12 May 2016
Professor Anne Grapin-Botton commented on two new achievements in human embryology
Professor Anne Grapin-Botton commented on two new controversial publications, about human embryos kept alive in the lab for unprecedented 13 days. The commentary was given to the Danish newspaper Politiken, which featured the research, conducted by two teams at the University of Cambridge and Rockefeller University in New York, and was published in parallel papers in Nature and Nature Cell Biology.
The researchers conducting these studies have used tissue culture plates where the embryos can attach, thereby mimicking implantation in the mother´s womb and a liquid medium sustaining embryo survival, growth and development. Common practice in fertilization clinics is to grow the embryos for 2-6 days in suspension and then implant them in the mother´s womb where it is difficult to see the cellular and molecular changes taking place. In the new conditions, one can observe with a microscope the first steps of organization when the egg divides and forms different cell types, including those that will later form the embryo, but also those that contribute to the placenta and yolk sac. The cells diversify and also self-organize to form layers similar to an embryo, though less spherical than in the womb.
Law in most countries ban laboratories from growing embryos for longer than 14 days as after two weeks. After this period, the embryo has cells that are precursors for the skin and brain, muscle and bone and digestive tract. Moreover twins can no longer form, and so it is deemed that an individual has started to develop.
According to Professor Grapin-Botton, this study is quite an achievement, and it is very interesting from a scientific point of view. "For now we can get insight into what happens in the earliest stages of human development, which has been a mystery. Especially the part of embryonic development, where the fetus adheres to the uterus in the female body".
"This is an opportunity to find out, for example, why some women lose their fetus in early pregnancy. It is also beginning to clarify the embryonic cell type that is the closest equivalent the human embryonic stem cells we have been able to grow in vitro and study for almost two decades and from which we expect so much for therapeutic purposes", adds Anne.
Anne Grapin-Botton is saying that without blood supply from a mother, it will be very hard to get a fetus to continue growth in a petri dish after day 14. But nevertheless, she believes scientists currently have to stick with the 14-day rule.
"If you grow a human embryo for more than 14 days, the cells begin to specialize, and the cells that will provide rise to the gut, skin, nervous system and the muscles, will be formed. It is also the time when each embryo will be individualized. Before this milestone the embryo is more a collection of cells with a limited structure, "said Anne Grapin-Botton. “Pushing this limit would require a concerted discussion”.
Link to the publications:
- Nature: Self-organization of the in vitro attached human embryo and
- Nature Cell Biology: Self-organization of the human embryo in the absence of maternal tissues