The belief has always been that women are born with approximately 2,000,000 egg-producing follicles, but that that number falls to about 400,000 by the time infants reach puberty. Ultimately, the number of eggs women have at menopause is so low, it’s virtually impossible for them to become pregnant. However, in 2005, scientists demonstrated the potential to obtain stem cells from the ovaries of adult women and grow those cells into mature egg cells.
Now, as part of new research conducted by Dr. Ji Wu and his colleagues from Jiao Tong University in Shanghai, China, a small number of female germline stem cells (FGSCs) have been isolated from the ovaries of adult mice. The cells, which were given a green fluorescent jellyfish protein to act as a marker, were grown in a laboratory setting for more than six months, then transplanted into infertile mice. The researchers discovered that the stem cells had developed into mature oocytes, which were capable of being fertilized. And in fact, eventually the mice gave birth to offspring carrying the fluorescent protein gene.
The researchers believe that this research lends proof that they may be able to produce new eggs in infertile women – even in women whose ovaries are damaged or who are beyond the typical age of conception. In theory, stem cell-derived eggs could be used to delay natural menopause or give hope to female cancer patients, who are no longer fertile due to their treatment for their disease. As Dr. Wu, notes, ” The system would work in humans as we share the same female germline stem cells. These cells can be used to extend female reproductive lifespan. The generation of new oocytes could postpone normal or premature ovarian failure, or be used in the treatment of infertility.”
Professor Robin Lovell-Badge, from the Medical Research Council National Institute for Medical Research, adds that: “The present paper suggests that there is a small population of cells persisting in the ovaries of mice from birth to adulthood that can be isolated, grown in culture, frozen and thawed if required, returned to ovaries of other mice that have been depleted of their own eggs, and then give rise to offspring after mating to normal male mice. If this is true and if it is applicable to humans,” says Professor Lovell-Badge, “then this is very important. For example, it could provide a means to restore fertility to women who have few eggs or who have had to undergo cancer treatments, by isolating these cells, expanding their number in culture and keeping them frozen until needed for IVF, etc.”
News Release: Stem cell breakthrough could help infertile women www.telegraph.co.uk April 12, 2009
