The science and ethics of human admixed embryos

Human admixed embryos contain various combinations of animal and human material but are nevertheless predominantly human. A new Human Fertilisation and Embryology Bill is due to come into force in October 2009 that will make provisions for research using four categories of human admixed embryos: cytoplasmic hybrids, true hybrids, transgenic embryos and chimeric embryos. The science underpinning this research relates to nuclear reprogramming and embryonic stem cell technology amongst others. The information gathered holds great promise for providing in-depth understanding of the molecular basis of disease as well as opening the door for exciting new therapeutic options. However, the use of such embryos has ignited public debate and raises contentious ethical issues. Here we outline some of the fundamental aspects of embryonic stem cell technology and the contribution of human admixed embryos to this and allied scientific endeavours. We also discuss the current regulatory climate in the UK and explore some of the ethical concerns raised by research on human admixed embryos.