Wednesday, December 1, 2004
Japanese pioneers raise kid in rubber womb
25 April 1992 by PETER HADFIELD , TOKYO
Aldous Huxley's Brave New World came a step closer to realisation earlier this month when Japanese scientists announced that they have raised a goat fetus in an artificial womb. The successful 'delivery' of the goat, believed to be the first of its kind in the world, increases the prospects of rescuing sick human fetuses and treating them in an artificial womb.
Yoshinori Kuwabara, a gynaecologist at Tokyo University's medical department, removed the fetus from its mother by Caesarean section after 120 days' gestation, about three-quarters of the way to its full term. He placed it in a rubber womb filled with artificial amniotic fluid, and the kid was delivered 17 days later.
'A goat fetus is very immature, even at 120 days,' says Kuwabara. 'It corresponds to about the 20th to 24th week of gestation of a human fetus.'
In its second womb, the fetus was fed via a catheter with normal fetal blood, which was oxygenated and recycled. Nutrients were added to the blood supply. The sac was filled with a near exact reproduction of natural amniotic fluid - a mixture of sodium and potassium chlorides, glucose and proteins. The temperature was kept at a constant 39.5 °C by passing warm water between two outer layers of rubber.
Creating an artificial womb has been tried before. In 1969, French scientists managed to keep a sheep fetus alive in one for two days. Kuwabara's goat fetus faced two principal dangers. The 42-litre sac is larger than a normal womb and the fetus had room to be more active than usual. Under these conditions Kuwabara says the fetus could have taken in too much oxygen, which can be toxic at high concentrations, or swallowed too much amniotic fluid, leading to severe fluid retention. To reduce the danger, Kuwabara and colleagues fed the fetus sedatives to slow down its activity and swallowing.
'We have two objectives in our research,' says Kuwabara. 'One is for animal models for fetal experimental medicine. The other is for clinical use, to rescue very immature or sick fetuses.'
One condition Kuwabara says may be treatable by artificial gestation is hypoplasia of the lungs, in which the lungs fail to mature. The disease kills around 100 babies a year in Japan. 'I don't worry about the ethical problems. I just want to rescue the fetus where it is impossible to be rescued by present treatment,' he says.
Kuwabara believes it may be possible to incubate a goat's fetus from as early as 90 days into gestation, and a human fetus from about the 16th week. The kid, now one month old, is still suffering the after-effects of the sedatives. It cannot stand or breath by itself. But as the muscle relaxants wear off it is gaining strength and will soon be able to function properly. Kuwabara says it is 'doing well'.