If genetically engineering cells to produce their own magnetic nanoparticles proves successful, this provides a new window through which to view many biological processes as they unfold, from the formation of tumors to the migration of stem cells injected to treat disease. "It's just amazing that they can get a mammalian cell to actually make the material," says Lee Josephson, an associate professor at the Harvard Medical School's Center for Molecular Imaging Research. "I think it's a really meaningful piece of work."

This is awesome! It will bring MRI imaging down to the cellular scale.

Maybe they will be able to use it to catch the cheats at the Olympics etc, who have used gene manipulation.