By injecting tiny magnets into your body, doctors hope to treat diseases without using chemicals or hormones. Don't worry about sticking to the refrigerator - the nano-sized magnets are only strong enough to affect your cells.

For the first time, doctors created bead-shaped magnets that bind with receptor molecules on cell walls. When a magnetic field is applied, the beads are attracted to each other and pull together, dragging the receptors with them. As they cluster, the receptors release biochemical signals that trigger cell functions.

"This technology allows us to control the behavior of living cells through magnetic forces rather than chemicals or hormones," said biologist Don Ingber of Children's Hospital Boston, who devised the technique.

The researchers used the magnets to stimulate an influx of calcium into immune system cells, proving the beads can trigger an important signal common to many cells.

The results of the study will be published in the January issue of the journal Nature Nanotechnology.

The technique could be used in different types of cells, and acts almost instantaneously, instead of taking minutes or hours as drugs do. Ingber said he envisions using the nanomagnets to create a pacemaker that could be controlled externally or to treat diabetes without the need for injections of insulin.