Medical News
Human-monkey hybrid organ production now seems less of a chimera
Still , ethical questions need to be answered before research moves into practice
R
esearchers in China and the US have injected human stem cells into primate embryos to create hybrid — or chimeric — embryos that they grew for up to 20 days .
They hope to use them to study early human development , model disease , and develop new approaches for drug screening , as well as potentially generating transplantable cells , tissues , or organs .
Some will find the idea of mixing human cells with any animal embryo to be highly questionable . For the researchers who led the study , their rationale was that they had long been interested in addressing the shortage of life-saving organs for human transplantation by creating human-pig chimeras .
While they had previously created a pig foetus that contained human cells , the contribution was of low value and the goal to create transplantable organs remained elusive . How to solve this challenge led to the latest experiment .
The researchers were not attempting to create human-monkey chimeras with a view to harvesting organs . Rather , they created a laboratory model to explore what would happen to the transferred human cells in an attempt to identify ways to enhance survival and ultimately improve human chimerism in pig and other evolutionarily distant species .
Mixing human embryonic stem cells with embryos from other species during embryonic development , known as blastocyst complementation , is emerging as a powerful platform for generating humanised functional organs and tissues for regenerative medicine .
The work of the researchers is a step towards that direction , and they seem to have successfully tweaked the molecular developmental stages of chimeric lines .
But while the study has provided important insights into developmental biology , it has also raised ethical questions that warrant careful consideration around application and oversight . The work has already begun to stimulate important conversations about where boundaries should lie .
For example , while developing such embryos may be one way to conduct research that would be ethically problematic to do in humans , an editorial accompanying the study highlights that these chimeric embryos themselves raise ethical challenges for society .
And then there are the more practical issues to contend with . According to Dr Bernard Tuch , a consultant endocrinologist and professor at the University of Sydney , the authors have shown great skill in achieving the survival of human cells in a monkey embryo .
If implanted in utero , he said , it could lead to the generation of human-type kidneys to be implanted in people with kidney failure .
“ This would help resolve the relative lack of transplantable kidneys . However , the availability of monkeys for this purpose is quite limited . Moreover , the law would need to be altered to allow this , something that today seems unlikely .
“ If the goal is to create organs in pigs suitable for transplanting into needy humans , for example , for someone with renal failure , there are technically and ethically easier means of trying to achieve this ,” he told Global Health Asia-Pacific .
24 JUNE 2021 GlobalHealthAsiaPacific . com