ISSCR updates guidelines to address advances in stem cell-based embryo models

The International Society for Stem Cell Research (ISSCR) released an update of its 2021 Guidelines for Stem Cell Research and Clinical Translation today. The targeted update addresses significant advances in the development and application of human stem cell-based embryo models (SCBEMs) and recommendations for research oversight outlined in a white paper from the ISSCR Embryo Models Working Group published in June.

SCBEMs are three-dimensional stem cell-derived structures that replicate key aspects of early embryonic development. These innovative models offer unprecedented potential to enhance our understanding of human developmental biology and reproductive science.

This Guidelines update underscores the ISSCR's steadfast commitment to proactively addressing the ethical and regulatory considerations that accompany scientific advances. Stem cell-based embryo models are transforming how we study early human development, and it is critical that this progress is supported by clear guidance, a strong sense of responsibility, and global consensus. I commend the ISSCR Embryo Models Working Group for their thoughtful and forward-looking leadership in ensuring our guidelines evolve in step with this rapidly advancing field."

Hideyuki Okano, ISSCR President 

The ISSCR Guidelines have long served as the international benchmark for scientific and ethical rigor, offering trusted guidance for oversight and transparency in stem cell research. They support the development of regulatory frameworks in countries where such systems are still emerging. Adherence to the guidelines provides assurance that research is conducted with integrity and new therapies are safe, effective, and evidence based.

The revisions included in the 2025 update to the Guidelines are limited to SCBEM technologies and are the result of a targeted, deliberative process led by Amander Clark, University of California, Los Angeles, USA, and Janet Rossant, Hospital for Sick Children, Toronto, Canada. This focused approach enabled the ISSCR to respond thoughtfully to a defined scientific and oversight need, and to offer updated international guidance for researchers, journal editors, regulators, funders, and the public. The ISSCR intends to continue using this agile, collaborative model to address evolving areas of stem cell research that warrant updated, globally harmonized oversight standards.

Key revisions

• Replaces the classification of models as "integrated" or "non-integrated" with the inclusive term "SCBEMs."
• Proposes that all 3D SCBEMs have a clear scientific rationale, have a defined endpoint and be subject to an appropriate oversight mechanism.
• Reiterates that all SCBEMs are in vitro models and must not be transplanted in the uterus of a living animal or human host.
• Includes a new recommendation that prohibits the ex vivo culture of SCBEMS to the point of potential viability – so-called ectogenesis.