Cloning to generate organisms, be they mice or humans, is a dead end

Nature Science Update ^ | 2 May 2003 | TOM CLARKE

[AndrewC]

Eggs made from embryos

Reprogramming step towards safer reproductive cloning.
2 May 2003

TOM CLARKE

Stem cells give rise to every part of the body.

© K. Hübner & H. Schöler.

By tweaking the chemical conditions in a test tube, researchers have for the first time coaxed stem cells from an embryo to produce a clutch of eggs¹.

The step offers scientists a new way to probe the genetic programming of the cells that give rise to every part of the body. The achievement also paves the way for creating sperm or eggs for infertile couples.

As concluded at a discussion at this week's Human Genetics Organisation meeting in Cancún, Mexico, taking stem cells from embryos cloned from adult cells, prompting them to develop into eggs and sperm and then fertilizing those in vitro would be a safer and less ethically fraught alternative to direct cloning for couples who want children who are genetically their own².

The breakthrough has wowed stem-cell researchers. Even though the findings are preliminary and in mouse cells, "it's very important, very impressive research", says developmental geneticist Wolf Reik, at the Babraham Institute in Cambridge, UK. "There are a number of key steps and they have put them together beautifully."

The embryonic stem (ES) cells also spontaneously assemble into tissues that resemble ovarian follicles - the body's egg factories. "People were beginning to think this was impossible," says Hans Schöler of the University of Pennsylvania in Philadelphia, who led the research team.

If the eggs turn out to be normal, and if they can be produced efficiently, researchers will use them to probe the mysterious molecular reprogramming that produces eggs and sperm. This process is crucial to understanding embryo development and fertility disorders.

Cloning to generate organisms is a
dead end

Hans Schöler
University of Pennsylvania

But there is a long way to go before ES cells can be used to replace reproductive cells, warns Reik. Making sperm requires yet more complex chemical signals; making them from female stem cells might even be impossible. "It will require much more investigation into what these gamete-like structures are," agrees Azim Surani, a stem cell researcher at the University of Cambridge in England.

Schöler himself is even more cautious. "Cloning to generate organisms, be they mice or humans, is a dead end," he says. "I see this approach as a source of interesting stem cells," he concludes.

References

1. Hübner, K. et al. Derivation of oocytes from mouse embryonic stem cells. Science, published online doi:10.1126/science.1083452 (2003). |Article|
2. Pearson, HDNA re-write could allay cloning fears. Nature Science Update, www.nature.com/nsu/030428/030428-6.html (2003). |Article|

[AndrewC]

Actually, the title of the source article is "Eggs made from embryos", but I think this particular comment has more oompf.

[AndrewC]

ping

[AndrewC]

ping

[Libertina]

The article title must be read carefully... ;)

[Alamo-Girl]

Hmmm ... thanks for the heads up!

[MHGinTN]

With rodent stem cells taken from rodent embryos, the researchers were able to chemically stimulate the stem cells into differentiating into ovary tiisue and pop out more ova when stimulated with the proper hormone that triggers folliculation (egg popping). Since the scientists involved would likely consider the embryo to be merely a 'pre-human being' any leap to human embryos will quickly follow ... unless the American public is informed that this manipulation of individual human lives is in reality cannibalism ... and then it'll still be a toss up, since so many now would accept cannibalism if it meant brother or sister gets a new kidney without a lifetime of anti-rejection drugs.

[VeritatisSplendor]

Let's see - it's bad to make a clone baby of yourself. But you may clone yourself, and kill the clone quite early, and harvest little stem cells and make gametes and have a baby that way.

Just learned today that the gametes originate in the yolk sac and migrate to the gonads during embryonic development. So maybe you could extract a little yolk and make your gametes AND let the clone live. For spare parts.

Have your cake and eat it too.

Mrs VS

[aruanan]

Schöler himself is even more cautious. "Cloning to generate organisms, be they mice or humans, is a dead end," he says.

Except for plants.

[gore3000]

Except for plants.

Non-sexual organisms essentially clone themselves so there is no artificial cloning to be done in them, they do it quite nicely by themselves. The problem Sholer is pointing at is that sexual species are not clonable, they need the genes from both sexes.

[aruanan]

The problem Sholer is pointing at is that sexual species are not clonable, they need the genes from both sexes.

Remember that most plants (as most people think of plants) are sexual species and are clonable. Some plants even have individuals that are entirely male or female (Ginko, for instance).

[FITZ]

Even in our animal breeding programs, we produce freaks that might serve our purposes but could never survive on their own. There is no breed created by man that would survive if man disappeared from the earth. The only dogs that could survive would be mutts that reverted back to their wild form.