EDITORIAL Virus-free iPS-derived cardiomyocytes: a new piece in the puzzle of patient-tailored therapies

This editorial refers to ‘Pharmacological response of human cardiomyocytes derived from virus-free induced pluripotent stem cells ’ by A. Mehta et al., pp. 577–586, this issue. The potential of human embryonic stem (hES) cells for therapeutic pur-poses became immediately clear after their derivation by Thomson’s group in 1998.1 It was also clear, though, that their origin represented their main limitation. The ethical and legislative issues challenging hES cell-based research have produced a ‘selective pressure ’ in response towhich a new type of stem cells has stemmed: human induced pluripo-tent stem (hiPS) cells.2 The generation of hiPS cells from somatic cells, by virus-mediated ectopic expression of a very limited number of plur-ipotency genes (Oct4, Nanog, Sox2, Kfl4, and c-myc),3 is undoubtedly one of the most important research advancements of the last decade. hiPS cells have indeed overcome two of the most important drawbacks of hES cells: their ethically questionable origin and their intrinsic immu