Live Cell Interferometry Reveals Cellular Dynamism During Force Propagation

Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles Young Drive East, Los Angeles, California 90095, USA.
ACS Nano (Impact Factor: 12.88). 06/2008; 2(5):841-6. DOI: 10.1021/nn700303f
Source: PubMed


Cancer and many other diseases are characterized by changes in cell morphology, motion, and mechanical rigidity. However, in live cell cytology, stimulus-induced morphologic changes typically take 10-30 min to detect. Here, we employ live-cell interferometry (LCI) to visualize the rapid response of a whole cell to mechanical stimulation, on a time scale of seconds, and we detect cytoskeletal remodeling behavior within 200 s. This behavior involved small, rapid changes in cell content and miniscule changes in shape; it would be difficult to detect with conventional or phase contrast microscopy alone and is beyond the dynamic capability of AFM. We demonstrate that LCI provides a rapid, quantitative reconstruction of the cell body with no labeling. This is an advantage over traditional microscopy and flow cytometry, which require cell surface tagging and/or destructive cell fixation for labeling.

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    • "Live cell interferometry (LCI) is a label-free optical microscopy technique which measures whole cell responses. LCI uses a Michelson-type interferometer to compare the optical thickness of living cells in a sample chamber to the optical thickness of fluid in a reference chamber in order to quantify the optical thickness difference between a cell and its surrounding media [12], [13]. The optical thickness difference due to the interaction of light with cellular biomass is linearly proportional to the material density of a cell [14]. "
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    • "The prolonged poking of every single cell can result in the remodeling of the cytoskeleton (Reed et al., 2008). The influence of the prolonged poking on a single cell can be easily checked by plotting the dependence between the obtained Young's modulus and the time elapsed during the indentation experiment. "
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    • "The current generation of AFMs can be integrated with complementary methodologies, including ionic conductance [87], total internal reflection fluorescence (TIRF) [88,89], fluorescence resonance energy transfer (FRET) [90] and other physico-chemical measurements [91], thereby enabling detailed structure-function studies of biofilms, dental surfaces and implants. Rapid quantitative changes in oral surfaces and cell morphology, motion and mechanical rigidity via live-cell interferometry (LCI) [92], can also be combined with the dynamic capability of AFM. Depending on the specific interests and technical requirements, the variety of combination techniques available with AFM would cover both transparent (e.g., dental biofilms) and non-transparent samples such as dental implants and fillings. "
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