Chennai: Scientists have reportedly produced monkey embryos containing human cells to create human-animal chimeras, sparking the once quietened debate once again.
A chimera is an organism whose cells come from two or more ‘individuals’. The word comes from a beast from Greek mythology which was said to be part lion, part goat and part snake.
The recent work however is looking at combinations from different species, in this case human and monkey.
The latest report, published in a Spanish newspaper, claims a team of researchers led by prof. Juan Carlos Izpisua Belmonte from the Salk Institute in the US have produced monkey-human chimeras. The research was conducted in China ‘to avoid legal issues’, according to the report.
Chimeras are seen as a potential way to address the lack of organs for transplantation, as well as problems of organ rejection. Scientists believe organs genetically matched to a particular human recipient could one day be grown inside animals.
The approach is based on taking cells from an adult human and reprogramming them to become stem cells, which can give rise to any type of cell in the body. They are then introduced into the embryo of another species.
Izpisúa Belmonte and other scientists have previously managed to produce both pig embryos and sheep embryos which contain human cells, although the proportions are tiny: in the latter case, researchers estimate that only one cell in 10,000 was human. Pig-human and sheep-human chimeras are attractive in part because pigs and sheep have organs about the right size for transplantation into humans.
Alejandro De Los Angeles, from the department of psychiatry at Yale University, said, according to a report from the Guardian, it was likely monkey-human chimeras were being developed to explore how to improve the proportion of human cells in such organisms.
‘Making human-monkey chimeras could teach us how to make human-pig chimeras with the hope of making organs for transplantation,’ he said. ‘It could teach us which types of stem cells we should be using, or other ways of enhancing what’s called ‘human chimerism levels’ inside pigs.’
De Los Angeles pointed out that, as with previous work in pigs and sheep, the human-monkey chimeras have reportedly only been allowed to develop for a few weeks – i.e., before organs actually form.
The news of the monkey-human chimeras comes shortly after it was reported Japanese researchers such as prof. Hiromitsu Nakauchi received government support to create mouse-human chimeras.
In March Japan lifted a ban on allowing such embryos to develop beyond 14 days and being implanted in a uterus, meaning these chimeras can, if permission for an experiment is granted, be brought to term. Nakauchi has said he does not plan to bring the human-mouse chimeras to term yet.