magnets control cell behaviour including calcium uptake

[Guest guest]

http://www.technologyreview.com/Nanotech/20087/

Friday, January 18, 2008

Controlling Cell Behavior with Magnets

Nanoparticles allow researchers to initiate biochemical events at

will.

By Bourzac

For the first time, researchers have demonstrated a means of

controlling cell functions with a physical, rather than chemical,

signal. Using a magnetic field to pull together tiny beads targeted

to particular cell receptors, Harvard researchers made cells take up

calcium, and then stop, then take it up again. Their work is the

first to prove that such a level of control over cells is possible.

If the approach can be used with many cell types and cell functions,

it could lead to a totally new class of therapies that rely on cells

themselves to make and release drugs.

The research, which appeared in the journal Nature Nanotechnology,

was led by Ingber, professor of pathology at Harvard Medical

School and cochair of the Harvard Institute for Biologically Inspired

Engineering. Ingber's group demonstrated its method for biomagnetic

control using a type of immune-system cell that mediates allergic

reactions. Targeted nanoparticles with iron oxide cores were used to

mimic antigens in vitro. Each is attached to a molecule that in turn

can attach to a single receptor on an immune cell. When Ingber

exposes cells bound with these particles to a weak magnetic field,

the nanoparticles become magnetic and draw together, pulling the

attached cell receptors into clusters. This causes the cells to take

in calcium. (In the body, this would initiate a chain of events that

leads the cells to release histamine.) When the magnetic field is

turned off, the particles are no longer attracted to each other, the

receptors move apart, and the influx of calcium stops.

" It's not the chemistry; it's the proximity " that activates such

receptors, says Ingber.

The approach could have a far-reaching impact, as many important cell

receptors are activated in a similar way and might be controlled

using Ingber's method.

" In recent years, there has been a realization that physical events,

not just chemical events, are important " to cell function, says Shu

Chien, a bioengineer at the University of California, San Diego.

Researchers have probed the effects of physical forces on cells by,

for example, squishing them between plates or pulling probes across

their surfaces. But none of these techniques work at as fine a level

of control as Ingber's magnetic beads, which act on single

biomolecules.

" Up to now, there hasn't been much control [over cells] at this

scale, " says Larry Nagahara, project manager in the National Cancer

Institute's Alliance for Nanotechnology in Cancer and a physics

professor at Arizona State University.

click link for next page of article