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. 2011 Jun 27;6(6):e21283. doi: 10.1371/journal.pone.0021283

Figure 3. Quantifying the spontaneous intercellular exchange rates of organelles in epithelial cells.

Figure 3

Qtracker 605 and 525 labeled cells were co-cultured for 24 h and analyzed by flow cytometry (A). FACS analysis revealed 15.8% “double +” cells. To overcome the limitation of FACS analysis to detect and discriminate double positive cells with a low number of transfered Qdots by the tubes, we employed high-throughput fluorescence image analysis using the ImageStream™ platform (B–D). By analyzing 9335 co-cultured RPTEC, spontaneous intercellular exchange was detected in 67.5% or 6305 cells (B–C). Inhibition of tube-genesis by Lat. B resulted in marked (62%) reduction of the intercellular exchange (from 67.5% to 25.9% double positive cells). Detailed analysis revealed that the intercellular exchange resulted in three categories of double positive cells: i) transfer of 525 Qtracker to 605 Qtracker labeled cells (46.30% or 2921 cells), ii) transfer of 605 Qtracker to 525 Qtracker labeled cells (48.3% or 3046 cells) or equal content of both Qtrackers (4.57% or 288 cells) (D). Thus, the transfer of few labeled Qdots organelles contributed to the majority of spontaneous intercellular exchange among RPTEC.