Non-human primate blood-brain barrier and in vitro brain endothelium: from transcriptome to the establishment of a new model

The blood-brain barrier (BBB) represents a major challenge when developing central nervous system (CNS)-active therapeutics. The non-human primate (NHP)-brain endothelium constitutes an essential alternative to human in the prediction of molecule trafficking across the BBB and in the search of new brain-specific transport mechanisms. This study presents a comparison between the NHP transcriptome of freshly isolated brain microcapillaries and in vitro-selected brain endothelial cells (BECs), focusing on important BBB features – tight junctions, receptors mediating transcytosis (RMT), ABC and SLC transporters. In vitro BECs conserved most of the BBB key elements for barrier integrity and control of molecular trafficking. We also assessed the function of RMT via the Transferrin Receptor (TFRC) in the characterized NHP-BBB model, where both human transferrin and anti-hTFRC antibody showed increased apical-to-basolateral passage in comparison to control molecules. In parallel, we investigated eventual BBB-related regional differences in 7-day in vitro-selected BECs from 5 brain structures: brainstem, cerebellum, cortex, hippocampus and striatum. Our analysis retrieved very few differences in the brain endothelium from these 5 brain regions, suggesting a rather homogeneous BBB role and function across the brain parenchyma. In conclusion, the presently established NHP-derived BBB model closely mimics the physiological BBB, therefore representing a ready-to-use tool for assessment of the penetration of biotherapeutics into the human CNS. Overall design: 7 sample groups: Isolated brain microvessels_Cortex_P0D0 Brain Endothetlail Cells (BECs)_Cortex_P0D7 Brain Endothetlail Cells (BECs)_Cortex-P1D7 Brain Endothetlail Cells (BECs)_Brainstem_P0D7 Brain Endothetlail Cells (BECs)_Hippocampus_P0D7 Brain Endothetlail Cells (BECs)_Striatum _P0D7 Brain Endothetlail Cells (BECs)_Cerebellum _P0D7