Article Figures & Data
Figures
- Fig 1.
Closed-loop in vitro circulation model for neurovascular stent testing by using fresh human whole blood. Schematic overview (A) and photograph (B) of the in vitro circulation model consisting of the following: 1) heparin-coated tubing (inner diameter = 3.2 mm, length = 75 cm), 2) connection tubing, 3) peristaltic pump (flow rate = 150 mL/min), 4) test device. C, Representative macroscopic images of uncoated and albumin- and heparin-coated stents after circulation for 60 minutes at 37°C (×20 magnification).
- Fig 2.
Neurovascular stents do not change hematocrit levels, erythrocyte number, or hemoglobin concentration. Heparin-coated tubing was loaded with bare metal, albumin-, or heparin-coated neurovascular stents and filled with 6 mL of fresh heparinized human blood. Tubing without a stent served as a negative control. Hematocrit level (A), erythrocyte numbers (B), and hemoglobin concentrations (C) were analyzed before and after 60 minutes of circulation at 150 mL/min. Data are given as means and standard error of the mean (n = 5) and were analyzed by using repeated-measures ANOVA with the Bonferroni multiple-comparison test. One asterisk indicates P < .05; two asterisks, P < .01; three asterisks, P < .001.
- Fig 3.
Platelet activation is significantly reduced due to albumin and heparin coating. Bare metal, albumin-, or heparin-coated neurovascular stents were circulated in the in vitro model for 60 minutes at 150 mL/min. Before and after circulation, PF-4 plasma levels (A), platelet counts (B), polymorphonuclear neutrophil-elastase concentrations (C), and white blood cell numbers (D) were analyzed in all groups. Data are given as mean and standard error of the mean (n = 5); groups were compared by using repeated-measures ANOVA with the Bonferroni multiple comparison test. One asterisk indicates P < .05; two asterisks, P < .01; three asterisks, P < .001.
- Fig 4.
Albumin and heparin coating of neurovascular stents profoundly reduces activation of the coagulation cascade. TAT levels (A) and Sc5b-9 concentrations (B) were measured in human whole blood before and after circulation in the bare metal, albumin-, or heparin-coated stent groups. Blood circulated without a stent served as a negative control. Data are given as mean and standard error of the mean (n = 5), and groups were compared by using repeated-measures ANOVA with the Bonferroni multiple comparison test. Three asterisks indicate P < .001.
- Fig 5.
Thrombogenicity is reduced by albumin and heparin coating of neurovascular stents. Representative SEM images of the inner lumen of a bare metal stent or stents coated with albumin and heparin after circulation for 60 minutes at 150 mL/min (magnification ×500, ×1000, and ×2500).
- Fig 6.
Endothelialization of neurovascular stents. Representative SEM images of the inner lumen of a bare metal stent (A) or stents coated with albumin (B) and heparin (C) after incubation with human umbilical vascular endothelial cells in a rotating bioreactor for 72 hours (magnification ×1000).
Tables
Classification of the bare metal, albumin-coated, and heparin-coated neurovascular stents based on results gained from the thrombogenicity and endothelialization modelsa
Neurovascular Stent Thrombogenicityb No. of Experiments Endothelializationc No. of Experiments Bare metal 1.87 ± 0.4 5 3 ± 0 3 Albumin-coated 0.4 ± 0.5 5 2.8 ± 0.3 3 Heparin-coated 0.2 ± 0.2 5 1.3 ± 0.6 3 ↵a Data are mean values ± SD.
↵b Thrombogenicity: 0 = no thrombogenicity, 1 = very minor thrombogenicity, 2 = minor thrombogenicity, 3 = moderate thrombogenicity, and 4 = serious thrombogenicity.
↵c Endothelialization performance: 0 = no endothelialization, 1 = very little endothelialization, 2 = little endothelialization, 3 = good endothelialization, and 4 = complete endothelialization.
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