ADHESION OF CELLS IN FLOWING SUSPENSIONS - EFFECTS OF SHEARING FORCE AND CELL KINETIC-ENERGY

The computation of the shearing force and torque operating upon L1210 leukemic cells, which adhere to the surface while flowing in a medium of a given velocity, yields information relevant to the problem of adhesion strength. The shearing force in a slowly moving fluid is too small to prevent the formation of adhesive bonds and the cell adhesion efficiency is relatively great. When the fluid velocity at a distance of 5 μm above the channel is 14 μm/sec, the shearing force is equal to 3.5 × 10-12 N and the torque is 7.6 × 10-18 N·m. The cell adhesion efficiency in a faster medium flow is smaller and drops to insignificant values if the fluid near-wall velocity exceeds 140 μm/sec, such as when the shearing force amounts to 3.4 × 10-11 N or more. Thus, the strength of the adhesive bonds of almost all cells is insufficient to resist the action of this force. As the above physical parameters are estimated at the very moment of the adhesive cell-surface bonding, they are not influenced by the contact time factor. For slowly moving cells the mean kinetic energy (translational and rotational motion before adhesion) is 2.2 × 10-22 J, approximately two orders of magnitude greater than when cells flow with a speed approaching the limits of compatibility with adhesion. © 1979.