Scientists Successfully Create Human-Pig Chimera Embryos

And they’re working on understanding how the cells develop into particular organs, so they can ensure that the chimeras won’t be “too human”, meaning they won’t have human brains. The U.S. government suspended taxpayer funding of experiments in 2015.

In other experiments, scientists made a decision to use pigs for human organs due to similar organ sizes and developmental timescales, according to the Salk Institute.

An American team started by trying to forge an embryo that combined rats and mice to see if stem cells could be turned into replacement organs.

Then they went a step further.

But let’s focus on the pig-human chimeras for now.

Still, the new line of research has been under the scrutiny of policy makers.

The project began with the research team attempting to prove that it could grow one animal’s organ cells within a different species of animal.

“You’re going to have to watch carefully what is happening during the course of development, and be ready to shut down something that looks like it’s an unintentional outcome”, he said, meaning a pig embryo with any kind of human feature. They might also prove to be a good platform for testing human drugs, they write. “This required a tour de force”, lead investigator Juan Carlos Izpisua Belmonte said.

The results described in Cell are far from realizing that dream. “Therefore before moving on to human it was important to gather more information about interspecies chimeras and rat-mouse is a ideal starting point”.

Wu added that the larger the evolutionary distance between humans and an animal species, the more hard it would be for scientists to integrate human cells and animal species. Izpisua Belmonte and Wu also successfully created human/cow chimeras at the blastocyst stage-a few days following fertilization, but before the ball of about 250 cells implants in the uterine wall-but only pursued pigs because of the animal’s long history in human medicine. However, the creation of chimeras, and research with stem cells in general, is not without issues.

“Interspecies blastocyst complementation might allow human organ generation in animals whose organ size, anatomy, and physiology are closer to humans”. However, this scenario is unlikely to happen, and it is worth noting that scientists are taking extra care to address the ethical concerns that their study might create. “We don’t really know”, New York Medical College professor Stuart Newman told NPR.

“It’s an interesting question, whether you could build an organ-even if it’s not for transplantation but just for study”, said Wilson. “I don’t think they’d be worse morally from how we raise pigs for meat, but my hunch is that the way to raise pigs to retrieve organs would require a departure from the way pigs are raised [for research]”. Would the pigs suddenly be more human? Only about one out of every 100,000 cells in the hybrid embryos was human. Such organs will be developed in animal’s body and they will be removed after being euthanized.

Then the researchers tried combining human induced pluripotent stem cells (reprogrammed adult cells that have regained the characteristics of embryonic cells) with pig embryos.

“The ultimate goal of this research is to generate organs that can match to your immune system”, said Dr Jun Wu from the Salk Institute, lead author of the research.

The hybrid embryo was then left to develop for three to four weeks.

Prof Belmonte said: “We are restricting development to one month in the pig, the reason is this is enough for us now to understand how cells mix, differentiate and integrate”.

They can be made using genetic engineering or gene editing. This step will actually diminish the human organs shortage.