Are human embryo models embryos?

With the development of modern biology, new kinds of embryonic human entities are now being generated which may have uncertain biological, moral, and legal status. This is because many of these entities may be severely compromised and, in some cases, divide only into a cluster of a few cells. In addition, some may not be generated through fertilisation, but through procedures such as cloning. Others may not even be entirely human.

With the development of stem-cell-based embryonic entities (see BioNews 1195), a number of similar questions relating to their moral status may be present (see BioNews 1194). In this regard, the International Society for Stem Cell Research used the term 'embryo models' when it presented, in 2021, its latest ethical guidelines for using such embryonic entities in research. This defined different categories of 'stem-cell-based embryo models', namely:

1. 'Non-integrated' stem-cell-based embryo models, which would have no reasonable expectation of achieving substantial development if any attempt was made to transfer them to a human or animal uterus. The guidelines indicated that the use of these models should be reported to the body responsible for the scientific and ethics surveillance of such research. However, at the discretion of this body (and subject to regulations and policies in the relevant jurisdiction), the research may not require further, or ongoing, review.
2. 'Integrated' stem-cell-based embryo models, which could potentially undergo further integrated development if cultured in appropriate conditions or, theoretically, if transferred to a uterus. In this case, the guidelines indicated that the use of these models would require a specialised oversight process. However, a paper accompanying the guidelines stated that these models 'are not bona fide embryos' due to their limited potential to reach the stages required for viable development.

But using the expression 'embryo model' without further information relating to moral status may be unfortunate, since it remains unclear whether the embryonic entity may actually be, or have been, an embryo. The 1996 Oxford English Reference Dictionary defines 'model' as 'a representation in three dimensions of an existing person or thing or of a proposed structure'. Thus, with the expression 'embryo model', it is uncertain whether the representation (the model) may eventually be considered as having the same moral status as the original (the embryo).

It is also important that the term 'embryo model' is not used to evade legal restrictions and regulations that exist in international law, and in countries such as the UK, relating to the embryo. For example, the Council of Europe Convention on Human Rights and Biomedicine, which entered into force in 1999 and has now been ratified by 30 European States (but not the UK), indicates in Article 18 that:

1. Where the law allows research on embryos in vitro, it shall ensure adequate protection of the embryo.
2. The creation of human embryos for research purposes is prohibited.

In addition, the UK Human Fertilisation and Embryology Act 2008, indicates in Section 1(2)(b) that 'In this Act... references to an embryo include an egg that is in the process of fertilisation or is undergoing any other process capable of resulting in an embryo'.

In this regard, it may be possible to define an embryo as a living organism consisting of cooperative and interdependent cellular systems that are united in a harmonious and integrated whole. Moreover, 'wholeness' in this sense represents the totality of the organism, which cannot be reduced to just a part of a greater whole. And, according to this description, an embryo can lose its wholeness and integration, but this does not mean that it was never whole in the past.

In a way, if an embryonic living entity may be considered as an integrated whole living being, with a beginning and an end in time, then it is an embryo. Thus, an alternative definition of an embryo may simply be: 'A living human being during the first eight weeks of his or her development'.

Moreover, even if an embryo is very sick or so compromised that it cannot survive into the advanced embryonic or fetal stages, and/or only exists for a very short time (such as a few seconds), it is still an embryo and should deserve protection. Indeed, the ability to survive (viability) and the prospective length of a life should not impact on its current moral status (which is also true of the moral status of all persons who are born – and who eventually die).

Thus, for the sake of clarity, it may be appropriate to emphasise that embryo models may have an uncertain moral status. And, if any doubt is present, such models should not be generated for research. Moreover, in the unfortunate situation where embryonic human entities of uncertain moral status are generated in certain countries, the only appropriate and responsible way forward is to give them the benefit of the doubt based on the precautionary principle.

Indeed, if some human embryonic living entities are not given the moral status to which they are entitled, nor given the benefit of the doubt if this status is uncertain, this could eventually challenge the very idea of conferring any kind of moral status to any embryonic entity. This is because the very practice of conferring and recognising moral status would be compromised. In this manner, the global protective network of a civilised society, which recognises that embryos are not just 'piles of cells', may become unstable, inconsistent, and unclear. In other words, the legal consequences resulting from the generation of embryonic human entities of uncertain moral status should not be underestimated.

Note: The views expressed in this article are those of the author and do not necessarily reflect the positions of the professional organisations with which he is affiliated.

The science, ethics and regulation of stem-cell-based embryo models will be discussed at the 2023 PET Annual Conference – How Much Change Do We Want? Updating Fertility, Embryo and Surrogacy Law – taking place online on Wednesday 6 December 2023.

Find out more and register here.