High Throughput Investigation of Human Blood-Brain Barrier Transport Regulation

Abstract

The brain exerts centralized control over a body’s other organs by receiving inputs from peripheral tissues and responding by regulating various sensations. It accounts for 2% of body weight but consumes 20% of glucose. To meet the high energetic need and compensate for the lack of fuel reserves, the brain vasculature provides a continuous supply of blood to the brain. The capillaries, contributing to 85% of ~400 miles of total cerebral vessel length, are the major site of the blood-brain barrier (BBB) and play an important role in maintaining optimal neuronal function. Unlike the leaky endothelium of other vascular beds in the body, the BBB is a highly selective interface. The BBB, whose functional properties are comprised of the brain microvascular endothelial cells that form the inner layer of the capillary vessel wall, strictly regulates bidirectional molecular exchange between the bloodstream and the brain. Impaired BBB transport has been implicated in many neurodegenerative diseases and other brain disorders, further causing huge medical, social, and economical burdens worldwide. In this dissertation, we aimed to use high throughput approaches to better understand human BBB transport regulation. Our strategy was to conduct an arrayed CRISPR screen and a nuclear receptor agonist drug screen to address this lack of understanding in the specific transporter expression at the BBB and molecular transport across the BBB. We applied interrogations in representative, reproducible human in vitro model systems through RNA sequencing and CRISPR techniques. These collective works provide important insights on the molecular underpinnings of BBB transport biology and offer frameworks for identifying neurodegenerative disease-modifying therapies.