Woodruff and Shea

Teresa Woodruff and Lonnie Shea

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Development and differentiation of secondary follicle in alginate scaffold. (A) At day 0, a multilayer secondary follicle with a centrally located immature oocyte and some attached theca cells was isolated and encapsulated in an alginate hydrogel. (B) The follicle maintained its three-dimensional structure and formed an antrum at the end of the culture. (C) The follicle displayed an in vivo preovulatory phenotype, a spherical shape with a central fluid filled antral cavity, an oocyte within tightly compacted cumulus cells, and layers of granulose cells outside. (D) Oocytes can be fertilized normally in vitro and implanted into the oviduct of a pseudopregnant mouse to produce a live birth.

New research may save fertility for cancer survivors

Collaboration pioneers field of oncofertility

For women battling cancer, the objective is clear: survive. Yet the lasting effects of cancer treatment can have a significant impact on the rest of a woman’s life. Of particular concern are the side effects to chemotherapy and radiation treatments — the very therapies that have so effectively helped increase survival — that may cause the loss of fertility. While male cancer patients have a number of viable options to preserve their fertility, fewer options exist for female patients.

Research from Lonnie Shea, associate professor of chemical and biological engineering, and Teresa Woodruff, Thomas J. Watkins Memorial Professor of Obstetrics and Gynecology at the Feinberg School of Medicine, may provide women with options to help preserve their fertility. Using new techniques, Shea and Woodruff are able to create an ex vivo environment in which a young follicle — an egg and the spherical group of specialized cells that surround it — can grow and mature to a stage at which it can be fertilized and implanted into the uterus. This technique could allow women to cryogenically preserve ovarian tissue containing follicles prior to treatment, which could be used to obtain mature follicles (oocytes) when they are ready to start a family.

A novel technique

At any given point, the ovary has follicles in many stages of development, with only a small percentage of the most mature ready to be fertilized. Shea and Woodruff aim to take that plentiful supply of young follicles and allow them to mature by placing them into a gel. The gel creates a three-dimensional culture system, a novel technique that differs from the two-dimensional cultures that had been previously researched. “Without the gel the collection of cells falls apart,” Shea says. “We maintain the cell-to-cell connections within the follicle, which allows for the coordinated growth of the follicle. Upon maturation, we can remove the oocyte, and it is ready to be fertilized.”

At the core of this new technique is alginate, a naturally occurring compound in brown algae that can be found in everything from antacids to jellies and even prosthetics. By using varying concentrations of alginate gel, the researchers are able to recreate phenomena found in the ovary.

Shea and Woodruff put their theory to the test with mice, allowing young follicles to develop ex vivo, fertilizing them, and then implanting them into a surrogate mother. The pups were born without incident and appeared to be completely healthy — and the success rate was a drastic improvement over related studies. “People had gotten live births before, but their success rate was about 3 percent,” Shea says. “Our success rate was 25 percent, which is comparable to the success rate with in vivo matured eggs — approximately 35 percent.”

Further research showed that even very young follicles could successfully develop into viable eggs, though the team determined that the culture system varied based on the developmental stage of each follicle. Recently the team has turned to freezing ovarian tissue, thawing it, then isolating the follicles and getting them to develop in the culture system. Early results show that the follicles can develop after being frozen, though the team hasn’t yet taken the mature follicles all the way through implantation. These results mark an advance because fully developed eggs rarely survive the process of being frozen and thawed.

Shea and Woodruff are now working with researchers from across the country to bring this technology closer to application. They are currently adapting the technique for rhesus monkeys, cows, dogs, and cats. Those steps are important as researchers try to bridge the gap between the follicles of mice and those of humans, which can grow to be 10 times as large as mouse follicles.

Woodruff is also leading a clinical trial in which women will have one of their ovaries frozen. Scientists will use 20 percent of each ovary for further study, with the remaining 80 percent stored for possible future use by the patient.

Filling a significant need

Shea and Woodruff’s technique may provide a significant new opportunity for female cancer patients to preserve their fertility. Currently, these women may freeze and store unfertilized eggs or undergo emergency in vitro–fertilization treatment and have their embryos frozen. However, such treatments may require additional hormone therapy, which can potentially speed the growth of certain kinds of cancer, including breast cancer. Success rates for pregnancy in these instances are also less than ideal, ranging from 10 to 25 percent for frozen embryos and just 3 percent for frozen eggs.

An additional concern is pediatric cancer, where there are extremely limited options for preserving fertility in prepubescent females. As survival rates for these patients improve, there is an increasing focus on preserving their fertility.

According to Woodruff, the potential uses of the technique she and Shea are working on could expand even further. “This breakthrough may permit not only the potential of fertility options for women and girls with cancer but also can be applied to normal in vitro–fertilization patients,” she says. “This procedure, when fully developed, could radically change the way infertility is viewed, reduce and eliminate embryo storage, and provide better options for women who do not respond to hormonal therapy.”

This research has played a large role in Northwestern’s efforts in oncofertility — a term coined at the University. In addition to the Northwestern’s Center for Reproductive Research, which coordinated this research project, the Feinberg School of Medicine has founded the Division of Fertility Preservation. Feinberg was also recently recognized as a Fertile Hope Center of Excellence, one of only five centers honored by Fertile Hope, a nonprofit organization that assists cancer patients with infertility.

Meeting more than halfway

One key to the research team’s success has been the interdisciplinary collaboration between faculty at McCormick and Feinberg. Even the funding agency for this research, the National Institutes of Health, has shown its support for this kind of collaboration. Elias Zerhouni, NIH director, commented on it in a recent article in the NIH Record. “This achievement opens up a new realm of exciting possibilities, from preserving fertility for patients to protecting endangered species,” he said. “This interdisciplinary effort — between materials scientists and reproductive specialists — yielded a promising new technique that researchers from either field, if working alone, probably would not have developed.”

Shea and Woodruff began collaborating several years ago thanks to successful research matchmaking by Steve Rosen, director of Northwestern’s Robert H. Lurie Comprehensive Cancer Center. Shea says that Rosen had a “great vision” for applications of engineering when introduced to the problem. After discussions with Woodruff, who had been working on two-dimensional cultures, they merged their ideas and began working on the mouse model.

In addition to the unique properties of their three-dimensional culture system, Shea credits the collaboration with Woodruff for the success of the project. “We met each other more than halfway,” he says. “I learned a lot more about reproductive biology than I ever would have, and she learned more about biomaterials than she would have.”

In addition, Shea and Woodruff have enlisted Laurie Zoloth, director of Northwestern’s Center for Bioethics, Science, and Society, to help determine how and when to make this technology available to women. As research progresses, they hope to also have economists and educators work to explore the implementation processes and implications of this technology.

While Shea and Woodruff work on refining their technique, they’ve also been laying the groundwork for further study. They hope to broaden their research through a national consortium that includes the University of Pennsylvania; the University of Oregon; the University of California, San Diego; and Baylor University.

—Kyle Delaney