A Magnetic Micromanipulation System for Intra-Cellular and Intra-Tissue Mechanics

为了揭示细胞内结构和细胞器的力学和功能，需要在细胞内进行直接的力学测量。与从细胞外进行的传统细胞力学相比，细胞内力学测量尚未得到充分探索。同样，很少有人尝试测量大块组织内部（相对于组织表面）的力学。众所周知，细胞在体外向基质的刚性区域迁移，这一过程被称为硬迁移。然而，组织内硬度的实验测量仍然缺乏。******此RTI应用程序要求磁性微操作仪器具有独特的能力，可以在单个细胞内或组织内部深处移动磁性微珠，以获得准确的力变形数据，用于细胞内和组织内力学表征。磁性微操作仪器包含八个放置在不同平面上的磁线圈，以产生三维磁场。它有两种工作模式：(1)使用八个磁线圈中的六个产生强大的磁场梯度，以移动微米大小的磁珠并施加高达200 pN的力，这将用于我们提出的细胞内力学工作；(2)利用八个磁线圈产生均匀的磁场梯度，对工作空间内的所有磁珠施加相同的力，这将用于我们提出的组织内力学工作。在实验中，磁性微珠和细胞结构将被荧光标记，它们的位移/变形将被荧光显微镜成像测量。******我们的HQP将使用所要求的设备在单个细胞内进行机械测量，机械地加载细胞内结构以诱导机械转导反应，并在组织深处实现机械测量。这些设备将用于培养大量的博士后和研究生，他们将获得细胞和组织力学、细胞力学转导、发育生物学、显微镜成像以及精密仪器控制和测量方面的技能。

To reveal the mechanics and functions of intracellular structures and organelles demands direct mechanical measurement inside a cell. Compared to conventional cell mechanics performed from outside the cell, intracellular mechanical measurement is underexplored. Similarly, few attempts have been made to measure the mechanics within bulk tissue (vs. on tissue surface). It is well recognized that cells in vitro migrate towards the stiff region of a substrate, a process termed durotaxis. However, experimental measurement of durotaxis inside tissue remains lacking.******This RTI application requests a magnetic micromanipulation instrument with unique capabilities of moving magnetic microbeads inside single cells or deep inside a tissue to obtain accurate force-deformation data for intracellular and intra-tissue mechanics characterization. The magnetic micromanipulation instrument contains eight magnetic coils placed on different planes to generate 3D magnetic fields. It has two operation modes: (1) the use of six of the eight magnetic coils to generate a strong magnetic field gradient for moving a micrometer-sized magnetic bead and applying forces up to 200 pN, which will be used for our proposed intracellular mechanics work; (2) the use of the eight magnetic coils to generate uniform magnetic field gradient for applying the same force on all the magnetic beads within the workspace, which will be used for our proposed intra-tissue mechanics work. In experiments, magnetic microbeads and cellular structures will be fluorescently labelled, and their displacement/deformation will be measured by fluorescence microscopy imaging. ******Our HQP will use the requested equipment to perform mechanical measurement inside individual cells, mechanically load intracellular structures to induce mechanotransduction responses, and achieve mechanical measurement deep within tissue. The equipment will be used to train a high number of postdocs and graduate students who will gain skills in cell and tissue mechanics, cell mechanotransduction, development biology, microscopy imaging, and precision instrument control and measurement.