In vitro microfluidic modelling of the human blood-brain-barrier microvasculature and testing of nanocarrier transport

The blood-brain barrier (BBB) constitute a nearly-impenetrable obstacle that protects from pathogens but also against therapeutic delivery to the central nervous system. Polymer-based nanoparticles (NPs), due to their size and potentially surface functionalization, have emerged as a possible solution to deliver therapeutic cargo across the BBB. However, most of the models to date have failed to reproduce the human anatomical complexity of brain barriers, contributing to less predictive experimental platforms and poor patient outcomes. To overcome those limitations, the development of a reliable in vitro models seems to be a crucial step toward more effective therapies. Here, an in vitro microfluidic model of the BBB was developed via vasculogenesis to accurately replicate the human neurovascular organization. This microfluidic model includes human induced pluripotent stem cell-derived endothelial cells, brain pericytes, and astrocytes as self-assembled microvascular networks in a 3-dimensional fibrin gel. The model expressed gene expression of tight junction, membrane transporters and extracellular matrix proteins, consistently with immunocytochemistry, indicating BBB maturation. Confocal microscopy imaging also exhibited pericyte-astrocyte contact interactions. The BBB model exhibited perfusable and selective microvasculature, with permeability lower than conventional in vitro models and comparable with in vivo rat brain. Permeability of polystyrene NPs and synthesized polyurethane NP has been measured across the BBB model and compared to Transwell assays. This physiologically relevant BBB model offers an innovative and valuable platform to preclinically predict transport efficacy of drugs and carriers, such as NPs formulation, and recapitulate patient-specific functions in healthy conditions and potentially suitable for neurodegenerative disease models.