Optimizing the parameters of PDT for specific cancer cells by identifying the mechanisms involved in the process represents a considerable tool for the development of photosensitizer delivery systems and the improvement of PDT targets for cancer. Proteoglycans, important constituents of extracellular matrix (ECM) play an important role in both progression and inhibition of tumor development. This study determines by gene expression whether proteoglycan are associated with PDT resistance observed in human epidermoid larynx carcinoma cells (HEp-2). We conclude that PDT increases the expression of DECORIN and BIGLYCAN genes, involved in metastatic dissemination, leading to inhibitory effect growth in Hep-2 cells
Human papillomavirus (HPVs) are a family of sexually viruses with over 100 different genotypes identified till date.
They are associated in 99% of cervical cancers, with HPV16 found in about 50% of cases. They are a cause of the
second most common female cancer worldwide. PDT may constitute an alternative treatment for condyloma by HPV. In
this work we present the development of a PDT device specifically designed for the treatment of vulvar and vaginal
lesions induced by HPV. This equipment has been used in a clinical protocol and it is optically based on 640 nm LED
(light emitting diodes) arrays. There are three illumination probes available that were anatomically designed for specific
site applications: a 30 mm x 115 mm diffuser cylinder for intravaginal illumination and uniform irradiance of 42
mW/cm<sup>2</sup>; a 36 mm circular probe with 118 mW/cm<sup>2</sup> and a 74 mm circular probe with 57 mW/cm<sup>2</sup>, both for external
illumination. The 10% aminolevulinic acid cream is topically placed over the lesions and 4-6 hours after the application
the illumination is performed. The illumination time is set depending on the chosen probe and treatment area to achieve a
fluence of 200 J/cm<sup>2</sup>. In this presentation, the preliminary results of this clinical trial will be presented.
Tissue heterogeneities as well as distinct metabolic status and cellular types within a tumor may results in a nonhomogenous
necrosis. The possibility of PDT surviving cells within a treated volume has relevant clinical significance.
The major aim of this study was to analyze, on normal rat liver, the cell viability and surviving after PDT. The porphyrin
was injected through the cava vein at concentration of 1.5 mg/Kg. The induced necrosis was qualitatively investigated
varying the used drug light interval (30 min, 1, 3, 6, 24 and 36 h) and total delivered dose (20, 50, 100, 150 and 200
J/cm<sup>2</sup>). A diode laser at 630 nm and irradiance of 150 mW/cm<sup>2</sup> was employed. The exposed livers were removed after
the animals were killed by anesthesia overdose, 30 h after illumination. Slides were processed by HE analysis for the
determination of the overall aspects of the necrotic and non-treated liver. We observed necrosis of central vein and
presence of surviving cell around the portal triad within the necrotic volume, suggesting PDT-resistant regions of the
tissue. Possible hypothesis for the observation may be: the absence of photosensitizer; insufficient light dose (below
threshold); and distinct metabolic status in the portal triad microregions decreases oxygen availability to photodynamic
reaction. The cells surrounding portal triad presented a higher resistance even when 200 J/cm<sup>2</sup> was applied. In contrast,
the cells closer to the central vein after 20 J/cm<sup>2</sup> were already susceptible to the action of PDT. Different aspects of the
problem are presented.
The efficacy of Photodynamic Therapy (PDT) combined with aminolevulinic acid (ALA) or methyl
aminolevulinate (MAL) in treatment of cancer has been studied for over ten years. However, there is no
established dose for the topical use of these drugs in PDT. The purpose of this study was the comparison
of induced PDT response of ALAsense (5-aminolevulinic acid - ALA) and Metvix (methyl
aminolevulinate - MAL). Depth of necrosis induced by PDT was analyzed in normal liver of male Wistar
rats, using different light doses and topical application of both PpIX precursors - ALA and MAL. PDT
was performed with a diode laser at 630 nm with different doses of light (20, 50, 100 and 200 J/cm<sup>2</sup>), and
intensity of 250 mW/cm<sup>2</sup>. Depth of necrosis analysis was used to calculate the threshold dose for each
drug. The results showed that MAL-PDT presented a better response than ALA-PDT, mainly due to
formulation differences. Moreover, the ability of the ALA PpIX production was more efficient.
Background and Objectives: The paper aim was to evaluate the efficacy of the fluorescence spectroscopy in
the detection of UV-induced skin change of Wistar rats.
Study Design/ Materials and Methods: In a group male Wistar rats, the skin damage was produced by an
UV-C lamp, periodically monitored using the laser-induced fluorescence, until complete healing process.
After determining a characteristic emission band present in the fluorescence spectra of the induced injuries,
the amplitude band monitoring allowed the follow up on the injury and the recovery.
Results: We observed the appearance of two new emission bands more evident at the injury spectra when
compared to the spectrums from normal non-exposed tissue. Following such spectral bands was possible to
observe the establishment and recovery.
Conclusions: The fluorescence spectroscopy is a promising technique in distinguishing between normal and
UV induced skin change helping the evaluation of changes which are irreversible cancer tissue characteristics.
The use of simple models to understand basic features of the Photodynamic Therapy may contribute to the solid establishment of its dosimetry enhancing its degree of clinical susccess . In this work we have used normal rat liver as a prototype for the determination of threshold dose as a function of photosensitize concentration in the tissue. For this purpose we have investigated the depth of necrosis induced by photodynamic therapy when varying doses of light and photosensitizer (Photogema) concentrations are employed. All experiments were done with a light intensity of 250 mW/cm<sup>2</sup>. We have determined that the depth of necrosis depends on the photosensitizer concentration injected in the animal. Stablishing the correlation of the light intensity at the point where lies the separation line between necrosed and health tissue, we measure the threshold dose.
We have performed an experiment to investigate the degradation of the photosensitizer Photogem in solution. The investigation was carried out at 630 nm diode laser for different intensities. The light degradation considered was from light that could cause modification of the solution fluorescence spectra under excitation of 535 nm. Knowing the degradation rate as a function of intensity, one can infer the rate of degradation during PDT application and its process efficiency loss.
Clinical application of Photodynamic Therapy (PDT) in Brazil is a result of a pioneering work in a collaborative program involving the Physics Institute and the Medical School of the University of Sao Paulo and the Amaral Carvalho Cancer Hospital in the city of Jau, Sao Paulo. This work began in 1997 with the first patient treated in 1999. Up to the end of 2003 this program has treated over 300 patients and the ones with correct follow up had their lesions included in this report. The majority of the lesions were of non-melanoma skin cancer located on the head and neck region, but the group has also treated Esophagus, Bladder, Gynecological, chest wall recurrence of breast cancer, among others. The results have shown to be compatible with internationally reported data, and we have modified some application procedures towards to a better benefit for the patient and an optimization of the results. We present the overall results observed after 5 year of experimental clinical treatment.