New stem cell method touted

Scientists have created human embryonic stem cells using a technique that does not require the destruction of any embryos – a development that offers a path to break the political roadblock over the highly touted but ethically troubled research.

The method, described today in the journal Nature, involves taking a normal three-day-old embryo with only eight to 10 cells and removing a single cell, which is then biochemically coaxed into producing embryonic stem cells.

The original embryo, despite missing one cell, is unharmed, thus avoiding concerns about destroying a potential life.

Fertility clinics have been removing cells from embryos created in vitro since 1990 to screen them for genetic diseases and chromosomal abnormalities. Doctors estimate at least 2,500 children alive today had a cell or two removed when they were early embryos.

The Bush administration, which has restricted federal support for human embryonic stem cell research to prevent taxpayers from funding the destruction of potential life, said it was too soon to say whether the new approach could solve the ethical dilemma at the heart of the research.

But White House spokeswoman Emily Lawrimore said the work appeared to be a step in the right direction.

“Any use of human embryos for research purposes raises serious ethical concerns, but it is encouraging to see scientists at least making serious efforts to move away from research that involves the destruction of embryos,” she said.

Robert Lanza, medical director of Advanced Cell Technology Inc. in Worcester, Mass., and senior author of the study, said he believed the technique satisfies reasonable ethical concerns that should make the research palatable to social conservatives.

Last month, President Bush vetoed a bipartisan bill to expand stem-cell funding beyond the 20 or so currently eligible cell lines to more than 100 newer ones.

If Bush warms to the new approach and opens the floodgates of federal funding, Lanza said, it would “give the field a badly needed jump-start.”

Still, social conservatives have already begun complaining that the technique falls short. They say that the method does injure nascent embryos, and they question whether the cell that’s removed from an embryo has the potential to develop on its own.

“The new study … raises more ethical questions than answers,” said Richard M. Doerflinger, secretariat for pro-life activities for the U.S. Conference of Catholic Bishops in Washington, D.C.

The new technique relies on an old procedure known as pre-implantation genetic diagnosis, or PGD.

An embryo created through in vitro fertilization is allowed to develop into a small ball of cells known as blastomeres. Specialists use a tiny glass tube to remove one cell for genetic testing. If the tests come up clean, the embryo can be implanted in the womb.

The procedure seems to be safe, said Joe Leigh Simpson, an OB-GYN and professor of molecular and human genetics at Baylor College of Medicine in Houston.

Between 20 percent and 25 percent of couples that use PGD end up with healthy babies, compared with a success rate of 28.3 percent for all IVF patients, according to figures from Simpson and the Centers for Disease Control and Prevention.

Lanza wanted to piggyback on that safety record. If the removed blastomere were allowed to divide once, one could be used for PGD and the other would be available for research.

The key was to find a way to get the cell to multiply in a laboratory dish long enough to produce stem cells. Embryonic stem cells, which are capable of becoming any cell in the body, are typically harvested from the inner cell mass of an older embryo that contains about 150 cells.

Scientists and doctors are intensely searching for ways to harness embryonic stem cells to grow healthy tissue and treat diseases such as Alzheimer’s, Parkinson’s and diabetes.

Lanza’s team thawed 16 frozen embryos donated by fertility clinic patients. To give themselves the greatest chance for success, they separated all 91 blastomeres and placed them in culture dishes. More than half of them started to multiply, and about half of those began forming clumps.

In two cases, the cells continued to multiply and became embryonic stem cells.

The approach avoids the ethical problem with the standard method of making stem cells – the embryo is destroyed once its inner cell mass is removed.

“It’s extremely unusual for a scientific development to resolve an ethical problem, and this is one of those very rare occasions where that’s happened,” said Ronald M. Green, a professor of ethics and human values at Dartmouth College who chairs the ethics advisory board for Advanced Cell.

Stem cell researchers who have felt stymied by the lack of federal support for their work were buoyed by Lanza’s feat.

“This is one of the major results of our field,” said Renee Reijo Pera, co-director of the Program in Human Stem Cell Biology at the University of California, San Francisco.

But it is still uncertain whether the technique can meet the tough federal standard designed to protect embryos.

The legislation that funds the Department of Health and Human Services forbids the use of federal money for “research in which a human embryo or embryos are destroyed, discarded, or knowingly subjected to risk of injury or death.”

Doerflinger said the safety of the single-cell biopsy procedure had not been scientifically established.

“Some embryos do not survive the process, and some survivors may have long-term effects later in life,” he said.

Fertility specialists who perform the procedure acknowledge there have been no scientific efforts to study its effect on embryos or to track the children after they are born.

Nicanor Austriaco, a Dominican friar and molecular biologist at Providence College in Providence, R.I., raised another potential problem: What if the single cell that has been removed can itself become an embryo?

In other mammals, researchers have found that a single blastomere can develop into an identical copy of the original embryo.

“This raises the concern that the blastomeres isolated by ACT in order to create a stem cell line are in fact bona fide embryos that are destroyed in the process of creating the stem cell lines,” Austriaco said.

Stem cell experts said that argument was speculative. While it may be possible to grow a human blastomere into a full-scale embryo, it does not occur naturally and has never been documented in a lab.

“They’re citing something without any medical evidence,” said Irving L. Weissman, director of Stanford University’s stem cell institute.