Abstract
Purpose: To investigate whether photodynamic diagnosis (PDD) using a portable fluorescence spectrophotometer (FC-1) can easily and objectively discriminate between normal and tumor cells at the dental chairside, and to further compare it with PDD that requires speculum examination by focusing on protoporphyrin IX (PPIX). Methods: Three cell lines (2 human oral squamous cell carcinoma-derived cell lines, HSC-2 and HSC-3 cells, and oral keratinocytes, HOK cells) were cultured. 5-Aminolevulinic acid hydrochloride (5-ALA) and deferoxamine mesylate (DFO) were mixed in DMEM, and the mixture was set to Control (DMEM only) and PDD (5-ALA+DFO) groups. And then, a fluorescence was measured under room temperature (RT) and 37°C (Incubation) by using FC-1. In this study, the two conditions were combined with the Control and PDD groups to form the Control/RT, Control/Incubate, PDD/RT, and PDD/Incubate groups. Additionally, the amount of singlet oxygen (1O2) generated by irradiation with 405 nm LED was measured using electron spin resonance spectroscopy to detect PPIX in the cell supernatant after 24 hours. Results: In HSC-2 and HSC-3, the fluorescence intensity values increased significantly at 2 hours between the Control/RT and PDD/RT groups. In addition, there was a significant difference between HSC-2 and HSC-3 compared to HOK. In all cell lines, the fluorescence intensity values of the PDD/Incubate group were significantly higher than those of the PDD/Control group. The amount of 1O2 generated by 405 nm LED irradiation was higher in the cell supernatants of all cell lines in the order of Control/RT < Control/Incubate < PDD/RT < PDD/Incubate group, and HSC-3 in the PDD/Incubate group showed a significant increase compared to HOK. Conclusion: It is suggested that PDD using FC-1 can clearly distinguish between normal cells and tumor cells in vitro studies using cell lines at 2 hours under 37°C, and it can detect not only intracellular PPIX, but also extracellular PPIX.
Highlights
Cancer of the oral cavity and pharyngeal region causes approximately 8,000 deaths per year in Japan, and the number of deaths has tripled over the past 30 years [1]
The amount of 1O2 generated by 405 nm LED irradiation was higher in the cell supernatants of all cell lines in the order of Control/room temperature (RT) < Control/Incubate < photodynamic diagnosis (PDD)/RT < PDD/Incubate group, and HSC-3 in the PDD/Incubate group showed a significant increase compared to HOK
It is suggested that PDD using FC-1 can clearly distinguish between normal cells and tumor cells in vitro studies using cell lines at 2 hours under 37 ̊C, and it can detect intracellular protoporphyrin IX (PPIX), and extracellular PPIX
Summary
Cancer of the oral cavity and pharyngeal region causes approximately 8,000 deaths per year in Japan, and the number of deaths has tripled over the past 30 years [1]. Visual inspection and digital palpation are mainly effective in detecting oral cancer [3], and various other examinations are performed [4] [5] [6] [7] [8]. These methods rely on the clinical experience of dentists, and there are still few objective screening methods that do not rely on experience. For the early detection of oral cancer, it is very important to establish an objective diagnostic method that is less prone to disparities among medical professionals
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