The Science of Chimeras

Science is without any inherent morality. Even the medical injunction, "First, do no harm", does not apply. Big science, as all science is these days, requires a grounding in regulation, because it will not regulate itself, especially in an elitist culture which accepts no moral restrictions for itself. If the will to assert moral principles over DNA science does not exist, then the day of Dr. Mengele-science and Dr. Moreau-science, will rapidly emerge to become commonplace, and it will be defended by chimeric super-soldiers.

In Search For Cures, Scientists Create Embryos That Are Both Animal And Human

After the embryos have had their DNA edited this way, Ross creates another hole in the membrane so he can inject human induced pluripotent stem cells, or iPS for short, into the pig embryos.

Like human embryonic stem cells, iPS cells can turn into any kind of cell or tissue in the body. The researchers' hope is that the human stem cells will take advantage of the void in the embryo to start forming a human pancreas.

Because iPS cells can be made from any adult's skin cells, any organs they form would match the patient who needs the transplant, vastly reducing the risk that the body would reject the new organ.

But for the embryo to develop and produce an organ, Ross has to put the chimera embryos into the wombs of adult pigs. That involves a surgical procedure, which is performed in a large operating room across the street from Ross's lab.
Pablo Ross of the University of California, Davis inserts human stem cells into a pig embryo as part of experiments to create chimeric embryos.

Pablo Ross of the University of California, Davis inserts human stem cells into a pig embryo as part of experiments to create chimeric embryos.
Rob Stein/NPR

The day Ross opened his lab to me, a surgical team was anesthetizing an adult female pig so surgeons could make an incision to get access to its uterus.

Ross then rushed over with a special syringe filled with chimera embryos. He injected 25 embryos into each side of the animal's uterus. The procedure took about an hour. He repeated the process on a second pig.

Every time Ross does this, he then waits a few weeks to allow the embryos to develop to their 28th day — a time when primitive structures such as organs start to form.

Ross then retrieves the chimeric embryos to dissect them so he can see what the human stem cells are doing inside. He examines whether the human stem cells have started to form a pancreas, and whether they have begun making any other types of tissues.

The uncertainty is part of what makes the work so controversial. Ross and other scientists conducting these experiments can't know exactly where the human stem cells will go. Ross hopes they'll only grow a human pancreas. But they could go elsewhere, such as to the brain.

"If you have pigs with partly human brains you would have animals that might actually have consciousness like a human," Newman says. "It might have human-type needs. We don't really know."

That possibility raises new questions about the morality of using the animals for experimentation. Another concern is that the stem cells could form human sperm and human eggs in the chimeras.

"If a male chimeric pig mated with a female chimeric pig, the result could be a human fetus developing in the uterus of that female chimera," Newman says. Another possibility is the animals could give birth to some kind of part-human, part-pig creature.

"One of the concerns that a lot of people have is that there's something sacrosanct about what it means to be human expressed in our DNA," says Jason Robert, a bioethicist at Arizona State University. "And that by inserting that into other animals and giving those other animals potentially some of the capacities of humans that this could be a kind of violation — a kind of, maybe, even a playing God."

Ross defends what his work. "I don't consider that we're playing God or even close to that," Ross says. "We're just trying to use the technologies that we have developed to improve peoples' life."