To be, or not to be?

in July 2009, two research groups indep­ endently reported the first successful generation of adult mice from induced pluripotent stem cells (ipScs; Kang et al, 2009; zhao et al, 2009). these experiments are part of ongoing research into the dif­ ferences and similarities between ipScs— which are derived from normal somatic cells by the activation of certain key genes—and embryonic stem cells (EScs). if ipScs are found to be similar to EScs in terms of their ability to differentiate into any cell type, it might make the use of the latter in research redundant in the long term. this would be beneficial to biomedical research on stem cells and their medical use, as ipScs are likely to be cheap and easy to produce and would circumvent many of the ethical issues posed by research using human EScs (hEScs). However, the very same research results might raise ethical challenges for those who accept ipSc research but reject hESc research as ethically objectionable: similarities could cast doubt on one of the main arguments against hESc research, that of ‘potentiality’.