NIH cut off fetal tissue funding and paused its embryonic stem cell registry

Two NIH Guide notices issued a day apart in late January change the terms on which the federal government funds research using human fetal tissue and human embryonic stem cells. They are short documents. Read together, they mark the end of one funding pathway and the suspension of another.

The fetal tissue notice

NOT-OD-26-028, released January 22, states that effective on the date of its publication, NIH funds will not be permitted for research using human fetal tissue from elective abortions [s1].

The policy applies to the NIH Intramural Research Program and to all extramural research, including competitive applications for grants and cooperative agreements, other transaction awards, and R&D contract proposals submitted to solicitations issued after the effective date [s1]. For currently funded projects, organisations may rebudget released funds to support work under the same project that is not unallowable under the policy [s1].

The notice supersedes NOT-OD-21-111 and NOT-OD-19-128, the two prior notices that governed this area [s1]. Research using fetal tissue obtained from miscarriage or stillbirth remains permitted, subject to the informed-consent and legal requirements set out in earlier notices [s1].

NIH's stated rationale is one of resource allocation. The notice says NIH-supported research using human fetal tissue "has been in sharp decline since 2019, with only 77 projects supported in Fiscal Year 2024," and that NIH is "prioritizing limited resources towards biomedical research models with more relevance to today's rapidly evolving research ecosystem" [s1].

That reasoning is worth examining rather than accepting or rejecting on sight. A field's decline can reflect scientific substitution — better models became available — or it can reflect the policy environment that preceded the decline. The notice observes the decline dating from 2019, a year in which the prior restrictions took effect [s1]. It does not distinguish between the two explanations.

The stem cell notice

NOT-OD-26-031, released January 23, pauses NIH's review and approval of applications to add new human embryonic stem cell lines to the NIH Human Embryonic Stem Cell Registry while the agency assesses the scientific utility of such lines [s2].

The Registry publicly lists hESC lines that comply with NIH policy and are eligible for use in NIH-funded research [s2]. Currently 503 hESC lines have been approved for NIH-supported research, including more than 200 cell lines carrying mutations associated with diseases [s2].

Three limits on the scope are stated explicitly. Previously approved lines on the Registry may continue to be used in NIH-funded research [s2]. The derivation of hESCs from human embryos continues to be prohibited in NIH-supported research, as it was before [s2]. And the action is framed as a pause during an assessment, not a closure [s2].

NIH's stated reasons parallel the fetal tissue notice: a decline in the number of cell lines submitted for review, with the last approved line added in December 2023; the increasing adoption of non-embryonic stem cells and human induced pluripotent stem cells; and NIH support for hESCs having generally plateaued since 2019 while support for hiPSCs steadily increases [s2].

The question NIH is actually asking

The second notice carries a Request for Information, and its four questions are the substantive core of the whole exercise [s2]:

• research areas in which currently approved hESC lines sufficiently meet the community's needs, and areas for which new lines are needed;
• research areas for which hESCs are the gold standard and could not be pursued if hESCs were unavailable;
• research areas in which emerging biotechnologies such as induced pluripotent stem cells and adult stem cells can replace hESCs;
• research areas in which additional investment should be made to bolster validated models that would replace hESCs.

Responses are accepted through April 24, 2026, may be submitted anonymously, and may be posted to the Office of Science Policy website without redaction [s2].

The second question is the one that matters scientifically. Induced pluripotent stem cells are genuinely powerful and have displaced embryonic lines for many purposes, which is why the usage figures NIH cites point the way they do [s2]. But "many purposes" is not "all purposes." Reprogrammed cells retain features of the somatic cells they came from, and hESC lines have historically served as the reference standard against which iPSC-derived models are validated. Whether a benchmark can be replaced by the thing it benchmarks is exactly the kind of question a scientific community should be asked, and NIH is asking it.

What the notice does not do is commit to any particular answer, or specify what happens at the end of the assessment. There is no stated end date for the pause [s2].

Context and constraint

The Registry and the accompanying NIH Guidelines for Stem Cell Research were established in 2009, following Executive Order 13505, which gave the HHS Secretary — through the NIH Director — authority to support responsible human stem cell research including embryonic stem cell research [s2].

The fetal tissue definition, meanwhile, implements a statutory provision at 42 U.S.C. Chapter 6A, Subchapter III, Part H, Sec. 289 [s1]. Neither notice changes statute; both change how the agency exercises discretion within it.

What to watch

Whether the pause on new Registry submissions ends with resumption, permanent closure, or a revised approval framework. The notice does not say [s2].

What the RFI responses show. If the research community identifies specific areas where hESCs remain irreplaceable, the record will exist publicly, because responses may be posted without redaction [s2].

And what happens to the 77 fiscal 2024 fetal tissue projects and their successors [s1]. The notice permits rebudgeting within existing projects but bars new applications, which means the practical effect appears over the next grant cycle rather than immediately.