The first entry in our former Blog was devoted to those disturbing little pets, the animal-human hybrid embryos.
At the time we noted: "Accessing the thousands of human eggs needed for cloning risks the lives and wellbeing of women (through ovarian hyperstimulation syndrome, which killed one IVF patient last month in Britain), but the rabbit option Trounson pulled out of his hat is equally unthinkable."
Professor Alan Trounson had commented in 2005, "Since there are plenty of rabbit eggs around, if we could make that work it would remove the concern about accessing human eggs in any numbers".
Last month, both scenarios – the ovary-as-commodity or the rabbit-as-mother - took potentially fatal blows.
Concerning ovarian hyperstimulation: the Journal of Epidemiology published findings that use of ovarian hyperstimulation was associated with a 36% increased risk of developing cancer.
In particular: "Treatment with ovulation-inducing drugs increased the risk of breast cancer by 42 percent; uterine cancer risk by more than 3-fold, and the risk of non-Hodgkin lymphoma by about 2.5-fold. Treatment with the ovulation-inducing drug clomiphene specifically was associated with 4.6-times the risk of uterine cancer and 2.6-times the risk of malignant melanoma."
So the proposal - giving a little extra ovary stimulation to provide scientists with a few nice fresh eggs for cloning – is more on the nose than ever.
That takes up back to Trounson's rabbits. Fortunately, the Senate in Australia threw out the provision for animal-human hybrids, but in the US and UK it has proceeded apace. How pleasing, then, to read the research from a leading cloning lab, Advanced Cell Technology in Boston, showing that these hybrids are non-starters. That animal eggs simply speak a different language to human eggs; they are out of synch with the human nucleus, and reprogramming the human DNA is a failure.
To borrow the succinct summary from Michael Cook at Bioedge (one of our favoured websites):
"Robert Lanza of Advanced Cell Technology, a California stem-cell company, published a paper in the journal Cloning and Stem Cells, which showed that human-cow, human-mouse and human-rabbit hybrid embryos fail to grow beyond 16 cells.
"There is no evidence that patient-specific human stem cells can be generated using animal oocytes," his team concluded. Genes thought to be critical for pluripotency -- the ability to develop into a wide variety of cell types - also failed to express properly. "At first we thought it would just be a matter of tweaking the culture conditions," Lanza told Nature. But "the problem was far more fundamental".
Critics of the hybrids felt vindicated. A British scientist commented on Nature's blog recalled that "Those who questioned the ethics or the prospects of this technology had to face angry patients who had been convinced that cybrids would be the holy grail that would cure them." He contended that "high profile public hyping of very speculative proposals, like cybrids, is a disservice to the public and to science".
But it was a bitter disappointment for scientists who had hoped that they could get pluripotent stem cells without having to use human eggs, which have proved all but impossible to obtain ethically in the vast quantities required for serious research.
The unpalatable conclusion seems to be that the supernova of "therapeutic cloning" is fading. ~ AFP, Feb 2;
One can only hope. Again, as we concluded our first Blog on the old site:
"No human cloning! Cloning violates our humanity, not only in creating embryos who have no identifiable human mother – just an emptied out egg nearly devoid of her genetic identity – but in proposing the further dehumanisation of an animal egg where the mother's egg should be."
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