The National Institutes of Health today announced a plan to lift a ban on funding for hybrid – or ‘chimera’ – stem cell research. The move could drastically change how future research is conducted and one which is sure to spark fierce debate.

In September 2015, the NIH informed the research community that it would not fund research in which human pluripotent cells were introduced into non-human vertebrate animal pre-gastrulation stage embryos.  Subsequently, in November 2015, a workshop with experts was conducted to assess the current state of the science. 

The proposed policy changes would affect two areas; 1: allowing for human pluripotent cells to be introduced into non-human vertebrate embryos through end of the gastrulation stage (with exceptions for non-human primates), and 2: for human cells to be introduced into post-gastrulation non-human mammals (excluding rodents), such that there could be either a substantial contribution or a substantial functional modification to the animal brain by the human cells. 

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Pluripotent cells can become any cells, leaving open the possibility of growing a human organ, such as a kidney, in a pig or goat. The prospect of human stem cells developing in an animal’s brain also becomes a possibility, raising serious ethical dilemmas that go to the core of what it is to be human.

“There’s no clear dividing line because we lack an understanding of at what point humanization of an animal brain could lead to more human-like thought or consciousness,” Paul Knoepfler, of the University of California, Davis, told the New York Times.

Opening access to this area of research may pave the way for groundbreaking discoveries, allowing for more accurate disease modeling and testing, which could lead to curing neurologic disorders such as Alzheimer’s disease. 

If the ban is lifted the types of research that become possible are still in their infancy. For instance, identifying which human stem cell can develop into certain tissues, in certain animal embryos. In a teleconference, Carrie Wolinetz, associate director for science policy at NIH, was open about the possibilities, saying she expected some, “on-the-job learning.”

The NIH have opened a 30-day period for public comment on the proposed, starting today.

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