Advance in Photosensitizers and Light Delivery for Photodynamic Therapy

The brief history of photodynamic therapy (PDT) research has been focused on photosensitizers (PSs) and light delivery was introduced recently. The appropriate PSs were developed from the first generation PS Photofrin (QLT) to the second (chlorins or bacteriochlorins derivatives) and third (conjugated PSs on carrier) generations PSs to overcome undesired disadvantages, and to increase selective tumor accumulation and excellent targeting. For the synthesis of new chlorin PSs chlorophyll a is isolated from natural plants or algae, and converted to methyl pheophorbide a (MPa) as an important starting material for further synthesis. MPa has various active functional groups easily modified for the preparation of different kinds of PSs, such as methyl pyropheophorbide a, purpurin-18, purpurinimide, and chlorin e6 derivatives. Combination therapy, such as chemotherapy and photothermal therapy with PDT, is shortly described here. Advanced light delivery system is shown to establish successful clinical applications of PDT. Phtodynamic efficiency of the PSs with light delivery was investigated in vitro and/or in vivo.

From the results of biological activity photosensitizers tested on the lung cancer cell / Монголын Анагаах Ухаан

BackgroundIn the present time Photodynamic therapy is a largely experimental treatment modality which is under development for application in both of neoplastic and non–neoplastic diseases. PDT involves a light-sensitive compound (photosensitizer), light and molecular oxygen. The photosensitizer is excited to its singlet state by light of the appropriate wavelength. Responses to photodynamic treatment are dependent on the photosensitizer used the an illumination conditions, the oxygenation status of the tissue and the type of cells involved.CoalTo study new photosensitizers from the pyrazole derivatives which is based on chlorine and porphyrin and produced from sea algae to the lung cancer cell (A549) that is cultured in vitro medium and tested by two ways that are light treatment and dark treatment. Furthermore we define how the photosensitizer dictate cancer cells by test MTT/3-/4.5-dimethylthiazole-2- yl/-2.5-biphenyl tetrzolium bromide a yellow tetrazole/, and how to change the cell morphological characteristics by its micro photo and determine potosensitizers that dictates on the least doze of the cell.Materials and MethodsThe cell line tested was A549 (human lung carcinoma cell). The cell line was obtained from the cell line bank at Seoul National University’s Cancer Research Center (Korea) and were grown in medium RPMI-1640 (Sigma-Aldrich) with 10% fetal bovine serum, glutamine, penicillin and streptomycin at 37 0C in humidified atmosphere of 5% CO2 in air. Phosphate buffered saline (PBS) (Sigma-Aldrich), microscope (Olympus, CK40-32 PH, Japan), Laser irradiation (BioSpec LED 670-700 nm, Russia), ELISA-reader (BioTek, Synergy HT, USA), trypsin-EDTA solution, incubator (37 0C, 5% CO2) were used. The PDT was carried out using a diode laser generator apparatus (BioSpec LED, Russia) equipped with a halogen lamp, a band-pass filter (670-700 nm), and a fiber optics bundle. The wavelength was set at 670±1 nm. Duration of the light irradiation, under PDT treatment, is calculated taking into account the empirically found effective dose of light energy in J/cm2. Figure 1 shows micrographs from an optical microscope illustrating the morphological changes of A549 cells at different points of time after PDT.ResultsThe morphological changes for all tested photosensitizers were revealed by the same patterns, hence we have shown the morphological changes for compound 8 in this paper (Fig 1). Untreated A549 cells as a control did not show any significant morphological changes. The changes in the state and activity of cellular organelles induced by PDT were clearly observed after 3 h. PDT treatment against A549 cells induced plasma membrane disruption and cell shrinkage, indicating the plasma membrane as the main target for the photosensitizer: the membrane of A549 cells began to shrink immediately after PDT, and cell death processes commenced with cytoplasm leakage around the membrane for the first 3 h. After 24 h, the membrane had disintegrated, confirming the loss of cell viability.СоnclusionThe morphological changes were determined in 3 h, 24 h and 48 h after PDT. The bioactivity of 23 new photosensitizers was examined. Among them, 8 photosensitizers showed a promising effect for PDT, therefore, their in vitro biological results are displayed in this study. It was observed from the experimental results that the tested photosensitizers showed more promising effects for PDT or light toxicity. These photosensitizers inhibited more than 50% cells at 2.5 μM after 24 h. Untreated cells as control did not show any significant morphological changes. The PDT treatment cells induced to plasma membrane disruption and cell shrinkage. After 24 h of treatment the membrane was disintegrated, and confirmed the loss of cell viability.