Double transfected cells

Cui, Y., J. Konig, and D. Keppler. Vectorial transport by double-transfected cells expressing the human uptake transporter SLC21A8 and the apical export pump ABCC2, Mol. Pharmacol. 2001, 60, 934—943... 

It is also important to predict the in vivo biliary excretion clearance in humans, and for this purpose MDCK II cell lines expressing both uptake and efflux transporters may be used (Fig. 12.3) [92, 93]. It has been shown that MRP2 is expressed on the apical membrane, whereas OATP2 and 8 are expressed on the basolateral membrane after cDNA transfection (Fig. 12.3) [92, 93]. The transcellular transport across such double-transfected cells may correspond to the excretion of ligands from blood into bile across hepatocytes. Indeed, the vectorial transport from the basal to apical side was observed for pravastatin only in OATP2- and MRP2-expressing... 

Drag Transport Mediated by SLC and ABC Transporters Using Double Transfected Cells 539... 

Inside-out vesicles can be perfectly used to study single efflux processes, because preloading of cells is not necessary and because of well-defined study conditions with transporter directly facing compound concentration in the incubation medium in contrast to double-transfected cell lines (3.1.2.4.L). Therefore, these studies allow establishing structure activity relationships (SAR) for one efflux transporter only. 

A brand-new approach to evaluate the uptake and efflux processes simultaneously is to use double-transfected cells that express both uptake and efflux transporters (Figure 11.5). Originally, Cui et al. and Sasaki et al. established OATP1B3/MRP2 and OATP1B1/MRP2 double transfectants, respectively [176, 177]. If a compound is a bisubstrate of uptake and efflux transfectants, basal-to-apical transcellular transport... 

Figure 11.5 Vectorial transcellular transport of pravastatin, its basal-to-apical transcellular drugs in double-transfected cells, (a) The double- transport is significantly higher compared to the transfected cells expressing OATP1B1 (uptake apical-to-basal transport [177]. (b) Prediction of transporter) on the basal side and MRP2 (efflux in vivo biliary clearance of several bisubstrates of transporter) on the apical side have been rat Oatplb2 and Mrp2 from their in vitro...

For efflux transporters, however, the functional interaction between the drug and the transporter occurs in the intracellular space. Some substrates, particularly the negatively charged MRP2 substrates, have very low permeability and in the absence of an uptake transporter may not give detectable transport. In these cases, double-transfected cell lines have been developed so that compounds with low permeability... 

That protein expression level ratio is not critical in determining transport rank order was further confirmed by the good correlation between the transport activity in human and rat double-transfected cell lines, and close prediction of in vivo biliary clearance from in vitro results obtained from double-transfected cell line [36]. 

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