Experiments Reveal How Cells Can Act Like Molten Glass   When
you think about an individual cell, you no doubt envision a tiny
water balloon. In fact, some theories describe cells in just
this way: elastic membranes filled with fluids. But a new set of
experiments carried out by Ben Fabry, team leader Jeffrey
Fredberg and colleagues at the Harvard School of Public Health,
Dalhousie University and the University of Barcelona suggest
that the behavior of cells is not so simple. They discovered
that when smooth muscle cells¿a type commonly found in the lungs
and bronchi¿are deformed, the cells respond like molten glass.
Specifically, they gradually become increasingly stiff.  The
researchers, who publish their work in the October 1 issue of
Physical Review Letters, tested the cells by vibrating them at
different speeds. To each cell, they attached a magnetic bead,
measuring only five micrometers in diameter. When they applied
an oscillating magnetic field at varying strengths and
frequencies, the bead rolled bac