The Download: experimental embryos and the US monkeypox emergency

In a search for novel forms of longevity medicine, a biotech company based in Israel says it intends to create embryo-stage versions of people in order to harvest tissues for use in transplant treatments. The company, Renewal Bio, is pursuing recent advances in stem-cell technology and artificial wombs, demonstrated by Jacob Hanna, a biologist at the Weizmann Institute of Science in Rehovot. Earlier this week, Hanna showed that starting with mouse stem cells, his lab could form highly realistic-looking mouse embryos and keep them growing in a mechanical womb for several days until they developed beating hearts, flowing blood, and cranial folds. It's the first time such an advanced embryo has been mimicked without sperm, eggs, or even a uterus. Now Hanna has set his sights on extending the technology to humans--he's already experimenting with human cells and hopes to eventually produce artificial models of human embryos.