Women may one day be able to delay the menopause, after a study showing that it is possible to prolong the working life of ovaries by transplanting female stem cells that develop into mature eggs.
The findings also raise the prospect of treating some female infertility where the ovaries do
not produce eggs. The hope is that one day stem cell transplants could replenish the fresh eggs in infertile women.
The accepted dogma in reproductive biology was that female mammals are born with a finite lifetime store of about two million egg-producing follicles. In humans, this number has fallen to about 400,000 by puberty, and at menopause too few eggs remain to permit fertility.
Four years ago United States scientists showed it was possible to obtain stem cells from the ovaries of adult women and grow them into mature egg cells.
Now scientists in China have shown that it is possible to isolate stem cells from immature and mature ovaries of mice, store the cells in the laboratory, and transplant them into sterile females to enable them to give birth to healthy offspring.
Research by Professor Ji Wu and colleagues at the Shanghai Jiao Tong University, published in the journal Nature Cell Biology, showed that it is possible to separate special cells in mice ovaries that seem to function as stem cells for the female germ-line cells in the eggs. These cells have the potential to divide indefinitely and can be stored for years.
The scientists isolated female germ-line stem cells of newborn mice and adult females. They cultured them for up to 15 months and six months respectively before transplanting into sterile mice, which gave birth to healthy offspring.
Professor Azim Surani, of the Gurdon Institute at Cambridge University, said the results have important implications for women who do not produce mature eggs. It might be possible, he said, to isolate these stem cells from a woman earlier in life so that she could have children later.
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