2023-07-23 22:51:56
In a study just published in the journal Cell[1]researchers at the University of Texas report having developed ” perigastruloid “, which they define as ” an embryo-like structure also including the yolk sac (cf. Human “synthetic embryos”: announcements are multiplying).
« The presence of embryonic and extra-embryonic tissues allows researchers to examine the interactions between the epiblast, amnion and yolk sac during gastrulation, which was previously impossible in humans says Jun Wu, a biologist from theUniversity of Texas Southwestern Medical Center and lead author of the study. Gastrulation, the stage of embryonic development during which the three layers are formed, occurs between 17 and 21 days following fertilization. Gold, ” human embryos are generally not cultured for longer than 14 days for bioethical reasons (cf. Research on the embryo: no more limits?).
Using another type of stem cell
Instead of using “committed” pluripotent stem cells[2], more common, researchers have used expanded pluripotent stem cells (EPSC) (see Expanded stem cells, a breakthrough?). These cells have already been shown to be able to differentiate into embryonic and extra-embryonic tissues in mice.
By adding the ” appropriate growth factors to human EPSCs, these have differentiated into these two types of tissues[3]. The cells then self-organized into structures resembling the human embryo ».
The perigastruloids developed the amniotic cavity in which the embryos live, as well as the yolk sac cavities which provide blood supply to the embryos. In addition they presented early signs of organogenesis ”, such as neurulation, which marks the very beginning of the development of the central nervous system.
No “ethical concerns”?
The researchers consider their method “ effective and reproducible “. In what they regard as a small-scale trial they generated hundreds of perigastruloids.
« The power of this model comes from its ability to harness the remarkable self-organizing capacity of human EPSCs with minimal external intervention. commented Jun Wu.
The team wants to reassure by saying that perigastruloids are not viable ” due to the exclusion of trophoblasts which give rise to the placenta ». « This helps to allay the ethical concerns of this research », estimate the scientists (cf. Research on the embryo: the ISSCR plays on words).
[1] Jun Wu, Modeling post-implantation stages of human development into early organogenesis with stem cell-derived peri-gastruloids, Cell (2023). DOI: 10.1016/j.cell.2023.07.018
[2] primed
[3] Embryonic and extra-embryonic
Source : Phys.org, Cell Press (20/07/2023) – Photo : iStock
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#embryoids #perigastruloids
