THIS year we took significant steps towards a future where prospective
parents鈥攈eterosexual or homosexual鈥攑refer to create embryos outside
the body, pick the best ones and perhaps even tinker with their genes before
letting them anywhere near a womb.
The reproductive technologies that could make this possible are still in the
very early stages. Not that this has stopped a few doctors greedy for fame and
fortune rushing to offer experimental methods like cloning to desperate would-be
parents. Finding a way to balance the needs of couples who can鈥檛 have babies the
usual way against the health and happiness of their future children has never
been more urgent.
The year began with the arrival of ANDi the monkey, the first ever
genetically modified primate. But the obstacles to engineering humans are still
enormous. ANDi was the only success out of 224 engineered eggs, and the
jellyfish gene added to his cells is not actually active.
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But in May, a heated debate on 鈥済enetically modified鈥� babies broke out when
it emerged that children had been born with three genetic parents instead of
two. Jacques Cohen and Jason Barritt of the St Barnabas Medical Center in New
Jersey injected cytoplasm鈥攖he fluid surrounding the nucleus of
cells鈥攆rom healthy eggs into the eggs of women with fertility problems in
the hope of rejuvenating them.
But not all genes reside in the nucleus. The transferred cytoplasm included
up to half a million mitochondria鈥攖iny cellular organs that contain around
forty genes. So several apparently healthy babies were born with two genetic
mothers as well as a genetic father.
Many biologists argue the babies aren鈥檛 genetically engineered, as the actual
DNA hadn鈥檛 been tampered with. Others say they are because they all have sets of
genes they wouldn鈥檛 normally, and the female children could pass them on to
future generations. No one yet knows what the long-term effects might be, if
any鈥攐r even if the technique improves pregnancy rates.
Later that month, the Brave New World clich茅 was wheeled out yet again
(for once aptly) when 快猫短视频 revealed that automated chips are
being developed to handle embryos. The chips should improve the success of IVF
because they can mimic conditions inside a woman鈥檚 reproductive tract more
closely, and would also make screening out faulty embryos easier. They could be
the first step towards a future where IVF is the norm.
And the embryos they handle might not come from the union of a normal sperm
and egg. In July, Gianpiero Palermo of Cornell University announced that he had
taken the first steps towards building artificial eggs. He transferred the
nucleus of a human body cell into a denucleated egg. When prodded with a pulse
of electricity, the egg spits out one of the nucleus鈥檚 two sets of chromosomes,
leaving the correct number for normal fertilisation.
In a separate bid to help men who can鈥檛 produce sperm, Orly Lacham-Kaplan of
Monash University in Melbourne succeeded in 鈥渇ertilising鈥� mouse eggs with nuclei
taken from body cells. When placed in normal mouse eggs, the body cell nucleus
again kicks out one set of chromosomes, before fusing with the egg nucleus.
But media speculation about how Lacham-Kaplan鈥檚 technique could allow
lesbians to have children missed the point. In theory, this has already been
possible for nearly 20 years. It would be relatively easy to add the nucleus
from one women鈥檚 egg to the egg of her partner, without the need to persuade a
body cell to spit out one of its two sets of chromosomes.
As with Palermo鈥檚 and Lacham-Kaplan鈥檚 techniques, however, such embryos never
develop for more than a few days. This is because a cell鈥檚 DNA has chemical
marks, or imprints, that switch key genes off. But a sperm cell鈥檚 imprints are
different to an egg鈥檚, and to those of other cells such as skin cells. Problems
with imprinting remain the major obstacle to such techniques.
Indeed, imprinting also seems to be why the success rate of cloning is so
dismally low. There鈥檚 growing evidence that the abnormalities in many cloned
animals are due to faulty imprinting. None of this is enough to dissuade Italian
fertility doctor Severino Antinori from pressing ahead with his bid to clone
humans, despite the opposition of cloning experts.