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

Dear Editors, We have read with great interest the recently published White Paper by Arias et al., ‘Human stem cell-based embryo models: innovation, ethics, and policy’ (Arias et al., 2026). We would like to commend the authors for addressing their considerations now to a reproductive sciences community forum, rather than to the stem cell science community. Ever since we first took a stand on this topic in 2022 (Boiani and Duncan, 2022), we had noted that it seemed unbalanced to us that guidelines on embryo models were coming from a stem cell society (the International Society for Stem Cell research (ISSCR)) (Lovell-Badge et al., 2021; Clark et al., 2025) rather than a reproductive society like the European Society for Human Reproduction and Embryology (ESHRE). Now this asymmetry has finally been rebalanced in the White Paper. On the other hand, the White Paper is authored by a group of scientists many of whom are directly involved in stem cell-based embryo models (SCBEMs) research, hold patents related to these technologies, or have commercial interests in the field (as the conflicts of interest section makes clear (Arias et al., 2026)). While recognizing the merit of Arias et al.’s contribution, we believe some aspects lack sufficient detachment. We raise three points that require further consideration from our perspective as outsider scientists without vested interest in the technology’s success. In essence, we are proposing a different perspective on what SCBEMs are and what they are good for.