z-bo 2020-11-24 331

　　Artificial embryos without sperm or eggs are implanted into female mice and begin to form live births for the first time, although the embryos still have some deformities.

　　This artificial mouse embryo is formed from scratch by a special kind of stem cells called expanded pluripotent stem cells. They are capable of producing all 3 cell types found in early embryos.

　　Jun Wu of the University of Texas Southwestern Medical Center and his colleagues soaked stem cells in nutrients and growth promoters to induce them to transform into three embryonic cell types and self-assemble into embryo-like structures.

　　Then, the researchers transplanted artificial embryos into the uterus of female mice, and 7% of the embryos were successfully transferred. One week later, the scientists removed the implanted embryos through a caesarean section. Microscopic examination showed that they had begun to form early fetal structures, despite severe malformations.

　　This experiment is the first time that an artificial embryo develops into fetal tissue in the uterus. Other research groups have used stem cells to create artificial mouse embryos, but these embryos have not been successfully implanted in the uterus, or can only form placental cells after implantation, other types of cells cannot.

　　The challenge now is to fine-tune the artificial mouse embryo so that it can develop into a fully formed fetus. According to Wu, this may include culturing them in a mixture of nutrients and growth promoters to bring them closer to the environment where embryos are normally exposed to the body.

　　However, Wu also stated that the reason for this is not to breed offspring. Testing the ability of artificial embryos to grow in the uterus allows humans to see how real they are. Once considered real enough, researchers will be able to use them to replace real embryos usually obtained from mice. "Our goal is to have a scalable system to produce hundreds or even thousands of embryo-like structures." Wu said.

　　At the same time, embryo models can be studied in petri dishes to better understand early mammalian development, optimize in vitro fertilization conditions, and screen drugs that may cause birth defects.