ISSCR urges NIH to continue support human embryonic stem cell research

The International Society for Stem Cell Research (ISSCR) has submitted a formal response to a Request for Information (RFI) issued by the National Institutes of Health (NIH) regarding its pause on new submissions to the NIH Human Embryonic Stem Cell (hESC) Registry and considerations to reduce reliance on hESCs in federally supported research.

Representing nearly 5,000 scientists, clinicians, ethicists, and industry leaders worldwide, the ISSCR underscores that continued investment in hESC research is essential to sustaining scientific progress and advancing life-saving therapies.

hESCs: Foundational to scientific discovery and clinical progress

Human embryonic stem cells remain a cornerstone of modern biomedical research due to their status as a "gold standard" for human pluripotency – that is, the ability to self-renew indefinitely and differentiate into all cell types in the human body. This pluripotency has enabled transformative advances in understanding human development, modeling disease, and developing regenerative medicine approaches.

Decades of NIH investment have built a robust research ecosystem around hESCs, supporting widely shared cell line repositories, standardized protocols, and specialized expertise. These resources have laid the groundwork for a growing pipeline of clinical applications, including Phase III clinical trials targeting conditions such as Parkinson's disease, Type 1 diabetes, and a drug-resistant form of epilepsy.

As of late 2024, nearly half of all global clinical trials using hESC-derived products are being conducted in the United States – highlighting both the scientific momentum and the importance of sustained federal support.

An irreplaceable scientific resource

While newer technologies such as induced pluripotent stem cells (iPSCs) and computational models have expanded the research toolkit, the ISSCR emphasizes that these systems do not replace hESCs. Instead, they rely on hESCs as a critical benchmark for validation and comparison. Other cell sources, such as adult stem cells, have fundamentally different properties, including more limited ability to differentiate and challenges with scaling in culture.

Moreover, hESCs play an essential role in the development of human-relevant drug discovery systems and new approach methodologies (NAMs), which aim to reduce reliance on animal testing while improving predictive accuracy in preclinical research. hESCs serve as stable, well-characterized reference materials to enable direct comparability and benchmarking in the development of rigorous and reproducible NAM platforms.

Policy stability critical at a translational inflection point

The ISSCR warns that limiting access to hESCs or disrupting the NIH registry could have far-reaching consequences. After years of foundational research, the field is now at a critical moment where continued policy stability will determine whether scientific discoveries translate into approved therapies for patients.

Restricting access would not only risk derailing ongoing clinical programs but could also undermine billions of dollars in prior federal investment and slow progress across multiple areas of biomedical research.

Strong ethical oversight already in place

The ISSCR also highlights that hESC research operates under a rigorous ethical and legal framework. NIH Guidelines, along with complementary oversight from leading scientific bodies, ensure that no federal funds are used for the derivation of new hESC lines or for any research involving the destruction of human embryos.

The ISSCR calls for evidence-based policy

Based on the scientific and translational evidence, the ISSCR concludes that there is no justification for reducing NIH support for hESC research or placing a pause on new submissions to the NIH Registry. The Society urges NIH to lift its current pause on registry submissions and reaffirm its long-standing commitment to funding scientifically meritorious research in this area.

Human embryonic stem cells are an essential and irreplaceable component of the biomedical research ecosystem. Maintaining access to these critical resources is vital to advancing discovery, supporting innovation, and ultimately delivering new therapies to patients.