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Exclusive from New Scientist magazine
The children of the future may be conceived and spend their first few days of development on a computer-controlled chip.
In a move recalling Aldous Huxley's famous production lines for making babies in Brave New World, researchers in the US are building a "chip" that can automatically carry out all the steps involved in IVF, from fertilising eggs to preparing embryos for implantation.
Ultimately, such devices - which amount to artificial reproductive tracts - may even be able to sort and test embryos for genetic flaws.
So far researchers David Beebe and Matthew Wheeler have built prototypes that can carry out the major steps involved in IVF, though not all on the same chip. Far more mouse embryos develop successfully on these devices than by traditional methods.
The researchers say they expect the technology will first be used for livestock production, but their eventual aim is to use it for human embryos. The work could be the first step towards a future in which IVF becomes the norm, says George Seidel, a reproductive physiologist at Colorado State University in Fort Collins.
"Fifty or 100 years from now, our in vitro procedures for parts or even all of pregnancy may end up being safer than dealing with the various things that occur in the body - in terms of viruses that the mother comes across, toxins, and so on."
Dumped in a dish
In conventional IVF, sperm and eggs are dumped into a Petri dish where the fertilised eggs grow until they're ready to be implanted. As embryos need different culture media at different stages, embryologists transfer them from one dish to another via a pipette.
"It's like being plucked out of the Atlantic Ocean and stuck into the Pacific Ocean," says Beebe, a biomedical engineer at the University of Wisconsin, Madison.
So Beebe and Wheeler, an embryologist at the University of Illinois at Urbana-Champaign, designed a device to mimic conditions inside a female's reproductive tract.
The device, made of a transparent elastomer, resembles a small glass slide and contains a network of tiny channels, each around 0.2 millimetres in depth and width. The researchers connect the channels to programmable syringe pumps, which can move embryos around and add or remove fluids.
Acid test
To test the device, the team cultured mouse embryos to see how many developed to the "blastocyst" stage, ready to be implanted.
"In 48 hours, in the traditional Petri dish, none of them made it to the blastocyst stage. In our channels, about 75 per cent made it," says Beebe. "The embryos were transplanted into hosts and live pups were born. So there doesn't appear to be any detrimental effect."
The researchers also used the device to remove the "zona pellucida" shell that encases early embryos. In human IVF, this "assisted hatching" can be used to encourage implantation. Traditionally, the embryo is put into an acid medium and quickly removed when the embryologist sees the zona break up.
But waiting this long may damage the embryos. By washing acid over mouse embryos "parked" in a microchannel on a chip (see Graphic), the team found even with a brief exposure, the zona broke up after the acid was removed. "People have been leaving embryos in the acid too long," says Beebe.
Embryo weeding
In a separate experiment, the team matured mouse eggs inside the channels, then fertilised them by squirting sperm over them. Eventually they hope to integrate all the steps into a single artificial reproductive tract.
Crucially, the chip-like device not only allows many embryos to be cultured at once, it allows each one to be individually manipulated and tracked in separate channels. That should make it easier to weed out poor-quality embryos before implantation.
Embryologists already inspect embryos under the microscope, and some IVF clinics also measure their consumption of oxygen and glucose and the amount of carbon dioxide they release. All this could be done more routinely on a reproductive chip, says Beebe.
"Major questions"
In time, the device could even make it easier to carry out pre-implantation genetic diagnosis, where a few cells are removed to screen embryos for genetic disorders. "That involves more sophisticated manipulation than our current devices can do. But it is something we are working on," says Beebe.
But quality control raises ethical issues, says Tom Shakespeare of the Policy, Ethics and Life Sciences Research Institute in Newcastle.
"If we are talking about maximising the chances of becoming pregnant and carrying to term, then there's less argument. But if we are talking about either reducing genetic diversity or indeed enhancing selection then there are major questions."
More at: IEEE Transactions on Biomedical Engineering (vol 48, p 570)
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1900 GMT, 23 May 2001
Anil Ananthaswamy
http://www.newscientist.com/dailynews/news.jsp?id=ns9999781
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