Fig. 9.

P-glycoprotein transfer from RBE4-MDR1-EGFP cells to RBE4 wildtype cells in cocultures. RBE4 wild type cells were labeled with either eFluor 670 (white) or CMTPX (red) and cocultured with an equal amount of RBE4-MDR1-EGFP cells until confluency. Cocultures were assessed by confocal laser scanning microscopy and live-cell imaging. Pgp is visible by the EGFP-tag (green) and nuclei are counterstained in blue by bisbenzimide H. The insets show RBE4-WT cells (#1) labeled by the eFluor 670 (A) or CMTPX (B) staining as well as RBE4-MDR1-EGFP cells (#2) visualized by the MDR1-EGFP fluorescence and RBE4-WT cells that received Pgp-EGFP from Pgp-EGFP cells (#3). Individual membranes of neighboring cells are representatively labeled (orange arrowheads in A). Highlighted is a Pgp containing membrane of an MDR1 cell close to the membrane of a WT cell after Pgp-EGFP transfer (as indicated by the green fluorescence). Similar experiments with similar outcomes were previously performed with cocultures of wildtype and MDR1-EGFP-transduced hCMEC/D3 cells [32], therefore these experiments were not repeated and again illustrated here