  Experimental studies of cell motility in culture have shown that under
adequate conditions these living organisms possess the ability to organize
themselves into complex structures. Such structures may exhibit a synergy that
greatly increases their survival rate and facilitate growth or spreading to
different tissues. These properties are even more significant for cancer cells
and related pathologies. Theoretical studies supported by experimental evidence
have also shown that adhesion plays a significant role in cellular
organization. Here we show that the directional persistence observed in
polarized displacements permits the formation of stable cell aggregates in the
absence of adhesion, even in low-density regimes. We introduce a discrete
stochastic model for the dispersal of polarized cells with exclusion and derive
the hydrodynamic limit. We demonstrate that the persistence coupled with the
cell-cell exclusion hinders the cellular motility around other cells, leading
to a non-linear diffusion which facilitates their capture into larger
aggregates.
