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Fearing a non-existing Minotaur? The ethical challenges of research on cytoplasmic hybrid embryos
  1. S Camporesi1,3,
  2. G Boniolo1,2,3
  1. 1
    European School of Molecular Medicine (SEMM), Milan, Italy
  2. 2
    Firc Institute of Molecular Oncology (IFOM), Milan, Italy
  3. 3
    University of Milan, Milan, Italy
  1. Miss S Camporesi, c/o IFOM-IEO Campus, Via Adamello 16, 20139 Milan, Italy; silvia.camporesi{at}


In this paper we address the ethical challenges of research on cytoplasmic hybrid embryos, or “cybrids”. The controversial pronouncement of the UK’s Human Embryology and Fertilisation Authority of September 2007 on the permissibility of this area of research is the starting point of our discussion, and we argue in its favour. By a rigorous definition of the entities at issue, we show how the terms “chimera” and “hybrid” are improper in the case of cybrids, and how their use can bias the debate creating moral prejudices. After analysing the scientific aspects of cybrids research and sketching out current alternatives, we enter the ethical debate, starting from the premise that research on early human embryos is ethically permissible under some circumstances. We emphasise how research on cybrids has positive consequences in terms of scientific and therapeutic applications, since it allows the derivation of human embryonic stem cells genetically tailored to the somatic cell donor. Such cell lines offer a unique in vitro model both for studies of human pathogenesis and for drug screening and discovery. Research on cybrids also circumvents the problem of the scarcity of human oocytes and their ethically dubious donation. Finally, we object to the most common arguments against cybrids research, that is, moral repugnance, the slippery slope argument, the appeal to “nature”, and the unfair distribution of economical resources.

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  • Competing interests: None.

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    BMJ Publishing Group Ltd and Institute of Medical Ethics