Sustaining Progress in Stem Cell Science: From hESC Research to Emerging Ethical Frontiers

Only a month ago, it felt as though spring had finally arrived in many parts of the Northern Hemisphere. Here in Tokyo, where I live, the season has already moved forward, and the fresh green leaves now fill the city with a sense of renewal. At ISSCR, we are also entering a season of anticipation. The program for ISSCR 2026 is now nearly complete, and it has developed into a truly exciting meeting. I very much look forward to seeing many of you in person this July in Montréal.

At the same time, ISSCR’s work extends well beyond the preparation of our Annual Meeting. As one important example, we have been actively engaged in responding to the recent NIH Request for Information concerning the future use of human embryonic stem cells, or hESCs, in NIH-supported research. I would like to take this opportunity to share the central message of our response.

ISSCR’s position is clear: hESC research remains an essential pillar of biomedical science and should continue to be supported under rigorous ethical and scientific oversight. Human embryonic stem cells remain the gold standard for human pluripotency. They provide a uniquely informative reference for understanding early human development, reproductive biology, congenital disorders, and disease mechanisms that cannot be fully modeled in animals.

The advent of iPSC technology has transformed our field and greatly expanded the experimental and clinical possibilities of stem cell science. Yet iPSCs, adult stem cell systems, organoids, and computational models should be viewed as complementary platforms, not complete substitutes. Indeed, many of these newer technologies still rely on well-characterized hESC lines for benchmarking, validation, and quality control.

We also emphasized the importance of continued access not only to existing hESC lines, but also to future lines that may better reflect genetic diversity, improved genomic and epigenetic stability, and contemporary manufacturing standards. This is especially important as hESC-derived therapies are now reaching a translational inflection point, with clinical programs advancing in areas such as diabetes, Parkinson’s disease, epilepsy, and retinal disease.

hESCs also remain central to the development of new approach methodologies, including organoids and microphysiological systems, which are helping to build more human-relevant models and reduce reliance on animal testing. For these reasons, ISSCR urged NIH to maintain stable support for scientifically meritorious hESC research and to preserve a pathway for the review and approval of additional ethically derived lines.

Beyond hESC research, ISSCR continues to articulate clear, science-based, and ethically grounded perspectives on other areas of profound importance to our field, including fetal tissue research and the emerging ethical questions surrounding neural organoids and assembloids. These issues require careful discussion, not only because they lie at the frontiers of science, but also because they shape the trust among researchers, patients, policymakers, and society.

At ISSCR 2026 in Montréal this July, I hope we will have the opportunity to engage deeply with many of you on these topics. Through open dialogue, scientific rigor, and shared ethical responsibility, we can continue to guide stem cell research in a way that advances discovery while honoring the values that sustain public confidence in our field.

Hideyuki Okano