A cell-and-plasma numerical model reveals hemodynamic stress and flow adaptation in zebrafish microvessels after morphological alteration

The development of a functional cardiovascular system ensures successful embryonic development and a sustainable oxygen, nutrient and hormones delivery system for homeostasis in adulthood. While early vessels are formed by biochemical signaling and genetic programming, the onset of blood flow provides mechanical cues that participate in the vascular remodeling of the embryonic cardiovascular system. The zebrafish is a prolific animal model for studying the quantitative relationship between blood flow and vascular morphogenesis due to a combination of favorable factors including blood flow visualization in optically transparent larvae. While imaging techniques can be employed for measuring flow velocity and blood perfusion levels, hemodynamic forces such as the lumen wall shear stress (WSS) and lumen blood pressure cannot be measured directly. In this study, we have developed a cell and plasma blood transport model using CFD to understand how red blood cell (RBC) partitioning asymmetries affect WSS in a network. Furthermore, we employed the CFD model on rheological and morphological alterations of a wildtype network. We discuss how careful consideration of boundary conditions and acquisition of systemic parameters of blood flow are required to understand the intimate relationship between flow physiology and compensatory responses to hemorheological or morphological alterations.