September 24, 2007

C.U. Prof Grows Human Ovaries in Mice to Study Pregnancy

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The mice at Cornell aren’t searching for cheese, they’re growing human ovaries.
Prof. Paula Cohen, genetics, has been growing human ovaries complete with eggs in mice in order to examine the complexities of how eggs develop in women and possible areas of deficiency.
“During meiosis, each chromosome has a pair: it finds it and then separates,” Cohen said. “Human error rate is over 20-60 percent in this process. It is remarkable how any women can give birth.”
Cohen’s focus of study is actually called the “grand maternal” effect because it is not a woman’s health that will affect the health of her pregnancy but actually the health of the woman’s mother. Disproving the idea that issues with ovarian development occur after birth, Cohen has found that the problem arises much earlier.
“The commonly held belief was that the distortion of women’s eggs was just a matter of time, 20 years or so before becoming pregnant,” Cohen said. “When trying to understand why women have so many errors in their eggs, however, we found that these errors are actually starting way, way earlier. We came to the conclusion that during the events leading up to chromosome pairings in meiosis of fetuses, the proteins involved in recombination are already faulty.”
Like any scientific experiment, Cohen’s research has ethical issues. Besides “humanizing” mice, which is strictly regulated on Cornell’s campus, the most delicate part of the research is obtaining tissue from abortions. To obtain aborted fetuses for experimentation, Cohen explained, is a very intricate issue.
“Cornell has a difficult regulation on human research. The issue of using aborted fetuses for scientific research is sensitive. Since these tissues that are being discarded anyway, we could really benefit from their use,” she said.
Because of the gravity of the situation, the hospital must take special precautions to ensure the process is morally sound.
Cohen said, “A hospital is unable to tell pregnant patients of the possibility of using her abortion for experimentation. A woman who is considering having an abortion must wait ten days to think about her decision. Once they decided on the abortion, they are asked if they want to allow scientific research to use the aborted fetus.”
The environment of the fetus is also important to Cohen’s research. Understanding where the fetus comes from helps Cohen identify possible causes of birth defects.
“We don’t know anything about the patients except things that help us understand the fetus’s environment, such as ethnicity or previous miscarriages,” Cohen said. “All defects could actually stem from changes in the environment. Sperm numbers, for example, are decreasing [more and more]. The reason why error has not been detected in sperm is because the production of sperm is much greater [than the production of eggs].”
Cohen is not the only Cornell researcher transplanting animal sex cells into mice. Prof. Alex Travis, animal health, has also used this technology, but for a different reason. Because of his concern for wildlife, Travis is seeing if sperm transplantation will help preserve animals that would otherwise become extinct.
“This process has been previously used for farm animals; however, we are now seeing if we can reproduce the sperm of carnivorous animals, such as ferrets and cats,” Travis said. “Using these amino-composed mice, we have been successful in our attempts to reproduce sperm. While working with the National Zoo, our next step is to see how well this reproduced sperm functions.”
For her part, Cohen is looking toward the future of research in the field of female reproduction. One of her goals is to use monkeys in her research to help find the problems with female reproductive organs.
“The use of monkeys would help in our research since a monkey’s body is so similar to that of the human. If we used monkeys, which have a much more complex body than mice, we would be able to draw closer conclusions to humans.”
The main difficulty of the research is the pace of the female reproductive system. This, however, cannot be altered.
“It’s really difficult to look at a human sample because it ovulates only one at a time and it takes a long time to collect data,” Cohen said. “The purpose of this translation is to see stages that we would otherwise not be able to.”
The overall sentiment of Cornell students about these breakthroughs in the University’s science veterinarian labs was mixed. While some people were surprised at such experiments, others thought it was simply furthering past research.
“It is not really a surprise since they have done other experiments like grow bladders and other organs,” John Harris ’11 said. “This just seems a little more complex.”