ISSCR Statement on the Scientific and Therapeutic Value of Human Embryonic Stem Cell Research
Human embryonic stem (hES) cells represent a foundational platform in stem cell science. Their capacity for sustained self-renewal and pluripotency—the ability to differentiate into all cell types in the body—enables critical research into human development, disease mechanisms, and the development of new regenerative medicines.
The ISSCR is concerned by a recent congressional letter urging President Trump to end federal funding for research involving hES cells. The use of federal funds to study human embryonic stem cells was initiated by President George W. Bush and continued under President Obama, President Trump, and President Biden. This research has been funded by federal agencies, including the National Institutes of Health (NIH), with bipartisan support, for more than 20 years. Several statements in the congressional letter reflect misunderstandings about stem cell research and do not align with present scientific knowledge or clinical progress.
The congressional letter claims to be motivated by a desire “to prevent taxpayer dollars from funding the destruction of human life.” However, federal funds have never been used to destroy a human embryo and cannot be legally used to do so today. All federally funded research is performed on hES cell lines that can be propagated indefinitely in laboratory dishes. These cell lines were derived decades ago using non-federal funds from embryos that were discarded after in vitro fertilization, either because they were unsuitable for clinical use or surplus to the clinical need.
The congressional letter implies that hES cell research has produced no new treatments. The truth is that promising new cell therapies derived from hES cells are currently being tested in clinical trials for the treatment of Parkinson’s disease, age-related macular degeneration, epilepsy, and Type 1 diabetes. In these contexts, hES cells have capabilities that adult stem cells, umbilical cord cells, or placenta cells do not have.
The congressional letter repeats the misleading claim that stem cells from adult tissues, umbilical cord, or placenta can be used to treat 75 diseases. Almost all of these diseases are conditions of the blood forming system that are treated with bone marrow, blood, or umbilical cord blood. There are very few diseases outside of the blood forming and immune systems that can be treated with adult stem cells, umbilical cord cells, or placenta cells. Indeed, placenta cells have never been shown to be effective for the treatment of any medical condition in controlled clinical trials, and umbilical cord cells have only been shown to be effective for the treatment of conditions that affect the blood-forming system.
There are many kinds of stem cells whose properties are matched to the tissue from which they are obtained. These stem cells have different biological properties and cannot be used interchangeably. For example, umbilical cord cells cannot generate the neural or pancreatic cells needed to treat neurodegenerative diseases or diabetes.
hES cell research is conducted under rigorous ethical oversight and has broad scientific support as well as a long history of bipartisan support in Congress. The National Academies, the NIH, and leading scientific, medical, and patient advocacy organizations support the responsible use of hES cells in research due to their unique biological properties and irreplaceable scientific value. NIH-funded research follows established ethical frameworks that includes independent review.
hES cells have enabled foundational advances in regenerative medicine and clinical translation. Research using hES cells has informed our understanding of cell differentiation and human development, supported disease modeling and drug screening platforms, and contributed to the development of other pluripotent stem cell–based approaches, such as those using induced pluripotent stem (iPS) cells. Without hES cell research, there would be no iPS cells.
Continued federal support for hES cell research is essential. Eliminating federal funding for hES cell research would not save a single embryo from destruction, it would only delay or prevent the discovery of therapies urgently needed by patients with serious medical conditions. We must leverage every available tool to advance responsible, innovative treatment strategies that improve patient outcomes.