循环癌细胞力学特性对癌症转移影响的机理研究

Cancer is one of the most malignant diseases which causes sickly spiritual and economic burden for patients and the society. Metastasis rather than primary tumor are responsible for above 90 percent of cancer deaths. Circulating tumor cells (CTCs) as the pre-requisite media for metastasis, whose mechanical properties are crucial in the complicated metastasis process. It is valuable for both academic and medical purposes to study the effect of mechanical properties of CTCs on metastasis. In this project, the effect of mechanical properties of CTCs on metastasis is studied with the variation of the CTCs numbers and the characteristics of the size and deformability distribution along the deterioration of cancer patients, and the effect of CTCs' mechanical properties on their pluripotencies and the capacity of inducing the formation of metastasis tumor. Taking the benefits of combining the engineering mechanics and medical superiority in our team, CTCs are extracted from the clinical blood samples of volunteered cancer patients with the microfludic biochips at state-of-art. Since CTCs are gathered without using any antibody, they are nearly at their natural state for further biophysical and mechanical tests. The size and deformability of CTCs are measured with the micropipette aspiration system, and their stem cell phenotype are checked by immunofluorescence technique with specific cancer type surface biomarker molecules. Using the characteristics of the possibility density function of CTCs' size and deformability distributiom, a dynamic monitoring system for cancer development is established. The effect of CTCs' mechanical properties on their pluripotencies is analyzed by correlating CTCs' size and deformability with their expression of stem cell phenotype. A numerical platform for simulating the deformation and adhesion behavior of CTCs is built up with coupling the cell stiffness, biofluid mechanics and the adhesion dynamics. Under the biological background of human circulatory system, the optimal shear rates of the blood flow for any given CTCs with certain size and stiffness to adhere on the vessel walls are investigated. The minimum diameter of the capillary for CTCs to pass through is also analyzed. Based on the experiments and numerical simulations above, a detailed analysis for the effect of CTCs' mechanical properties on cancer metastasis is performed. The success of the present project will help the understandings of metastasis from a mechanical point of view. The results proposing by the current project will be valuable for using the CTCs mechanical properties as the biophysical marker for the diagnosis of the cancer stage, and the development of physical treatment on metastasis prevention.

循环癌细胞(CTCs)的力学特性在癌症转移涉及的多个物理过程中发挥着至关重要的作用。本项目采用细胞力学、分子生物学实验和计算机数值模拟相结合的方法，研究CTCs力学特性对癌症转移影响的机理。通过医工交叉合作，采用先进的细胞物理分离方法，从不同种类和病理阶段的癌症患者血样中，获得具有良好的力学和生物学纯净度的CTCs，对其力学特性和干细胞特征检测；运用CTCs数目以及尺寸和弹性分布随癌症发展的变化规律作为生物物理标志物，构建癌症转移的动态监测体系；关联CTCs力学特性与其干细胞特征对应关系，分析CTCs力学特性对转移肿瘤诱发能力的影响；结合人体血液循环系统的生理条件，耦合细胞力学、血液动力学和粘附动力学进行计算机数值模拟，分析CTCs力学特性对转移肿瘤易发部位的综合影响。本研究旨在深入了解CTCs力学特性对癌症转移影响的机理，为开发癌症物理诊断和治疗新方法提供细胞力学的理论和实验依据。

循环肿瘤细胞引起的癌症转移是癌症致死的主要原因之一，围绕循环肿瘤细胞引起癌症转移的机理研究具有重要的学术和临床价值。本项目从细胞力学角度出发，围绕循环肿瘤细胞的力学特性，结合细胞力学、细胞分子生物学实验和计算机数值模拟，深入分析了循环肿瘤细胞力学特性对癌症转移的影响机理中的若干问题。主要完成了以下几方面的工作：1）循环肿瘤细胞活体分离技术的临床验证及新型柔性微流控循环肿瘤细胞分离富集技术创新。本项目结合稀有细胞物理富集技术和癌症患者临床血样，从血液中富集循环肿瘤细胞。在本项目执行过程中，对当前富集技术进行了临床验证和创新拓展。在本项目完成期间，我们不仅成功采用液体活检方式富集获得人体血液样本中的稀有细胞，新型柔性多维微流控芯片器件的发明，使得此项人体外周血富集活细胞的液体活检技术向全血、多功能发展变为可能。2）基于临床样本的癌症发展阶段癌症恶性程度与循环肿瘤细胞力学特性关联分析。结合临床，本项目完成了循环肿瘤细胞的数目和活体弹性与术后组织病理结果的对应分析。通过数据对照，发现了循环肿瘤细胞力学特性作为癌症后期和前期的液体活检的指标差异。研究发现，此指标具有统计意义，但对于单个临床样本，还需要结合细胞生化指标（如：EMT指标，或基因测序）进行深入定量。3）循环肿瘤细胞力学特性在其随血液转移过程中对转移的影响关联分析。在标定临床患者循环肿瘤细胞力学特性的基础上，对癌细胞在微循环随血液运动发生转移过程中自身弹性与血流动力学环境的相互作用对细胞运动规律和膜应力之间的影响进行了数值模拟和定量分析，深入探讨了血管直径、血红蛋白比、血液流动速度以及循环肿瘤细胞自身弹性对癌症转移易发部位的影响机理。本项目执行对循环肿瘤细胞力学特性对癌症转移的影响机理分析提供了细胞力学依据。