A MACHINE that measures the springiness of cancer cells is being developed to
show how likely a tumour is to spread. Called the Optical Cell Stretcher, the
laser-based machine could one day save patients from radical chemotherapy or
radiotherapy treatments they don鈥檛 need. Doctors can sometimes overestimate the
aggressiveness of particular cancers.
At the moment, technicians look at the shapes of the cancer cells from a
tumour biopsy. The more irregular the cells are, the more likely the cancer is
to have spread around the body. But doctors often disagree about the prognosis,
so they tend to err on the safe side.
Now Josef K盲s from the University of Texas in Austin has found a way to
take some of the guesswork out of the process. He realised that for cancer cells
to change shape and become irregular, they need to reduce the density of fibres
in their cytoskeleton鈥攖he network of fibres that give cells their
rigidity鈥攁nd that this makes the cells springier. The springier the cell,
the more likely it is to spread.
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Together with Evacyte, also in Austin, K盲s is now developing a
laser-based tabletop device to measure this springiness. It feeds cells one at a
time into a channel, and fires two laser beams at them
(see Graphic) from
opposite sides. As light from each laser beam enters the cell and slows down, it
exerts a small force on the cell membrane. A camera measures how much the cell
changes shape as the intensity of the laser increases.
鈥淧reviously, cell elasticity was measured with an atomic force microscope,
but that鈥檚 very slow,鈥� says K盲s. His device can examine one cell every
second.
In tests with tissue from cervical smears, K盲s found that cancerous
cells were three to four times more elastic than normal cells. He also saw some
increased stretchiness in apparently healthy cells, and speculates that these
may have been precancerous cells in which the cytoskeleton was beginning to
thin. Such cells might be missed by conventional monitoring techniques.