Reacción a "Reactions to the generation of synthetic stem cell-derived mouse embryos"

This work is an important addition to the work published by Jacob Hanna's group in Cell a few days ago. Both represent a major breakthrough, proving the need for interaction between embryonic and extra-embryonic cells in the formation of a mammal. Moreover, they show that it is possible to initiate mammalian development outside the womb. But it is more a 'proof of concept' than an absolute achievement. As in the case of Hanna's work, the number of synthetic embryos obtained with the method is small (in the order of 1% of the initial cultures) and their development collapses prematurely after a few days in culture. It is also important to note that the structures obtained, although they contain the elements of an embryo, have significant deficiencies and most of these structures are damaged or incomplete. It is also unclear what, exactly, is intended to be obtained from these structures, which, one has the impression, emerge from the culture almost magically. 

The need to emphasise the defects and underperformance of the experiment is important, because the idea that a mouse embryo has been obtained in culture will give rise to the notion that the same will soon be done with human cells and that a human embryo will be obtained. It is very likely that this will happen in the future and one value of this experiment is to alert us to this possibility so that we consider the ethical aspects of such experiments and the social impact they may have. 

Of course, both papers are important, but they are at very early stages and we will have to wait and see how they develop. Much more important will be to see what applications the system has. To take that step, efficiency and accuracy will have to increase. At the moment, female mice make perfect embryos more efficiently.