Abstract Despite advances in drug discovery, brain tumours remain the leading cause of cancer-related death in children. The delivery of therapeutics to the brain is often restricted by the blood-brain barrier (BBB). While current 2D in vitro models fail to capture the complexity of the BBB, animal models are associated with significant ethical and financial costs. Therefore, advanced in vitro models that better reflect the function and selectivity of the BBB are essential for screening brain-permeable drugs with improved predictive accuracy for clinical translation. Herein, we developed a 3D multicellular BBB spheroid model (consisting of human brain endothelial cells, astrocytes and pericytes) for high-throughput in vitro drug screening. Unlike other models, our cells were immortalised for ease of use and engineered to express GFP for visualisation. After 48 hours incubation, equal ratios of the different cells self-assemble into 3D BBB spheroids of ∼300 mm diameter. The BBB cellular organisation was confirmed by confocal microscopy, and the expression of key tight junction (e.g., ZO-1, Occludin) and transporter (e.g., P-gp) markers was verified by immunofluorescence. Selective barrier permeability to dextran and a gadolinium-based contrast agent was confirmed by confocal and magnetic resonance imaging, respectively. Moreover, using lactoferrin-conjugated mesoporous silica nanoparticles, we demonstrated the capability of this model to evaluate nanoparticle penetration and to quantify uptake using advanced imaging, with results that closely mimicked in vivo findings. Overall, this study demonstrates that a 3D BBB model integrated with quantitative imaging provides a physiologically relevant and predictive framework for assessing nanomedicine BBB transport, enhancing confidence in vitro-in vivo translation for brain drug delivery.
Acosta et al. (Tue,) studied this question.