Influence of microenvironmental parameters on the photophysical properties of protoporphyrin IX for bladder cancer diagnostics
Daria O. Suverneva1, Afraa A. Hasan1,5, Gleb S. Budylin2, Ivan D. Filippov1, Dmitry A. Davydov1,2, Natalia V. Korneva6, Dmitry A. Kislyakov3, Vladislav I. Shcheslavskiy4, Evgeny A. Shirshin1,2; 1Lomonosov Moscow State University, Moscow, Russia; 2I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia; 3Voskresensk Hospital, Voskresensk, Russia; 4Privolzhsky Research Medical University, Nizhny Novgorod, Russia; 5VPG Laserone LLC, Fryazino, Russia; 6University Clinic of the Medical Scientific and Educational Center of Lomonosov Moscow State University, Moscow, Russia
Abstract
Bladder cancer is one of the most pressing challenges in modern oncourology. More than 75% of cases are classified as non-muscle-invasive bladder cancer, where accurate identification of tumor tissue plays a key role in reducing recurrence rates. However, standard white-light cystoscopy has limited sensitivity, which has driven the development of advanced imaging techniques, including photodynamic diagnostics (PDD) using 5-aminolevulinic acid (5-ALA). This method is based on the accumulation of protoporphyrin IX (PpIX) in tumor cells. Upon excitation with blue light, PpIX emits a characteristic red fluorescence, enabling the visualization of areas with elevated PpIX accumulation. Despite the higher sensitivity of PDD (92–96%) compared to white light, its specificity remains limited due to potential PpIX accumulation in inflamed tissues.One of the most promising approaches to increasing specificity is the analysis of PpIX fluorescence lifetime. In contrast to fluorescence intensity, this parameter is less dependent on recording conditions and the optical properties of the medium; instead, it reflects the microenvironment of the fluorophore, making it a potentially more stable diagnostic indicator. In this work, an experimental setup was designed and assembled to record fluorescence decay kinetics using time-correlated single-photon counting (TCSPC).During the first phase of the study, measurements were performed in model biological systems to evaluate the effects of PpIX concentration and protein binding on fluorescence decay parameters. In the subsequent phase, fluorescence decay kinetics were measured ex vivo in bladder tumor, inflamed, and healthy tissue samples. These samples were obtained during endoscopic surgeries following 5-aminolevulinic acid administration and were subsequently confirmed by histological examination. Ex vivo data analysis demonstrated that tumor tissues are characterized by higher values of the long-lived lifetime component (τ₂) and a higher ratio of the long-lived to short-lived component amplitudes (a₂/a₁) compared to healthy and inflamed tissues. The identified differences demonstrate the diagnostic significance of these parameters and confirm the viability of using PpIX fluorescence lifetime to differentiate between tumor and non-tumor tissues.
Speaker
Daria
Lomonosov Moscow State University, Moscow, Russia
Russia
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