Optical diffraction tomography (ODT) enables imaging of unlabeled intracellular components by measuring the three-dimensional (3D) refractive index (RI). We aimed to detect intracellular monosodium urate (MSU) crystals in synovial leukocytes derived from gout patients using ODT. The 3D RI values of the synthetic MSU crystals, measured by ODT, ranged between 1.383 and 1.440. After adding synthetic MSU crystals to a macrophage, RI tomograms were reconstructed using ODT, and the reconstructed RI tomograms discerned intracellular and extracellular MSU crystals. We observed unlabeled synthetic MSU crystal entry into the cytoplasm of a macrophage through time-lapse imaging. Furthermore, using gout patient-derived synovial leukocytes, we successfully obtained RI tomogram images of intracellular MSU crystals. The 3D RI identification of MSU crystals was verified with birefringence through polarization-sensitive ODT measurements. Together, our results provide evidence that this novel ODT can identify birefringent MSU crystals in synovial leukocytes of patients with gout.
Bibliographical noteFunding Information:
This study was supported by a faculty research grant of Yonsei University College of Medicine (Grant Number 6-2020-0034 to J.J.S.), the Basic Science Research Program (Grant Number 2018R1D1A1B07045202 to J.J.S.) through the National Research Foundation of Korea funded by the Ministry of Education, Science, and Technology, Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI) (Grant Number HI18C1241 to S.L.) funded by the Ministry of Health and Welfare and partially supported by Commercializations Promotion Agency for R&D Outcomes (COMPA) (Grant Number 2018-jdh-3-sb2-2 to S.L.) funded by the Ministry of Science and ICT. This work was also supported by the KBSI Research Fund (Grant Number D110720 to S.L.).
© 2021, The Author(s).
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