Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Poster Abstracts

76-POS Board 38 Damage of Cancer Cells Evaluated by Intensity Fluctuation of Images under Phase Contrast Microscope Morito Sakuma , Yuichi Kondo, Hideo Higuchi. The University of Tokyo, Tokyo, Japan. Selective removal of cancer cell without side effects is necessarily for cancer therapy. Phototoxic dyes such as IR700 can specifically be delivered to cancer cells, and the cells are damaged by reactive oxygen species (ROS). But surviving cancer cells damaged by oxidative stress could obtain resistant to the therapy. Here to understand the effects of phototoxic dyes and detect resistant cancer cells, we developed a method to measure quantitatively cell damages induced by ROS of IR700. We evaluated cell damage by calculating the intensity fluctuation of each pixel in cell images under phase contrast microscopy. We succeeded in quantifying the change in motility of cell organelles by this method (Sakuma et al. Sci Technol Adv Mater. 2016). IR700 was labeled with the antibody which binds specifically to target cells. IR700-antibody complex was endocytosed into cultured cells and then cell was photodamaged by illumination of red laser (650 nm). The degree of cell damage was controlled by adjusting the irradiation time of red laser. The motility of cell organelles detected by the intensity fluctuation method decreased gradually with a progression of cell damage. To elucidate the mechanisms of decrease in the organelles motility, we analyzed the effects of photoactivation of IR700 on activities of organelles and motor proteins. Lysosomes containing IR700 in cells were damaged quickly by the photoactivation of IR700 and the contents in lysosomes were diffused out into cytoplasm. The contents diffused from lysosomes caused the dysfunction of transporter kinesin and mitochondria. Therefore, these damages of organelles and motors may be a primary factor for causing decrease of organelles motility. These results suggested that the cell organelles motility is a primary indicator of cell viability.

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