Discovery may explain pregnancy, infertility

Researchers at the University's Medical Center have reported the discovery of molecules that appear to play a key role in the start of pregnancy, raising the possibility of new ways to address both infertility and birth control. Researchers found that cell-adhesion molecules are produced in the lining of the uterus within a few days after ovulation. Just after conception, the cells apparently grab onto the new embryo and bind it to the womb, allowing the pregnancy to proceed. The molecules belong to a class of proteins called integrins, which are produced by the body's cells to monitor interactions between cells. They are the cell's "eyes and ears," said Bruce Lessey, a University reproductive endicronologist who headed the research. The results of the experiments, published in the July issue of the Journal of Clinical Investigation, may help doctors learn about forms of infertility that are not currently understood, and could eventually lead to new methods of treatment. "No one knows why the embryo sticks or doesn't stick to the [womb]," Lessey said. "But this cell-adhesion molecule is at the right place at the right time and meets the criteria for an embryo receptor. Its absence in some infertility patients now suggests a mechanism for their infertility." The experiments, conducted by researchers at the University and the Wistar Institute, found that for women with normal menstrual cycles, the integrins appear in the lining of the uterine wall when the womb is most receptive to implantation. The infertility that some women experience -- but which is not yet fully understood -- may be explained by the body's failure to produce the integrins until it is too late in the menstrual cycle to reel in the embryo. If future studies determine this to be true, Lessey said, hormone treatments could correct infertility in many women by better synchronizing ovulation and production of the integrins. At the other extreme, the information gathered by researchers may hold the key to a new form of contraception. Knowing how the embryo is bound to the womb, scientists could develop ways to prevent the integrin from ever grabbing the embryo. Without attaching to the lining of the uterus, the embryo would be unable to develop. "This integrin is turned on at the time pregnancy is established," Lessey said. "Certain molecules that block the attachment of embryonic cells specifically inhibit this receptor, suggesting the possibility for the development of new and better forms of birth control." Scientists could probably produce these molecules synthetically, according to researchers, and then apply them to the lining of the womb, possibly with an intrauterine device.

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