In an enormous breakthrough, scientists from Cambridge and Rockefeller University have created a new technique that allows embryos to develop beyond the stage in which they would normally implant in the womb—a feat that no one has managed to achieve before now.
“This portion of human development was a complete black box,” said Ali Brivanlou, professor at Rockefeller, in a statement.
Scientists can now analyze these embryos to better understand the key stages of human embryo development up to 13 days after fertilization has occurred—up until now, seven days has more or less been the limit of what science could achieve. This now means they’ll better be able to help families struggling to conceive via ICF, as they have a better understanding of how the process unfolds.
“Implantation is a milestone in human development as it is from this stage onwards that the embryo really begins to take shape and the overall body plan are decided,” said author and Cambridge professor Zernicka-Goetz in a statement.
“It is also the stage of pregnancy at which many developmental defects can become acquired. But until now, it has been impossible to study this in human embryos. This new technique provides us with a unique opportunity to get a deeper understanding of our own development during these crucial stages and help us understand what happens, for example, during miscarriage.”
The previous limit of about a week came about because of an issue surrounding embryonic implantation. If an embryo is unable to implant at this stage in development, it can no longer adapt or survive further—which, incidentally, is a major cause of early pregnancy loss.
But thanks to the new technique—which involves surrounding the embryo in a specific chemical environment and providing a suitable scaffold for the embryo to attach to—the number of days an embryo can survive is now about double. Well, technically it could actually be more, but the legal limit for the length of time an embryo can be studied is 14 days in the UK.
Plus, the researchers have now demonstrated that the reorganization of the embryo that normally occurs fairly quickly after the embryo implants can also now be achieved in a lab, given the conditions are right.
New discoveries made through the study
And after studying these embryos for 13 days, they have already made a few new discoveries, according to the researchers’ two papers, one in Nature Cell Biology (which discusses their new technique and finds), and a second in Nature (which calls for new discussion about the 14-day rule).
“Embryo development is an extremely complex process and while our system may not be able to fully reproduce every aspect of this process, it has allowed us to reveal a remarkable self-organising capacity of human blastocysts [a stage of embryonic development] that was previously unknown,” said Dr. Marta Shahbazi, one of the co-first authors of the study from the University of Cambridge.
Further, they have uncovered that a particular part of the development of the embryo—which involves forming a cavity in the embryo—does not occur as many scientists had hypothesized. Whereas it was assumed that apoptosis, or programmed cell death, created the cavity, they now know that this isn’t actually the case.
“This process is similar to what we have recently observed in mouse embryos, despite the significant differences in the structure of post-implantation embryos in these different mammalian species”, said Zernicka-Goetz. “This suggests it may be a fundamental process conserved across many species.”
And there are likely only more insights yet to come—which may provide new hope to those attempting to have a family via IVD.
“This is about much more than just understanding the biology of implantation embryo development,” said Dr. Simon Fishel, founder and President of CARE Fertility Group. “Knowledge of these processes could help improve the chances of success of IVF, of which only around one in four attempts are successful.”
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Image credit: Gist Croft, Alessia Deglincerti, and Ali H. Brivanlou/The Rockefeller University
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