New Embryo “Models” are Ontologically and Morally Human

 P.Pullicino, EJ Richard, WJ Burke

Researchers in the United Kingdom and Israel announced two months ago that they had grown late stage embryo “models”. These embryo “models” are different from embryos because they are formed without the combination of sperm and ovum. The method used to produce them is to take naive embryonic stem cells (ESC). These naive embryonic stem cells were treated with chemicals to induce them into transforming into four types of cells: epiblasts which are pluripotent ESCs, which become the embryo proper; hypoblasts which become the supportive yolk sac; trophoblasts which becomes the placenta and extraembryonic mesoderm cells. 120 of these cells are mixed in a precise ratio and grown in a shaker, which keeps the cells continually gently moving. The cells grow and self-organise into complete embryos but the experiment was not allowed to go beyond 14 days which is the legal limit allowed for experimentation on human embryos. When this procedure was performed in mice the embryo model was indistinguishable from the natural embryo. “Pseudo-embryos” that progressed to birth of live mice have already been developed by injecting modified skin cells (induced pluripotent cells or iPS cells) into an embryonic blastocyst and implanting them in a uterus. (It should be noted that epiblast cell component of the embryo “model” experiment are the equivalent of iPS cells.)

These new experiments bring up several ethical questions. Researchers say that these embryo models provide an ethical means of experimenting on early human development as it is a stage of development that is little known and the time of gestation when most miscarriages occur. The fact that these cells are beginning to form tissues spontaneously suggests that they are more than just randomly associating tissues and that there is some organising force at play. Many are asking the question: Is this research ethical?

The first major problem is that the naive ESCs are obtained from the inner cell mass of an embryo and harvesting them necessitates the destruction of a human life.  The second is that these embryos are not just “models” of grouping together of tissues. 

We have recently published an editorial showing that human iPS cells that are made from reprograming skin cells are ontologically and morally identical to human embryos.1 As mentioned above these iPS cells can produce live adult mice if these are injected into a mouse embryonic blastocyst. The ESC are the same as iPS cells. Both the ESC and the iPS cells are capable of differentiating into any of the organism’s cells or tissues.1 These pluripotent cells are morally and ontologically indistinguishable from human embryos, and human embryos have an individual spiritual soul. The fact that these cells when coaxed to transform and mixed start to form an embryo structure, is therefore not surprising.

In conclusion, as mentioned in our previous paper, the reprogramming of cells to a pluripotent state is not morally neutral and the reprogramming of human stem cells to pluripotency gives each cell the status of an embryo. Partially reprogrammed cells do not have the same ethical issue as they do not go through a pluripotent stage. These embryo “models” therefore have the ontological and moral status of human embryos and research to produce them should be prohibited. It should be noted that the term “embryo model” is being used to justify research on them continuing past 14 days which is a legal limit for research on embryos. These structures are not just “models” of embryos. They are embryos. It should be noted that any destructive research on human embryos is unethical.

1. Patrick Pullicino, Edward J. Richard, William J. Burke. Mass Production of Human

Embryoid” Cells from Developmentally Frozen Embryos: Is It Ethical? Linacre Quarterly. 2020; 87: 347-350.