Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
Thromb Res. 2012 Apr;129(4):e18-24. doi: 10.1016/j.thromres.2011.12.016. Epub 2012 Jan 20.
A precise approach to the diagnosis of von Willebrand disease (vWD) remains elusive. One important reason is that vWD is a blood flow-related disorder: a vW Factor-platelet GPIb binding defect exists in this condition under the high shear-rate (> 1000 sec-1 in whole blood; > 3000 sec-1 in PRP) conditions of physiologic blood flow which exist in the arterioles of mucous membranes, from which most bleeding in vWD occurs.
We therefore studied 28 patients (mean 18.9 yrs) with vWD, diagnosed according to the 2007 NHLBI clinical guidelines, and 26 healthy controls (mean 17.5 yrs). Blood was collected into a plastic tube containing 4 U/ml FC dalteparin, 1.75 μg/ml of the Tab (anti-CD41) monoclonal antibody directed against platelet GPIIb, and 1.0 μg/ml of an ALEXA 555-conjugated rabbit anti-mouse second antibody. Within 30-90 min, the blood was then withdrawn at 667 and 1330 sec(-1) through a special flow chamber allowing for real-time epifluorescence digital videomicroscopy of platelets interacting with a microfibrillar collagen substrate. With MetaMorph software (Universal Imaging) we quantified the percent area (PA) covered by and total volume (TV) of adherent platelet aggregates within a 435 μm × 580 μm field of view.
At 667 sec(-1) after 1 min PA and TV were similar for patients and controls, but at 1330 sec(-1) PA was 9.32 ± 4.21 (mean ± SD) for patients, a value lower (p < 0.001) than the 12.8 ± 3.39 for controls. TV was (1.43 ± 0.91) x 10(4) for patients, a value also lower (p < 0.001) than the (2.22 ± 0.77) x 10(4) for controls. PA or TV was below the 2.5th percentile for controls in 10 patients (36%) and both PA and TV were below the 2.5th percentile in eight.
The novel flow device found that PA and TV were significantly reduced under high shear stress in vWD patients compared to normal controls. However, there was some overlap between the vWD and the control group, suggesting that some vWD patients had normal platelet adhesion/aggregation under the conditions studied. Further study with a higher shear rate appears indicated.
对血管性血友病 (vWD) 的诊断仍然难以精确把握。一个重要的原因是 vWD 是一种血流相关的疾病：在生理血流的高剪切率（全血中 > 1000 sec-1；PRP 中 > 3000 sec-1）条件下，vW 因子-血小板 GPIb 结合缺陷存在于这种情况下，而大多数 vWD 出血发生在这种情况下的黏膜小动脉中。
因此，我们研究了 28 名根据 2007 年 NHLBI 临床指南诊断为 vWD 的患者（平均年龄 18.9 岁）和 26 名健康对照者（平均年龄 17.5 岁）。血液被收集到含有 4 U/ml FC 达肝素、1.75 μg/ml 的 Tab（抗 CD41）单克隆抗体和 1.0 μg/ml ALEXA 555 标记的兔抗鼠二抗的塑料管中。在 30-90 分钟内，通过特殊的流动室将血液以 667 和 1330 sec-1 的速度抽出，该流动室允许对与微纤维胶原底物相互作用的血小板进行实时荧光数字显微镜检查。使用 MetaMorph 软件（通用成像），我们定量了血小板聚集物在 435 μm×580 μm 视场中的覆盖面积百分比（PA）和总体积（TV）。
在 1 分钟后以 667 sec-1 的速度，患者和对照组的 PA 和 TV 相似，但以 1330 sec-1 的速度，患者的 PA 为 9.32 ± 4.21（平均值±标准差），低于对照组的 12.8 ± 3.39（p<0.001）。TV 为（1.43 ± 0.91）x 10(4)，也低于对照组的（2.22 ± 0.77）x 10(4)（p<0.001）。10 名患者（36%）的 PA 或 TV 低于对照组的第 2.5 百分位数，8 名患者的 PA 和 TV 均低于对照组的第 2.5 百分位数。
新型流动装置发现，与正常对照组相比，vWD 患者在高剪切应力下的 PA 和 TV 显著降低。然而，vWD 组和对照组之间存在一些重叠，这表明在研究条件下，一些 vWD 患者的血小板黏附/聚集正常。似乎需要进一步研究更高的剪切率。
