Led by George Daley of Children's Hospital in Boston, the researchers began their process by culturing mouse embryonic stem cells to formglobular clusters called embryoid bodies.
"Some theories say that small black holes in globular clusters should sink down to the center and form a medium-sized one, but our discovery suggests this isn't true, " said Daniel Stern, an astrophysicist at NASA's Jet Propulsion Laboratory in Pasadena, Calif.