Unraveling the metabolic journey of an embryo in its first days of life
Infertility affects 1 in 6 couples worldwide. Among the many contributing factors, obesity is known to negatively affect fertility. As rates of overweight and obesity continue to rise globally, understanding how these metabolic conditions impact reproductive health has become an important area of research.
Postdoc Johanna Gassler is one of the 15 fellows that have been selected to join the BRIDGE – Translational Excellence Programme, where she will further explore this challenge. The BRIDGE program consists of three core elements: education, mentoring, and research. It therefore involves ongoing interaction, unlike many other fellowships.
‘‘I really like the community of the BRIDGE Fellows. You will really get to know the other fellows in your cohort, and you will know what they are working on. It makes it easy to learn from each other and to ask for help,’’ says Johanna.
One of the unique aspects is that the program brings together both basic scientists and medical doctors. ‘‘You’ll learn a completely new perspective, because we have a different way of looking at problems,’’ states Johanna. ‘‘I’m really excited to go into the clinic and see how things are done and to see what things from basic research have already been implemented in the clinic.’’
Uncovering factors that affect early embryo development
Johanna’s project will explore how both internal factors and external factors play a role in the earliest stages of embryo development. Internal factors include what’s stored in the egg cell itself, while external factors involve the maternal environment, such as the metabolism and nutrition of the mother, in particular a high-fat diet.
Egg cells, unlike sperm cells, are present in a woman’s body from birth, and no new ones are made. This means that the environment in the ovary can have a positive or negative effect on the eggs and their internal metabolic stores throughout a woman’s life. In addition, in the time between fertilization and implantation, which spans about 5 to 9 days in humans, the embryo travels through the oviduct to the uterus. The surrounding environment of the embryo is constantly changing drastically during this journey, which in turn influences its development and metabolism.
The literature shows that the environment in the uterus can vary depending on maternal health. But how this influences the internal stores of the egg and how the embryo responds to nutrients and signals in its external environment remains unknown. Therefore, Johanna is particularly interested in how these shifting maternal environments, such as obesity and high-fat diets, affect the embryo’s environment and early development.
To unravel this challenge, Johanna will combine her expertise in early embryo development with guidance from two mentors. Professor Henriette Svarre Nielsen is a clinical expert in human development and early pregnancy loss, whereas Jan Żylicz has expertise in stem cells and using blastoid models. Additionally, she will collaborate with medical doctor and former BRIDGE fellow Dr Malene Hviid Saxtorph and the Rabelink Lab from reNEW Leiden.
Ultimately, Johanna hopes her research will bridge the gap between basic research and the clinic and contribute to making IVF treatments not only more efficient but also more successful. “If we better understand what factors affect the embryo in this early stage, we may be able to use this knowledge to improve the number of successful implantation rates in the future,’’ Johanna says. “That would be a major step forward for infertility treatments.’’