SignificanceFor therapeutic approaches for upper tract urothelial carcinomas, the absorption μa and reduced scattering μs′ coefficients of these tissues are essential parameters to quantitatively evaluate the distribution of light treatment effects.AimThe μa and μs′ spectra of the human ureter, fatty tissue, ureteral and renal pelvic carcinomas, and porcine ureter and fatty tissue are measured over 400 to 700 nm to evaluate projected light penetration depths δ.ApproachThe optical properties were determined with a double integrating sphere optical system and inverse Monte Carlo methods. δ was calculated and compared between normal and cancerous human tissues as well as between normal human and porcine tissues.Resultsμa and μs′ spectra of each tissue were determined. The δ of the normal human ureter was less than those of the ureteral and renal pelvic carcinomas, whereas that of the porcine ureter was similar to that of the human ureter over 400 to 600 nm and ∼0.2 times smaller above 600 nm.ConclusionOptical properties of human and porcine upper urinary tracts provide insights into light distributions and the validity of ex vivo porcine models in preclinical evaluations of laser treatments.
SignificancePhotobleaching of the photosensitizer reduces fluorescence observation time and the intensity of fluorescence emitted for tumor detection during 5-aminolevulinic acid-based photodynamic diagnosis.AimThis study aims to utilize the concept of fluorescence photoswitching, which uses the fluorescence emission from photosensitizer excitation followed by the simultaneous excitation of the photosensitizer and its photoproduct to increase the fluorescence detection intensity during PDD of deeply located tumors.ApproachThe fluorescence photobleaching of protoporphyrin IX (PpIX) and the formation of its photoproduct, photoprotoporhyrin (Ppp), caused by exposure to 505 nm light were investigated in solution, ex vivo, and in vivo, and the fluorescence photoswitching was analyzed. The fluorescence observations of PpIX and Ppp were performed with 505 and 450 or 455 nm excitation, respectively, which is the suited wavelength for the primary excitation of each fluorophore.ResultsFluorescence photoswitching was observed in all forms of PpIX investigated, and the fluorescence photoswitching time, fluorescence intensity relative to the initial PpIX and Ppp intensity, and fluorescence intensity relative to PpIX after photobleaching were obtained. The dependence of the fluorescence photoswitching time and intensity on the irradiation power density was noted. A fluorescence intensity increase between 1.6 and 3.9 times was achieved with simultaneous excitation of PpIX and Ppp after fluorescence photoswitching, compared with the excitation of PpIX alone.ConclusionsWe have demonstrated the potential of fluorescence photoswitching for the improvement of the fluorescence observation intensity for the PDD of deeply located tumors.
This study demonstrates a method to extend diagnostic depth in 5-aminolevulinic acid-based photodynamic diagnosis for bladder cancer by a prototype cystoscope system with green light source to excite a photosensitizer in a deep tissue.
Photodynamic therapy (PDT) and diagnosis (PDD) using 5-aminolevulinic acid (ALA) to drive the production of an intracellular photosensitizer, protoporphyrin IX (PpIX), are in common clinical use. However, the tendency to accumulate PpIX is not well understood. Patients with cancer can develop recurrent metastatic disease with latency periods. This pause can be explained by cancer dormancy. Here we created uniformly sized PC-3 prostate cancer spheroids using a 3D culture plate (EZSPHERE). We demonstrated that cancer cells exhibited dormancy in a cell density-dependent manner not only in spheroids but also in 2D culture. Dormant cancer cells accumulated high PpIX levels and were sensitive to ALA-PDT. In dormant cancer cells, transporter expressions of PEPT1, ALA importer, and ABCB6, an intermediate porphyrin transporter, were upregulated and that of ABCG2, a PpIX exporter, was downregulated. PpIX accumulation and ALA-PDT cytotoxicity were enhanced by G0/G1-phase arrestors in nondormant cancer cells. Our results demonstrate that ALA-PDT would be an effective approach for dormant cancer cells and can be enhanced by combining with a cell-growth inhibitor.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.