For the first time ever, scientists have created a human-sheep hybrid. It may sound really scary, but it serves a very important purpose.
A team at the Stanford University is responsible for this human-sheep hybrid. They successfully grew embryos inside a surrogate that contains both sheep and human cells. The result is that the human-sheep hybrid is 99% sheep and 1%, human. Therefore, one should not expect some monstrous half human half sheep monstrosity roaming about.
“The contribution of human cells so far is very small. It’s nothing like a pig with a human face or human brain,” stem cell biologist Hiro Nakauchi from Stanford University told media at a presentation of the research this week in Austin, Texas, explaining that, by cell count, only about one in 10,000 cells (or less) in the sheep embryos are human.
But why do this? The most important reason why scientists are doing this is that of organ transplants. Scientists want to grow human organs inside animals for medical reasons. This will help in organ transplants, which in turn will help in curing diseases like diabetes. Also, in the scientific and medical world, this means a lot. Researchers will not have to wait as long as they are waiting now to test new drugs for diseases.
Though the plan sounds radical – because it is – the need for donor organs in the US is at an all-time high, with roughly 30 people dying on the waiting list every day. Because of the relentless demand for organs, researchers have been working on making artificial organs or organs from another species a viable option for decades, but one question lingers: is all of this even ethical?
Before sheep, this was done on pigs too. Pigs were used as an incubator for human organs. A pig embryo, with human stem cells, was matured for 28 days and then was terminated. The half pig half human embryo seemed to be on track for developing a full human pancreas. If all goes as planned, then the pig will be born with a human pancreas, unaware of the existence of a human organ inside it.
The new chimaera with a sheep is the first-time scientists have done it. The study is based on the same study that guided the human-pig hybrids. Scientists chose sheep since their embryo is similar to that of the human embryo. Moreover, size of organs in sheep is similar to organs in humans.
However, this is still undergoing a lot of research. Organs cannot be directly transplanted from an animal to a human, even if that organ is a human organ. With pig-human hybrids, there was a chance of human’s organ receiver getting infected with pig diseases.
“Even today the best-matched organs, except if they come from identical twins, don’t last very long because with time the immune system continuously is attacking them,” says one of the team, reproductive biologist Pablo Ross from the University of California, Davis. Robin Lovell-Badge from the Francis Crick Institute in London says the organs will be rejected by the human body: “Even if they succeed in replacing all pancreatic cell types in the sheep with human cells, the blood vessels within the pancreas will be sheep-derived. The organs could not be used for transplants into humans without triggering the immune system to reject them — and this would probably be a very fast rejection.” However, there are still other bio-engineering methods such as gene editing that can help us create the perfect organs for humans even in other animals.
Although we are far off from actually making transplants, this field of biology is actually making progress. Using simply 1% of human cells in a sheep embryo allows us to track what happens when these cells are transplanted to the embryo. This tracking, in future, will allow us to make other organs with more accuracy.
Ross also said, “All of these approaches are controversial, and none of them is perfect, but they offer hope to people who are dying on a daily basis. We need to explore all possible alternatives to providing organs to ailing people.”
However, even though it is a breakthrough, there are a bunch of ethical questions that arise in this area. First of all, harvesting human organs in other species is not the most ethical thing to do. Ethics has been one of the reasons why research is not progressing much in this direction. How much should we exploit other animals still remains a question to be asked. This domain of research is still in its early stages without any practical implementations but may have something in future, not just for humans, but for other species as well. We can use similar methodologies to save diseased animals from nearly extinct species too.