  Chimera research inherits the ethical issues associated with traditional animal ethics and, when using hPSCs derived from embryos, with hESC research in general, but one striking feature of the chimera debate is the existence of several advisory bodies that exhibit a cautious reaction to certain kinds of chimeric research even though they maintain that non-human animal research and embryo research are generally permissible. For example, the Human Embryo Research Panel of the National Institutes of Health (NIH) issued a general endorsement of a wide range of embryo research (including hESC research) and research on non-human animals. Nonetheless, the panel expressed concern about the “extensive mixing” that would occur in some chimera research and unanimously opposed, “on ethical and scientific grounds, the creation of heterologous, or human-nonhuman chimeras, with or without transfer [into a uterus]” (NIH 1994, 80). Similar statements have been made by the Ethics Advisory Board of Geron, the private biotechnology company that financed Thomson’s original derivations (Geron Ethics Advisory Board 1999, 34), the University of Wisconsin’s Biotechnology Advisory Committee, which provided guidance to UW on hESC research policy (University of Wisconsin Biotechnology Advisory Committee 2001), the Committee on Guidelines for Human Stem Cell Research created by the National Academies’ Institute of Medicine and the National Research Council (National Academy of Sciences 2005), and the International Society for Stem Cell Research (International Society for Stem Cell Research 2006, 7). This suggests that chimera research raises some ethical concerns that are distinct from the traditional issues discussed about the use of non-human animals or human embryos in research.