Microsensors to Study Endothelial Cell Dynamics

描述(由申请人提供)： 动脉树中动脉粥样硬化病变的局灶性表明了血流动力学的重要性，即剪切力，在调节内皮细胞(EC)的生物学活动中。在体内，由于血管几何形状以及脉动流的时间和空间变化的分量，速度分布在形状上是不对称的。新兴的微电子机械系统(MEMS)技术为克服现有困难提供了新的切入点。动脉粥样硬化被认为是一种炎症性疾病。我们假设，具有波动参数(如频率、方向和幅度)的扰动流动在调节动脉分叉处的炎症反应中起着明显的作用。相比之下，单向脉动血流和向上冲程倾斜或定义为回转率，下调了炎症反应。为了验证我们的假设，我们提出了三个具体目标。具体目标1：实时获取动脉分叉处已知的非稳态剪应力。新设计的通道将用于向培养的内皮细胞产生稳定的、脉动的或振荡的流动。我们将开发和制造MEMS剪应力传感器，以提供必要的空间和时间分辨率，将剪应力与培养内皮细胞的炎症反应联系起来。具体目标2：阐明血管内皮细胞对脉动切应力和振荡切应力的分子反应和功能反应。在体外，我们将模拟血管内皮细胞和单核细胞在动脉分叉侧壁发生扰动流动时的相互作用。同时，我们将研究炎症介质如单核细胞趋化蛋白-1(MCP-1)和血管扩张剂如一氧化氮(NO)之间的动态关系。具体目标3：证明氧化脂质处理的内皮细胞在体力活动过程中发生的高和低剪切应力回转率的重要性。我们将通过研究内皮细胞的形态变化、与单核细胞的相互作用和炎症介质来分离转化率对内皮细胞的影响。这个拟议的项目既是设计导向的，也是假设驱动的。通过将MEMS技术和血管生物学相结合，这一建议将对动脉分叉处的流量调节机制产生新的见解。

DESCRIPTION (provided by applicant): The focal nature of the atherosclerotic lesions in the arterial trees demonstrates the importance of hemodynamics; namely, shear stress, in regulating the biological activities of endothelial cells (EC). In vivo, velocity profiles are asymmetric in shape due to vessel geometry, as well as the time- and spatial-varying components of pulsatile flow. The emerging Micro Electro Mechanical Systems (MEMS) technology offers a new entry point to overcome the existing difficulties. Atherosclerosis is considered to be an inflammatory disease. We hypothesize that disturbed flow with fluctuating parameters such as frequency, direction, and amplitudes plays a distinct role in modulating the inflammatory responses in the arterial bifurcations. In contrast, unidirectional pulsatile flow, and the upstroke slopes or defined as slew rates, downregulate the inflammatory responses. To test our hypotheses, three specific aims are proposed. Specific Aim 1: To acquire real-time unsteady shear stress known to occur in the arterial bifurcations. Newly designed channel will be used to generate steady, pulsatile, or oscillatory flow to cultured ECs. We will develop and fabricate MEMS shear stress sensors to provide both the spatial and temporal resolution necessary to link shear stress with the inflammatory responses of cultured ECs. Specific Aim 2: To elucidate the molecular and, consequently, functional responses of ECs to pulsatile vs. oscillatory shear stress. In vitro, we will simulate EC and monocyte interactions in the lateral wall of arterial bifurcations where disturbed flow occurs. In parallel, we will investigate the dynamic relation between the inflammatory mediators such as monocyte chemoattractant protein-1 (MCP-1) and vasodilators such as nitric oxide (NO). Specific Aim 3: To demonstrate the significance of high vs. low shear stress slew rates known to occur during physical activities on ECs pretreated with oxidized lipid. We will isolate the effects of slew rates on ECs by investigating EC morphologic changes, interactions with monocytes, and inflammatory mediators. This proposed project is both design-directed and hypothesis-driven. By combining MEMS technology and vascular biology, this proposal will generate new insights into the mechanism of flow regulation at the arterial bifurcations.