Department of Engineering Sciences, Uppsala University , PO Box 534, SE-751 21 Uppsala, Sweden.
Anal Chem. 2014 Sep 2;86(17):8671-9. doi: 10.1021/ac501880u. Epub 2014 Aug 11.
There is growing interest in cerebral microdialysis (MD) for sampling of protein biomarkers in neurointensive care (NIC) patients. Published data point to inherent problems with this methodology including protein interaction and biofouling leading to unstable catheter performance. This study tested the in vivo performance of a refined MD method including catheter surface modification, for protein biomarker sampling in a clinically relevant porcine brain injury model. Seven pigs of both sexes (10-12 weeks old; 22.2-27.3 kg) were included. Mean arterial blood pressure, heart rate, intracranial pressure (ICP) and cerebral perfusion pressure was recorded during the stepwise elevation of intracranial pressure by inflation of an epidural balloon catheter with saline (1 mL/20 min) until brain death. One naïve MD catheter and one surface modified with Pluronic F-127 (10 mm membrane, 100 kDa molecular weight cutoff MD catheter) were inserted into the right frontal cortex and perfused with mock CSF with 3% Dextran 500 at a flow rate of 1.0 μL/min and 20 min sample collection. Naïve catheters showed unstable fluid recovery, sensitive to ICP changes, which was significantly stabilized by surface modification. Three of seven naïve catheters failed to deliver a stable fluid recovery. MD levels of glucose, lactate, pyruvate, glutamate, glycerol and urea measured enzymatically showed an expected gradual ischemic and cellular distress response to the intervention without differences between naïve and surface modified catheters. The 17 most common proteins quantified by iTRAQ and nanoflow LC-MS/MS were used as biomarker models. These proteins showed a significantly more homogeneous response to the ICP intervention in surface modified compared to naïve MD catheters with improved extraction efficiency for most of the proteins. The refined MD method appears to improve the accuracy and precision of protein biomarker sampling in the NIC setting.
人们对脑微透析（MD）在神经重症监护（NIC）患者中采样蛋白质生物标志物越来越感兴趣。已发表的数据表明，该方法存在固有问题，包括蛋白质相互作用和生物污垢导致导管性能不稳定。本研究测试了包括导管表面修饰在内的改良 MD 方法的体内性能，用于在临床相关猪脑损伤模型中采样蛋白质生物标志物。纳入了 7 只雄性和雌性猪（10-12 周龄；22.2-27.3kg）。在通过用盐水（1mL/20min）充气硬膜外球囊导管逐步升高颅内压的过程中，记录平均动脉压、心率、颅内压（ICP）和脑灌注压，直到脑死亡。将一个未经修饰的 MD 导管和一个用 Pluronic F-127 修饰的导管（10mm 膜，100kDa 分子量截止 MD 导管）插入右侧额皮质，以 1.0μL/min 的流速和 20min 的样品采集用 3% Dextran 500 灌注模拟 CSF。未经修饰的导管显示出不稳定的液体回收率，对 ICP 变化敏感，而表面修饰则显著稳定了这一情况。7 个未经修饰的导管中有 3 个未能提供稳定的液体回收率。通过酶法测量的 MD 水平的葡萄糖、乳酸、丙酮酸、谷氨酸、甘油和尿素显示出预期的逐渐缺血和细胞应激反应，未经修饰和表面修饰的导管之间没有差异。通过 iTRAQ 和纳流 LC-MS/MS 定量的 17 种最常见蛋白质被用作生物标志物模型。与未经修饰的 MD 导管相比，这些蛋白质在表面修饰的导管中对 ICP 干预的反应更加均匀，大多数蛋白质的提取效率也得到了提高。改良的 MD 方法似乎提高了 NIC 环境中蛋白质生物标志物采样的准确性和精密度。
