WITHIN the next year mice will be incubating the eggs of women who risk
damaging their ovaries because of medical treatment, say Canadian scientists.
The team has already successfully harvested human eggs from the back muscles of
rodents, they told a meeting of the European Society of Human Reproduction and
Embryology in Bologna.
Ariel Revel of the Mount Sinai Hospital in Toronto, who leads the team
developing the technology, says it 鈥渙ffers new hope鈥� to young women who become
infertile after vital medical intervention, such as cancer treatment.
The development is sure to be controversial. There was an outcry last year
when Italian embryologist Severino Antinori claimed to have produced four babies
using sperm grown in rats鈥� testes
(快猫短视频, 27 March 1999, p 5).
Advertisement
Robert Casper, head of reproductive sciences at the University of Toronto and
part of the research team, says: 鈥淲e鈥檝e been through all the proper channels and
done everything ethically. Providing the process is safe and effective we don鈥檛
anticipate problems in introducing this on ethical grounds.鈥�
Many hospitals already freeze mature eggs from female patients. But freezing
is difficult and can damage mature eggs, while attempts to transplant ovarian
tissue back into patients have so far failed. In cancer patients, malignant
cells might also be reintroduced in the transplant process.
But now the Canadian researchers say they have successfully produced three
viable, mature eggs from tissue grafted onto mice. The graft contained immature
oocytes that had previously been frozen and stored. They think it should now be
possible to take ovarian tissue from a girl undergoing treatment for leukaemia,
and freeze the tissue until she is ready to have a family.
At this time, the tissue containing immature eggs will be thawed and grafted
onto the back muscles of the mice that can鈥檛 reject human tissue because they
have been genetically engineered to have weakened immune systems. The eggs will
mature in the mouse for about nine weeks before being harvested, further matured
in vitro and fertilised in the test tube. The fertilised eggs will then be
implanted in the mother鈥檚 womb.
Casper says the next stage of the research will be to check that the first
three mature eggs are normal. He says the researchers would be paying particular
attention to the number and structure of the eggs鈥� chromosomes, though he says,
鈥淭here鈥檚 no chance that mouse DNA could be mixed up with the human cells.鈥�
But IVF expert Alan Handyside of St James Hospital in Leeds says people are
bound to worry. 鈥淭his is very exciting stuff. But from a clinical viewpoint
there are bound to be some safety concerns. Clearly people are worried when you
mix human and animal tissue.鈥�