The black box of early development of human embryos is slowly opening?

The world's top journal, Nature, recently published online in the form of a long article, Professor Li Tianqing and Professor Ji Weizhi of Kunming University of Technology's Primate Translational Medicine Research Institute, in cooperation with the First People's Hospital of Yunnan Province, they for the first time set up a three-dimensional culture system of human embryos, the first systematic reveal of the development process of precursor embryos and pluripotent stem cellsThe panoramas of molecular and morphological development they have drawn fill the gaps in the relevant fields and establish an important research basis for the study of early development after the embryo is bedhuman embryo development is still mysterious "black box"the development of human fertilized eggs, starting with a series of cleavage and form rearrangement, forming a cystic embryo, before the formation of the original intestinal embryo on the 14th dayThe late blastocyst consists of three different cell lines, namely the upper embryo cell and the endoblast cell and the nourishing outer blastocyst layer of two extrapox tissuesAfter entering the uterus, the upper embryo cells produce three-embryo cells and the entire fetus, and the latter two produce the ovoid sac and placenta, respectivelyScientists have carried out extensive research on the development of pre-blast embryos and made some progressHowever, on the seventh day of development, human embryos need to be implanted in the mother's womb in order to continue to survive and developThis stage of embryo development in the uterine body three-dimensional space-time by complex and fine regulation, limited by ethical and research technology constraints, research materials can not be obtained, but also lack of the corresponding in vitro research system, from the fertilized egg bed to the 14th day before the formation of the original embryo, the development of the embryo has long been a mysterious "black box."" the original intestine began to form, the nervous system began to form, gradually forming the fetus, it is not an embryoWhat happens to early embryos in the womb? What molecular mechanism can regulate and maintain its normal development? What factors can affect its normal development? These are all issues that need to be addressedLi Tianqing told Science and Technology Daily that the first 2 to 3 weeks of pregnancy is the core key period to ensure fetal developmentthe production of the blastocyst, about 5 to 6 days, formed the first genealogy differentiation of life; the second stage is actually the beginning of the bed stage, which is the key process to determine whether the embryo can develop down, if the embryo development nutrition after bed to keep up with, normal development, can be successfully grow into a fetus; The first stage is currently more research, for the third stage, due to the existence of large ethical problems, it is not possible to carry out relevant researchtherefore, the study of the pre-intestinal stage, the understanding of the key events of human embryo development, as well as the research and application of human stem cells, tissue organ regeneration, and the prevention and treatment of infertility and early developmental diseases are criticalmapping molecular and morphological development A panorama of early embryonic development is expected to break throughIn fact, our study is to draw a complete picture of the molecular mechanism of the key development of the pre-intestinal embryo, as well as its morphological development process, reflecting what kind of changes this process has producedIn other words, our research is expected to open the 'black box' of the early stages of human embryos, promising breakthroughs in the perception of life Li Tianqing said the research team cultured human blastocyst symbiosis in three-dimensional (3D) conditions for the first time to the 14th day of the original stage, but did not show early nervous system development, in line with the international ethical guidelines for embryo research The breakthrough obtained in the study mainly reveals the dynamics and molecular regulation networkof of differentiation and development of the upper embryo cell, the lower embryo cell and the nourishing cell lineage; The team found that compared with the upper embryo cells, amniotic epithelial cells significantly lowered the plurier gene, its formation is significantly related to the absence of the substrate membrane, and has a unique molecular expression spectrum They also clarified for the first time the differentiation of cell nourishment layer, fluffy extracellular nourishment layer and conthisx nourishing cells after the embryo bed, as well as signals and transcription factors that cause differentiation, and revealed that the extracellular nourishment layer in the early embryo is different from the function of the medium and late placenta also revealed that the upper embryo cells, or polysaccotic stem cells, quickly changed from "primitive state" to "starter state" when they were beded The changes in the expression spectrum of its polysaccotic stem cells occur mainly in the two stages of intracellular clusters to the upper embryo layer cells before bed and the production of the original strip Pluripoturist stem cells remain relatively stable from bed to the 14th day, and their development and transformation are determined by the coordination of different pluripotent factors Through transcription group analysis of human and monkey embryos, the team found significant metabolic differences between monkey and human upper-level cells, while maintaining stem cell pluripoteticand and the key molecular and signaling pathways for development were conservative Li Tianqing, , said that through this study, our understanding of human life is also more profound In the future, one can improve the success rate of IVF and solve a series of problems in human reproductive development; secondly, some early markers may be found, such as how to screen high-quality embryos for eugenics, and again, this study has initially identified stem cell development as a very important problem in the field of regenerative medicine three-dimensional human blastocyst culture system to solve life development-related puzzles to provide a new platform
as mentioned above, before the academic community can not obtain natural post-pregnancy after the post-bed stage of human embryos, so more rodent embryos or non-human primate embryos and other model biological substitution research, but this can not accurately reflect the real situation of human molecular regulation and other laws At the same time, the results of recent human pre-pregnancy embryo development, including a recent paper published in the journal Science, are still limited by a two-dimensional technology platform that cannot simulate conditions in the body Li Tianqing, , said that under the condition siphone of strict ethical permission and patient informed consent, the research team used clinically donated embryos, first by improving the medium and culture methods, developed a three-dimensional (3D) human blastocyst culture system, overcoming two-dimensional (2D) can not simulate the defects of embryo development, the first human cystembryo culture in 3D conditions to the 14th day of the original stage, closer to the real conditions in the body " the core of the establishment of 3D embryos is that the growth of cells requires a culture system that is closest to the physiological environment of the human body, which can be understood as a space environment for the food and embryo growth of cells and embryos Previously, there are many defects in the research of the culture system at home and abroad, resulting in the embryo cells can not maintain the three-dimensional structure of space, such as a beach of water, the surface collapse, so the cell can only make surface contact with the petri dish to become a 2D environment, so that the cells can only one-on-one or only a small number of connections, which is a major defect for further study of the interaction between cells Li Tianqing said that, in fact, the contact between cells, the original three-dimensional environment, like we put a water beads hanging, do not let it collapse Due to the lack of spatially supported structure strapped to the 2D condition, the embryo cannot develop further at a certain time, so the 2D embryo can usually only reach the 12th day or so at present, their own research and development of the culture system can achieve the cultivation of 3D embryos, and can highly simulate the environment of the in vivo embryos, embryos under different forms of development and spontaneousassembly into 2D conditions can not produce 3D structures, including embryo double-layer cup plate, amniocyceum, substrate, primary and primate unique secondary egg sac, front and front shaft and original strip Li Tianqing is convinced that their independent research and development of the training system will provide a new platform for the academic community to study the frontiers of life related topics.