Egg cell research: "Egg cells are sensitive" BRIGITTE.de

The view goes far when Melina Schuh is sitting at her desk, through the large windows, over green and tree tops down the slope. The Max Planck Institute for Biophysical Chemistry is located just outside of Göttingen. Nested buildings, access roads on different levels, a very complex settlement of its own – and a place for top international research for almost 50 years.

"It is a great gift for me to be able to work in such an environment – including with Stefan Heil, who won the Nobel Prize in 2014 – and with so many freedoms and opportunities," says Melina Schuh, one of the director for four years * inside here and also award-winning: Last year, for example, it won the most important German research award, the Leibniz Prize, endowed with 2.5 million euros.

Make processes visible

The 40-year-old has seen things that no one has ever observed before her. In a research area that is the exact opposite of the distant view from her office: Melina Schuh looks inside, down to the smallest detail, where it all begins: the egg cell. "Its origin is at the beginning of every life," she says. "But we don't know very much about what exactly happens there – especially in humans." To change this, she and her team of 16 scientists from over ten nations observe the cells with high-performance microscopes at the price of a single-family home, especially with the so-called maturity division or meiosis. The double set of chromosomes that each of our body cells has is halved so that after fertilization, when the egg and sperm cells have fused, the genetic material is complete again.

Melina Schuh was fascinated by microscopes as a child; her father collected antique models. But not only this enthusiasm explains her research success. At least as important: creativity, persistence, frustration tolerance and a lot of patience. Anyone who talks to her quickly realizes that Melina Schuh has a very pleasant way of being both: relaxed and focused.

That's exactly why she has a knack for her test objects. Because: "Egg cells are sensitive." Countless failed attempts were required to make the processes inside visible: the breaking of the cell nucleus, the sorting of the chromosomes marked with fluorescent proteins, the formation of the so-called spindle, which pulls them apart.

Melina Schuh will not forget the moment when she – then a doctoral student in Heidelberg – witnessed this for the first time with the cell of a mouse: "I was still alone in front of the microscope in the evening, it was already dark outside, and thought: You are the first person who can observe this in detail. " Later, with her work group in Cambridge, she took the next step towards human egg cells. They are even more sensitive in meiosis because – nobody knows why yet – they take longer than all other mammals, namely around 24 hours and are only available to a very limited extent.

The beginning of life

In both England and now in Germany, Melina Schuh works with fertility centers. From time to time, women who are treated there leave surplus, unfertilized egg cells that would otherwise be discarded. "But nobody knows when," says Melina Schuh. "Then a call comes in the morning and one of us drives a mini incubator to pick up the cell." Back in the laboratory everything has to go very quickly otherwise the meiosis is already too advanced.

What Melina Schuh does is basic research and is initially not geared towards direct practical application. But it touches on an area that is crucial for many women and couples who want to have children. In the past year, the researcher and a colleague asked that the beginning of life should be discussed anew. The background was the knowledge of how long it takes for the chromosomes of the mother and father to be mixed after the fusion of the egg and sperm cells. "In legal terms, this is exactly the beginning of life in Germany. But obviously we don't even know when it really takes place," says Melina Schuh.

Nevertheless, the legal situation has far-reaching consequences, because we therefore have to select embryos for fertility treatment at a very early stage. This lowers the chances of success and leads to the fact that several embryos are often used at the same time. With multiple pregnancies, however, the dangers for mother and child (he) increase. In other countries, on the other hand, it remains to be seen which embryo is developing or is developing best. "Of course, we cannot move the beginning of life after every study," says Melina Schuh, "but we should take the new findings as an opportunity to rethink and change our very vague definition – for the benefit of women."

How exactly do egg cells age?

The researcher always draws motivation from helping people who want to have children: "When I was 30, my friends and I noticed that pregnancy didn't always work so quickly. We want to understand why the quality of the egg cells increases with age decreases, because only then can you take countermeasures. It is enriching to be able to contribute to the fact that women with infertility may be better helped at some point. "

But how exactly do egg cells age? "In each cell we have two copies of a chromosome – one from the mother, one from the father," explains Melina Schuh. "To ensure that they are correctly separated in the division of maturity, they lie side by side as a pair. And have been since the egg cells were created in the embryo. However, the pairs begin to fall apart over time." The chromosomes already slide apart before they are properly separated. In addition, the structures that pull apart the chromosomes, among other things, become more unstable.

And so with increasing age it happens more and more often that the genetic material is not correctly halved, but that sorting errors occur. Female fertility declines because most of them are unable to survive. Down syndrome is one of the very few exceptions. "Around the age of 20, the proportion of defective egg cells is between ten and 15 percent," says Melina Schuh, sounding a bit surprised at how much disorder nature can afford in this important process.

The researcher is skeptical whether the aging of the egg cells can be stopped at some point: "But decelerating it would be an important step." At the same time, she is critical of the belief in the feasibility of reproductive medicine: "The media often report on women, often celebrities, who get pregnant at over 50. This suggests that motherhood is practically possible at any time. But this is wrong: in many cases give birth to these babies by egg donation. The chance of having a child from the age of 40 is slim – also by means of in vitro fertilization. "

She hurried with family planning. "It was definitely an effect of my research," she says with a laugh. Melina Schuh became a mother for the first time at 32, now she has four children between seven and one. "It is a very positive development that medicine can make so many couples want to have children," says the researcher. "But there is and will always be a limit. We should be aware of this – even if it is difficult to accept it, perhaps because the processes in the cell are so complex."

The origin of man – a miracle

Freezing one's own eggs early has made the biological clock tick at least more slowly for a few years. "Basically, I think that's positive," says Melina Schuh. "But I don't think it makes sense to do it purely as a prophylactic measure at a younger age. One should not weigh oneself in false security. There is no guarantee that what is stored in the freezer will actually help a woman get pregnant later." For this reason, she has so far mostly only worked with fresh, unfertilized egg cells: "We are only just looking at how the cells behave after thawing. However, this is technically not that easy."

You can feel Melina Schuh's ambition and her curiosity to penetrate more and more, to understand more and more. And at the same time, I was more and more amazed: "The more I know, the more respect I have. It is amazing how many processes have to intermesh so that something as complex as humans can arise." She pauses briefly: "It's hard to believe that it works at all. It's a miracle!"

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