Development of experimental and numerical models of platelet deposition

血小板沉积实验和数值模型的开发

• 批准号: 257850537
• 负责人: Dr.-Ing. Ulrich Kertzscher
• 金额: --
• 依托单位: LaboMed Gerinnungszentrum Berlin
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/257850537?language=en
• 关键词: Development; experimental; numerical; models; platelet

The objective of this project is a better understanding of the role of platelet deposition as the beginning of thrombus formation. The formation of thrombi poses a great problem in cardiovascular diseases. The formation of thrombi does not only occur in naturally existing blood vessels but also in implants such as vascular implants, stents, heart valves, and cardiac support devices. This threatens the health of the corresponding patient. Two model flows will be used for the experimental investigation of the platelet deposition; the plane Couette flow and the stagnation point flow. Corresponding numerical models will be developed. The following objective shall be achieved: the development of a numerical model that is based on experimental data which can be used by an engineer to estimate the thrombogenicity of an implant allowing for an optimization in this regard. Recent publications in international literature demonstrate that the fluid flow itself is considered current and important for the platelet deposition and formation of thrombi. Numerical models are presented but there is a lack of experimental results. The hypothesis states, that the numerical model can closely simulate the results of the experimental models of complex flows. The applied numerical model is based on a Monte Carlo method. It includes a CFD-generated velocity field with a superimposed diffusion motion of the platelets. Therefore, problems with convergence as found in continuum models can be avoided and the amount of model parameters is limited. This can be experimentally validated. The problem shall be investigated based on Virchow's triad. According to Virchow, three parameters such as blood properties, wall properties, and fluid flow define the formation of a thrombus, which begins with the deposition of platelets. The experimental models are chosen such that blood properties, wall properties, and fluid flow can be separately investigated with regards to thrombogenicity. Fluorescence microscopy is used to measure the motion and deposition of platelets from human whole blood for the experimental models. The generated series of images can be evaluated with current methods of image processing. The numerical model simulates transport processes that move the platelets towards the artificial surface with which they can interact. The interaction between platelet and wall - the deposition - is considered a stochastic process, which is based on individual probabilities that result in a deposition likelihood if multiplied with each other. The latter ones are similar to the commonly used reaction rate. The likelihood of deposition is a quantifiable measure and can be experimentally estimated, dependent on platelet activation, wall property, and fluid flow.

该项目的目的是更好地了解血小板沉积作为血栓形成开始的作用。血栓的形成是心血管疾病的一大难题。血栓的形成不仅发生在天然存在的血管中，而且发生在植入物中，例如血管植入物、支架、心脏瓣膜和心脏支持装置。这威胁到相应患者的健康。两个模型流将用于血小板沉积的实验研究;平面Couette流和驻点流。将建立相应的数值模型。应实现以下目标：开发基于实验数据的数值模型，工程师可使用该模型来估计植入物的血栓形成性，从而在这方面进行优化。国际文献中的最新出版物表明，流体流动本身被认为是血小板沉积和血栓形成的当前和重要因素。数值模型，但缺乏实验结果。该假设指出，数值模型可以密切模拟复杂流动的实验模型的结果。应用的数值模型是基于蒙特卡罗方法。它包括一个CFD生成的速度场与叠加的扩散运动的血小板。因此，可以避免在连续模型中发现的收敛问题，并且模型参数的数量是有限的。这可以通过实验验证。这个问题应根据魏尔啸的三元组来研究。根据Virchow的说法，三个参数，如血液特性，壁特性和流体流动定义了血栓的形成，血栓的形成始于血小板的沉积。选择实验模型，使得血液特性、壁特性和流体流动可以分别研究致血栓性。荧光显微镜用于测量实验模型中人全血中血小板的运动和沉积。所生成的一系列图像可以用当前的图像处理方法进行评估。数值模型模拟运输过程，移动血小板对人工表面，他们可以相互作用。血小板和壁之间的相互作用-沉积-被认为是一个随机过程，这是基于个人的概率，导致沉积的可能性，如果彼此相乘。后者类似于常用的反应速率。沉积的可能性是一种可量化的量度，并且可以根据血小板活化、壁性质和流体流动进行实验估计。