'Silicon womb' to begin fertility trials

By Tom Simonite (Image: Anecova) (Image: Anecova) Trials of a “silicon womb” that holds test-tube embryos inside the womb to expose them to more natural conditions will shortly begin in the UK. Researchers say the new device may produce better quality embryos and reduce the need to harvest so many eggs from infertile women. In standard IVF, eggs harvested from a woman are fertilised in the lab and allowed to develop in an incubator for 2 to 5 days. The healthiest embryos are chosen to be transferred into the uterus. The new device allows embryos created in the lab to be incubated inside a perforated silicon container inserted into a woman’s own womb. After a few days, the capsule is recovered and some embryos are selected for implantation in the womb (see image, top right) Embryos incubated in the lab must have their growth medium changed every few hours to provide new nutrients and get rid of waste. The new device provides a more natural environment. The silicon capsule is about 5 millimetres long and less than a millimetre wide. Its walls are perforated with 360 holes, each around 40 microns across. After embryos have been loaded inside, the ends are sealed and the container is connected to a flexible wire that holds the device inside the uterus (see image, lower right). A thread trails through the cervix to allow it to be recovered later on. The device was developed by Swiss company Anecova, which has so far only conducted a small trial in Belgium. Results were encouraging but not conclusive, says Simon Fishel, who is leading the first large-scale trial, at UK fertility group CARE Fertility, in Nottingham, UK. Starting today, CARE is recruiting 40 women for the trials. Each will have between 8 and 12 eggs harvested, then half their embryos incubated in the lab, and the other half inside the new device. “We will be able to directly compare the results of the in vitro and in vivo techniques,” says Fishel. Regardless of which technique produced them, women will be made pregnant using only the healthiest embryos, he adds. Half of the devices used will be removed after 2 days, and the embryos tested for genetic defects. The rest will remain in place for 4 days, after which the more mature embryos can also be assessed visually. Fishel says the new device could take some of the guesswork out of incubating embryos. “We don’t really know the full ambient conditions of the reproductive tract,” he told New Scientist. “It is also a dynamic environment that changes constantly, and we can’t replicate that.” He believes embryos grown in the device will be more resilient, meaning fewer eggs may need to be harvested from women to achieve a successful pregnancy. Most IVF techniques require the woman to stimulate egg production by taking hormones, which can sometimes cause dangerous side-effects. But Fishel admits that the Anecova capsule will not be placed exactly where an early embryo would naturally develop, inside one of the fallopian tubes. An embryo normally spends around 7 days travelling down the tube towards the womb. “It’s a lot closer to a fallopian tube than a plastic tray, but this new device is not an artificial fallopian tube,” adds Laurence Shaw from the Bridge Centre fertility clinic in London and a spokesman for the British Fertility Society. “The trials will tell us whether the environment in the womb will do instead.” Peter Braude at King’s College London, UK, is more sceptical. Clinics that return 2-day-old embryos to the womb achieve at best a 30% pregnancy rate, he points out. “That’s because embryos that young don’t naturally belong in the womb,
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