E. Yu. Moskaleva

Migration and Proliferative Activity of Mesenchymal Stem Cells in 3D Polylactide Scaffolds Depends on Cell Seeding Technique and Collagen Modification

We analyzed viability of mesenchymal stem cells seeded by static and dynamic methods to highly porous fibrous 3D poly-L-lactide scaffolds with similar physical and chemical properties, but different spatial organization modified with collagen. Standard collagen coating promoted protein adsorption on the scaffold surface and improved adhesive properties of 100 μ-thick scaffolds. Modification of 600-μ scaffolds with collagen under pressure increased proliferative activity of mesenchymal stem cells seeded under static and dynamic (delivery of 100,000 cells in 10 ml medium in a perfusion system at a rate of 1 ml/min) conditions by 47 and 648%, respectively (measured after 120-h culturing by MTT test). Dynamic conditions provide more uniform distribution of collagen on scaffold fibers and promote cell penetration into 3D poly-L-lactide scaffolds with thickness >600 μ.

Proliferative and Differentiation Potential of Multipotent Mesenchymal Stem Cells Cultured on Biocompatible Polymer Scaffolds with Various Physicochemical Characteristics

Biocompatibility of film and fibrous scaffolds from polylactide-based polymers and the relationship between their architecture and the functional characteristics of mesenchymal stem cells were studied. Cell culturing on polylactide-based film and fibrous matrixes did not deteriorate cell morphology and their proliferation and differentiation capacities. The rate of cell proliferation and penetration in microporous 3D matrices with the same porosity parameters and pore size depended on their spatial organization. The above materials can be used as scaffolds for mesenchymal stem cells for creation of tissue engineering implants. The scaffold size and structure should be determined by the defects in the organs in which the regeneration processes have to be stimulated.

Characteristics of tumors that have developed in mice injected with syngenic irradiated mesenchymal stem cells of bone marrow

Mesenchymal stem cells (MSCs) are found in virtually all organs and tissues. These cells can presumably be transformed into tumor stem cells by genotoxic factors and, subsequently, initiate tumor growth. The aim of the present work consisted in analysis of the possibility of malignant transformation of cultured MSCs from the bone marrow (BM) of mice after in vitro exposure to γ-radiation and in the characterization of biochemical and histological features of tumors that developed after the transplantation of BM MSCs to syngenic mice. Two of five mice developed tumors 3 to 4 months after the subcutaneous injection of BM MSCs irradiated at a dose of 1 Gy, five of five animals developed tumors after the administration of BM MSCs irradiated at a dose of 6 Gy, and only one of five mice injected with nonirradiated BM MSCs developed a tumor 6 months after cell transplantation. Telomerase activity in a tumor that developed from BM MSCs irradiated at a dose of 6 Gy was twice as high as that in the tumor that developed from BM MSCs irradiated at a dose of 1 Gy. The histological structure of the neoplasms corresponded to that of multicomponent mesenchymoma, a malignant tumor also termed “a mix of sarcomas.” The tumors consisted of tissue fragments of different histological types. Thus, BM MSCs exposed to 1 or 6 Gy of radiation can be transformed into tumor cells and give rise to multicomponent mesenchymomas, whereas malignant transformation of control BM MSCs occurs much less often.

Molecular mechanisms of antitumor activity of the polymeric form of niclosamide with respect to human colorectal cancer cells

Using poly(lactic-co-glycolic) acid a polymeric form of niclosamide (PFN) has been developed and its antitumor activity against human colorectal cancer cell lines SW837, Caco-2, COLO 320 HSR has been investigated in comparison with free niclosamide. PFN was shown to be more cytotoxic against cancer cells and less cytotoxic against normal cells (human embryonic lung fibroblasts) as compared to niclosamide. Free niclosamide and PFN share a common mechanism of the cytotoxic action on tumor cells, which is associated with mitochondrial damage (evaluated as a decrease in rhodamine 123 accumulation), and increased levels of reactive oxygen species, particularly mitochondrial superoxide anion, causing oxidative damage of intracellular targets. The action of niclosamide and PFN was accompanied by G0/G1 cell cycle arrest.

Design of etoposide polymeric forms

The present work relates to the field of pharmacology and medicine, in particular, to a new generation of anticancer drugs based on biocompatible polymers containing etoposide as the drug substance. A polymeric composition containing a surfactant and cryoprotective agent in addition to polymer and drug substance was designed. The optimum formulation of the polymeric composition and process conditions for its preparation were selected. The samples of etoposide polymeric forms were found to exhibit in vitro cytotoxic activity against two human tumor cell lines, viz., MCF-7 breast adenocarcinoma and K562 myeloleukemia cell lines, which was either identical or higher than the activity of free etoposide. The samples of the PLGA-based polymeric form of etoposide exhibited the highest activity.

Activity of aspartate-carbamoyltransferase, DNA-polymerase, and deoxyribonucleases in the hematopoietic organs of rats after a single injection of DNA

Since the m e c h a n i s m s control l ing DNA biosynthes is include not only the cor responding k inases but a l so s eve ra l o ther enzymes [9], it was decided to study the effect of injection of DNA on the act ivi ty of some of these enzymes in the hematopoie t ic organs of intact ra ts , namelya s p a r t a t e c a r b a m o y l t r a n s f e r a s e ACT (EC 2.1.3.2) and DNA-po lymerase (EC 2.7.7.7). Activity of the deoxyr ibonucleases (EC3.1.4.5 and 3.1.4.6), pro tec t ing the cell genome agains t fore ign DNA, a lso was invest igated.

Antiproliferative Activity of Niclosamide Against Melanoma and Colorectal Cancer Cells

Studies of the actions of niclosamide against tumor cells and normal human cells (human embryo kidney cells and pulmonary embryo fibroblast cells) showed higher levels of cytotoxic activity against tumor cells, including melanoma (the Mel-8, Mel-10, MS lines) and colorectal cancer (the Caco-2, COLO 320 HSR, and SW827 cells). Niclosamide was shown to have a high level of cytotoxic activity against cells with the multidrug resistance phenotype due to high levels of expression of MDR1 protein on the plasma membrane (the Mel-8 and MCF-7Adr lines). The proportion of tumor stem cells (TSC) was measured by flow cytometry as the proportion of cells forming side populations (SP). Niclosamide was found to act on TSC cells either more effectively (colorectal cancer line SW 837, (decreases in SP fraction size) or with the same effectiveness as the main population of tumor cells (SP fraction size unaltered).

Antitumor Activity of a Polymer Composite of Etoposide and Biodegradable Poly(Lactide-Co-Glycolide)

A method for preparing an antitumor polymer form of etoposide (PFE) as submicron particles based on poly(lactide-co-glycolide) with a 50:50 ratio of monomers (PLGA 50/50) was described. It was shown that the PFE possessed high cytotoxicity against various types of human tumor cells. The activity of the PFE against multiple drug resistant K562ADR cell line was greater than that of free etoposide. A grafted solid P388 murine lymphatic leukemia model showed that the PFE exhibited high in vivo antitumor activity that was prolonged compared with that of free etoposide.

Neuronal differentiation of PC12 cells and mouse neural stem cells on carbon nanotube films

In development of methods of stimulation of regeneration of nerve tissues and creation of new-generation bioelectronic devices, studying the interaction of nerve cells with specially developed scaffolds with different characteristics of the surface within a nanometer range is a necessary stage. Carbon nanotubes (CNTs), flexible graphene films rolled up into nanosized cylindrical tubes, may represent a promising material for making these scaffolds. CNTs were obtained by chemical vapor deposition. Analysis of PC12 cells cultivated on quartz glasses covered with CNT films using electron and optical microscopy have been performed. It has been demonstrated that CNTs stimulate proliferation and do not inhibit neuronal differentiation of the PC12 cells. The possibility of obtaining neurons differentiated from mouse neural stem cells on quartz glasses covered with the CNT films has been shown. The data obtained indicate the possibility of using CNT films produced by chemical vapor deposition on quartz glasses as an electroconductive substrate for obtaining cells of neural origin and, possibly, mature neurons and studying their functions.

Radiation Stress Changes the Size of Side Population of Human Epithelial Cells.

Stem cell cultures are heterogeneous and include true stem cells and progenitor cells. True stem cells are identified by flow cytofluorometry as a cell subset characterized by low accumulation of fluorescent dye rhodamin-123 and forming a side population. Low-dose γ-irradiation (10-200 mGy) of human skin epithelial stem cells and epithelial H69 tumor cells to was followed by an increase in cell counts by day 7 after the exposure. In parallel, reduction of the side population to 4-30% from the control for epithelial stem cells on the next day after exposure and to 22-36% from the control for H69 cells in 3 days after exposure. The size of the side population remained reduced to 8-37% of that in the control cultures of epithelial stem cells and H69 cells for at least 7 days after exposure. The decrease of the side population fraction of cells was not caused by cell death, but could be due to radiation-induced activation of the signal pathways, regulating the velocity of autoregeneration of the pool of true stem cells and acceleration of their transition to the pool of rapidly proliferating progenitor cells, this leading to an increase in the total cell count in the studied cultures under the effect of low-dose γ-radiation.