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The future of fertility

Reproductive research seeks to fix bad sperm and pregnancy issues

Erin Hendry

A researcher injects guinea pig sperm samples with fluorescent dyes to tag abnormal sperm in a lab at the Animal Science Research Center. This research is part of MU Associate Professor Peter Sutovsky’s study on bad sperm, and it will later be applied to human reproductive issues.

December 9, 2010 | 12:00 a.m. CST

The future of fertility treatments and reproductive technologies looks, well, futuristic. Until recently, procedures such as cloning and culturing embryos in petri dishes seemed better-suited to mad scientists in bad sci-fi movies than reputable researchers at universities such as MU. Yet local researchers regularly use these and other technologies to solve common fertility problems.

One problem is that the success of fertility treatments has stayed the same for years — about 35 percent of people who seek fertility treatments end up with a baby. Peter Sutovsky, an associate professor of animal science and clinical obstetrics and gynecology at MU, is researching a solution to the problem of “bad sperm,” which is sperm that is defective and will not produce a viable embryo.

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Identifying and getting rid of defective sperm cells is the challenge. Bad sperm don’t always look deformed. Some look exactly like normal sperm, but they all have one feature that good sperm lacks — they are coated in
a protein called ubiquitin. Sutovsky’s laboratory uses magnetic beads that bind only to bad sperm, which
allows the researchers to pull the bad sperm to the bottom of a container and skim the good sperm off the
top in a procedure that is not so sci-fi in its simplicity.

Sutovsky’s lab mainly studies bull sperm, but animal researchers also think of how findings can apply to humans. In a study of 239 couples who used in vitro fertilization, when the male had 5 percent defective sperm, the female became pregnant around 50 percent of the time; when the male had 15 percent or more defective sperm, pregnancy rate dropped to around 17 percent.

The sharp drop in pregnancy rate might be partially because bad sperm can hinder successful fertilization in several ways. “Even if bad sperm cells are not high, they can damage the other sperm cells,” Sutovsky says. Defective sperm might also penetrate an egg and produce an embryo that is not viable.

“To have successful fertilization and then to lose the baby is very heartbreaking because they have hope,” Sutovsky says about people who seek fertility treatment. “My lab is concerned with how sperm can contribute to that spontaneous pregnancy loss.”

The laboratory of R. Michael Roberts, curators’ professor of animal science and biochemistry at MU, might also one day spare infertile couples heartache through its findings.

One of the more pressing fertility problems studied by this laboratory is preeclampsia, a common medical issue during pregnancy in which the fetal placenta fails to implant properly in the uterus. Preeclampsia is characterized by high blood pressure in the mother and endangers the health of both the fetus and the mother. It can even lead to death.

“With a fetus, you’ve got a little parasite,” Roberts says. “There’s a war between the mother and the fetus for control. The fetus wants a good blood supply.”

But sometimes the mother’s body fights too hard against the invading fetus, and this is probably the basis of some forms of preeclampsia. To study the cells involved in preeclampsia, researchers use animal and human embryonic stem cells to create different types of placental cells, which can then be studied.

“We are interested in converting umbilical cord cells into placental cells found in preeclampsia,” Roberts says.

Using this method, it will be possible to examine drugs that might modify the growth and behavior of the cells, which could treat the disease in the future.

An area that proves Mother Nature is as clever a reproductive biologist as any researcher is the role of maternal diet in the ratio of male-to-female offspring.

Cheryl Rosenfeld, associate professor of biomedical sciences at MU, studies the relationship between maternal diet and the sex of offspring in mice. With a diet consisting of about 60 percent saturated fat, says Rosenfeld, female mice bear about 65 percent male offspring. Under normal circumstances, the ratio of males to females would be about 50-50.

Rosenfeld’s findings to date have been consistent with the Trivers-Willard hypothesis, which states that in polygynous species — those in which dominant males mate with many females — it is better for a well fed female in good body condition to birth sons. The rationale is that these sons would receive better maternal care and support from a healthy mother and therefore stand a good chance of becoming one of the big, strong dominant males, which are the ones permitted to breed with the females in the group. Females in poor body condition pass on their genes by birthing daughters, who will then breed with the dominant male.

Although it is not advisable for human women to consume a diet this high in fat to get better than a 50-50 chance of having baby boys, the findings might be relevant to agriculture.

“The beef industry may want to alter diet conditions to produce more females,” Rosenfeld says. “The dairy industry might seek to decrease the fat content of the maternal diet to favor females.” Similar findings have also been reported in sheep.

Current reproductive research can be as futuristic as coaxing cells to differentiate or as low-tech as putting a test tube on a magnet or feeding farm animals junk food, but the business of solving fertility problems is rarely simple. There will always be problems to solve. What is certain about the future of reproductive technology is that scientists will always be looking to the future.

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