Expanded oversight of embryo model research recommended

The International Society for Stem Cell Research (ISSCR) has published recommended updates to its guidance concerning human stem-cell-based embryo models (SCBEMs).

The recommendations, published in Stem Cell Reports on the eve of the ISSCR's 2025 Annual Meeting in Hong Kong, were developed by the ISSCR Embryo Models Working Group over the past year. They include a suggested revision of the definition of a SCBEM, and a corresponding recommendation that oversight of SCBEM-related research should be expanded.

Professor Amander Clark, outgoing president of the ISSCR and co-chair of the ISSCR Embryo Models Working Group, said that the recommendations 'are designed to foster innovation while at the same time providing regulatory guidance for key stakeholders in this vital area of biomedical research'.

In previous ISSCR guidance, a SCBEM was defined as the result of 'assembly, differentiation, aggregation, or reassociation of cell populations in a manner that models or recapitulates key stages of embryonic development'. In the new recommendations, the definition of a SCBEM begins in the same way but adds the specification 'in 3D' after the words 'embryonic development', and further states that human SCBEMs 'are designed to model specific phenotypic features and developmental processes of human embryos'.

The previous version of the guidance distinguished between two types of SCBEM – 'integrated' and 'non-integrated' – with more stringent oversight required in the case of 'integrated' SCBEMs (see BioNews 1289). The recommendations remove this distinction, stating that it 'is no longer a distinction that will aid in effective guidance or regulation'.

This means that if the recommendations are implemented, questions of integration will cease to be the main deciding factor in the stringency of the oversight required when researchers use human stem cells to model aspects of embryos. Instead, the main deciding factor will be whether researchers are working with three-dimensional structures (in which case formal oversight will be required), or with two-dimensional cultures (in which case formal oversight might not be required).

Specifically, the recommendation is that 'all three-dimensional, spatially organised human SCBEMs should be subject to a formal scientific and ethical oversight process that is proportionate to the complexity of the model'.

Sandy Starr, deputy director of PET (the Progress Educational Trust) and project consultant for the UK's Code of Practice for the Generation and Use of Human Stem-Cell-Based Embryo Models (the SCBEM Code of Practice), said: 'In light of fast-moving developments in SCBEM research, the ISSCR recommends that there should be formal oversight of a wider class of SCBEMs than was the case previously. Because the UK has a dedicated SCBEM Code of Practice, we are well placed to meet this requirement. The next step will be to establish new governance structures proposed in the Code of Practice – specifically, a SCBEM Oversight Committee and a SCBEM Register.'

The new recommendations build upon a recent paper by the ISSCR's Ethics Committee, published in Stem Cell Reports, which clarifies the meaning of 'adequate and appropriate scientific justification' in relation to this area of research.

The recommendations also cite the UK's SCBEM Code of Practice, published jointly by PET and Cambridge Reproduction (see BioNews 1246a and 1246b), in relation to the decision to dispense with the integrated/non-integrated distinction and in relation to the importance of 'ethical reflection and robust public engagement' (see BioNews 1234).

Roger Sturmey, professor of reproductive medicine at Hull York Medical School and chair of the working group that produced the SCBEM Code of Practice, said: 'Members of the team that produced the SCBEM Code of Practice are working at pace to secure funding to implement the Code. This work will bring the UK firmly into line with the new ISSCR guidance.'