Looping Network Meetings

#46 January 29, 2024

Monday, 15:00 CET

Laureline Julien

Microvascular network of the retina : 1D-model, microfluidic device and high resolution data.

Abstract:
This thesis focuses on modeling the microvascular network of the retina to investigate circulatory processes in both the healthy retina and in the presence of retinopathies, bridging the gap between numerical modeling, experimental approaches, and clinical data. The retinal network offers the unique advantage of being the only non-invasively accessible microvascular network for in-vivo studies in the human body. We are currently experiencing significant advancements in the field of retinal imaging, with increased precision in morphometric and blood flow imaging, providing insights into the vascular status within the eye and the broader microvascular system. Furthermore, these data serve as a valuable resource for modeling, which complements clinical studies of the retina by providing access to parameters that cannot be measured throughout the entire network and enabling the simulation of controlled disturbances or pathologies. Cardiovascular pathologies can induce modifications in microvascular networks through alterations in biological processes and hemodynamic conditions. Associated clinical observations reveal anomalies in local morphometry and network topology. These vascular anomalies can lead to significant variations in blood flow, as there is a strong interaction between hemodynamics and morphology at the microvascular scale, causing changes in oxygenation and functional capacities. The discrete distribution of red blood cells and nutrients within the network is crucial for proper organ function. This distribution, guided by the network's topology, is the result of many complex nonlinear phenomena. A better understanding of what occurs at the microvascular level would be of significant interest in measuring the hemodynamic repercussions of a local anomaly and, more broadly, a pathology, which could enhance early detection and management. In this thesis, we present two types of approaches on the subject : one is a numerical modeling in-silico where we focus on the distribution of flow within the network using a continuous blood approach, and the other is an experimental modeling in-vitro where we concentrate on the distribution of red blood cells using a discrete blood approach. For both modeling approaches, clinical morphometric images obtained in-vivo serve as the foundation for constructing the network, a crucial step in the study of such systems. Initially, we developed a patient-specific one-dimensional model of arteriolar circulation in the retina. Our model is based on the principles of conservation and utilizes blood flow imaging data to impose realistic boundary conditions. To validate our model, we conducted a sensitivity analysis and compared its results to data from the literature. Overall, our model serves as a tool to explore the dynamics of retinal blood flow and its potential clinical implications. In parallel, we developed a microfluidic device that replicates the retinal arterial network. Furthermore, it yields new data on the distribution of red blood cells in a large network, offering insights for enhancing existing mathematical laws for modeling viscosity and red blood cell distribution.

Zoom link