Chunfeng Zhou, Pengtao Yue & James J. Feng
Ann. Biomed. Eng. 35, 766-780 (2007)
Abstract - It is well known that neutrophils
take much longer to traverse the pulmonary capillary bed than
erythrocytes, and this is likely due to differences in the structure
and rheology of the cells. In this study, we simulate the transit of a
neutrophil in a capillary using a Newtonian drop model and a
viscoelastic drop model. The cell membrane is represented by an
interface with isotropic and constant tension, and the cell motion and
deformation are described by a phase-field method. The governing
equations are solved using finite elements in an axisymmetric geometry,
and the thin interfaces are resolved by mesh adaptivity. With a fixed
pressure drop, the entry of a cell into a capillary consists of several
stages in which the flow rate varies in distinct manners. The entrance
time is consistent with experimental measurements. It decreases with
the pressure drop, increases with the cell viscosity and generally
decreases with the relaxation time of a viscoelastic cytoplasm. The
capillary geometry has a strong effect on the entry and transit of a
neutrophil. The entrance time increases sharply when the capillary
diameter decreases or when the capillary is constricted by a pinch.