Embryogenesis in Mechanical Womb
Reporter and Curator: Dr. Sudipta Saha, Ph.D.
A highly effective platforms for the ex utero culture of post-implantation mouse embryos have been developed in the present study by scientists of the Weizmann Institute of Science in Israel. The study was published in the journal Nature. They have grown more than 1,000 embryos in this way. This study enables the appropriate development of embryos from before gastrulation (embryonic day (E) 5.5) until the hindlimb formation stage (E11). Late gastrulating embryos (E7.5) are grown in three-dimensional rotating bottles, whereas extended culture from pre-gastrulation stages (E5.5 or E6.5) requires a combination of static and rotating bottle culture platforms.
At Day 11 of development more than halfway through a mouse pregnancy the researchers compared them to those developing in the uteruses of living mice and were found to be identical. Histological, molecular and single-cell RNA sequencing analyses confirm that the ex utero cultured embryos recapitulate in utero development precisely. The mouse embryos looked perfectly normal. All their organs developed as expected, along with their limbs and circulatory and nervous systems. Their tiny hearts were beating at a normal 170 beats per minute. But, the lab-grown embryos becomes too large to survive without a blood supply. They had a placenta and a yolk sack, but the nutrient solution that fed them through diffusion was no longer sufficient. So, a suitable mechanism for blood supply is required to be developed.
Till date the only way to study the development of tissues and organs is to turn to species like worms, frogs and flies that do not need a uterus, or to remove embryos from the uteruses of experimental animals at varying times, providing glimpses of development more like in snapshots than in live videos. This research will help scientists understand how mammals develop and how gene mutations, nutrients and environmental conditions may affect the fetus. This will allow researchers to mechanistically interrogate post-implantation morphogenesis and artificial embryogenesis in mammals. In the future it may be possible to develop a human embryo from fertilization to birth entirely outside the uterus. But the work may one day raise profound questions about whether other animals, even humans, should or could be cultured outside a living womb.
References:
https://www.nature.com/articles/s41586-021-03416-3
https://www.sciencedirect.com/science/article/pii/S0092867414000750?via%3Dihub
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-185X.1978.tb00993.x
https://www.nature.com/articles/199297a0
https://rep.bioscientifica.com/view/journals/rep/35/1/jrf_35_1_018.xml
This is very insightful. There is no doubt that there is the bias you refer to. 42 years ago, when I was postdocing in biochemistry/enzymology before completing my residency in pathology, I knew that there were very influential mambers of the faculty, who also had large programs, and attracted exceptional students. My mentor, it was said (although he was a great writer), could draft a project on toilet paper and call the NIH. It can’t be true, but it was a time in our history preceding a great explosion. It is bizarre for me to read now about eNOS and iNOS, and about CaMKII-á, â, ã, ä – isoenzymes. They were overlooked during the search for the genome, so intermediary metabolism took a back seat. But the work on protein conformation, and on the mechanism of action of enzymes and ligand and coenzyme was just out there, and became more important with the research on signaling pathways. The work on the mechanism of pyridine nucleotide isoenzymes preceded the work by Burton Sobel on the MB isoenzyme in heart. The Vietnam War cut into the funding, and it has actually declined linearly since.
A few years later, I was an Associate Professor at a new Medical School and I submitted a proposal that was reviewed by the Chairman of Pharmacology, who was a former Director of NSF. He thought it was good enough. I was a pathologist and it went to a Biochemistry Review Committee. It was approved, but not funded. The verdict was that I would not be able to carry out the studies needed, and they would have approached it differently. A thousand young investigators are out there now with similar letters. I was told that the Department Chairmen have to build up their faculty. It’s harder now than then. So I filed for and received 3 patents based on my work at the suggestion of my brother-in-law. When I took it to Boehringer-Mannheim, they were actually clueless.