Also known as SHEEFS (synthetic human entities with embryo-like features) these embryo models are not made from eggs and sperm but grown from pluripotent stem cells. They have great potential in allowing researchers to study early embryo development, and could reduce the number of animals and human embryos used in research. Knowledge gained from these models has the potential to improve understanding of pregnancy loss and congenital defects (see BioNews 1015.
The International Society for Stem Cell Research (ISSCR) announced that they have organised a working group to develop detailed guidance, expected to be released in early 2021. In the meantime, they have collated a list of 'principles and current recommendations' that they encourage researchers and institutions to follow.
The project is being led by Professor Robin Lovell-Badge, of the Francis Crick Institute, London with a working group that also includes further representatives from the UK, USA, Canada, Japan, the Netherlands and China.
The announcement was accompanied by an article in Stem Cell Reports, which discusses how legal definitions of embryos across different jurisdictions can mean they may be regulated as embryos in some countries, and not in others.
The review is timely, as Nature reports that US researchers are finding it difficult to get funding for studies using SHEEFs. A 1996 federal law bans any state funding of research that creates or destroys human embryos, and it appears that uncertainty around whether this applies to stem-cell models is leading to funders such as the National Institutes of Health (NIH) to err on the side of caution.
'The NIH of course is struggling with the question when is an embryo not an embryo,' co-author of the Stem Cell Reports paper, Dr Janet Rossant, a developmental biologist at the Hospital for Sick Children, Toronto, Canada told Nature. 'I would also absolutely say we're not close to a line that should not be crossed.'