type of cell. Faced with this problem, scientists supplied proteins that kept the stem cells from specializing. Now, they are studying ways to direct the cells to become precisely the type of cells they want.

This would enable them to grow cells that would be tailor-made for transplant -- dopamine-producing brain cells for people with Parkinson's disease; heart muscle cells for patients with heart failure; insulin-producing cells for diabetics.

"Not only should scientists be able to generate specific nerve, muscle, skin or other cells for transplantation, but we should also be able to alter these cells to reduce the likelihood of rejection," Gearhart said. "We could make universal donors."

Gearhart said the goal isn't to grow whole organs, but tissues that could help diseased organs to function properly. While it could take a decade to accomplish this, other valuable uses could be closer at hand.

Researchers could study how human tissues respond to new medicines. Also, they could observe more closely how tissues develop and, in some cases, become defective. Gearhart said he got involved in stem-cell culturing because of his long-standing interest in Down syndrome.

For more than a decade, several institutions have cultured embryonic stem cells from animals -- first mice and later monkeys. Today's reports mark the first time anyone has accomplished this with human cells.

"This is a work in progress," said Dr. Austin Smith, a stem cell researcher at the University of Edinburgh, Scotland. "The issue is how many of the cells in culture are stem cells -- it seems to be very difficult to grow up large numbers of them."

Gearhart said the women who agreed to donate fetal tissue had already made up their minds to have abortions and had no connection to the scientists.

"I feel strongly it was morally defensible to use these cells because they existed anyway," he said. "What we learn from this material and how it will be utilized will be of great benefit downstream."

David O'Steen, executive director of the National Right to Life Committee, said his group believes that "members of the human family certainly should not be used for harmful experimentation, or destroyed based on their method of creation." He did not specifically address the new research.

Dr. Arthur Caplan, director of the Center for Bioethics at the University of Pennsylvania, said the research is justified as long as researchers don't influence the patients making decisions about abortion or in-vitro fertilization.

"Telling someone in a wheelchair you are not going to attempt research that may enable them to walk because you are concerned about the moral status of a frozen embryo that is otherwise going to be destroyed is an argument that is not going to hold up long," he said.

Pub Date: 11/06/98

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