For the first time, human eggs have been matured in a three-dimensional “artificial ovary,” a development that could one day make in-vitro fertilization (IVF) treatment easier and more effective. If the findings are validated, a successful artificial ovary may also eventually help preserve women’s fertility later in life and lead to a better understanding of ovarian function.
“This is the first time to my knowledge that a three-dimensional artificial ovary has been constructed [that] allows [the] tissues of the human ovary to interact in ways that mimic physiology,” says Dr. Sandra Carson, a professor of obstetrics and gynecology at the Warren Alpert Medical School of Brown University and one of the authors of a new study describing the research.
In a normal menstrual cycle, a woman typically releases only one mature egg. In order to go through IVF or to freeze eggs to store for later use, however, multiple eggs are required per cycle. That’s because it often takes the transfer of several fertilized eggs at a time, and many separate attempts, to achieve even one pregnancy. Alternatively, women may freeze eggs for future cycles, but the very act of freezing an egg lowers the odds that it will result in pregnancy.
Stimulating the ovaries to produce mature eggs takes time — about two weeks’ worth of daily injections with costly drugs. But stimulation doesn’t always produce mature eggs; some remain immature when doctors retrieve them and, currently, these eggs cannot always be matured successfully outside the body. (More on Time.com: Diagnosing Postpartum Depression with a Brain Scan)
“Sperm are a breeze. There are millions of them, you can freeze them and thaw them, and they will still work and make babies,” says Dr. Nanette Santoro, chair of obstetrics and gynecology at the University of Colorado, Denver, who was not involved in the study. “Human eggs are much, much more challenging. A woman has a limited supply, and they are all in different stages of readiness.”
But with a working artificial ovary, immature eggs could be retrieved and matured outside the body. Women would not have to inject drugs for days in advance, sparing them multiple injections and systemic exposure to high levels of hormones. And immature eggs might also survive freezing better than mature ones: pregnancy rates using frozen eggs vary from 10% to 40%, depending on factors like the woman’s age at the time her eggs were frozen and the freezing technique used.
“[The artificial ovary is] one of several techniques that are underway to help scientists get human eggs to work better — by ‘better’ here I mean easier to manipulate for therapeutic purposes,” Santoro says.
It is possible, then, that an artificial ovary could make IVF less arduous both by helping to reduce the use of ovary-stimulating drugs, which are required to mature eggs in the body, and by allowing doctors to fully develop immature eggs after retrieval.
It could also help preserve fertility in women without current partners who want to save their eggs for later. “Young women who choose to freeze eggs to keep a supply in reserve might be able to freeze less-mature eggs and have a decent enough supply to be reasonably assured that [they will get] pregnant,” says Santoro. “The whole freezing technology is not quite where it needs to be to make this a really reasonable option at present, but it is my belief that we are going to get there — soon.” (More on Time.com: Try As You May, Morning Sickness Is Here To Stay)
But clinical use of the new artificial ovary is still untested. Dr. Zev Rosenwaks, director of the Ronald Perelman and Claudia Cohen Center for Reproductive Medicine at New York-Presbyterian/Weill Cornell Medical Center, says, ”This is a very nice attempt to mature immature eggs in a three dimensional system.” However, the researchers have not yet proven that they can improve fertilization or pregnancy rates already achieved with current technology. [Full disclosure: Rosenwaks is my IVF doctor.]
In experiments, the artificial ovary was able to coax one in three eggs into maturity. But other technologies that are already being used in the clinic to mature eggs have achieved higher rates of maturation and even successful pregnancies. Such techniques involve maturing eggs in culture. “The researchers recognize the limitations [of the new finding] so far, but this has potential in the future,” Rosenwaks says.
Carson hopes to use the artificial ovary not only to improve IVF treatment, but also to study ovarian function in great detail. Understanding the functioning of healthy ovaries could help elucidate why ovarian cells become cancerous, or how toxins affect egg development and health.
Such knowledge could, in turn lead to better treatment or even prevention of cancer and birth defects, and even to the development of new contraceptives and fertility treatments.
Although we cannot yet retire traditional IVF therapies — including the series of injections derived from substances like purified nuns’ urine — a working artificial ovary could potentially help many more women in the future.
[Note: Check out the Oct. 4 issue of TIME Magazine for an in-depth look at ways in which women facing cancer treatment can preserve their fertility].
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