模拟动脉间歇脉搏血流评价携血管细胞黏附分子-1单抗靶向微泡黏附效能

Binding capability of microbubbles targeted to VCAM-1 under pulsatile high-shear flow conditions

目的 应用平行板流动腔模拟间歇脉动的动脉血流评价携血管细胞黏附分子-1单抗靶向微泡（MBv）进行高剪切应力下靶向的可行性.方法 采用＂亲和素-生物素＂桥接法构建MBv在1000ng/ml小鼠血管细胞黏附分子-1 Fc段（VFc）包被的平行板流动腔中,分为连续输注组及间歇输注组,在不同剪切应力（0.5～16 dyn/cm^2）下,分别检测不同结合时间点（1～6 min）靶向微泡的结合数量.并用解离实验检测MBv达半数解离的剪切应力.所有实验均重复3次取平均值.结果 两组在0.5～2 dyn/cm^2时均见有明显的MBv结合.间歇输注组MBv在各个剪切应力的靶向结合效率均明显较连续输注组高（P＜0.05）,且只有间歇输注组MBv能在4～8 dyn/cm^2条件下实现靶向结合.解离实验显示靶向微泡达半数解离的剪切应力为（20.7±3.1）dyn/cm^2.结论 在间歇脉动的液体流动状态下,MBv可在更高的血流剪切应力条件下与VCAM-1特异有效结合,有望用于进行动脉系统的超声分子成像.

Objective To assess the binding capability of microbubbles targeted to VCAM-1 using the parallel plate flow chamber mimic the pulsatile high-shear flow conditions of artery. Methods Targeted microbubbles were designed by conjugating monoclonal antibodies against mouse VCAM-1 to the lipid shell of the microbubbles via an ＂avidin-biotin＂ bridge. The binding and retention of targeted microbubbles to VCAM-1 （MBv） immobilized on a culture dish were assessed in a flow chamber at variable shear stress （0.5～ 16.0 dynes/cm^2 ）. The pulsatile flow conditions were generated and compared to the continuous flow conditions. The retentive ability of MBv was evaluated by the detachment test. Results The marked binding of MBv were seen in pulsatile and continuous flow conditions at low-shear flow conditions of 0.5 ～ 2dyn/cm^2 ,but the binding rate in the pulsatile flow group was higher （ P 〈0. 05） than that in the continuous flow conditions. Furthermore,the marked binding of MBv was still noted at the highest shear rates （4～8dyn/cm^2） under pulsatile flow conditions, while it was not observed under continuous flow conditions. The half detachment rate of MBv was high up to （20.7 ± 3. 1）dyn/cm^2. Conclusions The targeted microbubbles binding to VCAM-1 specific and effective at high-shear stress under pulsatile flow conditions. The molecular ultrasound imaging can be potentially used in the high-shear conditions artery system.