A66: Changes in experimental tumors and surrounding tissue under antitumor influence of magnetite nanoparticles introduced into the peritumoral area

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• 作者：G. Zhukova^a ; ; A. Shikhliarova^a ; T. Gudtskova^a ; M. Bragina^a ; I. Novikova^a ; V. Zernov^b ; T. Barteneva^a ; O. Polozhentsev^c ; A. Soldatov^c ; M. Rudenko^b ; E. Shirnina^a
• 刊名：European Journal of Cancer Supplements
• 出版年：2015
• 出版时间：November 2015
• 年：2015
• 卷：13
• 期：1
• 页码：71-72
• 全文大小：45 K

文摘

In previous experiments the self-dependent antitumor effect of magnetite nanoparticles (NPs) injected in peritumoral area in form of magnetic fluid (MF) was shown. Elucidation of the mechanisms of this phenomenon is of theoretical and practical interest. The aim of the study was to investigate the cellular and ultrastructural changes in the tissue tumors regressed under the influence of magnetite NPs, as well as the composition of the cells of the immune system in the peritumoral area.

Materials and methods

The study was carried on white male rats, 180–200 g, with transplanted sarcoma 45 (59) or Pliss lymphosarcoma (50). Special antitumor agents were not used. Magnetite NPs (10 ± 2 nm) were applied in the form of the water-based MF. Original MF (20 kA/m) was diluted with saline in different degree and was injected into peritumoral zone along the tumor borders at a distance of 1.5 cm twice a week in a volume of 0.4–0.9 ml (depending on the animal weight) within 3 weeks. Special anti-tumor agents were not used. At the end of the experiments fragments of the tumor and surrounding tissue were taken for research. The study of changes in the tumor and peritumoral area were performed by the methods of cytology, histology, histochemistry, electron microscopy (microscope JEOL JEM-1011, Japan), flow cytometry, X-ray fluorescence spectroscopy (spectrometer M4 Tornado Bruker).

Results

At a dilution of the original MF in 30 times the treatment was effective in 75% of animals. Complete and partial (more than 2-fold) tumor regression was observed in 2/3 cases. In rats with Pliss lymphosarcoma tumor regression on 70–100% has been reported in 20–40% cases. The results of microscopic examination of sarcoma 45 with partial regression showed significant changes in their immune microenvironment compared with the cases of progressive tumor growth (p < 0.05–0.01). This was expressed in the increase in the number of lymphocytes and plasmacytes (respectively, in 12 and 2.5 fold), and in the appearance of macrophages and basophils that were missing in tumors with progressive growth. The results of flow cytometry of tissue from the tumor as well as from peritumoral zone indicate the predominance of plasmacytes in the case of inhibition of tumor growth and increasing the proportion of mature T lymphocytes in the cases of tumor regression (more than 1.5 times, p < 0.05). By electron microscopy, it was shown that in the cases of efficiency of the MF in addition to necrosis, observed also in growing tumors, such types of cell death were marked as apoptosis and autophagy. Numerous signs of activation of cell–cell interactions involved cells of the immune system were revealed. Different groups of 2–4 contacting cells (macrophages, lymphocytes, plasmacytes, mast cells, tumor-associated fibroblasts and neutrophils in various combinations) with signs of metabolic activity were marked. X-ray fluorescence spectroscopy preliminary results in rats with Pliss lymphosarcoma regression indicated dense arrangement of magnetite NPs and their aggregates in the peritumoral area and their practical absence in tumor.

Conclusion

The study results reflect the changes in the immune microenvironment of experimental tumors under effective action of magnetite NPs and indicate significant activation of local immune processes caused by these factors.