Relation between near-wall residence times of monocytes and early lesion growth in the rabbit aorto-celiac junction.

Transient particle-hemodynamic simulations were conducted in a model of the rabbit aorto-celiac junction to investigate mechanisms responsible for localized monocyte attachment and subsequent lesion formation. We hypothesized that the probability for monocyte deposition is related to discrete near-wall particle stasis and/or elevated concentrations, as encapsulated by a new near-wall residence time (NWRT) parameter. A low wall shear stress (WSS) condition accounted for factors such as endothelial cell expression of adhesive molecules as well as a reduced probability of monocyte rolling and detachment. To accurately simulate particle transport, terms for the near-wall drag modification and lift were included. Low WSS and high oscillatory shear index parameters proved ineffective compared to localized in vivo results of monocyte accumulation and lesion initialization. The NWRT parameter, with a limiting WSS condition, identified the lateral flow divider as most susceptible to monocyte deposition, as observed in vivo. A representative quantitative correlation between monocyte deposition and NWRT occurrence was established (r2 = 0.77 and p<10(-4)) on a highly focal basis for an averaged data set. Results indicate that cell transport and conditions for hemodyamically induced surface reactivity are necessary components in formulating an effective model for monocyte adhesion in complex three-dimensional vessel configurations.