A method that enables a collection of cells of different types to be easily sorted is reported online this week in Nature Physics. The paper shows that species-dependent motion of living cells can allow cells to be sorted by directing them into different reservoirs of a microfluidic device. This could ultimately enable new methods for filtering cancer cells from healthy ones.
Bartosz Grzybowski and colleagues based their work on the 'ratchet effect': when the walls of a channel have an asymmetric structure, such as that of a saw-tooth, it can force the cells to move preferentially in one direction. The team found that for certain channel structures, the direction of this preferential motion depends on the type of cell moving through a channel. They use this result to sort mixtures of two different types of cells ― chosen from healthy rat cells, mouse skin cancer cells and human breast cancer cells ― into two different reservoirs.
This effect is believed to be caused by differences in structure and mechanical properties of different cells ― differences that often occur between diseased cells and healthy ones.