Human Organs To Be Grown In Animals As Hybrid Embryo Experiments Approved
Stem-cell scientists have just received a world-first approval to create animal embryos containing human cells, with the goal of growing organs in animals that can be used for human transplants.
The funding given by the Japanese government to this research comes after a decision in March from the science ministry to allow the creation of human-animal embryos. The research is being done with the aim of improving organ transplant quality.
Organ transplantation is a last line of therapy for treating patients suffering from organ failure, but the process is historically inconsistent and heavily dependent on whether or not suitable replacement organs are actually available.
The eventual aim of the research is to produce animals with viable human organs -- rather than part-human part-animal hybrids.
The approval decision was applauded by global medical bodies including the International Society for Stem Cell Research ( ISSCR), which said responsibly conducting research with these 'chimeric' embryos "will allow scientists to gain a better understanding of human development and disease".
While human-animal embryos have been created previously, they have never been allowed to develop beyond a cluster of cells and have never been brought to term.
The process of developing these embryos and then implanting them into surrogate mothers can be likened to same premise used in IVF.
Hiromitsu Nakauchi, the scientist leading the teams at the University of Tokyo and Stanford University, is planning to grow human cells in rat and mouse embryos and then transplant those embryos into surrogate mothers.
This will be a long and tentative process -- Nakauchi said that he plans on growing mouse embryos only to 14 days old, when the organs are mostly formed, for observation.
He will then seek government approval to conduct the same near full-term development experiments with pig embyros.
There is concern among bio-ethicists that the implanting of human cells may lead to development changes within animals that may not be predicted, such as human cells straying to the brains of developing animals and affecting their cognition.
It is also extremely difficult to ensure the growth of human cells in genetically-distinct animals so Nakauchi will be conducting the experiments cautiously in subtle stages.