Reply: Stem cell-based embryo models: scientific promise clashes with ethical reality

We thank Boiani and Denker (Boiani and Denker 2026) for their engagement with our article. Like them, we welcome involvement with these issues by authors from a variety of backgrounds and disciplines. We refute, however, the suggestion that our white paper is coloured by the commercial interests of nine of its 44 authors. Our conflict of interest declaration is offered in good faith and in compliance with the requirements of the journal. We now address each of Denker and Boiani’s three substantive points: To their first point, we disagree that stem cell-based embryo models (SCBEMs) should be referred to as ‘asexual embryos’. This term is used to describe a method by which organisms reproduce and therefore is biologically imprecise if used to refer to the broad category of SCBEMs (as noted elsewhere, SCBEMs today are not able to develop into human beings). The term is rhetorically loaded and risks misleading the public. We note that in the past, IVF was sometimes labelled asexual, with consequences for public perception. The characterization of induced pluripotent stem cell (iPSC) donors as ‘parents’ of SCBEMs can lead to confusion; the relationship between a somatic cell donor and an entity derived from their reprogrammed cells is fundamentally different from parenthood in established biological, ethical, or legal senses.