US may fund research to create mixed human-animal embryos

Research that mixes human cells into animal embryos could get US government funds for the first time under a new proposal that has stoked concerns about ethics and the limits of science. One year ago, the US National Institutes of Health placed a moratorium on research proposing to introduce human pluripotent stem cells into animal embryos, deeming it too controversial. Now, the NIH is offering to fund research introducing human cells into certain kinds of animals.