Figure 5
From: Bioengineered kidney tubules efficiently excrete uremic toxins
Transepithelial clearance of indoxyl sulfate and kynurenic acid in the presence of human serum albumin and albumin-FITC handling in bioengineered renal tubules.
(a–d) Transepithelial clearance of indoxyl sulfate and kynurenic acid. Schematic presentation of the experimental set up of IS and KA transepithelial transport in the absence (a) or presence (b) of HSA is reported. Quantification of IS (c) and KA (d) clearance in the absence (−) or presence (+) of HSA. The protein bound fraction of IS was 73 ± 5% and 63 ± 8% of KA was bound to albumin. Data are shown as mean ± S.E.M. of three independent experiments performed in duplicate. *p < 0.05, **p < 0.01 compared to IS in the absence of HSA, ###p < 0.001 compared to IS in the presence of HSA. Statistical analysis was performed using one-way ANOVA followed by Tukey’s multiple comparison test. (e–g) Endocytosis-mediated albumin uptake in bioengineered renal tubules. Cellular BSA-FITC uptake (green) in renal tubules (nuclei: blue) after 30 min exposure from the (e) basolateral compartment at 37 °C (f ) apical compartment at 37 °C and (g) apical compartment at 4 °C. Active uptake was detected solely when BSA-FITC uptake was performed at 37 °C, as indicated by the red arrows. (h) Collagen IV expression (green) in renal tubules showed a highly similar pattern as BSA-FITC uptake as shown in b. Scale bare: 10 μm.
