(P 228) CHARACTERIZING ORGANELLES IN MYXOFIBROSARCOMA CELLS USING LABEL-FREE OPTICAL DIFFRACTION TOMOGRAPHY

Objective: Label-free optical diffraction tomography (ODT), an imaging technology that does not require fluorescent labeling or other staining, can overcome the limitations of conventional cell imaging technologies. Conventional microscope techniques are phototoxic and invasive, which limit their ability to be used to precisely determine the characteristic property of each organelles of cells. ODT is one of the non-invasive quantitative phase imaging (QPI) technologies that is now widely used in biology and medicine. However, there was no study on imaging sarcoma cells using ODT. In this study, we used ODT to characterize the cellular organelles of myxofibrosarcoma based on their refractive index and volume of organelles.

Methods: Myxofibrosarcoma cells were derived from excised tumor of patients and cultured. ODT measurement of single cells was performed with a commercial ODT microscope (HT-2H; Tomocube Inc., Korea). Using raw ODT images, the refractive index(RI) mapping image was reconstructed by dividing the corresponding RI ranges of the nucleolus, cytoplasm, vesicles, and plasma membrane. The RI iso-surface of the cytoplasm, nucleolus, and vesicle of the cell was rendered using TomoStudio software (2.6.25; Tomocube).

Results: Representative label-free ODT image of living myxofibrosarcoma cell is presented in Fig 1. Serial section(4𝜇𝑚) images of myxofibrosarcoma cell is presented in Fig 2. The cell membrane, cytoplasm, and nucleolus could be identified morphologically. Mean(± standard deviation) molecular density of the nucleus, cytoplasm, vesicles and plasma membrane were 0.0763 ± 0.0039g/ml, 0.0349 ± 0.0018g/ml, 0.1495 ± 0.0038g/ml and 0.0210g/ml, respectively.

Conclusion: Our findings demonstrate that ODT can be used to image myxofibrosarcoma cells and quantify the nucleoli and vesicular structures based on RI and volume.