3D Bioprinted Blood-Brain-Tumor Barrier Spheroid-Based In Situ Evaluation of Anticancer Compounds Against Glioblastoma: ROS-Producing Ruthenium as a Potential Therapeutic Candidate.

The blood-brain-tumor barrier (BBTB) penetration by anticancer drugs and their effects on glioblastoma (GBM) are assessed using 3D bioprinted-spheroids. Comparative analysis reveals prominent cytoplasmic mixing between pericytes and the human GBM cell line U-87MG, expressions of tight junction proteins ZO-1, occludin, and claudin-5, which act as a barrier to the paracellular transport across BBTB, and the expression of ABC transporter such as P-glycoprotein (P-gp) in the vascular endothelial cell layer of BBTB spheroids. Anticancer drug-induced U-87 MG cell death is quantified through in situ imaging of spheroids using a cancer cell death probe. Paclitaxel and cisplatin, known P-gp substrates, do not demonstrate transcellular transport in BBTB spheroids, whereas temozolomide and a ruthenium (Ru) compound induce marked U-87 MG cell death. Relative BBTB permeability is calculated as a function of IC50 and treatment concentration. The Ru compound, a partial P-gp substrate, exhibits greater anticancer efficacy compared with temozolomide, which is not a P-gp substrate, in BBTB spheroids. The Ru compound attenuates tight junction protein expression (occludin and ZO-1) in vascular endothelial cells through the released reactive oxygen species (ROS), increases ECM degradation via elevated matrix metalloproteinase-9 in vascular endothelial and astrocytes, and promotes expression of the vasoconstrictor endothelin-1.