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Our hybrid future? Should we worry about genetically ‘humanising’ pigs?

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This little piggy went to market: What is going on behind the headlines about ‘pig-human’ embryos?

Only a few millimetres of popular headline space greeted the news that scientists had grown a number of genetically modified pig embryos with the insertion of modified human body (somatic) cells.

The experimental creatures were called in the scientific media, “pig-human hybrids”, or echoing the stuff of myths and legends: “pig-human chimeras.” It was notable that some years ago, such stories would have been met by goggle-eyed “shock” but in January this year the news was greeted with a polite flutter.

Perhaps this is understandable. It is wise not to jump to Dr Frankenstein analogies just yet. (See on this Wesley Smith. The sophistication and complexity of genetic engineering is difficult to comprehend and the underlying philosophical and theological questions it raises are even more challenging.

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The story was the first of its kind to be published in a credible and peer-reviewed account, the journal Cell.

In 2016 Stanford University and other centres had reported the successful “manufacture” of rat-mouse hybrids.

Spanish and Californian laboratories of the Salk Institute for Biological Sciences conducted privately funded experiments. The experiments involved patching modified human stem-cells (originally from the skin of 40 human beings) into 2,000 pig embryos and inserting the surviving embryos into sows for the first trimester of the pig pregnancy. A small number of human cells did grow into early muscle and other cells in the surviving 186 embryos which were then destroyed before they could develop further.

The researchers reported that these embryonic hybrids represented small “first steps” in the creation of what is hoped will be: “humanised pancreases, hearts and livers in pigs” for the use in human organ transplantation. The overall plan is to experiment with such hybrids and eventually to produce pigs that in other respects look (and sound) like pigs, but who are modified to grow organs that contain sufficient human genetic code so that the organs will not be rejected by the sensitive human immunological system.

Many scientists around the world hailed this overcoming of the “species barrier” as “enthralling” and “exciting.”  Some bioethicists opined that although they had been caught a little off-guard they were “cautiously” optimistic about the news of the experiments. Christian bioethicists commented that the since experiments did not involve the destruction of human embryos or the creation of brain, reproductive cells or other organ tissue associated with “human identity or consciousness” in the pig embryos, they could not see any clear ethical objection to the venture. These are valid provisos.

Despite this, the research results do raise some complex new problems, which need to be examined more carefully and with more community discussion before the goal (and gold-mine) of distant organ “farms” become a reality. Some of these deeper problems can be foreshadowed in the language of and the responses to the Salk experiments themselves.

The first is that the researchers somewhat blithely reported that “only a tiny part” of each of the altered pig embryos (1/100,000 part or a million cells) was human. In genetics quantity is not everything. What is more important is what and how the genetic information unfolds within the new organism. Tiny differences in DNA have huge implications: as anyone who has infected by a “tiny” but dangerous virus will realise.

The second problem is that it is not only brain or reproductive cells which give us our identity as humans, but the entire organic form which makes us who and what we are.  Of course we share large amounts of DNA with chimps (over 96%), mice and mosquitoes and this makes it possible to graft skin, generate hormones and study diseases with our fellow creatures. However, these shared DNA “sentences” perform a different drama in human beings than in our fellow creatures. A human embryo gradually develops a brain, and person with severe dementia has a damaged one. In Christian ethics at least, we consider these entities, human beings worthy of respect, because they are “self-directed” unities or organisms of humankind.

The third is a familiar moral problem: that of justifying our actions as means of solving problems “in the end.”  Some commentators said of this news that although a pig-human hybrid “seems creepy” the goal of providing more organs for sick people justifies their creation.

Some science journalists noted that we “once thought IVF (In-vitro Fertilization)” technology was ethically problematic … “but we got over that.” There is a huge difference between resolving the many ethical headaches associated with IVF (the creation and destruction of thousands of human embryos, the exploitation of parenting “desire”, the risk to women and the pressure on couples, for example), and allowing an eroding pragmatism to undermine our ethical outlook.

The fourth issue was that of public and regulatory oversight. In 2016 the US National Institute for Science called for a funding moratorium on research which used animal embryos and “human pluripotent cells,” due to a range of social and ethical concerns. The temporary ban affected funding of projects using human cells in cross-species embryos, which themselves are not embryonic in origin but nonetheless can be adapted to become “pluripotent” (they can grow into a range of different tissue types in cross-species genetic modification).  The Salk team pursued the research despite these concerns, and are confident that in future they “need more human cells” to be inserted into their future pig embryos. What ethical standards or oversight do they use to guide their work? What accountability to the public and to their research participants do they offer?

The fifth question, is the most challenging of all. What does it mean to be human or humanised? What does it mean to “respect” the identity of other living things?

It is true that the Salk team were concerned that the stem-cells they used were “primed” to target specific organ tissue rather than randomly proliferating, and they found how difficult it was to encourage human cells to develop in another species (Of the 41 surrogate sows- in only 18 were embryos able to implant.) It was reported that the more human cells each pig embryos had, the less fully or normally developed it was. As one science reporter remarked “so it worked, but not well.” The scientists do not seem troubled by the research trajectory they have begun in generating humanised organs – will they become blasé about inserting up to 50%- 80% modified human cells

One of the Salk research authors, Jun Wu, argued that perhaps science will create anime-like “guardian creatures,” he said: “we need only look to mythical chimera, like the human-bird hybrids we know as angels, for a different perspective.” It was hard to know whether the scientist was being cynical or whimsical.

As the now deceased British theologian, Stratford Caldecott reflected in a thought provoking piece entitled “Animals in the Hierarchy of Creation” the Church herself needs join the public reflection, bringing to bioethics three crucial areas theological development: a) the “theology of the body”, b) listening to shared seams in the wisdom of traditional faiths and c) the importance of nature and ecology. As Caldecott concluded: “In my view all three are related, and they require a return to metaphysics.”

Perhaps some inter-disciplinary and humble reflection is called for. As one researcher noted: “No human cells emerged in the developing (pig embryo) brains …” however some human neural cells were found in the spinal tissue, and he added: “and we don’t know why.”

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