Alternative stem cell methods work in mice

WASHINGTON - Two alternative methods for making embryonic stem cells work in mice and might lead to a less controversial way to grow them, researchers report.

But the scientists who did the work said they still seek changes in US law that would give them federal funds to work with the human cells and find ways to use them in treating diseases such as cancer and genetic conditions, and studying others.

One team at Massachusetts-based Advanced Cell Technology used an established fertility technique called pre-implantation genetic diagnosis to take a single cell from a mouse embryo and use it to grow a batch, or line, of embryonic stem cells.

A second team at the Whitehead Institute for Biomedical Research at the Massachusetts Institute of Technology managed to genetically damage cells and then use cloning technology to make a crippled mouse embryo that could never develop in the womb. They then developed embryonic stem cells from the embryo.

Both methods had been discussed as ways to bypass objections that some people including US President George W. Bush have to embryonic stem cell research. The studies, published in the journal Nature, show they are technically feasible.

"They demonstrate that you can isolate the equivalent embryonic stem cells by alternative methods that may not raise the ethical questions. I would say they also raise more questions than answers," Dr George Daley of Children's Hospital Boston and Harvard Medical School, who was not involved in the research, told reporters in a telephone briefing.

Stem cells, the body's master cells, are used as a source of new cells and tissues. There are several kinds, but the controversial ones are those taken from very early human embryos.

Taken a few days after fertilisation, these cells have the power to produce any type of cell in the body and are considered enormously powerful if scientists can learn how to direct their development.

Opponents say any destruction or even manipulation of a human embryo is immoral. Currently, federal funds for experiments using human embryonic stem cells are restricted, and rival bills in Congress would lift these restrictions or tighten them further.

The debate crosses party and religious lines.

Dr Robert Lanza and colleagues at Advanced Cell Technology tried an alternative - taking a cell from an embryo when it only has eight cells, and using it as a source of stem cells. The remaining seven-cell embryo can develop normally.

It worked in mice, Lanza said. The single cell produced a batch of embryonic stem cells and the seven-cell embryos "developed to term without a reduction in their developmental capacity", he said.

About half grew to pups in mice, compared to half of the untouched embryos implanted into mouse mothers.

For the second study, Rudolf Jaenisch and Alexander Meissner of the Massachusetts Institute of Technology genetically disabled a gene in a mouse cell that is important to allow a fertilised egg to become an embryo. They then cloned the cell, grew an embryo, and extracted stem cells from it.

Daley said he was not sure this method would satisfy people opposed to cloning technology, or to the use of human embryos.

"This relies on generating an embryo and destroying the embryo to remove the stem cells. Some people in our society believe that would be wrong," Daley said.

Daley said he would like to learn how to take a cell, perhaps a skin cell, directly from a patient and transform it into a batch of embryonic stem cells without ever generating an embryo. This method would allow for tailor-made medical treatments or transplants.

All the researchers said there is no guarantee the alternative methods would work in human embryos.

"We should be very cautious not to mislead the public that these two papers demonstrate that we no longer need to do research on human embryos or human embryonic stem cell lines," said Andrew La Barbera of the American Society of Reproductive Medicine and an obstetrician at the University of Cincinnati medical school.

Sean Tipton, a spokesman for the Coalition for the Advancement of Medical Research, said he thinks legislation can pass Congress to lift the restrictions on embryonic stem cell research.

"We anticipate that we have the votes to prevail and it really is a question of timing," said Tipton, whose group lobbies in support of stem cell research.

- REUTERS