An isogenic neurovascular unit model comprised of human induced pluripotent stem cell-derived brain microvascular endothelial cells, pericytes, astrocytes, and neurons

Background: Brain microvascular endothelial cells (BMECs) astrocytes, neurons, and pericytes form the neurovascular unit (NVU). Interactions with NVU cells endow BMECs with extremely tight barriers via the expression of tight junction proteins, a host of active efflux and nutrient transporters, and reduced transcellular transport. To recreate the BMEC-enhancing functions of NVU cells, we combined BMECs, astrocytes, neurons, and brain pericyte-like cells.

Methods: BMECs, neurons, astrocytes, and brain like pericytes were differentiated from human induced pluripotent stem cells (iPSCs) and placed in a Transwell-type NVU model. BMECs were placed in co-culture with neurons, astrocytes, and/or pericytes alone or in varying combinations and critical barrier properties were monitored.

Results: Co-culture with pericytes followed by a mixture of neurons and astrocytes (1:3) induced the greatest barrier tightening in BMECs, supported by a significant increase in junctional localization of occludin. BMECs also expressed active P-glycoprotein (PGP) efflux transporters under baseline BMEC monoculture conditions and continued to express baseline active PGP efflux transporters regardless of co-culture conditions. Finally, brain-like pericyte co-culture significantly reduced the rate of non-specific transcytosis across BMECs.

Conclusions: Importantly, each cell type in the NVU model was differentiated from the same donor iPSC source, yielding an isogenic model that could prove enabling for enhanced personalized modeling of the NVU in human health and disease.