Effects of VEGFR-3 manipulation on platelet counts in TPO-stimulated and 5-FU–treated mice and on platelet recovery and CD41⁺ BM cells after sublethal irradiation in vivo. (A) Mice were either mock treated or stimulated with an initial dose of TPO. The mock-treated animals then received daily PBS injections (PBS/PBS). The TPO-treated mice received daily injections of either VEGF-C-Cys (TPO/VEGF-C-Cys) or carrier (TPO/PBS) as a control for 10 days, during which time platelet counts increased and then recovered. Blood was taken regularly and platelet counts were performed. (n = 8; error bars represent SEM; *P = .05). (B) Mice were administered with a single dose of 150 mg/kg of 5-FU and thereafter received daily injections of either VEGF-C-Cys (5-FU/VEGF-C-Cys) or carrier (5-FU/PBS) as a control for 52 days. Other control mice were administered with PBS instead of 5-FU (PBS) and were not further treated. Blood was taken regularly and platelet counts were performed. (n = 4-8; error bars represent SEM; *P < .05; **P ≤ .005 relative to 5-FU/PBS). (C-E) Mice were sublethally irradiated and injected with VEGFR-3 blocking Abs, isotype control Ig or carrier (PBS) every other day for 20 days. Blood was taken regularly and platelet counts were performed. (C) BM was isolated 20 days after irradiation, stained with CD41–specific Abs, and fixed. The DNA of the cells was then stained with Draq5 and the number (D) and ploidy (E) of CD41⁺ cells was subsequently analyzed in FACS (n = 8; error bars represent SEM; *P < .05). (F-H) Mice were sublethally irradiated and received daily injections of either VEGF-C-Cys or carrier (PBS) as a control for 20 days. Blood was taken regularly and platelet counts were performed. (F) BM was isolated 20 days after irradiation, stained with CD41–specific Abs, and then fixed. The DNA of the cells was then stained with Draq5 and the number (G) and ploidy (H) of CD41⁺ cells was subsequently analyzed in FACS. (n = 8; error bars represent SEM; *P < .05; **P < .01).