Ekaterina Borisova, Alexander Gisbrecht, Tsanislava Genova
Institute of Electronics, Bulgarian Academy of Sciences,
72, Tsarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria, *e-mail: borisova@ie.bas.bg;
Dobroslav Kyurkchiev, Kalina Tumangelova-Yuzeir, Ekaterina Ivanova-Todorova
Laboratory of Clinical immunology, University Hospital " St. Ivan Rilski", Department of clinical laboratory and clinical immunology, Medical University - Sofia, 15, Acad. Ivan Evstatiev Geshov Blvd., 1431 Sofia, Bulgaria
Ivan Angelov
Institute of Organic Chemistry with Center on Phytochemistry, Bulgarian Academy of Sciences, 9, Acad. G. Bonchev str., 1113 Sofia, Bulgaria
Oxana Semyachkina-Glushkovskaya
Biology Department, Saratov State University, 83, Astrakhanskaya Str., 410012 Saratov, Russia
Peter Karazapryanov, Krassimir Minkin
Neurosurgery Department, University Hospital " St. Ivan Rilski",
15, Acad. Ivan Evstatiev Geshov Blvd., 1431 Sofia, Bulgaria


Glioblastoma (GBM) is the most common and most malignant type of brain tumor. The average survival rates in patients with newly diagnosed GBM is only about 14 months, despite use of aggressive surgery, radiation therapy and chemotherapy. Glioblastoma, unlike other malignant tumors, rarely spreads outside of the brain and the main cause of death is the local intracranial progression. Photodynamic therapy (PDT) using 5-ALA/PpIX from the family of porphyrins and aluminium-phthalocyanine (AlPc) has proven its effectiveness in the treatment of different neoplasia, including brain ones. The mechanism of action is based on the formation of singlet oxygen resulting from the absorption of light at a specific wavelength from a photosensitizer molecule that is selectively accumulated in the tumor cells.
Application of porphyrins and phthalocyanines as photosensitizers leads to their selective accumulation in glioblastoma cells due to their hem metabolism disorders and could be used effectively for intraoperative fluorescence staining of the tumor formation and differentiation from normal brain parenchyma. The aim of this work is to investigate the photodynamic properties of 5-ALA/PpIX and AlPc on stem cell cultures isolated from glioblastoma. Several variables, such as histochemical and genetic variants of glioblastoma, various photosensitisers’ concentrations and light-emitting parameters are studied. The results of this in vitro work will be used as the basis for a further in vivo application on animal models of glioblastoma with applying irradiation using intracranial light sources and for a subsequent transfer of the obtained protocols of photodynamic treatment of glioblastoma lesions in such model systems for the needs of human medicine.
Acknowledgments: This work is supported by the NSF-Bulgaria under grant # KP06-N23/8/18.12.18 “Innovative photodynamic methods for treatment of stem cells cultivated from glioblastoma tumours”.

Representing author


Dr. Ekaterina Georgieva Borisova

Institute of Electronics, Bulgarian Academy of Sciences, Associate Professor
Sofia, Bulgaria

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