ИСТИНА

Gliomas are the most common brain tumors in adult patients, which are classified into four grades according to their malignancy with high-grade gliomas carrying the worst prognosis for the patient. In the present study we applied Raman microspectroscopy with laser excitations at 532 and 633 nm to assess the mitochondria redox state and the lipid-protein composition of cytoplasm of cells in the tumoral and peritumoral regions. The studied preparations were 200-250 μm brain slices prepared from the patient brain tissue removed during the surgery. All studies were carried out with thepermission of the Ethical Committee of the Privolzhskiy Research Medical University on the basis of informed consent of patients in accordance with the necessary ethical conventions. We demonstrated that Raman spectroscopy allows to discriminate between low-and high-grade gliomas and to distinguish peritumoral regions from the tumoral area and normal cortex (access tissue). Our results indicate the increase in the relative amount of protein in tumor cells under both low-and high-grade gliomas. Using the specified Raman peaks, we demonstrated that the relative amounts of reduced cytochromes b, c and a in the respiratory chain (electron transport chain, ETC) was increased in cells of the peritumoral area under low-grade gliomas and decreased in cells of peritumoral area under high-grade gliomas. The decrease in the relative amounts of reduced cytochromes indicates fewer electrons in the ETC and may suggest faster electron transfer due to the formation of the supercomplexes consisting of complexes III and IV in cells of peritumoral area under high-grade gliomas. The redox state of the mitochondrial ETC also changed in high-grade gliomas compared to the low-grade gliomas. The assembled dataset of Raman spectra acquired from different regions of patients tissue samples and the described metabolic characteristics was used for the development of the AI tools for the diagnostics of brain tumorgrades and regions. Overall, Raman microspectroscopy allows us to reveal the metabolic features specific for the peritumoral regions under gliomas of different grades. Acknowledgement: This study was supported by Non-commercial Foundation for Support of Science and Education “INTELLECT”