[IMPACT OF ACTIVE OXYGEN FORMS INDUCTION ON EXPRESSION OF MOLECULAR ADHESION AND PARACRINE ACTIVITY OF MESENCHIMAL STROMAL CELLS].

Impact of low doses of active oxygen forms (AOFs) on the paracrine activity of mesenchimal stromal cells (MSCs) was studied. Photodynamic treatment (PDT) was shown to be a method for controlled generation of intracellular AOFs. Active oxygen forms generated at a dose of 0.25J/cm² do not impact significantly the MSCs mitochondrial activity or viability and can be recognized as regulatory. This was the first discovery that low-intensity PDT modulates substantially the MSCs paracrine activity which was manifested by an increased secretion of proinflammatory cytokines (IL-6, IL-8), vascular endothelium growth factor (VEGF), and suppressed secretion of the transforming growth factor (TGFß). While expression of intercellular adhesion molecule ICAM-1 increases and of Thy-1 antigen (a common MSCs marker) decreases, no changes occur to expression of chemokine receptor CXCR4 or other adhesion molecules (H-CAM, MCAM and VCAM-1). Our data make it clear that low-dose PDT is the most important regulator of the MSCs function. Key words: active oxygen forms, mesenchimal stromal cells, paracrine activity, photodynamic exposure.

WNT-associated gene expression in human mesenchymal stromal cells under hypoxic stress.

The effect of short-term stress on the expression of 84 Wnt-related genes in mesenchymal stromal cells (MSCs) was analyzed. In MSCs permanently expanded at 5% O2, Dkk1, RHOA, CSNK1A1, CSNK2A1, GSK3ß, and PORCN genes were most highly expressed. FZD1, FZD3, SFRP1, and SFRP4 genes were up-regulated after short-term hypoxic stress (0.1% O2), whereas the expression of LEF-1 and RUVBL1 genes was significantly inhibited (down-regulated). The data suggest that Wnt signal transduction was suppressed under hypoxic stress, whereas the noncanonical Wnt signaling prevailed under the "physiological hypoxia" (5% O2).

[Photophysical properties and photodynamic activity of nanostructured aluminium phthalocyanines].

We developed water-soluble supramolecular complexes of aluminium phthalocyanine based on mesoporous silica nanoparticles and polyvinylpirrolidone containing rare photoactive nanoaggregates. Radiative lifetimes, extinction coefficients and energy of electronic transitions of isolated and associated metal phthalocyanine complexes were calculated. Nontoxic concentrations of synthesized nanocomposite photosensibilizers were in vitro determined. In present study we compared photodynamic treatment efficacy using different modifications of aluminium phthalocyanine (Photosens®, AlPc-nSiO2 and AlPc-PVP). Mesenchymal stromal cells were used as a model for photodynamic treatment. Intracellular accumulation of aluminium phthalocyanine based on mesoporous silica nanoparticles AlPc-nSiO2 was the most efficient. Illumination of phthalocyanine-loaded cells led to reactive oxygen species generation and subsequent apoptotic cell death. Silica nanoparticles provided a significant decrease of effective phthalocyanine concentration and enhanced cytotoxicity of photodynamic treatment.

Accumulation and elimination of photosens and protoporphyrin IX by different types of mesenchymal cells.

We studied the kinetics of accumulation and elimination of Photosens and accumulation of protoporphyrin IX in macrophages, endothelial cells, and mesenchymal stromal cells of the human adipose tissue in vitro. In all studied cells, the dynamics of Photosens accumulation was described by a multiphase curve and the maximum accumulation of the dye was observed during the second exponential phase. Elimination of Photosens did not depend on the cell function. Accumulation of protoporphyrin IX differed considerably in different cells: it was maximum in mesenchymal stromal cells was practically not detected in endothelial cells. Accumulation of the dye by macrophages depended on individual donor characteristics.

Low-fluence photodynamic treatment modifies functional properties of vascular cell wall.

We studied the effect of low-fluence photodynamic treatment with Photosence preparation on functional properties of macrophages and endothelium in vitro. It was shown that low-intensity photodynamic treatment did not affect viability of these cells. Exposure (0.25 J/cm(2)) of endothelial cells loaded with Photosence did not change the expression of adhesion molecules, but reduced adhesion of peripheral blood mononuclears to these cells. The same low-intensity exposure inhibited phagocytic activity of macrophages and reduced activity of matrix metalloproteinase-9 produced by them.

Effects of photodynamic exposure on endothelial cells in vitro.

Experiments on cultured human umbilical vein endotheliocytes showed that accumulation of photosensitive dye (aluminum phthalocyanin; PHOTOSENSE) in cells and laser exposure alone were inessential for the viability of endothelial cells. Contrary to this, exposure of the cells which have accumulated aluminum phthalocyanin (an average of 111.1 ng/mg protein) to low-intensity laser (λ=675 nm) led to a dose-dependent reduction of endotheliocyte viability. Hence, cultured endothelial cells can be used for screening of various photosensitizers and preliminary optimization of photodynamic therapy.