A method for quantifying cell size from differential interference contrast images: validation and application to osmotically stressed chondrocytes |
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| Authors: | L. G. Alexopoulos&Dagger ,G. R. Erickson&dagger ,& F. Guilak&dagger &Dagger |
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| Affiliation: | Orthopaedic Research Laboratories, Department of Surgery, Box 3093, Duke University Medical Center, Durham, NC 27710, U.S.A.;Department of Biomedical Engineering, Duke University, Box 90281, 136 Hudson Hall, Durham, NC 27708-0281, U.S.A.;Department of Mechanical Engineering &Materials Science, Duke University, Box 90300, 144 Hudson Hall, Durham, NC 27708-0300, U.S.A. |
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| Abstract: | An automatic image analysis method was developed to determine the shape and size of spheroidal cells from a time series of differential interference contrast (DIC) images. The program incorporates an edge detection algorithm and dynamic programming for edge linking. To assess the accuracy and working range of the method, results from DIC images of different focal planes and resolutions were compared to confocal images in which the cell membrane was fluorescently labelled. The results indicate that a 1‐µm focal drift from the in‐focus plane can lead to an overestimation of cell volume up to 14.1%, mostly due to shadowing effects of DIC microscopy. DIC images allow for accurate measurements when the focal plane lies in a zone slightly above the centre of a spherical cell. In this range the method performs with 1.9% overall volume error without taking into account the error introduced by the representation of the cell as a sphere. As a test case, the method was applied to quantify volume changes due to acute changes of osmotic stress. |
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| Keywords: | Cell measuring chondrocytes differential interference contrast (DIC) dynamic programming edge detection edge linking image analysis image processing morphology morphometry osmotic stress volume regulation |
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