About 60 percent of in vitro fertilization embryos stop developing and researchers have now uncovered why that may occur, New Scientist reports.
It adds that about these embryos stop developing about three days after fertilization and never reach the blastocyst stage when they would be transferred to a patient. To try to figure out why, researchers from the Southern University of Science and Technology in Shenzhen, China, analyzed the transcriptomes of arrested embryos.
As they report in PLOS Biology, the researchers identified three types of arrested embryos: Type I did not complete the maternal-zygotic transition, while Type II embryos have low levels of glycolysis but high levels of oxidative phosphorylation and Type III embryos have low levels of glycolysis but low levels of oxidative phosphorylation. This, New Scientist notes, suggests that Type II and Type III embryos do not make the switch from an oxygen-dependent metabolism to one that is not oxygen-dependent.
The researchers further found that treating the arrested embryos with the antioxidant resveratrol and nicotinamide riboside could spur a portion of embryos to get going again. New Scientist notes, though, that many of the coaxed-to-continue embryos stopped growing again later on and had abnormal gene activity.