Mature sperm and eggs grown from same stem cells
- Published online: 23 June 2006; | doi:10.1038/news060619-13Mature sperm and eggs grown from same stem cellsTechnological advance could help infertile people to have children.
Abstract:Stem cells from a mouse embryo have been coaxed into producing both eggs and sperm in the same dish. The eggs and sperm are the most mature yet grown in the lab, and the advance brings researchers closer to their ultimate aim: producing human eggs and sperm from adult body cells so that infertile men and women can have their own children.Applying the technique to humans would be controversial, not least because it raises the possibility that men might be able to produce eggs, and women sperm.In 2003, Hans Schöler of the University of Pennsylvania in Philadelphia and his colleagues reported that after such cells had been cultured for around 40 days, some of them spontaneously produced eggs1. The following year, researchers led by George Daley of the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, coaxed cells into producing sperm precursors, by adding a chemical messenger called retinoic acid2. These cells did not form mature sperm, but were able to fertilize eggs when injected into them.Irina Kerkis from the Roger Abdelmassih Clinic in Sao Paolo, Brazil, decided to see whether retinoic acid could trigger egg as well as sperm production. They took cells cultured from a male mouse embryo and grew them into hollow balls called embryoid bodies, which look rather like early embryos. Then they grew them with retinoic acid for four days. Two weeks later they were surprised to see both eggs and sperm produced. Cells on the outside of the embryoid bodies turned into mature, elongated sperm, whereas cells on the inside formed follicles, which released eggs. The eggs developed into embryo-like structures called blastocysts that then 'hatched', a process that normally occurs just before an embryo implants into the uterus wall.Alan Trounson, a stem-cell researcher at Monash University in Melbourne, Australia, is impressed by the eggs and sperm produced. "I haven't seen sperm of that maturity produced in the lab," he says.