February 27, 2012
Study Could Result In Egg Cell Production For Fertility Treatments
Researchers from Massachusetts General Hospital (MGH) have for the first time isolated stem cells that are capable of producing what appear to be normal egg cells or oocytes from the ovaries of reproductive age women.
According to BBC News Health and Science Reporter James Gallagher, the research demonstrates that it could be possible to someday create a virtually unlimited supply of human eggs to assist with fertility treatments and help women hoping to have a child.
The AFP said that the discovery, which is detailed in the March issue of the journal Nature Medicine, suggests that women do not have a limited stock of eggs, and instead replaces it with the theory that the supply of these reproductive cells is "continuously replenished from precursor cells in the ovary."
An MGH press release said that the study, which was spearheaded by Dr. Jonathan Tilly, director of the hospital's Vincent Center for Reproductive Biology, is a follow up to earlier research, published eight years ago, which suggested that female mammals continued producing egg cells into adulthood.
"The 2004 report from Tilly's team challenged the fundamental belief, held since the 1950s, that female mammals are born with a finite supply of eggs that is depleted throughout life and exhausted at menopause," the MGH press release said.
"That paper and a 2005 follow-up published in Cell showing that bone marrow or blood cell transplants could restore oocyte production in adult female mice after fertility-destroying chemotherapy were controversial; but in the intervening years, several studies from the MGH-Vincent group and other researchers around the world have supported Tilly's work and conclusions," it added.
Tilly and his colleagues told Gallagher that they were able to find and isolate these egg-producing stem cells by searching for the protein DDX4, which is only found on the surface of this specific type of stem cell.
"When grown in the lab, the stem cells 'spontaneously generated' immature eggs - or oocytes, which looked and acted like oocytes in the body," the BBC News reporter said. "The cells were 'matured' when surrounded by living human ovarian tissue, which had been grafted inside mice."
"The primary objective of the current study was to prove that oocyte-producing stem cells do in fact exist in the ovaries of women during reproductive life, which we feel this study demonstrates very clearly," Tilly added. "The discovery of oocyte precursor cells in adult human ovaries, coupled with the fact that these cells share the same characteristic features of their mouse counterparts that produce fully functional eggs, opens the door for development of unprecedented technologies to overcome infertility in women and perhaps even delay the timing of ovarian failure."
In addition to Tilly, co-author Dr. Yasushi Takai, formerly a research fellow at MGH and currently a faculty member at Saitama Medical University in Japan; Dr. Yvonne White and Dr. Dori Woods of the MGH Vincent Center for Reproductive Biology; and Dr. Osamu Ishihara and Hiroyuki Seki of Saitama Medical University.
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