LONDON -- In an achievement that may one day help young cancer patients become mothers, Japanese scientists have grown immature mice eggs in the laboratory and used them to create healthy animals.
If the results can be duplicated in larger animals and humans, which is still a long way away, ovaries from young girls diagnosed with cancer could be removed before they undergo cancer treatment to preserve their fertility and create babies through in vitro fertilization.
"Our system might eventually help women undergoing chemotherapy or radiotherapy to become mothers afterwards, by prior removal of an ovary," Izuho Hatada, of Gunma University in Japan, said in a report in the science journal Nature.
Chemotherapy and radiation can damage ovaries and leave patients infertile. Hatada and his team have shown that fetal mice eggs can be coaxed to develop in culture so they can be used to produce healthy offspring.
"It will be possible to regenerate eggs from the ovaries, which were removed from patients before undergoing chemotherapy or radiation. This could be especially effective for childhood cancer patients, because they don't have any fully mature eggs," Hatada said in an e-mail interview.
Eggs from older women can be removed before cancer treatment, and the eggs can be used to form an embryo, which can be frozen and stored.
Some fertility experts are also giving women the option of freezing eggs, although critics say this option is still in its experimental stages.
But these methods are not possible for young cancer patients without fully formed eggs. Before testing it on humans, Hatada stressed the technique must be used on bigger animals, and mice produced using the technique must be checked to make sure it is safe.
The finding could also improve scientific understanding of infertility and how eggs develop, and help to explain why birth defects occur.
It could also help to save endangered species by using immature eggs from rare animals that would normally go to waste, to continue dying breeds.
The scientists nurtured the mice eggs in culture for 28 days. To continue their development, they transferred the genetic material to mature eggs taken from an adult mouse, using the same technique used to create Dolly the cloned sheep.
When the eggs were mature enough, they fertilized them and transferred the embryos to a surrogate mother. Sixteen healthy mice were born. Hatada and his team said there were no obvious abnormalities, and the mice were fertile after puberty.
