'Virgin birth' method promises ethical stem cells

New Scientist ^ | 4.29.03 | New Scientist

[freepatriot32]

The phenomenon that leads to "virgin births" in some species looks like a promising source of embryonic stem cells. Researchers are on the brink of obtaining human stem cells this way for the first time, and animal experiments suggest such cells are indistinguishable from normal stem cells.

In parthenogenesis, an unfertilised egg keeps two sets of chromosomes and begins developing as if it had been fertilised. Some insects and reptiles can reproduce this way but even though an electric or chemical stimulus can induce parthenogenesis in mammals, the resulting embryos die after a few days

And that, according to its proponents, is the beauty of the technique as far as stem cells are concerned: it produces embryos that could never become human beings. So destroying these embryos to obtain stem cells would avoid the ethical concerns that have led to restrictions or bans on embryonic stem cell research in many countries.

However, while the technique works in mice and monkeys (New Scientist print edition, 26 October 2001), attempts with human eggs have not got far. Until now, that is. A team led by fertility specialist David Wininger at biotech firm Stemron of Maryland has grown parthenogenetic human embryos to the blastocyst stage, at which stem cells can be obtained. Cells taken from one of the embryos survived for a few days (Stem Cells, vol 21, p 152).

"It's the first time I know of parthenogenetic cells in humans," says Kent Vrana of Wake Forest University School of Medicine in North Carolina, whose team pioneered the work in monkeys.

Indefinite growth

The next step is to get the cells to grow in culture indefinitely: that is, to obtain a stem cell line. In monkeys, such a cell line has been growing for over two years, and it makes the human experiments all the more relevant.

According to Vrana, extensive analysis of the monkey cells suggests that they are indistinguishable from normal embryonic stem cells. "They are identical to ESCs by every known criterion we have tested," he says, adding that details will soon be published in a peer-reviewed journal.

A lot of work still has to be done to ensure any tissues made from parthenogenetic stem cells are absolutely normal, says Jerry Hall of the Institute for Reproductive Medicine and Genetics in Los Angeles. But he is optimistic. "Patients are so interested in this procedure, and we are confident enough in its feasibility, that we have been willing to store eggs for use as soon as safety and effectiveness is shown," he says.

Since eggs are needed to make parthenogenetic stem cells, one potential problem is that the technique could not be used to make matching stem cells for men or for women after menopause. Therapeutic cloning, by contrast, could provide matching stem cells for any individual.

However, because cells made by parthenogenesis have two identical sets of chromosomes, rather than one set each from the father and the mother, they have less variation in the surface proteins on cells that can trigger immune reactions. Wininger thinks it will possible to establish a bank of parthenogenetic stem cells that could provide cells to suit most individuals. And such banks would be much cheaper than creating stem cells from scratch for each individual.

[LiteKeeper]

read later

[blackdog]

Male honeybees develop from unfertilized egg. Explain that.

[toast]

In parthenogenesis, an unfertilised egg keeps two sets of chromosomes and begins developing as if it had been fertilised.

Sounds like a clone to me. Some species do it naturally. Human twins happen naturally also. This doesn't sound like a natural process.

I am not saying I object. Just call it what it is.

[Paleo Conservative]

Male honeybees develop from unfertilized egg. Explain that.

Male bees are haploid, while female bees are diploid.

[sanchmo]

Herein lies the fallacy:
it produces embryos that could never become human beings.

Human embryos are human beings. The thing that is common to human embryos, human infants, human children and human adults is that they're all human. The thing that is different between human embryos, human infants, human children and human adults is age / development.

Human embryos become human beings only insofar as human infants become human beings.

[blackdog]

OK, now explain it to stupid folk.

[GovernmentShrinker]

Since eggs are needed to make parthenogenetic stem cells, one potential problem is that the technique could not be used to make matching stem cells for . . . women after menopause.

Nonsense. The nucleus from a post-menopausal woman's egg can be transferred into a donor egg from which the nucleus has been removed, and most will develop normally. The nucleus isn't the part that "goes bad" in older women; it's the rest of the egg, which doesn't contain the genetic material.

[MHGinTN]

... chemical stimulus can induce parthenogenesis in mammals, the resulting embryos die after a few days.
And that, according to its proponents, is the beauty of the technique as far as stem cells are concerned: it produces embryos that could never become human beings. So, the beauty of this form of cannibalism is that the process conceives severely handicapped embryos for harvesting their body parts (stem cells are the embryo's body parts), and that's deemed 'enlightened' because these mebryonic individual lives are too handicapped to be born. I see, yes, perhaps finally i see the key to America embracing cannibalism. Demonically brilliant.

[LadyDoc]

ethical? YUKK>

If you mean it's ethical because it doesn't kill babies, maybe or maybe not.

You see, there is a question if such eggs could grow into a baby.

But there is another level of ethics: reverence for life, a refusal to do grotesque experiments. Our bioethics is so twisted that they actually call it the "yuck factor": you hear about this and say yuck.

the good news is that Leon Kass has written extensively about this aspect of bioethics and he now heads the president's bioethics council.

the scientific problem with this is the same as the problem with other clones: the dna doesn't match, and there is a real question if it works in primates due to this and other cellular factors...

[MHGinTN]

If an immature ovum is stimulated to begin mitosis that indicates it is forming a dual action embryo ('life capsule and individual body being formed), that 'lifeform' is expressing its individual self, thus I would define that embryo as an individual human being already traveling the continuum of a lifetime begun at its unusual conception. That such an embryo may not be healthy enough to make it all the way to the 40 week gestational age is not the deciding factor in defining its individual continuum of life. Within the next ten years, an artificial womb in which to gestate embryos will be realized. It is imperative that we establish the bounds of defining individual human life now, before the inevitable arrives and the public is not sufficiently educated to repudiate cannibalism.

[watchme]

whoa!! too much science alert!!!
(at least for me, I am sure there are many people who can understand this kind of thing but my brain sees it and shuts off)
:)

[Arpege92]

Virgin births huh? Well, that explains how Chelsea Clinton got here!

[irish_links]

"...Human embryos are human beings. The thing that is common to human embryos, human infants, human children and human adults is that they're all human. The thing that is different between human embryos, human infants, human children and human adults is age / development...."

This raises a gnarly question that cannot be easily resolved. Is an unfertilized egg which is undergoing some sort of "development" a human being? Or, is it merely a grouping of human cells, not materially different than a polyp or an appendix?

By virtue of the fact that the egg is undergoing development of some sort, it meets the definition of an embryo. But if it is not nor could develop into a human being or anything remotely like a human being than I don't think that it is a human being.

I think pro-lifers (of which I am one) should reserve judgement on this development before condemning it.