Instead, he and his colleagues want "to use the animals as an incubator.
#Chimera animals how to#
"We don't know how to guide the cells to become the cells we want," Izpisúa Belmonte says. Doing that in the lab, by recreating the 3D environment of a developing organ and reproducing all the signals it receives, is very difficult. Their goal is to learn how to coax stem cells to become specific tissues or organs. That is what several groups of researchers are now trying to do. They do not, however, prohibit injecting human pluripotent cells into the embryos of other animals and letting the chimeras develop. They prohibit breeding animals in which human stem cells might have become sperm or eggs, and they rule out primate-human experiments. Current NIH funding guidelines, finalized in 2009, reflect those recommendations. National Research Council and the Institute of Medicine recommended limits on such research in 2005, among them that no human stem cells be added to primate embryos and that animal. Some worry that such human cells, when combined with animal embryos, could develop into brain cells, sperm, or egg cells in the chimeric offspring. Pluripotent cells are a powerful type of stem cell that can become any cell type in the body. Chimeras that combine animal and human cells, especially those that involve pluripotent human cells, raise ethical questions, however.
Scientists see the term in a more positive light, using animal chimeras in a range of developmental biology and stem cell experiments. In ancient Greece, the chimera was a bad omen, appearing before shipwrecks, volcanoes, and other disasters. The mixtures of cells under debate are called chimeras, named for a monster of Greek mythology that had the body and head of a lion, a fire-breathing goat's head on its back, and a snakelike tail. I think it is great that we openly discuss this and hope that a conclusion is reached," he says. Izpisúa Belmonte took the news in stride. On 23 September, NIH issued a notice saying that it will not fund such research "while the Agency considers a possible policy revision in this area." And it has invited scientists and bioethicists to a meeting on 6 November to discuss the ethical questions raised by such experiments. The application is on hold, the agency has told him, as NIH reconsiders its rules for the kind of experiments he wants to do: mixing human stem cells into very early animal embryos and letting them develop, a strategy that could produce tissues or organs for transplantation.
So when Juan Carlos Izpisúaīelmonte, a developmental biologist at the Salk Institute for Biological Studies in San Diego, California, heard from NIH earlier this year that his was among the top-ranked applications, he was thrilled-but there was a catch. National Institutes of Health (NIH), which provides up to $500,000 annually forĥ years to a researcher pursuing innovative, potentially ground-breaking research. Please contact for more information about this collection, or to request permission to use these images.Few grants are more coveted than a Pioneer Award from the U.S. Responsibility for making an independent legal assessment of an item and securing any necessary permissions ultimately rests with persons desiring to use the item. This collection was digitized by Cornell University Library in 2013 from original materials, with funding from a Digital Collections in Arts and Sciences Grant to Caitlin Barrett and Verity Platt. The content in the Cornell Collection of Antiquities: Gems Collection (in part the White Collection of Historical Medallions, #8420, Division of Rare and Manuscript Collections) is believed to be in the public domain by virtue of the age of the underlying material, and is presented by Cornell University Library under the Guidelines for Using Text, Images, Audio, and Video from Cornell University Library Collections. Division of Rare and Manuscript Collections, Cornell University Library Archival Collection:Ĭornell Collections of Antiquities Format:
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