PRIMARY HUMAN RENAL PROXIMAL TUBULE CELL MODEL FOR STUDY OF TRANSEPITHELIAL TRANSPORT

Abstract

Renal elimination is a major clearance route for many drugs and their metabolites. This takes place primarily in the proximal tubule (PT) cells and is mediated by uptake and efflux transporters. Primary cells cultured on transwells have been shown to be an effective in vitro model and may represent a more physiologically relevant system versus renal slices, isolated tubule fragments, or animal-derived cells lines that have been used in the past (Brown et al. 2008). To that end, freshly isolated primary kidney cells were plated onto semipermeable membrane filters and assessed for monolayer integrity and transporter functionality. A gamma glutamyltransferase (GGT) assay, transepithelial electrical resistance (TEER) measurements, and mannitol permeability verified monolayer integrity. The prototypical substrate para-aminohippuric acid (PAH) was used to evaluate OAT1/3 to MRP2/4 pathway. The substrates 1-methyl-4-phenylpyridinium (MPP+) and creatinine were used to evaluate expression of the OCT2 to MATE1/2 pathway. A flux ratio of secretory to absorptive (B---A/A---B) was seen in every isolation. Shipment of these transwell cultures showed re-establishment of transporter functionality as measured by MPP+ movement and TEERs. Thus, a PT cell model has been shown to retain appropriate transporter expression after shipment.