Within a year, mice will be used to incubate the eggs of women who risk losing ovarian function from medical treatment. A Canadian team has successfully harvested human eggs that have been brought to maturity on the back muscles of genetically altered mice.
Ariel Revel of the Mount Sinai Hospital in Toronto leads the team
developing the technology. The team is excited as the technology "offers new hope" to young women who become infertile after vital medical intervention, such as cancer
There is sure to be an ethical and biological outcry over the procedure. No one really knows what happens when you mix human and animal tissue.
Many hospitals already freeze mature eggs from female patients; but
freezing is difficult and can damage mature eggs. Other treatments, such as attempts to
transplant ovarian tissue back into patients have so far failed. In
cancer patients, malignant cells might also be reintroduced in the
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 leukemia, and
freeze the tissue until she is ready to have a family.
The procedure works when researchers take the frozen tissue containing immature eggs and thaw them. They then graft the tissue onto the back muscles of the mice that can't 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. Then the eggs will undergo further maturation in vitro and be fertilized in a test tube. The fertilized eggs will then be implanted in the mother's womb.
The next stage of the research will be to check that the
mature eggs are normal. Researchers are
paying particular attention to the number and structure of the eggs'
chromosomes, though he says, "There's no chance that mouse DNA
could be mixed up with the human cells."
IVF experts say that people are bound to worry--even though the prospect of saving immature ovum is very exciting. From a
clinical viewpoint there are bound to be some safety concerns. Clearly
people are worried when you mix human and animal tissue.