(A) Urinary kidney injury biomarkers (osteoactivin, KIM-1, VEGF, and α-GST) were assayed from MPS effluents. There was a significant difference between PMB-treated control MPS effluent for urinary biomarkers KIM-1, osteoactivin, and α-GST. (B) Cell-associated HMOX1. HMOX1 was detected by immunocytochemistry (left panel, representative donor) and quantified (right panel, n = 2 donors, 9 controls, 8 treated). A significant induction (P < 0.05) for devices treated with 50 μM PMB relative to controls was observed. Values are reported as MFI ± SD. (C) PTECs in 2-D culture for 72 hours were exposed to increasing concentrations (top left, 0 μM; top right, 50 μM; bottom left, 100 μM; bottom right, 250 μM) of PMB for 24 hours. Using cellular stains, MitoSOX (red) and CellROX (green), ROS was measured. (D) ROS quantitation. Fluorescence intensity was quantified and normalized to control intensity values. A significant (P < 0.001) increase of cellular ROS was observed at 100 μM and 250 μM PMB. MitoSOX, an indicator of mitochondrial-specific ROS, showed a significant increase at doses higher than 50 μM PMB (100 μM) (n = 3 fields of view/dose for image quantitation, P < 0.05). (E) Urinary miRNA biomarkers. The effluent at 48 hours showed significant induction of miRNA-21, -200c, -132, -155, -16, -24, and -30e across multiple human donor cells (n = 3) cultured within the 3-D kidney MPS. Values are reported as the mean ± SD (*P < 0.05, **P < 0.01, ***P < 0.001).