In the absence of a law governing stem cell research, the US National Academies are studying guidelines on the production of chimaeric embryos, which mix cells and DNA from different species. Many researchers believe that they could learn valuable lessons about human development by injecting human embryonic stem cells into embryos, foetuses or newborn animals of other species.
For instance, Irving Weissman, of Stanford University, one of the leading figures in US stem cell research, feels that much of his own work is only be possible with human-mouse chimaeras. It would even be possible to construct a mouse whose entire brain would be made of human-derived cells, says Weissman, although this is not an experiment which he has performed. Although Weissman agrees that there should be some limits on research, he told Nature that "I haven't heard the reason yet for restricting certain experiments." He thinks that the "yuck factor" is no reason to ban an experiment.
After a two-day meeting earlier this month the academies plan to issue guidelines in February about chimaeras and other contentious issues in stem cell biology. These will not have the force of law, but the International Society for Stem Cell Research will recommend that its members observe them.
MORE ON THESE TOPICS |