wnol.info January 19 2018

A New Study Of The Human Embryo Is Based On Gene Editing

January 19 2018, 01:46 | Rex Rios

DNA editing in human embryos reveals role of fertility "master gene"

Scientists use gene-editing technology to knock out genes in human embryos for first time

They think this gene helps the fertilised egg decide which cells will go on to form a fetus, and which will form parts of the placenta and yolk sac.

Oct4 plays a key role in a viable pregnancy reveals British scientists.

ISTOCK, AWELSHLADScientists have used the gene-editing CRISPR-Cas9 system to suppress the gene encoding the protein OCT4 in experiments with human embryos. "Pluripotent" stem cells, which can be derived from human embryos, can form any type of tissue in the body and scientists use stem cell technology to create tissue that can fix damage or replace missing structures in the body.

To perform the study, a team led by developmental biologist Kathy Niakan of the Francis Crick Institute in London used a total of 58 embryos that had been generated in fertility clinics as a result of in vitro fertilization (IVF) treatments. Without it, the blastocyst can not form or develop normally. "We were surprised to see just how crucial this gene is for human embryo development, but we need to continue our work to confirm its role", said Norah Fogarty from the Francis Crick Institute.

Previously, OCT4 was known to be important in making cells pluripotent.

Among the OCT4 disrupted levels group, only a reported 19 percent made it to the blastocyst stage.

After seven days, embryo development was stopped and the specimens were analyzed.

"One way to find out what a gene does in the developing embryo is to see what happens when it isn't working", Dr Kathy Niakan from the Francis Crick Institute said.

The study found that human embryos need OCT4 to correctly form a blastocyst.

United Kingdom scientists have used a DNA editing technology known as CRISPR/Cas9 to eliminate a gene in embryos just a few days old, testing the technique's ability to interpret key gene functions in early human development.

Lead author Kathy Niakan (Francis Crick Institute, London) says she hopes the technique can be used by others to identify a whole host of genetic factors that affect pregnancy, but are now poorly understood: "One way to find out what a gene does in the developing embryo is to see what happens when it isn't working".

The research team used a total of 58 human embryos for its study. The researchers spent almost a year optimizing techniques in mouse embryos and human stem cells before conducting human embryo experiments, Niakan says. The acquisition of this knowledge will be essential to develop new treatments for developmental disorders and could also help understand adult diseases such as diabetes that may originate during the early stage of life.

"This proof-of-principle paper uses CRISPR genome editing to show that, although genetic expression in the early mouse embryo may be similar to a human embryo".

"It may take many years to achieve such an understanding, our study is just the first step", Niakan said. A lower activity of this gene could explain why miscarriage occurs after embryos fail to implant normally.

Vallier believes this further highlights human development is very specific and different from that of other species, meaning techniques based on animal models will have limitations. Niakan already had clues that it works at slightly different times in human embryos than it does in mice (SN: 10/3/15, p. 13).

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