On July 24, 2019, a lead stem cell researcher at the University of Tokyo and Stanford University, Hiromitsu Nakauchi received the approval from Japan Government to pursue one of the most controversial scientific studies: human-animal hybrids or we can say more precisely human-animal embryo experiments.
An assistant professor of neuroscience at Baylor College of Medicine in Houston said, “This project has a tremendous potential to help people who suffer from a broad variety of diseases or are in the need of tissue replacement”.
Nakauchi planned in moving with small steps. At first, he genetically manipulated the mice or rat so that they cannot make a pancreas. Then the injected human cells – called induced pluripotent stem (iPS) cells into those mice and rat. The goal is for the rodent embryo to use up the cells to build a pancreas for itself. Nakauchi team planned on watching these rodents grow and develop, carefully monitoring their organs and brains in the process. If this becomes successful, then the researchers will move forward and ask for approval to do the same with pigs.
The ultimate plan is to grow human organs inside animals. Perhaps these organs could one day be used for organs transplant in people. One of the biggest fears for this type of research is that the researchers do not know where the stem cells go in animals or what kind of cells they could develop into once they are injected. Suppose during the experiment; it detects that more than 30% of the rodent brains are human. In that case, they will have to stop the investigation, because then it would create a condition of “humanized” animals coming into existence.
Now, what is a humanized mouse? Scientists are concerned that if too many human cells injected inside the mouse’s brain. As a result, it would cause a change in its mental ability in some way. In other words, the hybrid mouse would have behaved like man. But, Nakauchi said this scenario is unlikely to happen because in an experiment they injected human iPS cells into a fertilized sheep egg. And then transplanted the embryo into the sheep at Stanford University. The number of human cells in the body of sheep was minimal, like one in thousands or one in ten thousand. So, considering all these, an animal with a human face will never be born.
Growing human cells in another species is not an easy task. The hybrid of human and sheep have risen for 28 days contained very few human cells and nothing resembling organs. This is because of the genetic distance between human and sheep. However, Nakauchi is experimenting with iPS cells at subtly different stages and trying to determine what limits the growth of individual cells in animal embryos.
Written by SHIVANGI SINGH.