Human-animal chimeric embryos—organisms created using cells from two or more species—have the potential to change how researchers study disease and generate organs and tissues for human transplants. One day, scientists have proposed, it may be possible for someone with, say, pancreatic cancer to have their stem cells injected into a modified swine embryo lacking its own pancreas so it can grow the human organ for donation.
Already, human-animal chimeric embryos (HACEs) have been created using human cells injected into pigs, sheep, mice, rats, and monkeys, although none in the US have been brought to term. In fact, their very existence is ethically contentious. What happens, for example, if scientists were to grow a human brain in an animal, blurring the line between species?
In response to ethical, social, and legal concerns, the National Institutes of Health (NIH) issued a moratorium on funding for HACE research in 2015 pending the development of a new set of regulatory guidelines. While research continues in other countries—and even in the US, through collaborations with foreign researchers and private funding—the NIH has yet to reverse its decision, despite previous announcements that it would do so.
To gauge the American public’s support for HACE research, Francis Shen, a professor of law at the University of Minnesota, recreated two recent surveys carried out in Japan, where many of the world’s HACE studies are done. In those surveys, Shen’s colleagues found that the majority of the Japanese public supported the use of HACEs, although their feelings varied depending on the type of organ or tissue being grown. “We thought, ‘Boy, it’d be really interesting to see if the American public thinks about things the same way,’” Shen tells The Scientist.
Shen’s team directly translated the Japanese surveys into English, asking 430 participants to rate their support for each of the three steps involved in producing an organ using HACE technology: the insertion of human stem cells into an animal embryo, the transplanting of the embryo into a surrogate, and the harvesting of the resulting organ for use in a human. As before, they gauged people’s reactions to organ and tissue types, including skin, liver, blood, heart, brain, and gametes.