Chimera Research and Stem Cell Therapies for Human Neurodegenerative Disorders

Abstract

In April 2005, the U.S. National Academy of Sciences (NAS) published its Guidelines for Human Embryonic Stem Cell Research. These voluntary guidelines are among the most permissive in the world—in a country that prohibits federal funding of research to derive human embryonic stem (hES) cells (cells that can self-renew or differentiate into most cells in the human body). One of the few research prohibitions in the NAS guidelines concerns the creation of certain kinds of human–nonhuman chimeras. A chimera is an organism with a mixture of cells from two different organisms, from the same or different species. Figure 1 provides a useful overview of different types of chimeras.