Scientists from the Francis Crick Institute have modified embryos after fertilization to understand why some women miscarry and to improve in-vitro fertilization (IVF) methods.It is the first time in the UK that researchers have altered human embryos, BBC reported.

After fertilization, the embryos were modified and allowed to develop for seven days.The researchers used CRISPR-Cas9, a gene-editing tool, to search the billions of letters of genetic code, find their genetic target, and break the genome to effectively disable it.The team initially optimized their techniques for a year using mouse embryos and then human embryonic stem cells and human embryos.

OCT4 gene

The gene suspected of causing miscarriage is OCT4.Relatively unknown in the scientific world, the gene has been compared to an army general issuing orders to keep development of the embryo on track.But its complete role is not understood completely.

For the experiment, the scientists used 41 embryos donated by couples who no longer needed them for IVF.The team then made the genetic modifications and watched the embryos develop without OCT4.

Within the first week, the healthy, normal embryo goes from one cell to about 200 from the first step of organizing itself to handing out specialized jobs to different cells.The blastocyst is a hollow sphere formed from the embryo with some cells destined to go on to form the placenta.Without OCT4, the blastocyst cannot form.Although it would attempt, the blastocyst would break down by itself.

Blastocyst implosion

The researchers got an unprecedented insight from the blastocyst implosion or breakdown.Dr.Kathy Niakan, a group leader at the Crick, said the study provided them a fountain of knowledge about early human development.In providing deepening understanding of the earliest moments in life, it could help explain the things that go wrong in infertility.

According to Niakan, during IVF, of 100 fertilized eggs, fewer than 50 reach the blastocyst stage, 25 are implanted in the womb, and only 13 develop beyond three months.But the research alone, published in Nature journal, cannot explain what went wrong or why some women miscarry.

Among the options the team is looking at is to boost embryos during IVF by growing them in a different culture media, such as a fertilizer for fertilized eggs.Since 2008, those kinds of experiments are legal in the UK, where embryos could be manipulated for 14 days, as long as they are not implanted.

When the gene is not working

Niakan explained that one way to find out what a gene does in developing an embryo is to see what will happen when it is not working.The experiment showed an efficient way of doing it.She hoped that the other scientists will find out the roles of the other genes.

Knowledge of the key genes that embryos need to develop successfully could improve IVF treatments and understand as well some causes why pregnancies fail.However, Niakan said it may take many years to reach such an understanding, but the Crick Institute study is the initial step, Medical Xpress reported.

Pluripotent stem cells

In human embryo development, the OCT4 is thought to be important in stem cell biology.Pluripotent stem cells can be derived from embryos, become any other type of cell, or be created from adult cells such as skin cells, Dr.James Turner, a co-author of the study, said.He added that learning more about how different genes cause cells to become and remain pluripotent will help us produce and use stem cells more reliably.

The research also offered new knowledge of the biological processes at work in the first five or six days of a human embryo's healthy development, Sir Paul Nurse, the director of the Francis Crick Institute, said.He said the team provided a new understanding of the genes responsible for a crucial change, when groups of cells in the very early embryo first become organized and set on different paths of development. 

Not designer babies

The experiment showed the power of the CRISPR genome editing basic research.It contrasted with a report by Shoukhrat Mitalipov of the Oregon Health & Science University this summer on the use of the technology that would correct a mutation that causes a heart problem by targeting the sperm as it enters the egg.

The Francis Crick Institute study continues the strategy of classical genetics to disrupt a gene to infer its normal function, but with better precision and efficiency.It applied CRISPR to explain basic biology and treat ailments in contrast with fears that it would be used for genetic enhancement or to make designer babies, Genetic Literacy Project reported.In the US, gene editing is allowed by a committee formed by the National Academy of Sciences and the National Academy of Medicine as the only option and solely for inheritable diseases.