Methods giving insight into embryos named Nature Method of the Year

Methods for modelling development, including stem-cell-based embryo models (SCBEMs), have been named 'Method of the Year' by the journal Nature Methods.

These methods were devised to enable scientists to study the 'black box' period of embryo development. The models are created entirely from stem cells, rather than from eggs and sperm.

Initially, research teams led by Professor Jacob Hanna, of the Weizmann Institute, Israel, and Professor Magdalena Zernicka-Goetz, of the California Institute of Technology and the University of Cambridge worked independently on mouse embryo models (see BioNews 1154 and 1157).

This was followed by both teams cultivating human stem cells that developed into structures that mimic aspects of the post-implantation human embryo just beyond 14 days post-fertilisation (see BioNews 1194, 1204 and 1206).

'These remarkable stem-cell-derived mouse and human embryo models demonstrate the astonishing power of [embryonic stem cells] to self-organise into embryo-like structures when provided with the appropriate environment and supporting cell populations.' Professor Zernicka-Goetz wrote in a new article for Nature Methods. 'It is amazing that none of these models go through a preimplantation stage and yet form postimplantation structures.'

The so-called 'black box' period between 14 and 28 days, is a time during which many pregnancies fail, and which remains poorly understood. Embryo models are allowing scientists to study early human development and pregnancy-related difficulties, including infertility and genetic conditions.

This is why SCBEMs – alongside analogous methods in the fields of single-cell omics, biomaterials and mechanobiology – were chosen as Method of the Year 2023, 'for the remarkable insights into embryogenesis enabled by these sophisticated models'.

However, these models have also prompted new ethical debates, which are also explored in accompanying articles in Nature Methods.

In one of these accompanying articles, bioethicists including Dr Lien De Proost and Dr Nienke de Graeff (of Leiden University Medical Centre, the Netherlands) and Professor Megan Munsie (of the Royal Melbourne Hospital, Australia) ask 'what status should these entities be attributed, and what ethical boundaries should govern our actions with them?'

They say that 'To navigate the validation challenges of embryo models, prevent repeated experiments with human embryos, foster international dialogue and enable transparency in research, we think the establishment of a contemporary Carnegie Collection for embryo models from the outset is advisable.'