Regulation of Immunity via Multipotent Mesenchymal Stromal Cells.

Immune cells responsible for inflammation development are involved in tissue damage caused by wounding and various pathologies. Control of immune cell activation could be of significant benefit for regenerative medicine and the treatment of patients with autoimmune and degenerative diseases. It is a proven fact that MCSs (multipotent mesenchymal stromal cells) are capable of suppressing immune responses via the inhibition of dendritic cell maturation and via the restraining of the T, B, and NK cell function in the course of autoimmune diseases and various forms of inflammation. MSCs can be isolated easily from almost every type of tissue or organ and subsequently expandedin vitro. These cells are self-renewable and can be differentiated into various cell types of mesenchymal lineage. The current review contains a collection and critical analysis of data regarding the molecular mechanisms responsible for cross-talk between immune cells and MSCs. Some of these mechanisms can be used for the development of new practical approaches for the treatment of autoimmune diseases.

Block and graft copolymers and NanoGel copolymer networks for DNA delivery into cell.

Self-assembling complexes from nucleic acids and synthetic polymers are evaluated for plasmid and oligonucleotide (oligo) delivery. Polycations having linear, branched, dendritic. block- or graft copolymer architectures are used in these studies. All these molecules bind to nucleic acids due to formation of cooperative systems of salt bonds between the cationic groups of the polycation and phosphate groups of the DNA. To improve solubility of the DNA/polycation complexes, cationic block and graft copolymers containing segments from polycations and non-ionic soluble polymers, for example, poly(ethylene oxide) (PEO) were developed. Binding of these copolymers with short DNA chains, such as oligos, results in formation of species containing hydrophobic sites from neutralized DNA polycation complex and hydrophilic sites from PEO. These species spontaneously associate into polyion complex micelles with a hydrophobic core from neutralized polyions and a hydrophilic shell from PEO. Such complexes are very small (10-40 nm) and stable in solution despite complete neutralization of charge. They reveal significant activity with oligos in vitro and in vivo. Binding of cationic copolymers to plasmid DNA forms larger (70-200 nm) complexes. which are practically inactive in cell transfection studies. It is likely that PEO prevents binding of these complexes with the cell membranes ("stealth effect"). However attaching specific ligands to the PEO-corona can produce complexes, which are both stable in solution and bind to target cells. The most efficient complexes were obtained when PEO in the cationic copolymer was replaced with membrane-active PEO-b-poly(propylene oxide)-b-PEO molecules (Pluronic 123). Such complexes exhibited elevated levels of transgene expression in liver following systemic administration in mice. To increase stability of the complexes, NanoGel carriers were developed that represent small hydrogel particles synthesized by cross-linking of PEI with double end activated PEO using an emulsification/solvent evaporation technique. Oligos are immobilized by mixing with NanoGel suspension, which results in the formation of small particles (80 nm). Oligos incorporated in NanoGel are able to reach targets within the cell and suppress gene expression in a sequence-specific fashion. Further. loaded NanoGel particles cross-polarized monolayers of intestinal cells (Caco-2) suggesting potential usefulness of these systems for oral administration of oligos. In conclusion the approaches using polycations for gene delivery for the design of gene transfer complexes that exhibit a very broad range of physicochemical and biological properties, which is essential for design of a new generation of more effective non-viral gene delivery systems.

Block polycationic oligonucleotide derivative: synthesis and inhibition of herpes virus reproduction.

The block polycationic oligonucleotide (oligo) consisting of a phosphodiester 12-mer linked to the polycation chain at the 3'-end and cholesteryl group at the 5'-end was synthesized. The polycation chain was grown on the solid support using the monomer, H-phosphonate of 1-O-(4,4'-dimethoxytrityl)-1,3-butanediol. Amino groups were introduced in the polymer backbone using 1,4-diaminobutane, and then the oligo chain was formed at the free end of the polymer. The last stage of the synthesis was the attachment of the cholesteryl group to the 5'-end of the oligo prior to cleavage and deprotection of the copolymer. The nucleotide sequence of this copolymer, CGTTCCTCCTGC, was complementary to the splicing site of immediate early (IE) mRNA 4 and 5 of herpes simplex virus type 1 (HSV-1). The stability of the duplexes formed between the copolymer and the complementary 12-mer was similar to that of unmodified oligo. The stability of the block polycationic oligo against phosphodiesterase digestion was significantly increased compared to that of the unmodified oligo. The block polycationic oligo inhibited the reproduction of HSV-1 in Vero cells; however, the effect was significantly less than the effect of 12-mer oligo modified with cholesterol at the 5'-end. The decreased antiviral activity of the copolymer is explained by the polycation-induced stimulation of the virus infection.

Water-soluble block polycations as carriers for oligonucleotide delivery.

Water-soluble, block copolymeric carriers consisting of polyoxyethylene (PEO) and polyspermine (PS) chains have been developed for the delivery of antisense oligonucleotides (oligo) into the target cells. These copolymers spontaneously form complexes with oligos in aqueous solutions. The PS block electrostatically binds to the oligo, and as a result, the stability of the oligo is increased. Similarly, the polar PEO block provides for the aqueous solubility of the complex. This paper (i) reports the synthesis of the diblock PEO-PS copolymer and (ii) evaluates the effects of the complexes formed between this copolymer and phosphodiester oligo, complementary to the splice junction of herpes simplex virus type 1 immediate early pre-mRNAs 4 and 5, on the reproduction of this virus in Vero cells. Infectious titer data 22 and 39 h post infection indicates that the copolymer-oligo complex inhibits the reproduction of the virus beyond the detection limit. Conversely, the free oligo inhibits the reproduction of the virus only 22 h postinfection, while 39 h postinfection significant virus titers are observed. The results of this study suggest that the copolymer complex increases the sequence-specific inhibition effect of oligo on the virus reproduction.