Bifurcations: Focal Points of Particle Adhesion in Microvascular Networks

Objective: Particle adhesion in vivo is dependent on the microcirculation environment, which features unique anatomical (bifurcations, tortuosity, cross-sectional changes) and physiological (complex hemodynamics) characteristics. The mechanisms behind these complex phenomena are not well understood. In this study, we used a recently developed in vitro model of microvascular networks, called SMN, for characterizing particle adhesion patterns in the microcirculation. Methods: SMNs were fabricated using soft-lithography processes followed by particle adhesion studies using avidin and biotin-conjugated microspheres. Particle adhesion patterns were subsequently analyzed using CFD-based modeling. Results: Experimental and modeling studies highlighted the complex and heterogeneous fluid flow patterns encountered by particles in microvascular networks resulting in significantly higher propensity of adhesion (>1.5x) near bifurcations compared with the branches of the microvascular networks. Conclusion: Bifurcations are the focal points of particle adhesion in microvascular networks. Changing flow patterns and morphology near bifurcations are the primary factors controlling the preferential adhesion of functionalized particles in microvascular networks. SMNs provide an in vitro framework for understanding particle adhesion.