Open microfluidics platforms for the in vitro assessment of drug transport in microtumour samples

如何为晚期癌症患者找到正确的治疗方法？在基因组学的世纪里，临床医生越来越意识到肿瘤具有高度的患者特异性，并且可能对不同类型的抗癌药物具有不同的敏感性。考虑到大多数药物的治疗效果只能在几周后才能感受到，在治疗的早期识别无反应应该会大大减少副作用，并节省与无临床益处相关的成本。为了给病人开正确的药，今天的临床医生使用生物标志物来统计治疗结果与病人的遗传/表观遗传特征之间的关系。在过去的几年里，另一种有希望的针对患者的治疗方法出现了：直接在体外评估药物对患者自身肿瘤样本的反应，这些样本被捕获或生长在直径仅为一毫米的微型通道网络中。在这些微流体系统或芯片实验室中，微观肿瘤样本可以被捕获或在3D中进行组织工程，以恢复体内组织的一些特征。许多人认为，在这个意义上，它们比培养皿中的二维培养更适合研究细胞对药物的反应，因为后者忽略了肿瘤的一个重要方面：在复杂的三维细胞结构中，药物、氧气、营养物质、细胞因子和其他分析物的生化运输限制。微流体系统中的生化运输科学是我们的主要科学专长。它研究的是平流，扩散，以及粒子和分子在各种力的作用下在微型通道中的反应。芯片实验室应用中的许多技术挑战的解决方案，包括基于表面传感器的动力学测量和蛋白质或DNA分析中的有效分离，已经通过系统地了解微尺度的传质特性而成为可能。由于微流体技术可以精确控制肿瘤微环境，因此它有望在药物发现平台的开发中发挥重要作用，该平台采用3D体外模型作为小鼠模型体内测试的有效替代品。我们在这项建议中所描述的正是将这一设想变为现实的挑战。这个研究项目的长期研究目标是双重的。在基本层面上，我们将寻求在芯片实验室系统中详细了解质量传输，重点是在微流体系统中捕获的周围3D生物样品内部传输，以了解肿瘤如何对药物作出反应。在更实用的工程水平上，我们将使用先进的运输概念，数值模拟，微加工以及细胞和组织培养技术来设计快速分析工具，通过将肿瘤分析的所有步骤集成到芯片上，加快生物和医学数据的获取。为了实现这一目标，我们将建议将问题分解为三个主要目标，作为博士生的三个平行独立项目：i)系统探索开放微流体几何中的平流/扩散输运；ii)模拟球体和肿瘤组织切片内和周围的分析物运输及其对肿瘤化学反应的影响；iii)系统研究生长条件对球体尺寸的影响。通过拟议的项目，我们将在工程和癌症生物学之间培养优秀的学生，我们将与临床医生合作，以最终用户为中心开发我们的技术，最重要的是，我们将努力对癌症患者的治疗方式产生持久的影响，以提高他们的总体生活质量。

How to find the right treatment for a patient suffering from advanced cancer? In the century of genomics, there has been a growing awareness among clinicians that tumors are highly patient-specific and likely to have different sensitivities to different types of anti-cancer drugs. Given that the therapeutic effects of most drugs can only be felt after several weeks, identifying non-responders early in a treatment should greatly reduce side-effects and save costs associated with no clinical benefit. To prescribe the right drugs to a given patient, clinicians today use biomarkers to statistically correlate the outcome of a treatment with the patient’s genetic/epigenetic profile. Over the past years another promising approach to tailor treatments to patients has emerged: the direct in vitro assessment of drug response on samples from the patient’s own tumor trapped or grown in a network of miniature channels only fractions of a millimeter in diameter. In these microfluidic systems, or lab-on-a-chip, microscopic tumor samples can be trapped or tissue-engineered in 3D to recover some of the features of in vivo tissues. Many argue that they are in this sense superior to 2D cultures in petri dishes to study the response of cells to drugs as the latter neglect an important aspect of tumors: the biochemical transport limitations of drugs, oxygen, nutrients, cytokines and other analytes in complex 3D cellular architectures. Biochemical transport science in microfluidic systems is our primary scientific expertise. It deals with the study of advection, diffusion, and reactions of particles and molecules submitted to various forces in miniature channels. The solution to many technological challenges in lab-on-a-chip applications, including kinetics measurements in surface-based sensors and efficient separation in protein or DNA analysis, has been made possible through systematic understanding of mass transfer properties at the microscale. Since microfluidics allow for the precise control of the tumor microenvironment, it is poised to play a major role in the development of drug discovery platforms employing 3D in vitro models as efficient surrogates for in vivo testing in mouse models. It is the very challenge of bringing this vision to reality that we are describing in this proposal. The long term research goals of this research program is two-fold. On a fundamental level, we will seek to develop a detailed understanding of mass transport in lab-on-a-chip systems, with a focus on transport inside an around 3D biological samples trapped in microfluidics systems to understand how tumors respond to drugs. On a more applied, engineering level, we will use advanced transport concepts, numerical simulations, microfabrication and cell and tissue culture techniques to design fast analytical tools to speed up biological and medical data acquisition by integrating all steps of tumor analysis onto a chip. To achieve this goal, we will propose to break down the problem in three main objectives to be pursued as three parallel independent projects for Ph. D. students: i) Systematic exploration of advective/diffusive transport in open microfluidic geometries; ii) Modeling of analyte transport in and around spheroids and cancer tissue microsections and its effect on tumor chemoresponse ; iii) Systematic investigation of the effect of growth conditions on spheroid sizes. Through the proposed projects, we will train outstanding students at the interface between engineering and cancer biology, we will collaborate with clinicians to develop our technologies with the end user in mind, and, above all, we will strive to have a lasting impact in the way cancer patients are being treated to improve their general quality of life.