Figure 1
Figure 1. ODSH but not dabigatran or rivaroxaban displaces PF4 or PF4/heparin complexes from cell surfaces. (A) UFH strongly increased PF4 binding to the platelet surface at low concentrations and inhibited PF4 binding at high concentrations. ODSH was even more effective in displacing PF4 from platelets starting at concentrations of 2.08 μg/mL while there was only a weak enhancement at lower concentrations. Dabigatran had no effect. The increase of PF4 binding by rivaroxaban at higher concentrations was because of the solvent carrier DMSO. GFPs were incubated with 25 μg/mL PF4 in the presence of increasing concentrations of UFH, ODSH, dabigatran, or rivaroxaban. PF4 binding was detected with a FITC-labeled anti–human PF4 Ab using flow cytometry and Ab binding was quantified by geometric mean fluorescent intensity (MFI). PF4 binding without anticoagulant was defined as 100%. Data are mean ± SD of 4 (DMSO = 3) independent experiments. (B) ODSH displaced PF4 from a PF4-expressing HEK-293 cell line more efficiently than UFH. Dabigatran and rivaroxaban showed no effect. PF4-transfected HEK-293 cells were incubated with increasing concentrations of UFH, ODSH, dabigatran, or rivaroxaban. PF4 expression was detected with a FITC-labeled anti–human PF4 Ab using flow cytometry and Ab binding was quantified by geometric MFI. Surface-bound PF4 without anticoagulant was defined as 100%. Data are mean ± SD of 4 (UFH = 5) independent experiments. (C) ODSH and UFH equally displaced PF4/heparin complexes from the platelet surface. Dabigatran had no effect. The increase of PF4 binding with high concentrations of rivaroxaban was because of the solvent carrier. GFPs preincubated with PF4/heparin complexes (formed at optimal ratios) and then washed, were incubated with increasing concentrations of UFH, ODSH, dabigatran, and rivaroxaban. PF4 binding was detected with a FITC-labeled anti–human PF4 Ab using flow cytometry and Ab binding was quantified by geometric MFI. Preincubation of platelets with PF4/heparin complexes was defined as 100% binding. Data are mean ± SD of 4 (DMSO = 3) independent experiments.

ODSH but not dabigatran or rivaroxaban displaces PF4 or PF4/heparin complexes from cell surfaces. (A) UFH strongly increased PF4 binding to the platelet surface at low concentrations and inhibited PF4 binding at high concentrations. ODSH was even more effective in displacing PF4 from platelets starting at concentrations of 2.08 μg/mL while there was only a weak enhancement at lower concentrations. Dabigatran had no effect. The increase of PF4 binding by rivaroxaban at higher concentrations was because of the solvent carrier DMSO. GFPs were incubated with 25 μg/mL PF4 in the presence of increasing concentrations of UFH, ODSH, dabigatran, or rivaroxaban. PF4 binding was detected with a FITC-labeled anti–human PF4 Ab using flow cytometry and Ab binding was quantified by geometric mean fluorescent intensity (MFI). PF4 binding without anticoagulant was defined as 100%. Data are mean ± SD of 4 (DMSO = 3) independent experiments. (B) ODSH displaced PF4 from a PF4-expressing HEK-293 cell line more efficiently than UFH. Dabigatran and rivaroxaban showed no effect. PF4-transfected HEK-293 cells were incubated with increasing concentrations of UFH, ODSH, dabigatran, or rivaroxaban. PF4 expression was detected with a FITC-labeled anti–human PF4 Ab using flow cytometry and Ab binding was quantified by geometric MFI. Surface-bound PF4 without anticoagulant was defined as 100%. Data are mean ± SD of 4 (UFH = 5) independent experiments. (C) ODSH and UFH equally displaced PF4/heparin complexes from the platelet surface. Dabigatran had no effect. The increase of PF4 binding with high concentrations of rivaroxaban was because of the solvent carrier. GFPs preincubated with PF4/heparin complexes (formed at optimal ratios) and then washed, were incubated with increasing concentrations of UFH, ODSH, dabigatran, and rivaroxaban. PF4 binding was detected with a FITC-labeled anti–human PF4 Ab using flow cytometry and Ab binding was quantified by geometric MFI. Preincubation of platelets with PF4/heparin complexes was defined as 100% binding. Data are mean ± SD of 4 (DMSO = 3) independent experiments.

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