Aug
27
2006

Harvesting stem cells without harming embryos

in

Embryo, 8 cells: Courtesy of Wikimedia Commons.
Embryo, 8 cells: Courtesy of Wikimedia Commons.

Stem cell research is a hot topic in our country these days. Much of the controversy surrounds embryonic stem cell research and the issue of extracting cells from, and in turn destroying, developing embryos.

If only there was a way to obtain stem cells without killing the developing embryo…

Well, it looks like there is.

Researchers have found a way to extract a single cell from an embryo to be used for stem cells, while keeping the embryo intact.

Usually, stem cells are removed from an embryo when they are about 4 or 5 days old and the embryo has developed into a microscopic hollow ball structure known as a blastocyst. Extracting cells from the blastocyst causes it to fall apart and destroys the embryo. The new research findings show that stem cells can be harvested from less developed embryos, those with only 8 to 10 cells, and can leave the embryos unharmed.

Sounds like a solution to the stem cell debate, doesn’t it?

However, there are still ethical concerns with the new stem cell research technique. Critics fear that an embryo that had a cell extracted from it will be less likely to be able to implant in the womb or will not develop properly, leading to health problems in the resulting child. Others are opposed because the extracted cell potentially could have developed into a new embryo itself.

It seems that the stem cell controversy will never end. But this discovery may be a step towards a solution.

What do you think? Is the new stem cell extraction technique ethical?

Your Comments, Thoughts, Questions, Ideas

Laurie's picture
Laurie says:

Since they use this same technique to test some embryos before implantation (so it has been done before and the embryo survived) and since most embryos don't split into identical twins this sounds like a good compromise to me.

posted on Mon, 08/28/2006 - 4:26pm
Liza's picture
Liza says:
Read an Buzz blog post on pre-implantation genetic diagnosis, which relies on the same method of removing a single cell from a developing embryo. (This is the screening technique that Laurie is referring to above.) You can also check out a poll on the technique from a few months ago. (Be sure to read the comments, as they're far more interesting than the straight data.)
posted on Mon, 08/28/2006 - 8:36pm
Liza's picture
Liza says:

But wait! Yes, the stem cell researcher isn't destroying the embryo as he or she harvests the single cell. But...I assume that most soon-to-be-discarded embryos from fertility clinics are frozen. So the researcher would have to thaw an embryo, let it develop for a few days, then extract the needed cell. And then what? Re-freeze it? Can we do that? Or find someone to adopt it and carry it to term? Seems like IF we're stuck in an ethical trap now, we'll be stuck in the same one there.

Or maybe they're using fresh embryos? Will couples planning on IVF donate single cells from the embryo(s) that will later be implanted? Can we combine pre-implantation genetic diagnosis AND stem cell harvest?

posted on Mon, 08/28/2006 - 8:43pm
Liza's picture
Liza says:

According to an article in the New York Times ("Stem cell news could intensify political debate," Nicholas Wade; August 24, 2006),

"Although [Dr. Robert Lanza, vice president of Advanced Cell Technology and leader of the research team] used discarded human embryos, he said that anyone who wished to derive human embryonic stem cells without destroying an embryo could use a blastomere removed for [preimplantation genetic diagnosis].

'By growing the biopsied cell overnight,' he said, 'the resulting cells could be used for both PGD and the generation of stem cells without affecting the subsequent chances of having a child.'"

Right now, government funding for embryonic stem cell research is mostly prohibited by the Dickey-Wicker amendment, which says a human embryo cannot be harmed or exposed to undue risk.

So now the debate on federal funding will likely shift to the definition of "undue risk." Obviously, removing a blastomere involves some risk, yet embryos that have undergone PGD seem as healthy as other babies conceived by in vitro fertilization. (In the last decade, more than 2000 babies have been born in the US after PGD.)

Some groups applaud this new development as a way of ending the impasse about the permissibility of embryonic stem cell research.

Others still have ethical qualms.

  • The United States Conference of Catholic Bishops opposes both in vitro fertilization and preimplantation genetic diagnosis, as well as any form of embryonic stem cell research, because "of the high death rate of embryos in clinics and because divorcing procreation from the act of love [makes] the embryo seem more a product of manufacture than a gift."
  • Dr. Leon Kass, former chairman of the President's Council on Bioethics, said that the long-term risk of preimplantation genetic diagnosis is unknown and that the present [stem cell harvest technique] is inefficient, requiring many embryos to produce a single stem cell line.
  • And Dr. Irving Weissman, a stem cell expert at Stanford University, said that the new method, using only blastomeres from PGD, would not provide researchers with cells derived from patients with a specific disease. (Many scientists feel that embryonic stem cells will allow them to explore the basic mechanisms of disease, but they need access to cells with those genes.)
posted on Wed, 08/30/2006 - 11:07am
Liza's picture
Liza says:

Experts in the UK warn that only a handful of stem cell therapies have been developed and tested. Desperate patients have been duped into paying lots of money for stem cell treatments "not available in the UK." Yeah, well, that's because they're not published, proven therapies. Stem cell research holds out a lot of promise for possibly curing heartbreaking diseases, but that day isn't here yet.

posted on Tue, 08/29/2006 - 6:31pm
Liza's picture
Liza says:

Whoa! Italian-French researchers, published in Nature, say that they transplanted stem cells into dogs with Duchenne muscular distrophy, and the dogs' symptoms greatly improved.

Muscular dystrophy is a group of genetic disorders that causes muscles to weaken over time. It also limits mobility, and shortens life span, and right now there is no cure. Duchenne muscular dystrophy affects one in 3,500 boys, and is caused by a lack of dystrophin, a protein that helps maintain muscles.

The researchers used stem cells from healthy dogs and also from dogs with muscular dystrophy (MD). (They modified the MD dogs' stem cells to "correct" the bad gene.) They injected the stem cells into dogs with MD.

According to this article,

"Four out of the six dogs who received...stem cells [from healthy dogs] saw the return of dystrophin and regained muscle strength. One dog that was injected at an early-stage of the disease retained the ability to walk, and two dogs injected at a late-stage of the disease had their mobility returned. Of the remaining two, one died early and the other, the scientists believe, did not receive enough cells.'

MD dogs injected with their own "corrected" stem cells showed much less improvement, although the dystrophin protein returned. (That's a bummer, because the researchers had hoped that, when and if the treatment is ever used on humans, patients could be injected with their own cells, sparing them from the risk of rejection and a lifetime need for immunosuppressant drugs.)

It's promising, but even if this research is repeated and improved upon, use of stem cells to treat Duchenne muscular dystrophy in humans is still years away.

posted on Fri, 11/17/2006 - 1:20pm
Liza's picture
Liza says:

Nature has published two clarifications about Advanced Cell Technology's paper about their ability to generate embryonic stem cell lines without destroying embryos.

According to the Baltimore Sun,

"Nature editors acknowledge they erred in describing the study as 'plucking single cells from human embryos' in a way to generate new stem cell lines 'leaving the embryo intact.'

A subsequent clarification noted that the researchers removed 'multiple cells' from some of the embryos, and a second clarification pointed out that the experiments destroyed the embryos."

And although ACT's team experimented with 16 embryos, and 91 cells, only 2 new stem cell lines were produced. It's not clear yet why such a small percentage of the extracted cells formed new stem cell lines.

But Dr. Robert Lanza, the senior author of the paper, is standing by his findings. According to the Sun article:

"[Lanza] noted he never claimed that the embryos survived the experiments. But [he] had noted in interviews that embryos routinely survive when single cells are extracted in genetic tests at fertility clinics.

He said it was clear in the Nature report that the eight- to ten-cell embryos were destroyed, because it noted that a total of 91 cells were extracted from the crop of embryos used.
... 'The study conclusions and the implications remain 100 percent accurate.'"

posted on Fri, 09/01/2006 - 11:02am
Liza's picture
Liza says:

The Massachusetts Department of Health has issued new regulations banning the creation of embryos for research purposes. Governor Mitt Romney said,

"I believe it crosses a very bright moral line to take sperm and eggs in the laboratory and start creating human life. ... It is Orwellian in its scope. In laboratories you could have trays of new embryos being created."

But Massachusetts legislators passed a law in 2005 (over Romney's veto) that allows stem cell research in the state.

And this week State Representative Daniel Bosley wrote to his fellow legislators,

"The legislature debated, and soundly defeated, the exact language the Department (of public health) has adopted as a regulation. Consequently, we should oppose this language."

What do you think? Is it ethical to create embryos for research purposes? Why or why not?

posted on Fri, 09/01/2006 - 12:37pm
m.a's picture
m.a says:

imagine if the extracted stem cells could be frozen for use on the adult individual from which it was obtained later in life, this would solve the problem of rejection of tissues but would obviously provide technical problems, maybe a thought for the future...

posted on Sat, 11/11/2006 - 9:27am

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