Placed in tiny prisons, cells feel the walls and prepare to escape at the corners.
5 March 2003

Cells are good at geometry, a new study shows. They prefer acute to obtuse angles¹.

Donald Ingber of Harvard Medical School in Boston, Massachusetts, and colleagues put single cells into tiny cages of different shapes, and studied how they push out limb-like protrusions to escape their confines.

These cell limbs, called lamellipodia, are narrower and more focused in sharp corners, the researchers found.

The cells aren't trying to squeeze into a tight corner. The cages have very weak walls, that, in theory, the cells could breach anywhere, once they are stimulated with a growth factor.

Nonetheless cells push out lamellipodia preferentially from the corners of a cage. And this isn't just a squeezing effect, like putty being pushed through a funnel. Cells seem to sense the shape of their prison, and gather their limb-forming proteins at the corners, ready for use once the growth factor triggers their movement.

Understanding cell movement is important for numerous reasons. Cells move during embryo growth, when they gather into organs. As the brain develops, nerve cells grow towards one another to form a vast network, and throughout life, cells shift to heal wounds.

Researchers are now trying to build artificial scaffolds to promote tissue regrowth, perhaps even to make artificial organs or to repair damaged nerves. Such scaffolds, Ingber's team suggests, could be printed with microscopic geometric patterns to guide cell movement.

Cell block

To watch cells perform contorted breakouts, the Harvard group imprison them on tiny islands, printed on a flat gold film, in shapes ranging from stars to squares, triangles, trapeziums and rhombuses. The islands are patches of a protein called fibronectin, to which cells stick. Between them is a sea of polymer that repels cells.

All the islands are 900 thousandths of a millimetre square. This is just big enough for a single tissue-forming cell, called a fibroblast. The cells adapt their shapes to fit neatly onto the islands.

Reference:
Brock, A. et al. Geometric determinants of directional cell motility revealed using microcontact printing. Langmuir, 19, 1611 - 1617, (2003). |Article|

Source: www.nature.com