Effect of reduced BMPR-II expression in HPAECs on leukocyte recruitment under physiologic flow conditions. Mock-transfected HPAECs or HPAECs transfected with siRNA targeting BMPR-II or nontargeting control siRNA were seeded into Ibidi IV flow slides, then unstimulated (A) or stimulated with TNF-α for 4 hours (B) or TGF-β1 for 24 hours (C). Neutrophils (left panel) or mononuclear cells (right panel) were flowed across the endothelial monolayer for 2 minutes, followed by washout. Adherent leukocytes were deemed as rolling, firmly adherent, or transmigrated. Time zero was the start of leukocyte perfusion. Data are the mean ± SEM for 5 independent experiments for TNF-α–stimulated HPAECs and 6 experiments for unstimulated and TGF-β1–stimulated HPAECs. *P < .05, **P < .01, compared with NTCsi-transfected HPAECs by Student t test.