It is established that alpha-tocopherol (alpha-TPh) shows cytoprotective effect at the induction of rats' thymocytes apoptosis by endocellular protein kinase inhibitors--staurosporine and phorbol ether in high concentration, and also on necrosis of the cells caused by sphyngosine. The effect of alpha-TPh on thymocytes death caused by protein phosphatase type 2A inhibitor ocadaic acid is much less expressed. The obtained data testify that the known ability of alpha-TPh to the inhibition of PKC and to the activation of protein phosphatase type 2A is not the main mechanism of its cytoprotective action. Partial reproduction of alpha-TPh effects by its analogue alpha-tocopheryl acetate which is not capable to enter in redox reactions, and the absence of influence on the studied processes of an antioxidant of N-acetyl-L-cysteine do not confirm the antioxidant mechanism of alpha-TPh action in this case. The inhibition by alpha-TPh of the release of cytochrome c in the cytosol of cells testifies to the implementation of its cytoprotective effect at the level of mitochondrial membranes. We assume the existence of the universal mechanism of alpha-TPh cytoprotective action that does not depend on the nature of apoptogenes and realized on the general for the majority of them stage of the cells death induction. The prevention by alpha-TPh of mitochondria dysfunction by stabilizing mitochondrial membranes and reduction of their permeabilization is supposed as that.

Despite the advances of modern medicine, malignant glioblastoma cure remains an elusive goal. Both the invasive nature and location in vital areas of the brain make this type of tumors difficult for surgical treatment, while the current adjuvant therapy is not as successful as expected. Frequent recurrence and invasiveness of malignant gliomas is due to resistance of glioma stem cells to conventional radiation and chemotherapy. Technological advances in constructing recombinant viruses have allowed creating strains with high oncolytic activity toward glial tumors. Many of these strains have passed Phase I of clinical trials and demonstrated high safety. Despite the obvious potential of the approach, efficiency of the existing strains is still far from being sufficient for effectively curing the disease and require further improvement. The review summarizes results obtained with the most successful variants of oncolytic viruses that come down to the clinical trials and discusses the prospects for new approaches in virotherapy of malignant gliomas.

Transcription factor RUNX1 is one of the key regulatory proteins in vertebrates. It controls hematopoiesis and angiogenesis. It is indispensable during embryogenesis for the emergence of sites of definitive hematopoiesis and later in mature organisms for bone marrow blood stem cells differentiation. Moreover, RUNX1 gene is a frequent target for chromosomal translocations which cause acute forms of leukemia. A lot of types of human leukemia are somehow associated with mutations in this gene. Nevertheless, to this day the precise mechanism guiding the tissue-specific manner of the RUNX1 gene expression remains unknown. In this review we tried to summarize all the experimental data accumulated during the past twenty years beginning from the date when the cDNA sequence of the RUNX1 gene was first annotated. In the first part of the review we shall focus on structure, isoforms, covalent modifications of the RUNX1 transcription factor and its participation in different regulatory cascades. In the second part we shall discuss expression regulation, mutations and chromosomal translocations of the RUNX1 gene.

Human mesenchymal stem cells (MSCs) are now widely adopted in regenerative medicine. However, many questions on the role of different signaling pathways in the regulation of stem cell (SC) functional activity within the organism remain unaswered. In damaged regions the level of cell death increases and DNA fragments from dead cells (cell-free DNA, cfDNA) are accumulated in blood. We showed that in adipose-derived MSCs exposed in vitro to cfDNA fragments the transcription level increased (the total amount of cellular RNA and the rRNA amount rose). GC-rich CfDNA fragments (GC-DNA) activated the TLR9-dependent signal pathway: the expression of TLR9 and of TLR9-signaling pathway adapter--MyD88--was up-regulated. AT-rich DNA fragments did not increase the TLR9 expression, though, the MyD88 expression level rose. So we suggest that AT-DNA acts via some other receptors that nevertheless activate MyD88-dependent signalling in MSCs. We also showed that cfDNA fragments decreased the activity of caspase, an apoptotic enzyme. So, ctDNA can significantly influence the functional activity ofMSC by activating TLR9- and MyD88-dependent signal pathways and lowering the apoptosis level.

This literature review summarizes the data on the general principles of the structure and functions of keratinocytes, melanocytes, dendritic cells (DC) and tactile epithelial cells. Special attention is paid to the process of keratinization, the formation of lipid barrier of the stratum corneum. The problem of the stem and transitional cell surface markers is discussed. Detailed current data are presented on the structure and functions of keratinosomes, their participation in the process of desquamation and the formation of intercellular cement, forming the basis of polar lipids. It is shown that lipid profile of the intercellular space of the stratum corneum is changing in the direction of the surface of the epidermis. Considerable part of the review is devoted to the data demonstrating the functions of keratinocytes: synthesis of mitogens, chemokines that attract DC and T-lymphocytes to the epidermis; production of antimicrobial peptides. In this report, the questions are discussed of the existence of two types of tactile epitheliocytes, of the participation of DC in the process of keratinization, on the transfer of information on an antigen to T-lymphocytes. The data are presented on the participation of melanocytes in the protective function of the epidermis.

G-CSF mobilized peripheral blood and cord blood are major sources of hematopoietic progenitor cells. These cells are characterized by the expression of "early" antigens. We have evaluated the coexpression of hematopoietic cell markers CD34, CD133, CD90, CDCP1, CD117 and activation antigen CD38 using multicolor flow cytometry. We show that (1) cells being positive for every single antigen form a separate population. (2) Percentage of cells expressing each "early" antigen are twice more in the cord blood than in the mobilized blood. The content of cells with complex progenitor phenotype (CD34+/CD38-/CD117, CD133+/CD34+/CD38-, CDCP1+/CD34+/CD38- etc.) is equal in mobilized and cord blood. (3) There are strong positive correlations between the expression of CD34, CD133, CD117 and CDCP1 in both groups. Positive correlation exists for CD90 with CD34, CD133, CDCP1 and CD117 only in cord blood and is not significant in mobilized blood. The analyses of early antigens coexpression with activation marker CD38 revealed that hypothesis on sequential activation and loss of expression of the aforementioned antigens is not confirmed. We assume that there is global regulation of the expression of CD34, CD133, CDCP1 and CD117. Yet expression of CD38 could be reversibly abolished during maturation of the hemapoetic cells and CD117 could be expressed not only on myeloid cells.

Cytotoxic effect of anti-cancer drug, doxorubicin (DR), has been examined on human embryonic stem cells (ESC) C910 and fibroblasts spontaneously differentiated from these cells. The fibroblasts retained diploid karyotype. It was found that ESC are more sensitive to DR than fibroblasts: DR dose killing 20% cells was 0.01 and 0.1 microg/ml, respectively. DR induced ESC apoptotic death and reduced both ESC and fibroblast proliferation. Unlike fibroblasts DR reversibly inhibited ESC proliferation. Thus, we have demonstrated that ESC and their differentiated derivates differ their sensitivity and response to the genotoxic agent.

The purpose of the work--the choice of optimal treatment tactics of patients at the extremity tissue ischemia due to nonspecific aortoarteritis (NA). In the surgical treatment of patients with NA, particularly with concomitant peripheral lesions, and to a greater degree of terminal arterial bed, significantly limited the possibility of direct revascularization. Conservative treatment and subthoracal sympathectomy are ineffective. Autotransplantation of mesenchymal stem cells (MSCs), adipose tissue or bone marrow in ischemic tissue in the form of aspirates or selected from these aspirates cell cultures allowed to correct hemodynamic disorders by stimulating angiogenesis and development of collateral circulation.

Male Wistar-Kyoto rats (12 and 22-24 months old) were intracerebrally transplantated with syngeneic mesenchymal stem cells (MSC). Three weeks or one year later, orientation and exploratory behavior of the same animals (not 2 years old) was assessed using an «open field» test. Older rats (22-24 months old) were inhibited in the basic behavioral acts in comparison to younger animals (2-3 months old). Transplantation of MSC did not cause improvement of an orientation and exploratory behavior of aged rats. Morphological and immunohistochemical analysis suggests intracerebral MSC transplantation led to the injury of the cortex of the ipsilateral hemisphere.

Investigations of transcriptional regulation of Oct4 gene in mouse embryonic stem cells have revealed an important cis-element--the distal enhancer (DE). DE consists of two functionally significant elements--DEa and DEb. Both elements are necessary to complete the DE-mediated expression of Oct4 gene in pluripotent cells. The most likely candidates for the binding site DEb are Oct4 itself in complex with Sox2 protein. It remains unclear which transcriptional proteins bind to the DEa site and what is the mechanism of the co-operation between the DEa and the DEb. Through the use of using the EMSA and chromatographic fractionation of proteins from extracts of mouse embryonic stem cells and mouse tissues, were isolated proteins specifically interacting with the sequence DEa Oct4 gene.

The effect of cell culture conditions on numerical and structural karyotypic variability was investigated in two Indian muntjac skin fibroblast "markerless" cell lines, M and MT. The cells cultivated on the substrate consisting of extracellular matrix proteins (ECM), synthesized by human mesenchymal stem cells (SC5-MSC). The character of cell distribution for chromosome number of cell line M changed after cultivation for 1 and 4 days as compared to control cells, which were cultured on hydrophilic surface without ECM-coating. These changes involve a significant decrease in frequency of cells with modal numbers of chromosomes and an increase in frequency of cells with lower chromosome numbers. Many new types of additional structural variants of the karyotype (SVK) appear. MT cell line, differing from M line in the number of homologous chromosomes, demonstrated similar with M line the character of cell distribution for chromosome number only for 1 day after cultivating on the ECM-substrate, but not after 4 days in the same culture conditions, no difference from the control cells was observed. The observed alterations seem to be due to disturbances in correct chromosome segregation process, which were caused by abrupt shift in the cell culture conditions. The analysis of the structural karyotypic variability revealed significant increase in frequency of chromosomal aberrations in M cell line for 1 and 4 days in culture on the ECM-substrate as compared to the control cells. The frequency of dicentric chromosomes (telomeric associations) was increased and constituted more than 50% of all chromosome aberrations. No increase in frequency of chromosome aberrations was observed for MT cells cultured in the same conditions. The obtained results show that the cell lines of the same origin but of different karyotypic structure react to substrate in a different way. In contrast to M line, in MT line a fast normalization of numerical karyotypic characteristics and no enhancement of structural karyotypic variability takes place. This provides a possibility to cultivate MT cell on the given protein substrate maintaining a balanced karyotypic structure characteristic of MT cell line.

Limited knowledge about behaviour of stem cells in culture seems to be one of the reasons for problems in their successful introduction to applied medicine. To address this issue we have studied in vitro interaction of human mesenchymal stromal cells (MSCs) with various substrates (plastic, type I collagen, fibronectin, and mixtures of these proteins at various ratios) during the 16-18 h after cell plating. Several cell morphology features such as Area, Perimeter, spreading coefficient, polarization coefficient were determined. It has been shown that MSCs respond specifically to the substrate and can be classified into several groups according to the parameters studied. Collagen preferably fibronectin have opposite effects on polarization and spreading of the cells. Collagen preferably enhances polarization of the cells, whereas fibronectin stimulates proportional spreading of cells. Effect of collagen-fibronectin mixture on the cells cannot be considered as a simple additive effect. We assume that variation in the ratio of these proteins in the extracellular matrix might be one of the possible ways to influence the morphology of stem cells when they are induced to differentiate.

In the current work we make an attempt to compare cancer cells of one origin, but differing in the expression of CEA protein, a clinical marker of metastatic carcinomas, presumably one of the key factors in metastatic activity. We have explored the morphology of cell colonies in vitro, expression patterns of epithelial markers, the ability of these cells to form tumors and metastases in vivo, and evaluated their stem compartment with the aid of a suicidal genetic construct sensitive to the embryonic stem cell marker, Oct4.

As it was shown by us earlier, side population (SP) cells are more resistant to the low-LET radiation than the other part of mouse melanoma B16 cells (Matchuk et al., 2012). The aim of our research was finding some mechanisms of radioresistance, therefore we analyzed SP and nonSP cell cycle distribution, spontaneous and radiation induced DNA double-strand breaks (number of γH2AX foci) and intracellular NO concentration. The results indicate that SP cells have significantly less DNA double-strand breaks after irradiation at dose of 3 Gy than nonSP cells (24.4 vs 40.3, accordingly, P < 0.05 Mann-Whitney Ucriterion). SP cells are more quiescent compared to nonSP G1/G0 fraction is 85 vs 39%, accordingly, P < 0.01 Mann-Whitney U criterion). Most nonSP cells reside in S, G2/M phases (61%), believed to be rather radiosensitive. Thus, the difference of SP and nonSP cells radiosensitivity can be partly explained by peculiarities of cell cycle distribution. NO concentration is 1.5 times higher in SP than nonSP cells (P < 0.05 Mann-Whitney U criterion); since it is known that NO inhibits apoptosis, being one of the mechanisms of genetic stability maintenance, greater number of spontaneous DNA double-strand breaks in SP cells is unsurprising (P < 0.05 Mann-Whitney U criterion). The above-listed results explain considerably the higher resistance of SP cells to the action of low-LET radiation in comparison with other melanoma B16 cells. Further study of this question can become the basis for development of tools to target SP cells and, ultimately, more effective cancer treatment.

This study is dedicated to the problem of the origin of progenitor cells of sarcomas induced by implantation of a foreign body (polyvinilchloride plates) to mice. It is known that such cells are found among the cells of the monolayer covering the surface of implanted plate without any signs of tumor growth in 6 and more months after implantation. We studied the existence of endothelial features of mesenchymal type cells that had been grown by culturing the cells from the implanted plate surface in 9 and 14 months after implantation. We have shown that these cells are really the precursors of FB sarcomas thou they had different tumor potential depending on the period since implantation moment. We studied the behavior of these pretumor cells in 2D (on plastic) and 3D (on matrigel) cultures. We have found that in the case of a dense monolayer on plastic such cells show growth of endothelial type (cobblestone). When sown on matrigel they are organized in more or less typical capillary-like structures that subsequently form secondary branching vascular-like structures named "secondary sprouting". Such behavior is also characteristic for endothelial cells. This observations allow us to postulate the possibility of endothelial origin of FB sarcomas.

Oxidative stress has been shown to induce either apoptosis or stress-induced premature senescence (SIPS) in different cell types. At present, it is generally accepted that stem cells have high resistance to oxidative stress; however data reported by various authors are controversial. In this study, we investigated stress responses of human embryonic stem cells (hESC) and human mesenchymal stem cells (hMESC) derived from desquamated endometrium to hydrogen peroxide (H2O2). Cell viability was evaluated by MTT assay. LD50 were determined as 300-350, 350-400 and 600-700 μM for hESC, human embryonic fibroblasts and hMESC, respectively. Thus, among the cell lines studied, hMESC demonstrated the most resistance to increased H2O2 concentration. We have found for the first time that sub-lethal doses of H2O2 induce premature senescence phenotype in hMESC, like in HEF, which is characterized by increased expression of cyclin-dependent kinase inhibitor p21(Waf1/Cip1), an irreversible cell cycle arrest, the permanent loss of proliferative potential, cell hypertrophy and SA-β-Gal staining. While a sub-lethal H2O2 dose (200 μM) promoted in hMESC only SIPS, the higher H2O2 doses induced also apoptosis in the part of the cell population. On the contrary, in hESC, H2O2 regardless of the doses tested (from 50 to 500 μM) triggered apoptosis, that was the only pronounced response of these cells to oxidative damage. The data obtained demonstrate that stem cells of various origins under oxidative stress utilize the different defense mechanisms: hESC rapidly eliminate damaged cells through apoptosis, whereas hMESC may enter SIPS.

We have shown that the decrease in oxygen tension in the culture medium of multipotent mesenchymal stromal cells (MMSCs) results in a short-term reduction in the proportion of CD73(+)-cells in the population, without effecting the number of cells expressing other constitutive surface markers (CD90 and CD105). In this case, the heterogeneity of the cell population declined: large spread cells disappeared. The proliferative activity of MMSCs significantly increased and remained stable in conditions in which the oxygen content was close to the tissue oxygen levels (5% O2). At lower oxygen concentration, proliferative activity of the cells gradually reduced from passages 3-4. The increase in proliferative activity was not accompanied by increased expression of telomerase gene indicateding the alsance of cell transformation. However, genome-wide analysis of MMSC gene expression level revealed changes in expression of cyclins (CCND2 and PCNA), regulatory subunit cyclin-dependent kinase (CKS2) and an inhibitor of cyclin-dependent kinase (CDKN2C), regulating the cell cycle, which is obviously facilitated the increase in the proliferative capacity of cells at lower oxygen tension.

Embryonic stem cells (ESCs) are the progenitors of all adult cells so any disruption in their genome can have disastrous consequences for the developing organism. ESCs are characterized by a high proliferation activity and do not undergo checkpoints upon DNA-damage executing only G2/M delay after DNA damage. ATM and ATR kinase are key sensors of DNA double strands breaks and activate downstream signaling pathways involving checkpoints, DNA repair and apoptosis. We estimated ATM/ATR signaling pathway activation in human ESCs and have revealed that irradiation induced ATM, ATR Chk2 phosphorylation, γH2AX foci formation and their co-localization with 53BP1 and Rad51 proteins. Interestingly, human ESCs display non-induced yH2AX foci co-localized with Rad51 and marking DNA single-strand breaks. Next we have revealed the substantial contribution of ATM, Chk1 and Chk2 kinases to G2/M block after irradiation of human ESCs and ATM-dependent activation (phosphorylation) of p53. However p53 activation and subsequent induction of p21 gene expression after DNA damage do not result in p21 protein accumulation due to proteasomal degradation.

THE PURPOSE OF THE REVIEW: Discuss the background and available results of transplantation of bone marrow stem cells as a promising treatment of hepatic fibrosis. KEY PROVISIONS: Actuality of the problem of chronic hepatitis is present due to their progressive course with the formation of liver cirrhosis and a high level of mortality. Conservative treatment of patients with decompensated process requires a liver transplantation that is compounded by the high percentage of graft reinfection in infectious hepatology. It is necessary to study the use of bone marrow-derived stem cells transplantation, because MSCs have certain therapeutic potential, low immunogenicity and the capacity for directional migration. In experimental models MSCs mechanisms of action are shown to limit the progression of liver fibrosis and stimulation of regeneration processes. In clinical studies good tolerability and relative safety of administration of autologous MSCs have reported as well as the positive effects on liver synthetic function, a decrease in the severity of cirrhosis on class Child-Pugh and MELD, reduction in overall mortality are shown. The results of our own prospective pilot study using autologous MSCs from bone marrow in patients with HCV-associated liver cirrhosis are described.