  The migration of cells is relevant for processes such as morphogenesis, wound
healing, and invasion of cancer cells. In order to move, single cells deform
cyclically. However, it is not understood how these shape oscillations
influence collective properties. Here we demonstrate, using numerical
simulations, that the interplay of directed motion, shape oscillations, and
excluded volume enables cells to locally "synchronize" their motion and thus
enhance collective migration. Our model captures elongation and contraction of
crawling ameboid cells controlled by an internal clock with a fixed period,
mimicking the internal cycle of biological cells. We show that shape
oscillations are crucial for local rearrangements that induce ordering of
internal clocks between neighboring cells even in the absence of signaling and
regularization. Our findings reveal a novel, purely physical mechanism through
which the internal dynamics of cells influences their collective behavior,
which is distinct from well known mechanisms like chemotaxis, cell division,
and cell-cell adhesion.
