Nanobiotechnology for health-care

Mechanisms of anti-tumor effect of nanocomposites based on orthovanadates of rare earth metals 
Goltsev A.M.1, Malyukin Yu.V.2, Babenko N.M.1, Gaevska Yu.O.1, Bondarovych M.O.1, Dubrava T.G.1, Klochkov V.K.2
 1 Institute for Problems of Cryobiology & Cryomedicine of the National Academy of Sciences of Ukraine, Pereyaslavska Str. 23, 61016 Kharkiv, Ukraine
E-mail:  cryo@online.kharkov.ua
2 Institutes for Scintillation Materials of the National Academy of Sciences of Ukraine, 60 Nauki ave., 61001 Kharkiv, Ukraine

Previous studies have demonstrated an effective inhibition of the growth of Ehrlich carcinoma (EC) under the effect of nanocomposites, in particular nanoparticles (NPs) of orthovanadate of rare earth metals and hybrid nanocomplexes (NCs) based on their addition with cholesterol. However the mechanisms for implementing this effect remain unstudied. One of the possible ways of nanocomposites action is the generation of reactive oxygen species with subsequent impairment of the mitochondria function, which can induce a cell death via apoptosis/necrosis. The research purpose was to investigate the level of mitochondrial respiration and to count the number of apoptotic and necrotic cells after incubation of EC cells with NCs and NPs for 1-4 hours.
Mitochondrial respiration of EC cells was evaluated using Cell Growth Determination Kit MTT based (Sigma, USA). The number of necrotic/apoptotic cells was determined using Annexin-V (BD, USA) and PI (Sigma, USA) on the FACS Calibur flow cytometer (BD, USA). The nanocomposites-treated EC cells were injected into BALB /C mice in a dose of 3x106 cells / mouse, and cultured for 7 days, after which the tumor growth rate was assessed.
According to the results of MTT test, the strongest damage to mitochondria was observed after 3 hours of incubation with nanocomposites, moreover the NCs significantly contributed to this. The most marked reduction in the number of living cells (An-/PI-) was observed after 3 hours of incubation, the NPs led to a cell death via necrosis (An-/PI+) and apoptosis (An+/PI+), while the NCs contributed to an increased percentage of necrotic cells. The 3-hour incubation period led to a decrease in the intensity of tumor growth, herewith the use of NCs to have a superiority over the NPs (74.7% vs. 58.24%). Thus, the chosen period of incubation contributed to the greatest extent to the implementation of nanocomposites of antitumor activity in the aggregate of studied parameters.