Three-Dimensional Reflectance Traction Microscopy

Cells in three-dimensional (3D) environments exhibit very different biochemical and biophysical phenotypes compared to the behavior of cells in two-dimensional (2D) environments. As an important biomechanical measurement, 2D traction force microscopy can not be directly extended into 3D cases. In order to quantitatively characterize the contraction field, we have developed 3D reflectance traction microscopy which combines confocal reflection imaging and partial volume correlation postprocessing. We have measured the deformation field of collagen gel under controlled mechanical stress. We have also characterized the deformation field generated by invasive breast cancer cells of different morphologies in 3D collagen matrix. In contrast to employ dispersed tracing particles or fluorescently-tagged matrix proteins, our methods provide a label-free, computationally effective strategy to study the cell mechanics in native 3D extracellular matrix.

相较于二维（2D）环境中的细胞行为，三维（3D）环境内的细胞会展现出截然不同的生化与生物物理表型。作为一项重要的生物力学检测手段，二维牵引力显微镜（traction force microscopy）无法直接推广应用至三维场景中。为了定量表征收缩场，我们开发了三维反射式牵引力显微镜技术，该技术整合了共聚焦反射成像（confocal reflection imaging）与部分体积相关后处理（partial volume correlation postprocessing）算法。我们已在可控机械应力条件下，测定了胶原凝胶的变形场。此外，我们还对不同形态的侵袭性乳腺癌细胞在三维胶原基质中产生的变形场进行了表征。相较于采用分散示踪粒子或荧光标记基质蛋白的传统方法，本技术提供了一种无需标记、计算高效的策略，用以研究天然三维细胞外基质中的细胞力学特性。