Simulation model for flow of neutrophils in pulmonary capillary network

The concentration of neutrophils in the pulmonary microvasculature is higher than in systemic large vessels. It is thought that the high concentration of neutrophils facilitates their effective recruitment to sites of inflammation. Thus, in order to understand the role of neutrophils in the immune system, it is important to clarify their flow characteristics in the pulmonary microvasculature. In previous studies, we numerically investigated the motion of a neutrophil through a single capillary segment modeled by a moderate axisymmetric constriction in a straight pipe, developing a mathematical model for the prediction of the transit time of the cell through the segment. In the present study, this model was extended for application to network simulation of the motion of neutrophils. First, we numerically investigated shape recovery of a neutrophil after expulsion from a narrow capillary segment. This process was modeled in two different phases: elastic recovery and viscous recovery. The resulting model was combined with the previously developed models to simulate motion of the cells and plasma flow in a capillary network. A numerical simulation of the motion of neutrophils and plasma flow in a simple lattice capillary network showed that neutrophils were widely dispersed in the network with an increased concentration.