The United Kingdom has developed its first rules to guide research using human embryo models. Scientists say they are pleased the country has clarified its position on the fast-moving field.

The voluntary code of practice, published today, prohibits researchers from implanting embryo models made from human stem cells into the uterus of a living person or other animal. But it does not set fixed time limits on how long models can be grown in the laboratory, as some other countries have proposed. Instead, the code requires that projects propose their own limits on the basis of the minimum time needed to achieve their scientific objectives, and that an oversight committee be established to review and approve projects.

Research using human embryos is tightly regulated in most countries, including the United Kingdom, but until now the country has not had specific rules guiding research using lab-grown embryo models. The new code, developed by the University of Cambridge, the London-based charity Progress Educational Trust (PET) and a team of researchers, fills a gap in governance and addresses ethical concerns raised by advances in the field.

“The UK has a history of swiftly establishing national rules on human embryo research and reproductive medicine, often through public consultations,” says Misao Fujita, a bioethicist at Kyoto University in Japan. “The world is paying close attention to developments in the UK.”

Fast-paced research

Research into stem-cell-based embryo models has exploded in the past five years. The models recreate various aspects of early embryonic development, and could provide insights into infertility and pregnancy loss. They are attractive to researchers because they don’t face the same legal and ethical restrictions as real human embryos, and can be grown in large batches.

But as models have become more advanced, they have raised their own ethical questions, which many countries are tackling.

The UK code will help researchers to “move forward with a clear understanding of the process within their jurisdiction”, says stem-cell and developmental biologist Amander Clark, who is president of the International Society for Stem Cell Research (ISSCR) in Evanston, Illinois. Last month, the ISSCR announced that it had set up a working group on embryo models, co-led by Clark, which will make recommendations for updating the ISSCR guidelines.

Community reaction

Although the UK code is not legally binding, Sandy Starr, deputy director of the PET, said in a press briefing that he was “confident” it would be widely adopted by the research community, including funders, publishers and regulators. As a consequence, he expected that “those who did not abide by it would find it impossible or difficult to publish in a reputable journal, to obtain funding for their research and, furthermore, those people would face the opprobrium of their peers”.

In developing the guidelines, the team sent an early draft for review to more than 50 researchers from around the world, including Israel, Japan and Australia. Jacob Hanna, a stem-cell biologist at the Weizmann Institute of Science in Rehovot, Israel, who was among those who reviewed an early draft, says that the code integrates their comments well, and its inclusive approach will give it added importance globally. “The guidelines and recommendations are sensible, careful, with a look to the future,” he adds.

Oversight committee

The code recommends that the oversight committee review proposals for research using stem-cell-based embryo models, and that all proposals be logged in a register. Projects should be approved if they adhere to a set of research principles, including that they have a well-justified scientific objective, acquire appropriate consent from donors of the starting cells and clarify the research benefits.

The code, which will be updated periodically, also requires that researchers specify how their models will be terminated, using methods such as flash-freezing or chemical fixation to destroy the cells’ functions.

But Søren Holm, a bioethicist at the University of Manchester, UK, who is also based in Oslo, says the large amount of discretion given to the oversight committee could raise suspicions that it will prioritize scientific promise over ethical concerns — in other words, people might worry that “it will not regulate the science, but merely legitimate it”. Because it does not commit to hard limits on culture time or the emergence of problematic features such as embryo models with advanced stages of neural development, “quite a lot of people will find the code weak”. he says. If members of the committee are seen as biased for any reason or lacking the necessary expertise, this could create a “stumbling block” to the code’s adoption, says Holm.

Nicolas Rivron, a developmental biologist at the Institute of Molecular Biotechnology of the Austrian Academy of Sciences in Vienna, who also reviewed an early draft of the code, agrees that setting a time limit for models is useful to give “the public reassurance that research is not run untethered”. Agencies in France and the Netherlands have proposed that certain kinds of embryo models not be cultured beyond the equivalent of 28 days post-fertilization.