Yuliya Svenskaya, Saratov State University, Saratov
Anna Zanina, Saratov State Agrarian University, Saratov,
Alla Bucharskaya, Saratov State Medical University, Russia
Olga Matveeva, Saratov State Medical University, Russia,
Nikita Navolokin,Saratov State Medical University, Russia
Galina Maslyakova, Saratov State Medical University, Russia Georgy Terentyuk, Saratov State University, Saratov State Medical University, Ulyanovsky State University, Russia
Dmitry Gorin, Saratov State University, Russia
Photodynamic therapy of cancer treatment is a gentle method in oncology. Nowadays, it causes a great research interest. This method is based on the usage of light-sensitive substances, named photosensitizers (photodynamic dyes), and the irradiation with determined wavelength. Photosensitizes are accumulated mostly within tumor tissue which allows to destroy them by irradiation using wavelength corresponding to the absorption maximum of these photodynamic substances. Irradiation induces a photochemical reaction leading to the death of cancer cells. Currently, there are some various methods of dye localization to provide targeted drug delivery and decreasing toxicity of phodynamic dye. We proposed phodynamic dye encapsulation using calcium carbonate microcontainers.
Ultrasound treatment was used to provide containers destruction and release of encapsulated dye. In addition, this approach allows to achieve some synergistic effects. Nowadays, a lot of research in the field of sonodynamic therapy are conducted. It were published some articles related to synergetic approach at combine influences of photodynamic and sonodynamic therapy.
Objective: to study morphological changes in transplanted rat tumors after combined effect of ultrasound and photodynamic therapy on transplanted rat tumors at intratumoral introduction of CaCO3 microcontainers containing photosensitizer «Photosens».
Materials and Methods: microcontainers of calcium carbonate carbonate with photosensitizer «Photosens» (GNC«NIOPIK»), 15 male albino rats with transplanted liver cancer PC-1 and 15 male albino rats with transplanted sarcoma 45.
Microcontainers loaded with photodynamic dye were synthesized. It were calcium carbonate microparticles containing “Photosens” as photosensitizer . The photodynamic dye was embedded into calcium carbonate microparticles by direct precipitation at synthesis. An average size of the prepared microparticles was 1 μm. The concentration of encapsulated dye was estimated using photometric method. It was established that 1mg of obtained structures contains 22 μg of photosensitizer.
In experiment intratumorally introduction of synthesized containers carried by the procedure: the test solution in an amount of 30% from the tumor volume were injected locally with two opposite points of the tumor bolus at the rate of 0.1 ml per minute, in 15 minutes after the injection ultrasonication was carried out in continuous mode within 10 minutes with 1W per cm (output of CO2 with formation of bubbles and cavitation effect), after 15 minutes the photodynamic therapy was performed - exposure to light with a wavelength of 670 nm, 50 mW for 10 minutes. To assess the therapeutic pathomorphosis on the 1st, 3.5 days after exposure the animals were taken from experiment and the material for histological examination was picked up.
Pathomorphosis of liver cancer after combined influence of introduction of microcontainers of calcium carbonate with photosensitizer «Phtalasens» manifested as degenerative changes of tumor cells and the appearance of foci of necrosis, which occupied the area from 10% to 60% of the total area of the tumor.
Morphological changes in the sarcoma is also characterized by the development of necrosis, which covered an area of 50-80%. Around the area of necrosis with 3 days of segmented leukocytes infiltration was detected, signs obezvestvleniya.
Conclusions: intratumoral injection of micron particles of calcium carbonate with photosensitizer with subsequent conduction of ultrasound and photodynamic therapy causes damage to the tumor cells from the degenerative to necrotic changes, which indicates the effectiveness of the method and requires further study.
Alla Borisovna Bucharskaya
Saratov State Medical University , Head of Centre of Collective Use
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