Mechanical cues in the form of ECM compliance have been shown to affect a wide range of physiological processes including stem cell differentiation¹, vascular development², fibroblast motility³, glioblastoma metastasis⁴ and breast cancer tumor progression including invasion and metastasis^5-7. However, despite excellent and creative work by a number of research groups, understanding of mechanoreciprocity remains limited to a conceptual framework supported by important but sparse instances of specific molecular information⁸. Mechanoreciprocity remains vaguely understood because tools that quantitatively probe the cell-ECM force balance are lacking. Although, significant progress has been made in the last 10 years as the biological community has turned its attention to these problems^9-11, large and critical areas of experiment space remain inaccessible, figure 1. Of particular need are tools that directly measure the cell-ECM force balance with sufficient resolution to observe the initial ECM compliance sensing events and sufficient dynamic range to track the evolution of those events into whole cell phenotype and genotype changes, such as metastasis. Furthermore, it is insufficient to merely be able to access larger portions of the relevant experiment space, rather scalable tools that provide robust and repeatable quantitative data are needed in order to identify the critical proteins in each specific system.

We are developing a tool, called Single Cell Pico Force Microscopy (SCPFM), specifically for systematic study of the cell-ECM interface from the molecular up to the whole cell level. At the core of SCPFM are Nano-Electro-Mechanical-Systems (NEMS)-based force sensors that directly measure the force a cell under study exerts on its surroundings with near-single molecule force resolution and whole cell dynamic range. We have additionally developed a suite of supporting technologies that are required to execute force measurements with NEMS, and we have demonstrated SCPFM's capabilities by measuring Cytochalasin D induced force collapse and recovery with unprecedented resolution and dynamic range. SCPFM integrates NEMS force sensors with microscopy and microfluidics to enable cell-ECM force measurement that runs simultaneously with precise pharmacological or mechanical perturbation and microscopy in a system that is automated and scalable. With this combination of abilities SCPFM is uniquely positioned to carry out systematic studies of the role mechanoreciprocity plays in regulating processes including tumor progression, tissue formation and stem cell differentiation.

Personnel
Blake W. Axelrod and Paula F. Popescu

Funding
Army Research Office

References

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