Abstract
Cellular traction forces (CTFs) play an integral role in both physiological processes and disease, and are a topic of interest in mechanobiology. Traction force microscopy (TFM) is a family of methods used to quantify CTFs in a variety of settings. State-of-the-art 3D TFM methods typically rely on confocal fluorescence microscopy, which can impose limitations on acquisition speed, volumetric coverage, and temporal sampling or coverage. In this report, we present the first quantitative implementation of a new TFM technique: traction force optical coherence microscopy (TF-OCM). TF-OCM leverages the capabilities of optical coherence microscopy and computational adaptive optics (CAO) to enable the quantitative reconstruction of 3D CTFs in scattering media with minute-scale temporal sampling. We applied TF-OCM to quantify CTFs exerted by isolated NIH-3T3 fibroblasts embedded in Matrigel, with five-minute temporal sampling, using images spanning a 500 × 500 × 500 μm3 field-of-view. Due to the reliance of TF-OCM on computational imaging methods, we have provided extensive discussion of the equations, assumptions, and failure modes of these methods. By providing high-throughput, label-free, volumetric imaging in scattering media, TF-OCM is well-suited to the study of 3D CTF dynamics, and may prove advantageous for the study of large cell collectives, such as the spheroid models prevalent in mechanobiology.
Highlights
The field of mechanobiology seeks to understand the role of mechanical interactions and forces in both physiological processes and disease
As our implementation of traction force optical coherence microscopy (TF-optical coherence microscopy (OCM)) relies upon the accurate reconstruction of high resolution volumes via computational adaptive optics (CAO), we had to design our computational image formation module to ensure that interferometric phase instability and other factors would not corrupt the image data[23,24]
Given that the red channel of Supplementary Movie 1 exhibits the behavior we expect to observe, we conclude that our phase registration and bulk demodulation procedures are effective at mitigating shearing and motion artifacts in computationally refocused OCM images, and are beneficial to the accuracy of TF-OCM
Summary
The field of mechanobiology seeks to understand the role of mechanical interactions and forces in both physiological processes and disease. The method, which we named traction force optical coherence microscopy (TF-OCM)[15], would leverage multiple advantages offered by OCM and computed imaging methods to enable quantitative reconstruction of 3D CTFs with high temporal sampling in scattering media These advantages include a rapid (minute-scale) volumetric acquisition rate provided by Fourier domain OCM systems, focal plane resolution over an extended depth-of-field achieved with the aid of computational adaptive optics (CAO)[22], and label-free imaging at near-IR wavelengths to mitigate scattering and photobleaching/phototoxicity concerns. We expand upon the methods reported in ref.[15], and present a complete quantitative implementation of TF-OCM With this new technique, we quantified time-varying 3D CTFs exerted by isolated NIH-3T3 fibroblasts embedded within a Matrigel substrate. A brief overview of TF-OCM here is pertinent to interpreting the results in the sections that follow
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
