Here we present an in vitro, vascular-perfusable Brain-Chip model building upon our previously established miBrain platform: a 3D co-culture of induced pluripotent stem cell (iPSC)-derived brain microvascular endothelial cells (BMECs), astrocytes, pericytes, oligodendroglia, microglia, and neurons within a hydrogel engineered to support all six cell types. The Brain-Chip model consists of a microfluidic platform to support the formation of lumenized human BBB-mimetic vessel networks and to enable perfusion of solutes across the vasculature of this hydrogel-encapsulated co-culture. We employ an image analysis pipeline to quantify vessel parameters including vessel diameter, branch length, and cross-network permeability from perfusion assays. The Brain-Chip model addresses the challenge of replicating the structural and functional complexity of the human BBB more closely than previously established 2D monolayer, non-perfusable cultures and previously established 3D cultures comprising only a subset of the major brain cell types incorporated in the Brain-Chip.
The generation of cell types within the Brain-Chip model from patient-derived iPSCs enables systematic experimental control and inquiry into genotype-modulated disease pathology across these cell types. We leverage the Brain-Chip platform to study the role of APOE4, the strongest known genetic risk factor for Alzheimer’s disease, on human BBB function. We demonstrate alterations in vascular networks within Brain-Chip systems constructed using APOE4-positive cell types consistent with observations of BBB dysfunction in human APOE4 carriers, further validating the Brain-Chip as a useful model for investigating biological mechanisms involved in human BBB function and assessing potential therapeutic avenues for neurological diseases.