A parallel multilayered neurovascular unit-on-a-chip for modeling neurovascular microenvironment and screening chemotherapeutic drugs

 Humans are grappling with increasing occurrence rate of brain tumors, which are associated with unfavorable prognosis and cognitive neurotoxicity caused by chemotherapy. Ideally, therapeutic drugs for brain tumors should efficiently suppress the tumors while minimizing neurotoxic effects. To facilitate drug development, in vitro pathological models of human brain tumors are essential. Here, we engineered a sophisticated human neurovascular unit (hNVU) chip that simulates the microenvironment of pediatric brain using three-dimensional bioprinting technology. The hNVU chip featured a multilayer parallel architecture composed of a biomimetic blood–blood barrier (BBB) and brain region. An automated perfusion system in the chip simulated the blood flow within the brain. The specialized liquid channels within the brain region enabled comprehensive analysis of drug metabolites. The blood–brain barrier (BBB) structure is composed of endothelial cells, pericytes, and astrocytes, and the brain region contains endothelial cells, pericytes, astrocytes, microglia, and neural progenitor cells, representing the cellular components found in pediatric brain. To replicate the basal membrane, we utilized GelMA (gelatin methacryloyl), gelatin, and laminin as primary bioinks, with the addition of fibrin to mimic the pathological characteristics of brain extracellular matrix (ECM). The BBB membrane exhibited a maximum electrical resistance of 360 Ω cm2 and demonstrated impressive semipermeability by effectively blocking the permeability of large molecules with a molecular weight of 10 kDa. Gene expression analysis and immunofluorescence staining revealed a gradual increase in COL4A1 and fibrin, indicating remodeling of the ECM by the cells. Astrocytoma cells (SF188) were introduced in the model to construct a neurovascular unit containing pediatric brain tumor cells. We evaluated the therapeutic effects and toxicity profiles of chemotherapeutic drugs, including vorinostat and 5-fluorouracil. Encouragingly, our investigations revealed that vorinostat not only exhibited remarkable tumor-suppressing efficacy but also induced lower neurocognitive toxicity than 5-fluorouracil. In summary, the hNVU chip served as a reliable and versatile platform for conducting comprehensive studies on the therapeutic effects of chemotherapy drugs for brain tumors.