In vitro side-view imaging technique and analysis of human T-leukemic cell adhesion to ICAM-1 in shear flow

The objective of the present study is to apply a novel side-view imaging technique to investigate T-leukemic Jurkat cell adhesion to a surface-immobilized ICAM-1 in shear flow, a ligand for leukocyte LFA-1. Images have revealed that Jurkat cell adhesion on ICAM-1 under flow conditions in vitro is quasistatic. The cell-substrate contact length steadily increased with time during the initial cell attachment to the ICAM-1-coated surface and subsequently decreased with time as the trailing edge of the cell membrane peeled away from the substrate under the influence of fluid shear forces. Changes in flow shear stresses, cell deformability, or substrate ligand strength resulted in a significant change in the characteristic adhesion binding time and contact length. A 3-D flow field with shear stresses acting on an adherent cell was calculated by using finite element methods based on cell shapes obtained from the in vitro images. The maximum shear stress acting on an actual cell body was found to be 3-5 times greater than the upstream inlet wall shear stress and was influenced by the extent of cell deformation within the flow channel. Therefore, the application of such a side-view imaging technique has provided a practical assay to study the mechanics of cell-surface adhesion in 3-D. The elongation of cells in shear flow tempers hydrodynamic shear forces on the cell, which affects the transients in cell-surface adhesion.