Hydrodynamics of cell-cell mechanical signaling in the initial stages of aggregation.

Mechanotactic cell motility has recently been shown to be a key player in the initial aggregation of crawling cells such as leukocytes and amoebae. The effects of mechanotactic signaling in the early aggregation of amoeboid cells are here investigated using a general mathematical model based on known biological evidence. We elucidate the hydrodynamic fundamentals of the direct guiding of a cell through mechanotaxis in the case where one cell transmits a mechanotactic signal through the fluid flow by changing its shape. It is found that any mechanosensing cells placed in the stimulus field of mechanical stress are able to determine the signal transmission direction with a certain angular dispersion which does not preclude the aggregation from happening. The ubiquitous presence of noise is accounted for by the model. Finally, the mesoscopic pattern of aggregation is obtained which constitutes the bridge between, on one hand, the microscopic world where the changes in the cell shape occur and, on the other hand, the cooperative behavior of the cells at the mesoscopic scale.