A PREDICTIVE MICROFLUIDIC MODEL OF VASCULARIZED GLIOMA TUMORS TO ASSESS TRAFFICKING OF THERAPEUTICS ACROSS THE BLOOD-BRAIN BARRIER

Abstract Although important distinctions exist between subtypes of HGGs, all patients fare poorly with a 5-year survival of < 5%. The infiltrative growth of HGGs imposes significant challenges to treatment, with the presence of residual microscopic tumors post-surgery and hampered chemotherapeutic penetration due to the blood-brain barrier (BBB), a highly selective endothelium regulating transport between blood and brain. Moreover, current preclinical models are costly, low throughput, and often fail to predict drug performance in the clinic. There is thus an increasing need for in vitro models of HGG tumors, surrounded by a realistic BBB vasculature, to recapitulate therapeutic trafficking. To this end, we engineered a high-throughput microfluidic model composed entirely of human cells where HGG spheroids are embedded in a BBB microvascular network of endothelial cells, pericytes, and astrocytes. Tumors co-opt the vasculature as observed in patients and BBB permeability measurements with perfused dextran demonstrate unaltered paracellular transport near and far from the tumors. Lipoprotein receptor protein 1 (LRP1) expression, however, is increased near HGG spheroids. These results were leveraged to synthesize layer-by-layer nanoparticles with angiopep-2 ligands exhibiting high affinity to LRP1 for targeted delivery. Angiopep-2 nanoparticles displayed the largest permeability across the BBB near tumors compared to bare nanoparticles. Knock-down of LRP1 in the BBB-HGG model decreased angiopep-2 nanoparticle permeability confirming LRP1-mediated transport. We next assessed the therapeutic implications of our findings by encapsulating cisplatin in the particles. Administration of cisplatin-loaded angiopep-2 nanoparticles resulted in significant tumor shrinkage with targeted apoptosis in the tumor area compared to bare cisplatin nanoparticles or free cisplatin which damaged the surrounding healthy BBB vessels. Validations in orthotopic tumor-bearing mice are ongoing. In summary, we propose a novel preclinical model with a functional human BBB vasculature surrounding HGG tumors for high-throughput investigations and validate that this platform predicts the transport of targeted drug-loaded carriers.