Multiscale Human Brain Microvascular Model for Studying Vascular Activation, Dysfunction, and Injury in Inflammatory Diseases

Abstract

The brain microvasculature is a dense network of small vessels that supports proper brain function through microcirculation and blood-brain barrier regulation. Inflammatory injury to this microvascular network contributes to barrier breakdown associated with cerebral edema in both infectious and non-infectious diseases, including cerebral malaria and CAR T cell-associated neurotoxicity. However, due to the inaccessibility of the human brain and the lack of suitable disease models, our ability to resolve the dynamic interactions among circulating pathogens, host factors, and the vascular wall that drive microvascular dysfunction and leakage remains limited. This dissertation addresses this challenge by developing and applying multiscale human microvessel models to study brain microcirculation and inflammatory microvascular disease processes in an in vivo-like setting. In Chapter 2, we explored and optimized soft lithographic and multiphoton photoablation-based fabrication techniques to bioengineer human microvascular networks with multiscale control over geometry, organ specificity, perfusion, and spatiotemporal monitoring. To apply these models to disease modeling, in Chapter 3, we engineered 3D brain microvessels to model host-parasite interactions in the context of cerebral malaria pathogenesis. Using flow-based Plasmodium falciparum-infected erythrocyte (IE) adhesion assays, we investigated disease-associated and protective mechanisms of IE-vessel binding interactions modulated by fever and antibodies. By extending the IE-microvessel culture duration, we further identified localized changes in endothelial barrier function induced by maturation of adherent P. falciparum-IEs in situ on the microvessel wall. Building on this 3D modeling platform, in Chapter 4, we applied microvessel and capillary-scale models to study acute vascular inflammation and barrier injury during systemic cytokine release, a shared phase of many inflammatory diseases. Using permeability assays, transcriptional profiling, and immune cell perfusion, we first investigated microvessel responses to the circulating pro-inflammatory cytokines TNF-α and IFN-γ at patient-relevant concentrations. Distinct from parasite-driven inflammation, cytokine exposure alone induced largely non-barrier disruptive changes across engineered vessel scales and activated cell adhesion pathways associated with increased human leukocyte and CAR T cell recruitment under flow. Through stepwise manipulation of microvessel and immune cell states, we showed key contributors leading to brain endothelial barrier breakdown during immune-endothelial crosstalk. Finally, Chapter 5 discusses the potential of the 3D microvessel system as a versatile platform for future studies of vascular health and disease. Collectively, this dissertation provides a generalizable 3D human microvascular framework for mechanistic studies of the dynamics and kinetics of vascular disease processes, as well as future therapeutic screening and toxicity testing.