Tatjana Kozlovska

The True Story and Advantages of RNA Phage Capsids as Nanotools

RNA phages are often used as prototypes for modern recombinant virus-like particle (VLP) technologies. Icosahedral RNA phage VLPs can be formed from coat proteins (CPs) and are efficiently produced in bacteria and yeast. Both genetic fusion and chemical coupling have been successfully used for the production of numerous chimeras based on RNA phage VLPs. In this review, we describe advances in RNA phage VLP technology along with the history of the Leviviridae family, including its taxonomical organization, genomic structure, and important role in the development of molecular biology. Comparative 3D structures of different RNA phage VLPs are used to explain the level of VLP tolerance to foreign elements displayed on VLP surfaces. We also summarize data that demonstrate the ability of CPs to tolerate different organic (peptides, oligonucleotides, and carbohydrates) and inorganic (metal ions) compounds either chemically coupled or noncovalently added to the outer and/or inner surfaces of VLPs. Finally, we present lists of nanotechnological RNA phage VLP applications, such as experimental vaccines constructed by genetic fusion and chemical coupling methodologies, nanocontainers for targeted drug delivery, and bioimaging tools.

Characterization of Senescence of Culture-expanded Human Adipose-derived Mesenchymal Stem Cells

Background and Objectives Adipose-derived mesenchymal stem cells (ADSCs) are promising candidates in regenerative medicine. The need for in vitro propagation to obtain therapeutic quantities of the cells imposes a risk of impaired functionality due to cellular senescence. The aim of the study was to analyze in vitro senescence of previously cryopreserved human ADSCs subjected to serial passages in cell culture. Methods and Results ADSC cultures from 8 donors were cultivated until proliferation arrest was reached. A gradual decline of ADSC fitness was observed by altered cell morphology, loss of proliferative, clonogenic and differentiation abilities and increased β-galactosidase expression all of which occurred in a donor-specific manner. Relative telomere length (RTL) analysis revealed that only three tested cultures encountered replicative senescence. The presence of two ADSC subsets with significantly different RTL and cell size was discovered. The heterogeneity of ADSC cultures was supported by the intermittent nature of aging seen in tested samples. Conclusions We conclude that the onset of in vitro senescence of ADSCs is a strongly donor-specific process which is complicated by the intricate dynamics of cell subsets present in ADSC population. This complexity needs to be carefully considered when elaborating protocols for personalized cellular therapy.

Growth Properties and Pluripotency Marker Expression of Spontaneously Formed Three-dimensional Aggregates of Human Adipose-derived Stem Cells.

Background and Objectives: Recent findings suggest that therapeutic potential of mesenchymal stem cells (MSCs) could be increased through aggregation into three-dimensional (3D) bodies, and different culture methods have been employed to obtain 3D spheroids of MSCs. In the current study we report accidentally encountered spontaneous formation of adipose-derived stem cell (ASC) bodies in standard ASC culture of a single donor. Methods and Results: Human ASCs from passages 1 to 3, cultured in a medium containing 5% autologous serum (AS), spontaneously clustered and formed floating 3D bodies. After a transfer of floating ASC bodies onto new adherent plastic dish, they attached to the surface and gradual migration of spindle-shaped ASCs out of the bodies was detected. A substitution of AS with allogeneic sera did not hinder this ability, but commercial medium containing fetal bovine serum delayed the process. Substantial part of ASCs surrounding transferred ASC bodies showed alkaline phosphatase (AP) activity, while ASC aggregates were AP negative. Similar 3D bodies formed when ASCs were grown on an uncoated glass surface. These ASC aggregates as well as clusters of ASCs, where formation of the 3D bodies is initiated, expressed pluripotency marker NANOG, but the expression of OCT4A was not detected. Conclusions: Obtained results suggest that spontaneously formed ASC aggregates may represent a more primitive cell subpopulation within the individual ASC culture. The ability to form 3D aggregates, the expression of NANOG, and the lack of the AP activity may be used to enrich ASC cultures with potentially more primitive cells serving as an excellent basis for therapeutic applications.

Adipose-derived stem cells cultured in autologous serum maintain the characteristics of mesenchymal stem cells

Adipose-derived stem cells cultured in autologous serum maintain the characteristics of mesenchymal stem cells Human adipose tissue is known to be an attractive and readily available source of mesenchymal stem cells (MSC), which are becoming increasingly popular for application in regenerative medicine. Most of the protocols currently used for in vitro expansion of MSC include fetal bovine serum (FBS) supplementation. When MSC are cultured in such a way for clinical applications this rises concerns about immunogenicity of FBS proteins. A possible solution to this problem is the use of autologous serum (AS) instead of FBS. In this study we investigated whether adipose-derived stem cells (ADSC), cultivated in medium containing AS, maintain characteristics of MSC. The results show that the obtained ADSC were plastic adherent, rapidly dividing (doubling time 40 ± 4 hours), spindle-shaped cells with fibroblastoid morphology and exhibited normal karyotype. No less than 95% of the obtained cells displayed MSC surface markers, including CD73, CD90 and CD105, but showed no expression of the hematopoietic markers CD34 and CD45. ADSC cultured in the presence of AS underwent in vitro differentiation into adipocytes, osteoblasts and chondroblasts, confirmed by Oil Red O, Alizarin Red S and Alcian Blue stains, respectively. These findings suggest that ADSC may be expanded in the AS without the loss of characteristics of MSC. No taukaudiem izdalītas cilmes šūnas, kuras kultivētas barotnē ar autologo serumu, saglabā mezenhimālo cilmes šūnu īpašības Cilvēka taukaudi ir viegli pieejams un vērtīgs mezenhimālo cilmes šūnu (mesenchymal stem cells, MSC) avots, un to pielietojums regeneratīvajā medicīnā arvien palielinās. Lielākā daļa protokolu, kas pašlaik tiek izmantoti MSC pavairošanai in vitro, satur fetālo teļa serumu (fetal calf serum, FCS). Šādi kultivētas MSC, kuras paredzētas klīniskiem mērķiem, rada bažas par FCS proteīnu imunogenitāti. Lai no tā izvairītos, FCS vietā var izmantot autologo serumu (AS). Šajā darbā mēs pētījām, vai no taukaudiem iegūtās cilmes šūnas (adipose-derived stem cells, ADSC), kuras tiek kultivētas barotnē ar AS, saglabā MSC īpašības. Rezultāti rāda, ka iegūtās cilmes šūnas bija plastmasas adherentas, vārpstveida šūnas ar fibroblastiem līdzīgu morfologiju un normālu kariotipu, tās strauji dalījās (dubultošanās laiks 40 ± 4 stundas). Vismaz uz 95% no iegūtajām šūnām tika detektēti MSC virsmas marķieri CD73, CD90 un CD105, bet netika detektēti tādi hematopoētisko šūnu marķieri kā CD34 un CD45. ADSC, kuras kultivētas barotnē ar AS, diferenciējās in vitro par adipocītiem, osteoblastiem un hondroblastiem, ko apliecināja diferenciēto šūnu krāsošana ar Oil Red O, Alizarin Red S un Alcian Blue. Iegūtie rezultāti rāda, ka ADSC var tikt pavairotas barotnē ar AS bez MSC raksturīgo iezīmju zuduma.

Studies of the physicochemical and structural properties of self-assembling cationic pyridine derivatives as gene delivery agents

New amphiphilic pyridine derivatives containing dodecyloxycarbonyl substituents at positions 3 and 5 and cationic moieties at positions 2 and 6 have been designed and synthesised. Compounds of this type can be considered as synthetic lipids. The corresponding 1,4-dihydropyridine (1,4-DHP) derivatives have earlier been proposed as a promising tool for plasmid DNA (pDNA) delivery in vitro. In this work studies of the self-assembling properties of amphiphilic pyridine derivatives leading to the formation of liposomes, determination of particle size, zeta-potential and critical micelle concentration (CMC) with dynamic light scattering (DLS) measurements are described. Furthermore, thermal analysis of pyridine derivatives was performed using thermogravimetry analysis (TGA) and differential thermal analysis (DTA) as well as the ability to deliver the pEGFP-C1 plasmid DNA (that encodes GFP reporter) into the Baby hamster kidney-derived (BHK-21) cell line was used for evaluation of gene delivery properties. We have revealed that the new pyridine derivatives possessed self-assembling properties which were proved by formation of nanoparticles with the average size from 115 to 743nm, the zeta-potentials in the range of 48-79mV and CMC values in the range of 2-67μM. DTA data showed that all processes were endothermic for all compounds. Additionally, we established that among the tested pyridines the representatives with N-methylpyrrolidinium or pyridinium moieties as cationic head-group at the positions 2 and 6 possessed higher pEGFP-C1 transfection activity into the BHK-21 cell line. Nevertheless, the obtained results indicated that correlation of the physicochemical, structural properties and gene delivery activities of the tested compounds were not completely elucidated yet. On the other hand, the synthesised pyridines as possible metabolites of promising delivery systems on the 1,4-DHP core possessed lower pDNA transfection activity than the corresponding 1,4-DHP amphiphiles.

Characterisation and In Vivo Safety of Canine Adipose-Derived Stem Cells

Abstract The study characterises canine adipose-derived stem cells (cASCs) in comparison to human ASCs (hASCs) and tests their safety in a canine model after intravenous administration. cASCs from two dogs were cultured under hypoxic conditions in a medium supplemented with autologous serum. They were plastic adherent, spindle-shaped cells that expressed CD73, CD90, and CD44 but lacked CD45, CD14, HLA-DR, and CD34. cASCs differentiated toward adipogenic, osteogenic, and chondrogenic lineages, although adipogenic differentiation capacity was low. Blast transformation reaction demonstrated that these cells significantly suppress T-cell proliferation, and this ability is dose-dependent. Intravenous administration of a cell freezing medium, therapeutic dose of cASCs (2 × 106 live cells/kg), and five times higher dose of cASCs showed no significant side effects in two dogs. Microscopic tissue lesions were limited to only mild, non-specific changes. There were no signs of malignancy. The results of the study indicate that cASCs are similar to hASCs and are safe for therapeutic applications in a canine model. The proposed methodology for ASC preparation on a non-routine basis, which includes individually optimised cell culture conditions and offers risk-adapted treatment, could be used for future personalised off-the-shelf therapies, for example, in myocardial infarction or stroke.

Synthesis and Comparative Evaluation of Novel Cationic Amphiphile C12-Man-Q as an Efficient DNA Delivery Agent In Vitro

New amphiphilic 1,4-DHP derivative C12-Man-Q with remoted cationic moieties at positions 2 and 6 was synthesised to study DNA delivery activity. The results were compared with data obtained for cationic 1,4-DHP derivative D19, which is known to be the most efficient one among the previously tested 1,4-DHP amphiphiles. We analysed the effects of C12-Man-Q concentration, complexation media, and complex/cell contact time on the gene delivery effectiveness and cell viability. Transmission electron microscopy data confirms that lipoplexes formed by the compound C12-Man-Q were quite uniform, vesicular-like structures with sizes of about 50 nm, and lipoplexes produced by compound D19 were of irregular shapes, varied in size in the range of 25–80 nm. Additionally, confocal microscopy results revealed that both amphiphiles effectively delivered green fluorescent protein expression plasmid into BHK-21 cells and produced a fluorescent signal with satisfactory efficiency, although compound C12-Man-Q was more cytotoxic to the BHK-21 cells with an increase of concentration. It can be concluded that optimal conditions for C12-Man-Q lipoplexes delivery in BHK-21 cells were the serum free media without 0.15 M NaCl, at an N/P ratio of 0.9. Compound D19 showed higher transfection efficiency to transfect BHK-21 and Cos-7 cell lines, when transfecting active proliferating cells. Although D19 was not able to transfect all studied cell lines we propose that it could be cell type specific. The compound C12-Man-Q showed modest delivery activity in all used cell lines, and higher activity was obtained in the case of H2-35 and B16 cells. The transfection efficiency in cell lines MCF-7, HeLa, and Huh-7 appears to be comparable to the reference compound D19 and minimal in the HepG2 cell line.

Comparative protein profiling of B16 mouse melanoma cells susceptible and non-susceptible to alphavirus infection: Effect of the tumor microenvironment

ABSTRACT Alphavirus vectors are promising tools for cancer treatment. However, relevant entry mechanisms and interactions with host cells are still not clearly understood. The first step toward a more effective therapy is the identification of novel intracellular alterations that could be associated with cancer aggressiveness and could affect the therapeutic potential of these vectors. In this study, we observed that alphaviruses efficiently infected B16 mouse melanoma tumors/tumor cells in vivo, whereas their transduction efficiency in B16 cells under in vitro conditions was blocked. Therefore, we further aimed to understand the mechanisms pertaining to the differential transduction efficacy of alphaviruses in B16 tumor cells under varying growth conditions. We hypothesized that the tumor microenvironment might alter gene expression in B16 cells, leading to an up-regulation of the expression of virus-binding receptors or factors associated with virus entry and replication. To test our hypothesis, we performed a proteomics analysis of B16 cells cultured in vitro and of B16 cells isolated from tumors, and we identified 277 differentially regulated proteins. A further in-depth analysis to identify the biological and molecular functions of the detected proteins revealed a set of candidate genes that could affect virus infectivity. Importantly, we observed a decrease in the expression of interferon α (IFN-α) in tumor-isolated cells that resulted in the suppression of several IFN-regulated genes, thereby abrogating host cell antiviral defense. Additionally, differences in the expression of genes that regulate cytoskeletal organization caused significant alterations in cell membrane elasticity. Taken together, our findings demonstrated favorable intracellular conditions for alphavirus transduction/replication that occurred during tumor transformation. These results pave the way for optimizing the development of strategies for the application of alphaviral vectors as a potent cancer therapy.

Posttranslational modifications and secretion efficiency of immunogenic hepatitis B virus L protein deletion variants

BackgroundSubviral particles of hepatitis B virus (HBV) composed of L protein deletion variants with the 48 N-terminal amino acids of preS joined to the N-terminus of S protein (1-48preS/S) induced broadly neutralizing antibodies after immunization of mice with a Semliki Forest virus vector. A practical limitation for use as vaccine is the suboptimal secretion of such particles. The role of the N-terminal preS myristoylation in the cellular retention of full-length L protein is described controversially in the literature and the relation of these data to the truncated L protein was unknown. Thus, we studied the effect of preS myristoylation signal suppression on 1-48preS/S secretion efficiency, glycosylation and subcellular distribution.FindingsThe findings are that 1-48preS/S is secreted, and that removal of the N-terminal myristoylation signal in its G2A variant reduced secretion slightly, but significantly. The glycosylation pattern of 1-48preS/S was not affected by the removal of the myristoylation signal (G2A mutant) but was different than natural L protein, whereby N4 of the preS and N3 of the S domain were ectopically glycosylated. This suggested cotranslational translocation of 1-48preS in contrast to natural L protein. The 1-48preS/S bearing a myristoylation signal was localized in a compact, perinuclear pattern with strong colocalization of preS and S epitopes, while the non-myristoylated mutants demonstrated a dispersed, granular cytoplasmic distribution with weaker colocalization.ConclusionsThe large deletion in 1-48preS/S in presence of the myristoylation site facilitated formation and secretion of protein particles with neutralizing preS1 epitopes at their surface and could be a useful feature for future hepatitis B vaccines.