The researchers transferred the “blastoids” into the uterus of female macaques: in three cases they were able to implant themselves and elicit a hormonal response comparable to that which occurs in pregnancy
“We’ve landed on Mars, but we don’t know anything about the early stages of human development.” As Carlo Alberto Redifull professor of Zoology at the University of Pavia and Accademico dei Lincei, comments on the results of a study that would appear to be “science fiction”, conducted in China by the Shanghai Academy of Sciences and published in the journal Cell Stem Cell
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The experiment
The authors, starting from embryonic stem cells of monkeys (cynomolgus macaques), have created in the laboratory structures similar to embryos (called “blastoids”) which, once grown in vitro, have been implanted in the uterus. The procedure was successful in three out of eight cases, initiating reactions similar to those that occur in pregnancy but without leading to the development of a real fetus. The researchers, coordinated by Zhen Liu, they cultured macaque embryonic stem cells using growth factors (proteins capable of stimulating the proliferation and differentiation of cells). In this way they managed to get for the first time embryonic structures of non-human primates that have been found to be similar to those existing in nature (blastocyst, i.e. 5-6 day old embryos) and which have begun to form the different types of cells at the basis of the development of the organism. So have been transferred into the uterus of eight female macaques, where they implanted (in three cases), causing the release of the hormones normally associated with pregnancy, progesterone and chorionic gonadotropin. At that point the training process started early gestational sacsfluid-filled structures that develop in early pregnancy to enclose the embryo and amniotic fluid. However, development did not result in a fetus and the blastoids disappeared after about a week.
The study of embryos
The development of the human embryo and the formation of the first organs remain largely unexplored, both for ethical reasons and for the limited availability of study materials. «The molecular mechanisms of embryogenesis (embryonic development) and human organogenesis (construction and growth of the various parts of the embryo) are unclear – explained Zhen Liu, of the Chinese Academy of Sciences, first author of the study -. Since apes are evolutionarily very close to humans, we hope that studying these models will deepen our understanding of human embryonic development, as well as shed light on some causes of early miscarriage». “We have created a system that can be induced and cultivated indefinitely – added Quian Sun, of the Chinese Academy of Sciences and one of the authors of the work -. Provides new tools and perspectives for the exploration of primate embryos and reproductive health”. Indeed, RNA sequencing revealed that the different cell types present within the blastoids had gene expression patterns similar to those of cells present in natural blastocysts or post-implantation embryos.
Therapeutic opportunities
The researchers pointed out that there are many differences between the embryonic-like structures and natural blastocysts, saying that lab-created blastoids do not have full developmental potential. However, it is the first time that a study of this kind has been carried out on monkeys; similar jobs had previously been done starting from mouse stem cells. “In the West it would not have been possible to conduct the experiment on primates,” he stresses Carlo Alberto Redi —, but, beyond the possible and just ethical doubts, we need to understand what the objective of this line of research is. Today we know in detail the process of organ formation in the fetus, child and adult. We know almost nothing instead of the processes that follow the implantation of a sperm on the uterine epithelium and of the early post-implantation phases. Here, studies such as the one by the Chinese Academy of Sciences are important precisely to advance knowledge in a field that is still mysterious, despite the experiments on mice that have been conducted for at least twenty years and which have made great strides in research. From the fetus onwards we have study materials, which are bodies. We do not have access to the previous stages, starting with the pre-implantation cell (and then the implantation and development of the embryo); however, these are crucial phases, for example for the development of numerous diseases. Furthermore, the knowledge of these mechanisms could shed light on some causes of female infertility and early miscarriages. About 60% of one hundred conceptions are lost naturally before implantation, but we don’t know why this happens. The progress of knowledge on the early stages of human and mammalian development will pave the way for enormous knowledge and therapeutic opportunities”.
April 13, 2023 (change April 13, 2023 | 06:51)
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