JULY marked the 25th birthday of Louise Brown, the first test-tube baby. For those of us who can鈥檛 remember a world without IVF, it is astonishing to read about the intense controversy her birth caused. Nowadays, reproductive researchers have to work rather harder to shock.
Plenty succeeded this year, though. A picture of a bunny-eared man-rabbit was how one British tabloid reported a Chinese team鈥檚 claim to have grown embryos created by transferring the genomes of human cells to rabbit eggs. Outrage also greeted the news that a Chinese woman had been pregnant with embryos created by transferring the nucleus of her fertilised eggs to the eggs of a donor, the same method used for cloning, while Israeli researchers tried to mature eggs taken from aborted fetuses.
But for me, all this controversy overshadowed what could turn out to be the most significant development in assisted reproduction since Brown鈥檚 birth. Teams in the US and Japan turned mouse embryonic stem cells into eggs and sperm. If the same can be done in humans, women or men who cannot normally produce eggs or sperm might be able to have children with 鈥渁rtificial鈥� eggs or sperm derived from their own bodies, instead of resorting to donors. Two men could even have children (with the help of a surrogate mother) as male cells can also be turned into eggs. The work prompted Australian stem cell researcher Alan Trounson to make a bold claim: in future, all forms of infertility will be treatable.
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That鈥檚 a long way off. Neither team has yet shown that embryos created with artificial eggs or sperm develop into healthy mice, although this month a Harvard University team reported that mouse eggs injected with sperm precursors derived from stem cells begin to develop normally.
Even if the method works in mice, there鈥檚 no guarantee it will work in people. And getting the embryonic stem cells from the would-be mother or father in the first place is a problem in itself. It would take therapeutic cloning: creating an embryo by cloning and destroying it to get the stem cells. No one has yet done this with human cells.
Most worryingly, children conceived with artificial eggs or sperm obtained via therapeutic cloning could suffer a high rate of abnormalities. Society may have to ask itself just what rate of abnormalities is acceptable for an assisted reproduction technique.