Generation of hiPSC-derived brain microvascular endothelial cells using a combination of directed differentiation and transcriptional reprogramming strategies

The blood-brain barrier (BBB), formed by specialized brain microvascular endothelial cells (BMECs), regulates brain function in health and disease. In vitro modeling of the human BBB is limited by the lack of robust protocols to generate BMECs from iPSCs. Here, we report generation of reprogrammed BMECs (rBMECs) through a combination of hiPSC differentiation into BBB-primed endothelial cells (bpECs) and subsequent reprogramming with two BBB transcription factors, FOXF2 and ZIC3. rBMECs express a subset of the BBB gene repertoire including tight junctions and transporters, exhibit higher paracellular barrier properties, and have lower tracer diffusion and transcellular transport compared to primary hBMECs, and can be activated by oligomeric Ab42 . We then generated an hiPSC 3D microfluidic system that incorporates rBMECs, pericytes and astrocytes using the MIMETAS platform. This novel 3D system closely resembles the in vivo BBB at structural, functional and transcriptome levels, and can be used to study pathogenic mechanisms of neurological diseases.