Fig. 3

EV-OAT1 and CM-OAT1 support functional maturation of tubuloids. a Representative confocal images of OAT1 localization in the tubuloids under different experimental conditions. The nuclei of the tubuloid cell were stained with DAPI (in blue). The tubuloid spatial organization is indicated by actin disposition, stained with phalloidin (in red). OAT1 localization is observed by the green staining. The last column represents the merge of the three images of each respective experimental condition (scale bar = 50 µm). b OAT1 protein expression in the tubuloids. Upper panel shows representative images of Western blot for OAT1 and Actin. The graph shows the quantification of OAT1 expression after Western blotting (n = 3). c Na⁺/K⁺-ATPase protein expression in the tubuloids. Upper panel shows representative images of Western blot for Na⁺/K⁺-ATPase and Actin. The graph shows the quantification of Na⁺/K⁺-ATPase expression after Western blotting (n = 3). d Fluorescein uptake capacity by the tubuloids. The graph shows the intracellular fluorescence intensity of tubuloids after 10 min incubation with fluorescein (FLUO), in the presence or absence of probenecid (PB) (OATs inhibitor) (n = 4). The fluorescence intensity is expressed as arbitrary units (a.u.). e Net fluorescent uptake specific to OAT in tubuloids. The graph shows the increase of fluorescein uptake of tubuloids cultured with CM-OAT1 or EV-OAT1 in respect to tubuloids under standard differentiation condition. The specificity of transport was given by the difference in the fluorescence intensity between the presence and absence of probenecid. The data is presented as ration in respect to TUB CTR condition (n = 4). In all graphs, data represent mean ± SEM, *p < 0.05 compared to TUB CTR group, ^&p < 0.05 compared to FLUO + PB for each experimental condition