Stem cell society objects to Human Embryonic Stem Cell Registry pause

Pausing new submissions to the US National Institutes of Health (NIH) Human Embryonic Stem Cell Registry could jeopardise treatments and stall decades of research, the International Society for Stem Cell Research (ISSCR) has warned.

On 22 January 2026, the NIH announced that it would end federal support for research using human fetal tissue from elective abortions, claiming that alternative methods – such as organoids, tissue chips and computational biology – 'can drive discovery while reducing ethical concerns'. The following day, the NIH issued a Request for Information on whether emerging technologies could replace human embryonic stem cells (hESCs) in federally funded research, while also announcing a temporary pause in reviewing new hESC lines for the Registry (which currently lists 503 approved lines).

'This Request for Information seeks public input as NIH assesses the current and future utility of human embryonic stem cells in biomedical research and evaluates emerging alternatives, during a temporary pause in the review and approval of new human embryonic stem cell lines for inclusion in the NIH Registry,' said Dr Jay Bhattacharya, director of the NIH.

In a formal response submitted on 24 April 2026, the ISSCR urged the NIH to lift the pause on hESC registry applications, warning that the pause could disrupt clinical research in major neurological and metabolic diseases. The ISSCR – which represents almost 5000 scientists, clinicians and ethicists – argued that there is no scientific or ethical basis for reducing reliance on hESCs, stating: 'hESCs are an essential "gold standard" for human pluripotency and are an indispensable tool for studying human development and reproductive biology.'

The ISSCR argued that alternative approaches, such as induced pluripotent stem cells (iPSCs), cannot fully replicate the ability of hESCs to self-renew and differentiate into any cell type. It also noted that several late-stage clinical trials using hESC-derived therapies are underway in the USA, including treatments for type 1 diabetes and Parkinson's disease, and that a trial for drug-resistant epilepsy is due to begin. The ISSCR said: 'Future hESC lines may offer important scientific and translational advantages while filling critical gaps not captured by existing lines.'

Other research bodies have raised similar concerns. The Federation of American Societies for Experimental Biology, which represents more than 100,000 researchers, has called for clear criteria governing approval of new hESC lines. The Council on Governmental Relations, which speaks for more than 230 research institutions, has urged continued support for both existing and new hESC lines alongside investment in alternatives.

The ISSCR further highlighted that hESC research is already governed by a robust ethical and legal framework. Under existing law – including the Dickey-Wicker Amendment, which prohibits federal funding of research that destroys human embryos – federal funds cannot be used to derive new hESC lines. According to the ISSCR, 'any new restrictions on hESC research would not prevent a single human embryo from being destroyed, it would only impede scientific progress'.

A Nature editorial cautioned that organoids do not yet accurately reproduce fetal cell biology, and that some neural organoids do not fully reflect the gene expression patterns seen in real brain tissue.