>The pushing of limits never stops.
First, as far as we know, no one’s been able to make an embryo by injecting the nucleus of a human into the emptied cell of a cow oocyte. If they have, they aren’t publishing the results and there’s definitely no reports about stem cells from the results.
However, the BBC News and USAToday are now telling us that if the UK authorities refuse to license researchers who wish to do this research, then cures for “even Alzheimer’s disease” are at jeopardy and threatened. The Telegraph claims that a ban “would cost patient lives.”
The Times tells us that these embryos are
. . . are purely for laboratory use and will be used in the valuable search for genetic causes of such deadly afflictions as motor neuron disease. Animal eggs are far easier to harvest than human ones, but once emptied of their DNA can be used to produce an embryo that is more than 99.5 per cent human. They are therefore not technically hybrids or chimeras and there is no question of such embryos being implanted in a womb — which is already illegal.
I’m reassured, aren’t you? Especially since the Times goes on to imply that our real problem is that we don’t understand what the smart scientists are doing, and an Editorial in Nature (sorry, subscription only) warns of a “quagmire” if scientists allow the public to regulate them.
At least the controversy brings up the fact that harvesting eggs from women is not “practical.”
Several stem cell experts submitted applications for a license to create human stem cells using animal eggs. The process involves injecting an empty cow or rabbit egg with human DNA. That would produce an egg with human genetic material inside, with minute traces of animal genetic material.
After a burst of electricity, the egg would be tricked into dividing regularly, becoming a very early embryo from which stem cells could be extracted.
Removing the animal’s nucleus ensures that it would not be a chimera, or human-animal hybrid. “When you remove the nucleus with its DNA, you remove the species identity of the egg,” said Dr. Stephen Minger, director of the stem cell biology laboratory at King’s College. The proportion of animal to human genes would be tiny, with 13 animal genes versus 30 000 human genes.
Minger and colleagues applied for licenses to do this kind of work to better understand degenerative diseases at the cellular level, with the aim of finding targets for new drug treatments. The embryos would not be allowed to develop for more than 14 days.
Using human eggs is not practical because transferring genetic material into a host egg is extremely inefficient. In addition, there are too few human eggs available. Scientists say they would be lucky to get two or three human eggs in one month. In contrast, they could easily get 200 cow eggs in a single day.
All of this makes the research sound like a given. It’s anything but.
There was a report out of China that embryos were created using rabbit oocyte cell bodies and human nuclear material. (Articles from 2003: a report from the Washington Post here and the abstract of the original article in Cell Research, here.)The embryonic cells that resulted supposedly manufactured human proteins and appeared to follow human development. Last January, researchers were asking for permission to repeat this experiment in the UK. I haven’t been able to find reports that this sort of Somatic Cell Nuclear Transplantation or cloning of hybrid or human-animal embryos has ever been replicated in other labs, or whether the stem cells from this report have been examined by other researchers.
As I wrote yesterday, there is no way to discover how normal or abnormal these cells – if they are ever produced in other labs – is by implanting them in humans.
And, of course, the real ethical question is whether or not the embryos would be “human.” If they produce human embryonic stem cells, I would say, “yes.” And it is not ethical to destroy even
“potential” human lives in research.
>I think this has been done successfully in animal-to-animal transfer, so its technicly quite feasible. I cant remember where I read it though… probably an old issue of New Scientist. The egg-shortage would be relieved very effectively too.They might produce a cure, might not… but even if no cures, research like this is going to discover something. Noone can be quite sure what until its tried.