Correlation of in vitro cell viability and cumulative singlet oxygen luminescence from protoporphyrin IX in mitochondria and plasma membrane.

SIGNIFICANCE: Photodynamic therapy (PDT) can be targeted toward different subcellular localizations, and it is proposed that different subcellular targets vary in their sensitivity to photobiological damage. Since singlet oxygen (1O2) has a very short lifetime with a limited diffusion length in cellular environments, measurement of cumulative 1O2 luminescence is the most direct approach to compare the PDT sensitivity of mitochondria and plasma membrane. APPROACH: PDT-generated near-infrared 1O2 luminescence at 1270 nm was measured together with cell viability for 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) and exogenous PpIX, at different incubation times. Confocal fluorescence microscopy indicated that ALA-induced PpIX (2 h) localized in the mitochondria, whereas exogenous PpIX (1 h) mainly localized to the plasma membrane. Cell viability was determined at several time points during PDT treatments using colony-forming assays, and the surviving fraction correlated well with cumulative 1O2 luminescence counts from PpIX in mitochondria and plasmas membrane, respectively. RESULTS: The mitochondria are more sensitive than the plasma membrane by a factor of 1.7. CONCLUSIONS: Direct 1O2 luminescence dosimetry's potential value for comparing the PDT sensitivity of different subcellular organelles was demonstrated. This could be useful for developing subcellular targeted novel photosensitizers to enhance PDT efficiency.

Updated retinoblastoma incidence and outcome in children in Taiwan from 1980 to 2019: a 40-year nationwide study.

BACKGROUND: Retinoblastoma is a potentially fatal disease, and its incidence and mortality varies among different countries and periods. METHODS: This is a nationwide population-based retrospective study from January 1980 to December 2019 in Taiwan. Patients diagnosed as retinoblastoma were identified from the Taiwan National Cancer Registry. To update the literature on retinoblastoma incidence, mortality and trends in Taiwan, we analysed changes in incidence and survival rates over time according to sex, diagnostic age, laterality and treatment. RESULTS: During 1980-2019, the incidence of retinoblastoma in Taiwan was 1 per 16 489 live births (95% CI: 13 415-19 564). The diagnostic age decreased from 2.21 ± 0.26 during 1980-1984 to 1.24 ± 0.26 during 1985-2019. Compared with that observed during 1980-1989, the incidence rate observed after 1990 increased significantly in children aged <10 years (RR: 1.62-2.40, P = 0.0049 to < 0.0001). From 1980 to 2019, the incidence rate for the 0-4-year age group increased and that for the 5-9-year age group remained constant. The mean diagnostic age for bilateral retinoblastoma (0.36 ± 0.47 years) was significantly less than that for unilateral retinoblastoma (1.37 ± 0.35 years) during 2007-2019 (P < 0.0001). The 10-year survival rate was highest in the enucleation group (89.8%) compared with radiotherapy (52.2%) and others (70.0%; P < 0.0001). CONCLUSIONS: During 1980-2019 in Taiwan, the incidence of retinoblastoma increased significantly, and the diagnostic age decreased, which are similar to the ones from other developed countries. However, the survival rate was still lower than that of most developed countries.