Jan 11, 2008 9:38 AM

New Source of Embryonic Stem Cells: Will Bush Say OK?

Scientists have made embryonic stem cells out of single cells plucked from two-day-old human embryos. But unlike traditional methods for producing ESCs, the embryos weren’t destroyed; they continued to develop and appeared to be healthy. The technique, pioneered by Advanced Cell Technologies scientist Robert Lanza and his colleagues at the Wake Forest University Institute for […]

Scientists have made embryonic stem cells out of single cells plucked from two-day-old human embryos. But unlike traditional methods for producing ESCs, the embryos weren't destroyed; they continued to develop and appeared to be healthy.

The technique, pioneered by Advanced Cell Technologies scientist Robert Lanza and his colleagues at the Wake Forest University Institute for Regenerative medicine, could turn ESCs from a moral dilemma to a medical one. Scientists say the cells, capable of becoming any other type of cell in the body, hold the key to lifesaving cures; but critics say embryo destruction is murder.

In August of 2001, President Bush denied federal funding for research on ESC lines that hadn't already been created. Scientists say those early lines are too limited and defective to develop treatments. Bush has invited researchers to find ways of making ESCs without destroying embryos; one such technique, known as reprogramming, was announced to great acclaim in November, but the resulting cells are prone to turning cancerous.

If Bush approves the latest technique, said Lanza, researchers could get their hands on new lines of embryonic stem cells immediately. So what's the catch? Only 80 percent of the embryos used by Lanza continued to develop. That's comparable to the success rates seen in pre-implantation genetic diagnosis, an assisted reproduction technique during which a single cell is removed from an embryo for genetic testing. But according to Stanford bioethicist William Hurlbut, that's not enough: the embryos are still in danger.

I talked yesterday with Story Landis, head of the NIH's Stem Cell Task
Force. The NIH will likely review Lanza's technique, then pass a report to President Bush for final approval. Said Landis:

Any new lines that would get listed [in the registry of federally-approved embryonic stem cell lines] would have to get derived without destroying or harming an embryo. It's clear that embryos were not destroyed in the lines created in Lanza's paper.

I asked Landis about Hurlbut's critique -- that pre-implantation genetic diagnosis isn't entirely safe.

That's true. There's a paper in the New England Journal of Medicine in
July of last year, from a group in the Netherlands. They looked at 408
women who underwent 836 [in-vitro fertilization] cycles; about one-half of those cycles had pre-implantation genetic diagnosis, and the other half did not. The ongoing pregnancy rate was significantly lower -- 25
percent versus 37 percent -- in the PGD group. To my knowledge, this is the most extensive collection of cases that look at whether or not doing PGD influences the ability to establish a pregnancy an carry to live birth.
[...] So if you were going to be really hard-nosed, this suggests that embryos are harmed; on the other hand, they're clearly not destroyed.
It's an interesting qustion as to where one would draw the line.

Would Lanza's technique satisfy the Dickey Amendment, a federal law that prohibits embryo endangerment? That, said Landis, was a legal question, and beyond her purview. However, she brought up an interesting possibility: in some species, individual cells are totipotent, or capable of giving rise to whole embryos.

Should we be thinking about that? It depends on -- well, you can imagine what it epends on. Personally, as a citizen -- not as an NIH
person -- I don't have a problem taking embryos that would be discarded and making stem cell lines out of them. But if you have a problem with that, then this question of blastomere totipotency becomes an important one. It's a scientifically valid question.

That hypothetical aside ... what would the NIH say about Lanza's technique? And, finally, President Bush? After the NIH looks at it, said Landis,

There will be a legal determination, based on the scientific data, of whether or not embryos were harmed. [And after that] I don't even have a clue.

Image: Cell Press