Microsensors to Study Endothelial Cell Dynamics

描述（由申请人提供）： 动脉树中的动脉粥样硬化病变的局灶性性质证明了血流动力学的重要性，即剪切应力，在调节内皮细胞（EC）的生物活性。在体内，由于血管几何形状以及脉动流的时间和空间变化分量，速度分布在形状上是不对称的。新兴的微机电系统（MEMS）技术为克服现有困难提供了一个新的切入点。动脉粥样硬化被认为是一种炎症性疾病。我们假设，扰动流的波动参数，如频率，方向和振幅在调制动脉分叉的炎症反应中起着独特的作用。相反，单向脉动流，和上行斜率或定义为转换率，下调炎症反应。为了验证我们的假设，提出了三个具体目标。具体目标1：获取已知发生在动脉分叉处的实时非稳态剪切应力。新设计的通道将用于产生稳定的，脉动的，或振荡流培养的EC。我们将开发和制造MEMS剪切应力传感器，以提供必要的空间和时间分辨率，将剪切应力与培养的内皮细胞的炎症反应联系起来。具体目标2：阐明EC对脉动剪切应力与振荡剪切应力的分子响应以及相应的功能响应。在体外，我们将模拟EC和单核细胞的相互作用，在动脉分叉处的侧壁干扰流发生。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：证明在用氧化脂质预处理的EC上进行物理活动期间已知发生的高与低剪切应力转换速率的意义。我们将通过研究EC形态学变化、与单核细胞的相互作用以及炎症介质来分离转换速率对EC的影响。这个项目是设计导向和假设驱动的。通过将MEMS技术与血管生物学相结合，该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.