Artificial embryos, also called embryoids, embryonic models or blastoids, are cell agglomerates obtained from stem cells that reflect, to a certain extent, some structures and functions of embryos. In order to be able to study this intriguing and complex stage of our development without resorting to the use of human embryos, the ethical and legal impediments of these investigations are avoided.

A year ago, the prestigious scientific journal Nature published the creation of an artificial embryo, from human stem cells, which was capable of implanting itself in a kind of artificial uterus.

The objective of the research was to generate an artificial embryo model with which to study the complex phenomenon of implantation, the moment in which the embryo nestles in the maternal womb. Numerous cases of spontaneous abortions are related to the inability of some embryos to implant successfully.

These artificial embryos have been called blastoids, in reference to the blastocyst, which is the embryo at the stage where uterine implantation occurs. Human stem cells of different types were used to generate them, including embryonic stem cells and induced pluripotent cells. These are obtained by reprogramming adult cells to a state of development similar to that of the embryo.

Similar structures were achieved with comparably high efficiency with both types of stem cells, the authors of the research conclude.

Subsequently, these artificial embryos were placed in a kind of artificial uterus, which consisted of a set of endometrial cells that lined the inside of the uterus. The researchers found that by adding estrogen and progesterone in the same amount that is produced during pregnancy, the blastoids attached to the endometrial cells, simulating implantation.

The researchers hope that this artificial embryo-uterus model will allow the phenomenon of implantation to be studied in greater depth, since it would help to better understand the causes of spontaneous abortions.

From the bioethical point of view, this research has advantages and disadvantages.

On the one hand, the possibility of studying embryonic development and the beginning of pregnancy without having to use real embryos, thanks to artificial embryonic models, is very positive. In addition, the knowledge generated in this research could lead to the development of treatments to prevent repeat miscarriages.

On the contrary, studies with these artificial embryonic models also raise some bioethical issues that need to be resolved. On the one hand, that in some cases the embryoids are obtained from embryonic stem cells, which at first instance have been obtained from human embryos that are destroyed in the process. Likewise, human embryos are usually included in the studies as controls, in order to compare the results obtained with the embryoid models and with real embryos.

Faced with the problem of destroying embryos, promoting the use of induced pluripotent stem cells seems the best solution. Regarding the inclusion of human embryos as a control to compare the results, it would be possible to use the data already available from other investigations. In no case is it justified to use human embryos as research material.

However, the researchers do not seem to consider this possibility, since they state in their work that blastoids represent an ethical opportunity to complement embryo research not to completely replace it.

On the other hand, in the same way that these studies open the door to the development of therapies against infertility, they also do so to the possibility of generating new contraceptives and abortion methods.

Finally, the ever-increasing development of these embryoids means that they are increasingly complex embryonic models similar to the structure and physiology of real embryos. This is currently an advantage, but there is a risk that there will come a time when the models will be so perfect that they will constitute a real embryo, which would imply the artificial generation of life.

In addition, this would imply the same problem as current embryo research, contempt for human dignity and the destruction of human beings in their embryonic stage. Added to this is the aggravating circumstance that the embryos generated would be clones of the stem cell donors.

Nicolas Rivron, director of the research we are discussing, points out that an attempt should never be made to implant an embryoid in a woman to give birth to a baby and that it would probably not be successful. His team has been trying for years to implant a mouse pseudo-embryo in the uterus of a female mouse. On no occasion have they succeeded in generating newborn mice. The author stresses that in all probability it would not work in humans either.

Lucía Gómez Tatay

Bioethics Observatory – Institute of Life Sciences

Catholic University of Valencia


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