Stem cell embryo models recreate early pregnancy stages in lab

Scientists in multiple laboratories have developed embryo models called blastoids from human stem cells. The models form hollow spheres that resemble early embryos and can be used to study implantation outside the body. In Vienna, a team led by Nicolas Rivron created blastoids that were placed into a three-dimensional model of the uterine lining.

More than 80 percent of the models implanted within three days. At the University of Texas Southwestern Medical Center, Jun Wu and colleagues built small chips containing uterine tissue samples. When blastoids were added, about 60 percent implanted; the rate dropped to 20 percent when tissue came from people who had multiple failed IVF attempts.

Testing drug effects on implantation The Texas researchers screened more than 1,000 previously approved drugs and identified several that raised implantation rates by up to 60 percent in some samples. Work continues to find a drug effective across most tissue types.

IVF procedures Start-up companies are using the models to develop tests that predict whether an embryo transfer will succeed. One firm grows uterine tissue from a client’s sample and checks whether blastoids implant. Another company identified seven metabolites that improved embryo quality markers by day five of development.

Researchers say the models allow experiments that cannot be performed on actual human embryos.