It’s a new, rather dicey form of life insurance. A company in California called StemLifeLine has announced that it will offer a service to generate stem cells from excess frozen embryos stored after in vitro fertilization (IVF). The company promises a huge potential payoff: the cells could one day be used to treat disease in the buyers or in their families. But the service is already garnering criticism from some scientists and ethicists who say that without current medical uses for those cells, there’s no point in people paying for them.

“I think the company’s website overly hypes what may be possible,” says Lawrence Goldstein, director of the stem-cell research program at the University of California, San Diego. “They are almost guaranteeing that therapies are around the corner, and now is the time to start banking stem cells, but that strikes me as premature for the field.”

The new service is meant to take advantage of a growing interest in the field of regenerative medicine. Stem cells from adult blood or umbilical-cord blood are already used to treat some diseases, including sickle-cell anemia and several forms of leukemia. But these cells are largely limited to treating blood-related disorders and can’t be grown in large numbers. Embryonic stem cells, on the other hand, can be coaxed to form virtually any type of cell in the body and can theoretically be replicated indefinitely. Scientists are developing ways to use them to replenish cells lost or damaged in ailments such as diabetes, Parkinson’s disease, and heart disease. But as of now, those treatments are limited to the lab: no embryonic stem-cell-based therapies are approved for human use.

Couples who have had children via IVF are often left with extra embryos–and the rather difficult decision of what to do with them. As of 2003, an estimated 400,000 embryos remained in cryopreservation in the United States. Embryos can be donated to research or to other couples, destroyed, or left languishing in frozen storage. According to Ana Krtolica, StemLifeLine’s CEO, the inspiration to form the company came from requests from clients at IVF clinics who were donating their embryos to research but wanted to know if they would have access to those cells if they were ever needed. (The answer is no.)

“We had a patient whose husband is a paraplegic,” says Russell Foulk, a member of StemLifeLine’s advisory board andmedical director of the Centers for Reproductive Medicine, a private clinic with offices in Nevada and Idaho. “They wanted to have a child and were excited about the possibility of creating neural cells from the extra embryos.”

The technology to derive these cells is not new. Scientists at StemLifeLine use a similar procedure to that employed by research scientists for almost a decade, although the StemLifeLine scientists have refined it so that the resulting cells are fit for human use. For less than $10,000 (actual price depends on the collaborating IVF clinic), clients can send in their excess embryos and, in return, receive a line of stem cells that have been “quality assured,” meaning they have been checked for the molecular markers that signify that the cells can be differentiated into multiple cell types. The company received certification as a tissue bank from the state of California last month, and it’s in the process of generating cell lines for its first group of clients.

However, critics say that the service is premature. Extra embryos can remain in frozen storage for years. And in the case of the paraplegic man, no treatments using neural stem cells are yet available. “There is no reason to take your embryos out of cryopreservation and make a line of stem cells and then freeze them again until the technology is available to actually use them,” says Eric Chiao, a stem-cell biologist at Stanford’s Institute for Stem Cell Biology and Regenerative Medicine, in Palo Alto.

Chiao and others argue that by the time scientists have figured out how to use embryonic stem cells as therapies, they will likely have developed better ways of generating the stem cells themselves, possibly using cloning, in which scientists would generate perfectly matched stem cells from an adult cell of the patient to be treated. “My offspring would be better off if they used cloning to generate stem cells for themselves,” says Arthur Caplan, an ethicist at the University of Pennsylvania. “In America, the best thing you can do is take the money you would have used and invest it in an insurance policy to maximize the likelihood that your kid will have health insurance someday.”

Krtolica counters that because it takes two to three months to generate the cells, it’s better to have them ready before an approved use in case a client needs them immediately.

Stem-cell scientists also say that StemLifeLine’s description of its product as “personalized” stem cells is misleading. As with organ transplants, cell transplants require that the immune profile of the transplanted cells match the host as closely as possible. Scientists generally use the term personalized stem cells to refer to a type of stem cell not yet possible to create: those generated through cloning, making them a perfect genetic match to the donor. Cells made from discarded embryos would not be a perfect match to family members, says Doug Melton, codirector of the Harvard Stem Cell Institute, in Cambridge, MA. “This would be like having stem cells from a sibling, so immunosuppression is still an issue.”

The prospect of generating stem-cell lines from embryos is likely to ignite new ethical arguments over embryonic stem cells. Critics of embryonic-stem-cell research oppose generating stem cells from embryos for any reason. But this service could spark growth of a practice that some find even more problematic: the creation of embryos solely as a source of cells. For example, some people might want to undergo IVF expressly for the stem cells, not to have a child. Krtolica says that she hasn’t yet fielded any such requests but that ultimately, it would be up to the fertility clinics. Foulk, for one, says he would not perform IVF under these circumstances.

*Due to a typo in a previous version of this piece, Russel Foulk was incorrectly stated to have said that he would perform IVF for someone who wanted to create embryos solely to generate stem cells.