Interesting article on embryo development from Europe

Two-thirds of Embryos Stop Developing – And Scientists are Learning Why

Shared from IVF Babble

It’s no secret to anyone going through IVF that it’s a numbers game

Eggs, blastocysts, and embryos stop growing at every stage, whittling down your chances of success. Up to two-thirds of all embryos stop developing and go into “developmental arrest,” and researchers are now developing treatments that could help them continue growing.

If successful, this could lead to higher IVF success rates

Currently, only 1 in 4 cycles lead to a live birth in Europe.

During the IVF process, scientists place eggs in a petri dish with sperm and check to see if they have been fertilized. Treatments such as ICSI go one step further and actually inject sperm into each mature harvested egg. They check up on them regularly with a microscope.

Some of these fertilized eggs then go on to develop into a blastocyst, which contains around 100 cells, and are then transferred into the uterus. However, only around 4 in 10 make it this far. Instead, they stop growing around three days after they are fertilized, when they are just a few cells.

This has long been a mysterious process, but Andrew Hutchins at the Southern University of Science and Technology in Shenzhen, China is hoping to find answers.

A Study on Arrested Embryos – With Promising Findings

His team investigated 17 arrested embryos to learn more about what went wrong. They sequenced the embryo’s RNA and chromosomes. They then compared what they found with embryos that developed normally.

They were expecting to find that the arrested embryos were chromosomally abnormal when compared to the healthy embryos. However, this was not the case.

The arrested embryos were classified into three groups. Group 1 made RNA protein as an egg but failed to make new proteins with its own DNA. Without this step, the embryo will not grow. But with Types 2 and 3, the arrested embryos didn’t transition to obtaining energy in the necessary way.

In a healthy embryo, a shift occurs to require less oxygen in early pregnancy. That’s because oxygen levels are low immediately after implantation and before the placenta develops. Type 2 fails to make this transition at all, while Type 3 does not do so to a sufficient degree.

Hutchins’ team then tried to create solutions for this problem. They treated the Type 2 and Type 3 embryos with antioxidant compounds, such as resveratrol, found in red wine. According to Hutchins, “we will basically be forcing the cells… to alter the balance of their metabolism.”

This treatment seemed to restart development in roughly 50% of the embryos. However, most still stopped growing at a later stage. Three did reach the blastocyst stage, but they did not have normal gene activity. “We’re sort of forcing them to develop, even though they really don’t want to.”

That said, the abnormality may be down to staying too long in the arrested stage. This is the early stage of research, and more studies need to be completed to assess if this will be possible in the future.

Virginia Bolton at King’s College London says that the research is promising and “could increase the number of embryos a couple would have available to them for pregnancy.”

“What they found is absolutely fascinating.”