Effect of treatment schedule of chemotherapy on apoptosis of retinoblastoma and endothelial cells.

<p>Retinoblastoma and endothelial cells were cultured at the conventional or metronomic IC50 of melphalan or topotecan. The rate of apoptosis was assessed by flow cytometry after double-staining with Annexin V-FITC and PI. (<b>A)</b> Representative dot plot of Y79 after conventional and metronomic treatment with topotecan or melphalan. Lower left and right quadrants represent viable (Annexin V^-/PI^-) and early apoptotic (Annexin V⁺/PI^-) cells, respectively; the upper right and left quadrants show late apoptotic (Annexin V⁺/PI⁺) and necrotic (Annexin V^-/PI⁺) cells, respectively. Numbers in each quadrant represent percentages of cells. (<b>B, C</b>) Percentages of viable (grey bars), early apoptotic (white bars), late apoptotic (dashed bars), and necrotic cells (black bars) are shown after conventional and metronomic treatment of Y79 and WERI-RB1 with (<b>B</b>) topotecan or (<b>C</b>) melphalan. Thereafter, we studied the impact of (<b>D</b>) topotecan or (<b>E</b>) melphalan conventional and metronomic treatment on HUVEC and EPC apoptosis. (<b>F</b>) Representative images of the morphologic changes of Y79 after conventional (upper row) or continuous treatment (lower row) with melphalan or topotecan observed by fluorescent microscopy (Magnification: 200X). Each experiment was performed in triplicate and repeated three times. Percentages correspond to mean (SD). Abbreviations: CC, control cells; CV, conventional treatment; MT, metronomic schedule.