In August 2016, the National Institutes of Health announced that it was lifting its ban on research that introduces stem cells from humans into animal embryos. Stem cells have the ability to evolve into any human cell and can grow into any human tissue. The goal of this type of research is to grow human tissues and eventually human replacement organs in animals. What an innovative way to improve upon transplantation medicine! But to realize this potential, we would create an organism that is part animal and part human! These hybrids are the stuff of ancient mythology. These mixtures of different animals are called chimeras after the mythical ancient Greek creature that was part lion, snake and goat. One goal of today’s research is to produce tissues and organs for experimentation that will improve our understanding of human disease. An alternative and longer term goal would be to produce organs directly for human transplantation. Imagine an infinite source of human organs – one wears out and you produce a new one as a replacement.
When human stem cells are introduced into an animal embryo, that creature becomes part human.