Scientists have been able to study for the first time key stages of human life in embryos developed in vitro up to 13 days after fertilisation.
The technique, developed by researchers at the University of Cambridge, England, means new avenues of research that could improve the chances of IVF success.
Although the pre-implantation period has been extensively studied in human embryos using in vitro culture methods, the embryos have to be implanted into the mother’s uterus on the seventh day to survive.
However, parallel papers published in Nature and Nature Cell Biology, reveal how two international teams have developed a technique that allows them to culture human embryos outside the mother’s body up to day 13 after fertilisation.
After the embryos were implanted, the teams found for the first time the three cell types that comprise the blastocyst reorganise into a new configuration.
Professor Zernicka-Goetz, who led the UK research and is an author on both studies, said: "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.
“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.”
She said the stem cells in the epiblast have the “remarkable ability” to self-organise themselves and create a cavity that represents the basic structure of the early post-implantation human embryo.
“Without this cavity, it would be impossible for the embryo to develop further as it is the basis for its future development. It is also a mechanism that we can study using human embryonic stem cells,” she added.
This cavity was thought to occur due to apoptosis, but using human embryonic stem cell models, the researchers showed that cell death is not required for the cavity formation in human embryos.
“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,” explained Professor Zernicka-Goetz. “This suggests it may be a fundamental process conserved across many species.”
Shahbazi, MN et al. Self-organisation of the human embryo in the absence of maternal tissues. Nature Cell Biology. 4, May 2016. DOI: 10.1038/ncb3347
Deglincerti, A et al. Self-organization of the in vitro attached human embryo. Nature 4 May 2016
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