3.4.3 Transgenesis

In order to optimise the chance of survival of organs in human beings, the genetic modification of the potential animal-donors seems to be an obvious option. The donor pigs used in 2022 and 2023 were genetically modified with 3 knockouts and 7 gene modifications, which would reduce the organs’ rejection reactions after transplantation. The changing of the genetic make-up of animals is acceptable as long as a number of ethical principles are taken into consideration:

1. The changes resulting from the genetic modifications may not cause the animal pain, fear, and suffering.
2. The effects on the offspring of the human recipient and the environment must be taken into consideration.
3. Transgenic animals must be well-controlled and may not just be set free in the environment.
4. The number of transgenic animals which is brought into being for the purpose of transplantation must be kept to a minimum.
5. The removal of organs and/or tissue must be carried out in one single surgery.
6. Every experiment must be judged by a competent ethical commission.
   It is also important that recipients are fully informed about the origin of the organs and the accompanying risks and that one obtain from the recipients an informed consent for the procedure (Pontifical Academy for Life 2001, no. 15-16) [1: Pontifical Academy for Life. Prospects for xenotransplantation scientific aspects and ethical considerations. Vatican City 2001.].

Not all Catholic ethicists, though, agree with this point of view of the Pontifical Academy for Life. [2: N. Tonti-Filippini, J.I. Fleming, G.K. Pike and R. Campbell. Ethics and Human-Animal Transgenesis. National Catholic Bioethics Quarterly 2006, 6, 689–704.] Tonti-Filippini, Fleming, Pike and Campbell are opposed to the intentional mixing of human DNA with that of animals.

1. In the first place they read a prohibition not only of hybridisation in the sense of fertilisation between human and animal gametes, but of any human-animal transgenesis in Donum Vitae (I,6). [3: Congregatio pro Doctrina Fidei. Donum Vitae. Instructio de observantia erga vitam humanam nascentem deque procreationis dignitate tuenda. Acta Apostolicae Sedis 1988, 80, 70-102.] They are of the opinion that the term ‘hybrid’ does not only mean an organism having its origin in
   a fertilisation process, but any organism of which its inherited characteristics stem from organisms of different species. Therefore, the Congregation for the Doctrine of the Faith would condemn in its instruction Donum Vitae apart from hybridisation by means of fertilisation of human and animal gametes every form of human-animal transgenesis.
2. Secondly, they are convinced that human-animal transgenesis of whatever proportion, also in the case of the transmission of one human gene to an animal ovum or zygote, causes an unacceptable confusion of identity.

A hybrid resulting from fertilisation of a human and an animal gamete has a full set of genes from human origin. Even if it would become a full-grown individual without specific human features as rational capacities and the capacity of free decision making, one could not by all means exclude that it is animated by a human soul and hence a human person. For the presence of the full set of genes from the animal part could prevent the spiritual faculties from coming to expression. It is of course impossible to say which proportion of human-animal transgenesis would result in an organism with the ‘disposition of the material’ (see this Manual II.1.1.2.4) to be animated by a human soul. The Pontifical Academy obviously supposes that this is not the case when only one or a few human genes, especially those which might prevent a immunological rejection of an organ from the resulting organism after transplantation to humans, are added to the genome of an animal ovum or zygote, and that this is therefore morally licit. However, it is a fact that not all Catholic ethicists share this view. Tonti-Filippini, Fleming, et al. think that “the confusion of identity arises as soon as any human genes become formative of the new being” [4: N. Tonti-Filippini, J.I. Fleming, G.K. Pike and R. Campbell. Ethics and Human-Animal Transgenesis. National Catholic Bioethics Quarterly 2006, 6, 689–704.] and that the transmission of only one human gene to an animal ovum or zygote is an infringement on human dignity and an abuse of the human generative faculties (they do however not reject adding human genes to bacteria, because these cannot develop into embryos, such that no confusion of identity will arise).