Influence of VEGFR-3 manipulation on the ploidy of primary murine BM cultures in vitro. (A) VEGFR-3 activation. BM cells were cultivated with physiologic concentrations of TPO in presence or absence of VEGF-C-Cys for 72 hours. The TPO concentration was then increased to 37 ng/mL and the cells were incubated for a further 72 hours, after which time they were harvested, stained with CD41-specific Abs, and fixed. After DNA staining with Draq 5, the CD41⁺ cells were analyzed for their DNA content. The upper plot shows the ploidy distribution of CD41⁺ BM cells. (n = 6; error bars represent SEM; *P < .05). Histogram plots of representative FACS results are presented below. (B) VEGFR-3–blocking. BM cells were cultivated in the presence of physiologic concentrations of TPO and VEGFR-3–blocking Abs or an appropriate isotype control for 72 hours. The TPO concentration was then increased to 37 ng/mL and the cells were incubated for a further 72 hours, after which time they were harvested, stained with CD41–specific Abs, and fixed. After DNA staining with Draq 5, the CD41⁺ cells were analyzed for their DNA content. The upper plot shows the ploidy distribution of CD41⁺ BM cells. (n = 10; error bars represent SEM; *P < .05). Histogram plots of representative FACS results are presented below.