Quantifying the impact of vessel topology on oxygen supply to the brain

Blood flow disturbances within the brain microvasculature may cause microinfarcts, which are associated with the development of neurodegenerative diseases. Understanding oxygen dynamics in the brain tissue surrounding the microvasculature is essential to assess the vascular network’s robustness to microinfarcts. This work investigates whether local blood flow direction influences the contribution of individual vessels to cerebral oxygen supply. An in silico approach is adopted, since direct measurements of oxygen concentration are limited. Computational models of blood flow and oxygen dynamics are developed and applied. Simulations are performed on a realistic microvascular network extracted from a mouse somatosensory cortex. The variable vessel topology is introduced, classifying vessels into four groups, called topological configurations, based on local blood flow direction. Then, additional oxygen-related and topological variables, directly linked to oxygen supply, are defined. The impact of vessel topology is assessed based on the distribution of these variables across different topological configurations. Results indicate that different topological configurations have different roles in oxygen supply to the brain. Vessels with one inflow and two outflows, that tend to be closer to arterioles, most strongly affect oxygen distribution throughout the microvasculature and local tissue oxygenation. In contrast, vessels with one inflow and one outflow are the most important for overall brain oxygenation, efficiently releasing oxygen into the surrounding tissue. However, the microvascular network is globally resistant to their occlusion. Since the majority of blood vessels have one inflow and one outflow, these findings point to an inherent resilience of the brain microvasculature to microinfarcts.