Scientists are well on their way to growing human organs inside pigs, organs that will then be used for a transplant.
One of the drawbacks, however, is the fear that the pigs will actually develop human-like brains!
If it works, growing human organs inside pigs would solve the severe problem of donor organ shortages. Currently, thousands of people who need organ transplants die while waiting for an organ to become available.
Researchers at the University of California, Davis, are reporting tremendous progress using adult stem cells.
How It Works
In a laboratory, scientists combine a male pig sperm and a female pig egg to make a pig embryo. Soon thereafter they use a process called "gene editing" to remove part of the embryo's DNA. Let's say they want to grow a human pancreas for transplantation. The scientists would remove the part of the pig embryo's DNA that allows it to grow a pancreas.
Now there's a void in the pig embryo's DNA. That void is then filled with stem cells from the human who needs a new pancreas.
The embryo is then implanted in the pig to grow. The end result is an embryo with a human pancreas, but all its other organs are pig.
It sounds like a pretty good plan. However there is the issue of "unintended consequences."
BBC News reports The National Institutes of Health is banning such experiments out of concern that something might go terribly wrong. Among other things, they're worried the human cells will get into the developing pig embryo's brain, and make it human-like.
Too far fetched? Not so much.
Pablo Ross, a reproductive biologist who is leading the research told BBC, "We think there is very low potential for a human brain to grow, but this is something we will be investigating."
Although there are some serious ethical concerns, researchers can't help but imagine the implications of this project extending beyond organ transplants.
For example, Walter Low, a professor in the department of neurosurgery at the University of Minnesota is leading a team of researchers to create dopamine-producing human neurons from pig embryos to treat patients with Parkinson's disease, according to the BBC.
He admits they are proceeding cautiously.
"With every organ we will look at what's happening in the brain," he said, "and if we find that it's too human like, then we won't let those fetuses be born."
Meanwhile, animal rights activists are somewhat opposed to the idea of harvesting, then destroying pig embryos to save human lives, but are less bothered by it if, at the same time, people would cut back on their ham and bacon consumption.
Peter Stevenson, from Compassion in World Farming, told the BBC, "I'm nervous about opening up a new source of animal suffering. Let's first get many more people to donate organs. If there is still a shortage after that, we can consider using pigs, but on the basis that we eat less meat so that there is no overall increase in the number of pigs being used for human purposes."