I only understand a few words of this paper in Cell, like “human”, “pig”, “embryo”, and “implantation”, but they are enough to raise both my eyebrows. I’ll quote the last paragraph of the paper rather than the abstract because it contains a little less jargon. There are some understandable, or possibly hair-raising depending on your point of view, pictures in the paper too.

Interspecies Chimerism with Mammalian Pluripotent Stem Cells. Wu, Jun et al. Cell, Volume 168 , Issue 3 , 473 – 486

The procedures and observations reported here on the capability of human pluripotent stem cells to integrate and differentiate in a ungulate embryo, albeit at a low level and efficiency, when optimized, may constitute a first step towards realizing the potential of interspecies blastocyst complementation with hPSCs. In particular, they may provide a better understanding of human embryogenesis, facilitate the development and implementation of humanized animal drug test platforms, as well as offer new insights on the onset and progression of human diseases in an in vivo setting. Ultimately, these observations also raise the possibility of xeno-generating transplantable human tissues and organs towards addressing the worldwide shortage of organ donors.

Of course rich people are going to have copies of all their vital organs cloned in pigs as soon as this technology is available. And some mad dictator or Bond villain on an island somewhere is going to be breeding pig people. Now speaking of madmen on islands, there was a story about a certain Dr. Moreau…but it was only a story, right?

 “Monsters manufactured!” said I. “Then you mean to tell me—”

“Yes. These creatures you have seen are animals carven and wrought into new shapes. To that, to the study of the plasticity of living forms, my life has been devoted. I have studied for years, gaining in knowledge as I go. I see you look horrified, and yet I am telling you nothing new. It all lay in the surface of practical anatomy years ago, but no one had the temerity to touch it. It is not simply the outward form of an animal which I can change. The physiology, the chemical rhythm of the creature, may also be made to undergo an enduring modification,—of which vaccination and other methods of inoculation with living or dead matter are examples that will, no doubt, be familiar to you. A similar operation is the transfusion of blood,—with which subject, indeed, I began. These are all familiar cases. Less so, and probably far more extensive, were the operations of those mediaeval practitioners who made dwarfs and beggar-cripples, show-monsters,—some vestiges of whose art still remain in the preliminary manipulation of the young mountebank or contortionist. Victor Hugo gives an account of them in ‘L’Homme qui Rit.’—But perhaps my meaning grows plain now. You begin to see that it is a possible thing to transplant tissue from one part of an animal to another, or from one animal to another; to alter its chemical reactions and methods of growth; to modify the articulations of its limbs; and, indeed, to change it in its most intimate structure.

“And yet this extraordinary branch of knowledge has never been sought as an end, and systematically, by modern investigators until I took it up! Some of such things have been hit upon in the last resort of surgery; most of the kindred evidence that will recur to your mind has been demonstrated as it were by accident,—by tyrants, by criminals, by the breeders of horses and dogs, by all kinds of untrained clumsy-handed men working for their own immediate ends. I was the first man to take up this question armed with antiseptic surgery, and with a really scientific knowledge of the laws of growth. Yet one would imagine it must have been practised in secret before. Such creatures as the Siamese Twins—And in the vaults of the Inquisition. No doubt their chief aim was artistic torture, but some at least of the inquisitors must have had a touch of scientific curiosity.”

“But,” said I, “these things—these animals talk!”

He said that was so, and proceeded to point out that the possibility of vivisection does not stop at a mere physical metamorphosis. A pig may be educated. The mental structure is even less determinate than the bodily. In our growing science of hypnotism we find the promise of a possibility of superseding old inherent instincts by new suggestions, grafting upon or replacing the inherited fixed ideas. Very much indeed of what we call moral education, he said, is such an artificial modification and perversion of instinct; pugnacity is trained into courageous self-sacrifice, and suppressed sexuality into religious emotion. And the great difference between man and monkey is in the larynx, he continued,—in the incapacity to frame delicately different sound-symbols by which thought could be sustained. In this I failed to agree with him, but with a certain incivility he declined to notice my objection. He repeated that the thing was so, and continued his account of his work.

I asked him why he had taken the human form as a model. There seemed to me then, and there still seems to me now, a strange wickedness for that choice.

He confessed that he had chosen that form by chance. “I might just as well have worked to form sheep into llamas and llamas into sheep. I suppose there is something in the human form that appeals to the artistic turn more powerfully than any animal shape can.