Choosing the best embryos

October 23, 2019

Montreal, October 23, 2019 -- Struggling with infertility? You are not alone. Infertility affects one out of every six Canadian couples. Some resort to in vitro fertilization, with mixed results. In a study published in Nature Communications, researchers from the University of Montreal Hospital Research Centre (CRCHUM) unveiled a mechanism that likely contributes to the low level of pregnancy success in some fertility clinics. This new information could ultimately increase women's chances of having a baby.

Healthy cells usually have one nucleus, where DNA containing our genetic information is stored. Embryos that are created in vitro in fertility clinics to enable women to have a child, often have cells with two nuclei. As of today, many fertility clinics still transfer these so-called "binucleated embryos" back to the patient's uterus.

"In our study, we showed in mouse embryos that binucleation has profound consequences. Basically, having two nuclei is bad news for the embryo. We found that binucleation increases the chances of the embryo developing a condition called aneuploidy, which reduces embryo health and could contribute to pregnancy failures," explained Lia Paim, first author and PhD student in Dr. Greg FitzHarris lab.

"We hope our results will help fertility clinics to select the best embryos to be transferred back to the patients. This step is one of the keys to success when it comes to in vitro fertilization. Ultimately it could increase some couples' chances of giving birth," said Mrs. Paim.

This study is at the basic research stage and was carried out in the laboratory on mice. "Basic science experiments such as Lia's allow us to understand how embryos develop, to help inform our clinical colleagues how to select the best embryos in the clinic," added Dr. Fitzharris, CRCHUM researcher and professor at the Université de Montréal.

Infertility may be more common than you think. The number of people with fertility problems has doubled since the 1980s.
This research was funded by the Canadian Institutes of Health Research, the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation and the Fondation Jean-Louis Lévesque. Lia Paim is also supported by Fonds de Recherche du Québec--Santé Doctoral Scholarship.

Further reading: "Tetraploidy causes chromosomal instability in acentriolar mouse embryos" by Lia Mara Gomes Paim et al. in Nature Communications. DOI: 10.1038/s41467-019-12772-8

Information and statistics on fertility: Public Health Agency of Canada website

About the CRCHUM

The University of Montreal Hospital Research Centre (CRCHUM) is one of North America's leading hospital research centres. It strives to improve adult health through a research continuum covering such disciplines as the fundamental sciences, clinical research and public health. Over 1,861 people work at the CRCHUM, including 542 scientists and 719 students and research assistants.

About Université de Montréal

Deeply rooted in Montreal and dedicated to its international mission, Université de Montréal is one of the top universities in the French-speaking world. Founded in 1878, Université de Montréal today has 16 faculties and schools, and together with its two affiliated schools, HEC Montréal and Polytechnique Montréal, constitutes the largest centre of higher education and research in Québec and one of the major centres in North America. It brings together 2,500 professors and researchers and has more than 60,000 students.

University of Montreal Hospital Research Centre (CRCHUM)

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