Human embryos grown in a lab dish for 13 DAYS: Experts smash previous six-day record... but should they go any further? 

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Scientists have kept a human embryo growing in a laboratory for nearly a fortnight in a controversial breakthrough that could help childless couples.

The advance means existing technology is capable of developing eggs for longer than the internationally accepted legal limit of 14 days.

It raises hopes for better IVF treatments – but would generate huge ethical questions. Until now no human embryo has been successfully grown outside a mother’s body for longer than six days.

Scientists have achieved the feat of growing a human embryo in a laboratory for 13 days for the first time. No human embryo has previously been successfully grown outside of a mother’s body for longer than six days. Pictured is a human embryo, shown here 12 days after fertilisation

On the seventh day, the developing egg needs to implant itself into a womb to keep on growing. But now scientists from Cambridge University and Rockefeller University in New York have managed to get the embryo to ‘implant’ itself in a soup of chemicals in a laboratory dish and grow for 13 days.

Researchers yesterday called for a public debate about whether it is socially acceptable to allow scientists to grow embryos for a longer period – possibly up to a further week.

Magdalena Zernicka-Goetz, professor of mammalian development and stem cell biology at Cambridge, said the advance gave experts a unique understanding of how a developing egg grows into a human. ‘This is the black box of development which we have never been able to look into before,’ she said.

Ethics issue: Magdalena Zernicka-Goetz said the findings raise questions about breaking through the current 14-day limit

Prof Zernicka-Goetz said her team’s research was particularly important because the implantation stage was ‘one of the major causes of early pregnancy loss’.

The failure rate in IVF at implantation is up to 70 per cent, but it is impossible to carry out studies into what causes this on embryos developing in the womb. The embryos used for the breakthrough research were donated by couples undergoing IVF treatment. They were developed in a growth medium that had previously been used with mouse embryos.

The lab-grown eggs did not develop entirely the same as one in the womb. Because it was grown in a flat environment, the embryo was more two-dimensional.

The research, which took six years to complete, is also expected to help understand embryo ‘malformations’ that can lead to early pregnancy loss as well as helping to grow better stem cells.

At around 14 days the embryo begins ‘gastrulation’, when it develops layers that will go on to become the skin, muscles, spine, brain and internal organs.

Prof Zernicka-Goetz said the findings – published in the journals Nature and Cell Biology – raises ethical questions about breaking through the 14-day limit.

She said ‘a few more days’ would help, adding: ‘I think longer cultures could provide absolutely critical information for basic biology, it can improve IVF success and improve stem cell differentiation.’

Aldous Huxley’s 1931 novel Brave New World depicted a nightmare scenario where babies were grown in laboratories. But Prof Zernicka-Goetz insisted we are ‘extremely far’ away from growing a whole baby outside a womb, adding: ‘That’s science fiction’.

The academic said she was inspired to carry out her research after giving birth to a healthy boy at 44 – despite a test that showed there was a high chance her child might have a rare genetic disease.

The advance means existing technology is capable of growing a human embryo in the lab for longer than the current, internationally accepted, legal limit of 14 days

The breakthrough increases pressure to relax the law on conducting experiments on human embryos, enshrined in the 1990 Human Fertilisation and Embryology Act.

Independent policy advisers the Nuffield Council on Bioethics now plans to review its position on the law. Experts were last night divided on the issue of developing embryos beyond 14 days.

Dr Robin Lovell-Badge, of the Francis Crick Institute in London, said an extra two days to a week might be useful to researchers, but said it was a matter for wider society to decide. Professor Harry Moore, professor of reproductive biology at Sheffield University, said it could help treat conditions of pregnancy such as recurrent miscarriage and pre-eclampsia.

But Peter Braude, emeritus professor of obstetrics and gynaecology at King’s College London, said much information has already been gathered using stem cells.

And Henry Greely, of the Stanford School of Medicine, said: ‘I do not see a politically, or, for most people, morally acceptable line after 14 days.’

UNLOCKING THE SECRETS OF AN EMBRYO... 

WHAT HAVE THE SCIENTISTS DONE?

Researchers have grown a human embryo in a glass dish in a laboratory for 13 days.

Previously the limit was up to six days, as on the seventh day, the embryo needs to implant in a womb.

The scientists managed to trick the embryo to implant in a chemical soup in a laboratory.

WHAT IS THE LAW?

The Human Fertilisation and Embryology Act 1990 and the Human Fertilisation and Embryology (Research Purposes) Regulations 2001 bans any research allowing human embryos to be grown past 14 days. 

National scientific guidelines restrict research in many other countries around the world such as the US. 

In the UK all research must be licensed by the Human Fertilisation and Embryology Authority.

Until now, exactly how the bundle of cells that can grow into a human has been a ‘black box’ which we have not been able to peer into, researchers said today

WHAT’S SO SPECIAL ABOUT 14 DAYS?

This legal limit has been chosen because some religious groups see this point as when the soul enters the human embryo. 

After this point the cell cannot split in twins, so it is the beginning of true individuality.

WHY IS THIS EXCITING?

How human embryos grow beyond the seventh day is a mystery – yet is a critical period when we begin to lay down our body shape and develop the beginnings of a spine. 

It could lead to improved fertility treatments such as IVF. 

Implantation is the most tricky period in IVF treatment – around 70 per cent of attempts at implantation fail. It will also improve understanding of how stem cells in the embryo are formed.

WHY IS THIS CONTROVERSIAL?

The 14 day limit was technically impossible to breach when it was first drawn up in the late 80s and early 90s. But now science has caught up. Supporters of lifting the limit say the a few more days would allow vital research that could allow new medical breakthroughs.

Critics say the time limit could be a slippery slope that could eventually result in experiments on older embryos – even up to the abortion limit of 23 weeks.

DOES THIS MEAN BABIES CAN BE GROWN IN THE LABORATORY?

The researchers say this idea is very distant and ‘science fiction’ at present. Currently, it is not possible to grow a human embryo much beyond a few days past 14. 

As the embryo gets bigger, it becomes much more complicated to to bring nutrients to the growing foetus and take away waste, although the research is advancing rapidly.