Current Stem Cell Reports

, Volume 4, Issue 3, pp 235–239 | Cite as

The Ethics of Chimera Creation in Stem Cell Research

  • Insoo HyunEmail author
Ethics in Stem/Progenitor Cell Therapeutics (S Latham, Section Editor)
Part of the following topical collections:
  1. Topical Collection on Ethics in Stem/Progenitor Cell Therapeutics


Purpose of review

To summarize and clarify the main ethical issues surrounding the generation and use of human-animal chimeras in stem cell research.

Recent findings

US federal funding remains restricted for certain forms of human-animal chimera research despite the widespread promulgation and acceptance of national and international stem cell-specific research guidelines.


Stem cell-based human-animal chimera research can promote advances in basic human developmental biology, disease modeling, and new drug discoveries. National and international guidelines for this form of stem cell research have been developed over the past several years but ethical concerns persist around human dignity and the possible moral humanization of chimeric animals. These concerns can be defused and ought to be replaced with a more tractable focus on animal welfare.


Chimeras Stem cells Ethics Research oversight Animal welfare 


Compliance with Ethical Standards

Conflict of Interest

Dr. Insoo Hyun reports no conflicts of interest.

Human and Animal Rights and Informed Consent

This article does not contain any studies with human or animal subjects performed by any of the authors.


Papers of particular interest, published recently, have been highlighted as: • Of importance

  1. 1.
    Behringer R. Human-animal chimeras in biomedical research. Cell Stem Cell. 2007;1:259–62.CrossRefPubMedGoogle Scholar
  2. 2.
    Wu J, Greely HT, Jaenisch R, Nakauchi H, et al. Stem cells and interspecies chimaeras. Nature. 2016;540:51–9.CrossRefPubMedGoogle Scholar
  3. 3.
    • Wu J, et al. Interspecies chimerism with mammalian pluripotent stem cells. Cell. 2017;168:473–86. This study shows that an intermediate human pluripotent stem cell type can generate limited contribution to post-implantation pig embryos. It is a significant first step toward the goal of eventually producing transplantable human organs in livestock animals.CrossRefPubMedPubMedCentralGoogle Scholar
  4. 4.
    • Rashid T, Kobayashi T, Nakauchi H. Revisiting the flight of Icarus: making human organs from PSCs with large animal chimeras. Cell Stem Cell. 2014;15:406–9. This review outlines several strategic technical approaches for generating transplantable human organs in large animals.CrossRefPubMedGoogle Scholar
  5. 5.
    Wade N. New prospects for growing human replacement organs in animals. New York Times. Accessed 26 Jan 2017.
  6. 6.
    Windrem MS, et al. Human iPSC glial mouse chimeras reveal glial contributions to schizophrenia. Cell Stem Cell. 2017;21:195–208.CrossRefPubMedPubMedCentralGoogle Scholar
  7. 7.
    Streiffer R. At the edge of humanity: human stem cells, chimeras, and moral status. KIEJ. 2005;15:347–70.Google Scholar
  8. 8.
    Greely HT, Cho M, Hogle L, Satz D. Thinking about the human neuron mouse. Am J Bioeth. 2007;7:27–40.CrossRefPubMedPubMedCentralGoogle Scholar
  9. 9.
    Greene M, Schill K, Takahashi S, Bateman-House A, et al. Moral issues in human-non-human primate neural grafting. Science. 2005;309:385–6.CrossRefPubMedGoogle Scholar
  10. 10.
    Hyun I. Illusory fears must not stifle chimaera research. Nature. 2016;537:281.CrossRefPubMedGoogle Scholar
  11. 11.
    Hyun I. What’s wrong with human/nonhuman chimera research? PLoS Biol. 2016;14:e1002535. Scholar
  12. 12.
    United States National Institutes of Health. NIH research involving introduction of human pluripotent cells into non-human vertebrate animal pre-gastrulation embryos. 2015.
  13. 13.
    Reardon S. U.S. agency to lift ban on funding human-animal hybrids. Nature. 2016;536:135.CrossRefPubMedGoogle Scholar
  14. 14.
    McLean CY, et al. Human-specific loss of regulatory DNA and the evolution of human-specific traits. Nature. 2011;471:216–9.CrossRefPubMedPubMedCentralGoogle Scholar
  15. 15.
    Han X, et al. Forebrain engraftment by human glial progenitor cells enhances synaptic plasticity and learning in adult mice. Cell Stem Cell. 2013;12:342–53.CrossRefPubMedPubMedCentralGoogle Scholar
  16. 16.
    National Research Council. Guide for the care and use of laboratory animals. Washington DC: National Academies Press; 1996.Google Scholar
  17. 17.
    Committee on Guidelines for Human Embryonic Stem Cell Research. Guidelines for human embryonic stem cell research. Washington DC: National Academies Press; 2005.Google Scholar
  18. 18.
    • International Society for Stem Cell Research, Guidelines for stem cell science and clinical translation 2016. These scientific guidelines constitute the most current ethical standards for stem cell-based human-animal chimera research.
  19. 19.
    Hyun I, Taylor P, Testa G, Dickens B, et al. Ethical standards for human-to-animal chimera experiments in stem cell research. Cell Stem Cell. 2007;1:159–63.CrossRefPubMedGoogle Scholar
  20. 20.
    Karpowicz P, Cohen CB, van der Kooy D. It is ethical to transplant human stem cells into nonhuman embryos. Nat Med. 2004;10:331–5.CrossRefPubMedGoogle Scholar
  21. 21.
    Kass LR. Life, liberty and the defense of dignity: the challenge for bioethics. San Francisco: Encounter Books; 2002.Google Scholar
  22. 22.
    Schulman A. Bioethics and the question of human dignity. In Human dignity and bioethics: essays commissioned by the President’s Council on Bioethics. 2008. Washington DC:

Copyright information

© Springer Nature Switzerland AG 2018

Authors and Affiliations

  1. 1.Department of Bioethics, School of MedicineCase Western Reserve UniversityClevelandUSA

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