Department of Cardiology and Angiology, University Hospital of Freiburg, Freiburg, Germany.
Invest Radiol. 2010 Oct;45(10):586-91. doi: 10.1097/RLI.0b013e3181ed1b3b.
To evaluate targeting of a microbubble contrast agent to platelets under high shear flow using the natural selectin ligand sialyl Lewis.
Biotinylated polyacrylamide Sialyl Lewis or biotinylated carbohydrate-free polymer (used as a control) were attached to biotinylated microbubbles via a streptavidin linker. Activated human platelets were isolated and attached to fibrinogen-coated culture dishes. Fibrinogen-coated dishes without platelets or platelet dishes blocked by an anti-P-selectin antibody served as negative control substrates. Dishes coated by recombinant P-selectin served as a positive control substrate. Microbubble adhesion was assessed by microscopy in an inverted parallel plate flow chamber, with wall shear stress values of 40, 30, 20, 10, and 5 dynes/cm2. The ratio of binding and passing microbubbles was defined as capture efficiency.
There was no significant difference between the groups regarding the number of microbubbles in the fluid flow at each shear rate. Sialyl Lewis-targeted microbubbles were binding and slowly rolling on the surface of activated platelets and P-selectin-coated dishes at all the flow conditions including 40 dynes/cm2. Capture efficiency of targeted microbubbles to activated platelets and recombinant P-selectin decreased with increasing shear flow: at 5 dynes/cm2, capture efficiency was 16.11% on activated platelets versus 21.83% on P-selectin, and, at 40 dynes/cm2, adhesion efficiency was still 3.4% in both groups. There was neither significant adhesion of Sialyl Lewis-targeted microbubbles to control substrates, nor adhesion of control microbubbles to activated platelets or to recombinant P-selectin.
Microbubble targeting using sialyl Lewis, a fast-binding ligand to P-selectin, is a promising strategy for the design of ultrasound contrast binding to activated platelets under high shear stress conditions.
使用天然选择素配体唾液酸路易斯（sialyl Lewis）评估微泡对比剂在高切变流下单核细胞的靶向性。
将生物素化聚丙酰胺唾液酸路易斯或生物素化无碳水化合物聚合物（用作对照）通过链霉亲和素连接子连接到生物素化微泡上。分离并附着于纤维蛋白原包被培养皿上的活化血小板。无血小板纤维蛋白原包被的培养皿或被抗 P-选择素抗体阻断的血小板培养皿作为阴性对照底物。包被重组 P-选择素的培养皿作为阳性对照底物。通过在倒置平行板流动室中的显微镜评估微泡粘附，壁切应力值为 40、30、20、10 和 5 达因/厘米 2。将结合和通过微泡的比例定义为捕获效率。
在每个剪切速率下，各组在流体中的微泡数量之间没有显著差异。在所有条件下，包括 40 达因/厘米 2，靶向唾液酸路易斯的微泡都在活化血小板和 P-选择素包被的表面结合并缓慢滚动。靶向微泡与活化血小板和重组 P-选择素的结合效率随着切变流的增加而降低：在 5 达因/厘米 2时，活化血小板上的捕获效率为 16.11%，而 P-选择素上为 21.83%，在 40 达因/厘米 2时，两组的粘附效率仍分别为 3.4%。靶向 Sialyl Lewis 的微泡既没有显著地附着在对照底物上，也没有附着在活化血小板或重组 P-选择素上。
使用快速结合 P-选择素的配体唾液酸路易斯进行微泡靶向，是在高切应力条件下设计超声对比剂与活化血小板结合的一种有前途的策略。
