Qualitative real-time RT-PCR assay for nOPV2 poliovirus detection.

Based on the success of the Sabin2-based vaccine, a next-generation nOPV2 poliovirus vaccine has been developed. For epidemic monitoring and conducting epidemiological investigations, it is necessary to have a diagnostic assay with the ability to differentiate this variant from others. Here we describe such a real-time RT-PCR assay. The region with the cre insertion in the 5'-UTR was chosen as the target, and the limit of detection was 103 copies/mL (2.5×103 copies/mL using Probit analysis) determined using armored RNA particles. Sensitivity and specificity were 86.28 - 100 % and 76.84 - 100 %, respectively (with 95 % CI). Thus, this method can be effectively used when it is necessary to make a differential diagnosis of poliovirus strains.

Current State-of-the-Art and Unresolved Problems in Using Human Induced Pluripotent Stem Cell-Derived Dopamine Neurons for Parkinson's Disease Drug Development.

Human induced pluripotent stem (iPS) cells have the potential to give rise to a new era in Parkinson's disease (PD) research. As a unique source of midbrain dopaminergic (DA) neurons, iPS cells provide unparalleled capabilities for investigating the pathogenesis of PD, the development of novel anti-parkinsonian drugs, and personalized therapy design. Significant progress in developmental biology of midbrain DA neurons laid the foundation for their efficient derivation from iPS cells. The introduction of 3D culture methods to mimic the brain microenvironment further expanded the vast opportunities of iPS cell-based research of the neurodegenerative diseases. However, while the benefits for basic and applied studies provided by iPS cells receive widespread coverage in the current literature, the drawbacks of this model in its current state, and in particular, the aspects of differentiation protocols requiring further refinement are commonly overlooked. This review summarizes the recent data on general and subtype-specific features of midbrain DA neurons and their development. Here, we review the current protocols for derivation of DA neurons from human iPS cells and outline their general weak spots. The associated gaps in the contemporary knowledge are considered and the possible directions for future research that may assist in improving the differentiation conditions and increase the efficiency of using iPS cell-derived neurons for PD drug development are discussed.

The Use of Human Induced Pluripotent Stem Cells for Testing Neuroprotective Activity of Pharmacological Compounds.

Development of therapeutic preparations involves several steps, starting with the synthesis of chemical compounds and testing them in different models for selecting the most effective and safest ones to clinical trials and introduction into medical practice. Cultured animal cells (both primary and transformed) are commonly used as models for compound screening. However, cell models display a number of disadvantages, including insufficient standardization (primary cells) and disruption of cell genotypes (transformed cells). Generation of human induced pluripotent stem cells (IPSCs) offers new possibilities for the development of high-throughput test systems for screening potential therapeutic preparations with different activity spectra. Due to the capacity to differentiate into all cell types of an adult organism, IPSCs are a unique model that allows examining the activity and potential toxicity of tested compounds during the entire differentiation process in vitro. In this work, we demonstrated the efficiency of IPSCs and their neuronal derivatives for selecting substances with the neuroprotective activity using two classes of compounds - melanocortin family peptides and endocannabinoids. None of the tested compounds displayed cyto- or embryotoxicity. Both melanocortin peptides and endocannabinoids exerted neuroprotective effect in the neuronal precursors and IPSC-derived neurons subjected to hydrogen peroxide. The endocannabinoid N-docosahexaenoyl dopamine exhibited the highest neuroprotective effect (~70%) in the differentiated cultures enriched with dopaminergic neurons; the effect of melanocortin Semax was ~40%. The possibility of using other IPSC derivatives for selecting compounds with the neuroprotective activity is discussed.

Expression and Functional Properties of NMDA and GABAA Receptors during Differentiation of Human Induced Pluripotent Stem Cells into Ventral Mesencephalic Neurons.

Ionotropic glutamate and GABA receptors regulate the differentiation and determine the functional properties of mature neurons. Both insufficient and excessive activity of these neurotransmission systems are associated with various nervous system diseases. Our knowledge regarding the expression profiles of these receptors and the mechanisms of their regulation during the differentiation of specialized human neuron subtypes is limited. Here the expression profiles of the NMDA and GABAA receptor subunits were explored during in vitro differentiation of human induced pluripotent stem cells (iPSCs) into ventral mesencephalic neurons. The correlation between the neuronal maturation and the expression dynamics of these genes was investigated, and the functional activity of these receptors was assessed by calcium imaging. The role of NMDA and GABAA receptors in neurite outgrowth and the development of spontaneous activity was analyzed using the viral transduction of neural progenitors with the reporter genes TagGFP and TagRFP. The data indicate that agonists of the investigated receptors can be employed for optimization of existing protocols for neural differentiation of iPSCs, in particular for acceleration of neuronal maturation.

Flow cytometric HyPer-based assay for hydrogen peroxide.

HyPer is a genetically encoded fluorogenic sensor for hydrogen peroxide which is generally used for the ratiometric imaging of H2O2 fluxes in living cells. Here, we demonstrate the advantages of HyPer-based ratiometric flow cytometry assay for H2O2, by using K562 and human mesenchymal stem cell lines expressing HyPer. We show that flow cytometry analysis is suitable to detect HyPer response to submicromolar concentrations of extracellularly added H2O2 that is much lower than concentrations addressed previously in the other HyPer-based assays (such as cell imaging or fluorimetry). Suggested technique is also much more sensitive to hydrogen peroxide than the widespread flow cytometry assay exploiting H2O2-reactive dye H2DCFDA and, contrary to the H2DCFDA-based assay, can be employed for the kinetic studies of H2O2 utilization by cells, including measurements of the rate constants of H2O2 removal. In addition, flow cytometry multi-parameter ratiometric measurements enable rapid and high-throughput detection of endogenously generated H2O2 in different subpopulations of HyPer-expressing cells. To sum up, HyPer can be used in multi-parameter flow cytometry studies as a highly sensitive indicator of intracellular H2O2.

Effect of Nerve Growth Factor on Neural Differentiation of Mouse Embryonic Stem Cells.

The cholinergic, GABAergic, and catecholaminergic neurons derived from mouse embryonic stem cells in a culture medium supplemented with recombinant NGF were phenotyped and scored. NGF stimulated generation of neurons, but not neuronal progenitors from embryonic stem cells and affected the proportion of specific types of neurons in cultures of differentiating embryonic stem cells. These findings open vista to employ NGF for generation of specific neuron types from embryonic stem cells for fundamental and toxicological studies.

The Transcriptional Changes of trim Genes Associated with Parkinson's Disease on a Model of Human Induced Pluripotent Stem Cells.

Over the last few years, in vitro models, based on patient-derived induced pluripotent stem cells (iPSCs), have received considerable attention for modeling different neurodegenerative disorders. Using this model, we analyzed transcription of 15 tripartite motif (trim) genes in iPSCs, derived from the different groups: Parkinson's disease (PD) patients bearing mutations in different genes, patient with the sporadic form of PD, and the healthy individuals. The transcription was observed during neuronal differentiation of the cells in vitro into neuronal stem cells and terminally differentiated neurons. The transcription of over 50 % of these genes, belonging to different sub-groups of the TRIM family, varied between PD patients and healthy individuals during the reprogramming of fibroblasts into iPSCs and the following neuronal differentiation. Moreover, the transcription of the trim6 and trim24 genes was different between cells, derived from PD patients, and control cells at all stages. The transcription of the four trim genes (trim5α, 26, 27, 31) remained unchanged during almost all investigated stages, compared with the controls. We suppose that the revealed changes in the transcription of several trim genes reflect their possible role in neurodegenerative processes at the early stages of PD. These genes may act as a gear unit between the PD progression and the deregulation of the immune system.

Investigation of the effects of GABA receptor agonists in the differentiation of human induced pluripotent stem cells into dopaminergic neurons.

The influence of GABA receptor agonists on the terminal differentiation in vitro of dopaminergic (DA) neurons derived from IPS cells was investigated. GABA-A agonist muscimol induced transient elevation of intracellular Ca2+ level ([Ca2+] i ) in the investigated cells at days 5 to 21 of differentiation. Differentiation of cells in the presence of muscimol reduced tyrosine hydroxylase expression. Thus, the presence of active GABA-A receptors, associated with phenotype determination via Ca2+-signalling was demonstrated in differentiating human DA neurons.

[Obtainment of chimeric blastocysts of mice by methods of laser nanosurgery].

The procedure of obtainment of chimeric blastocysts of mice by laser nanosurgery methods without using any other techniques is described. To perform the experiments, a special laser micromanipulator was invented. The murine embryonic stem cells (ESC), which were transformed with pEF-GFP vector, encoding the green fluorescent protein, were used in the experiments. ESC were introduced into the perivitelline space of murine embryos at the stage of 8 cells using the laser micromanipulator. The operated embryos were cultured in vitro until the stage of emergence from zona pellucida. The fluorescence and its precise localization were registered using a confocal microscope. It was shown for the first time that the inclusions of ESC introduced with the lased micromanipulator were found not only in the inner cell mass (ICM) but also in the trophectoderm of the chimeric blastocyst. The technology of nanosurgical operations at early stage preimplanted mammalian embryos using laser techniques opens great opportunities not only for solution of fundamental tasks of experimental embryology of mammals but also for obtainment of chimeric and transgenic animals with predetermined genotype.

[Quaternary structure formation by recombinant analogues of spider silk].

A study has been conducted on the morphology of artificial spider silk fibers, prepared from recombinant analogues of spiridons 1 and 2. It has been shown that by stretching out the "as spun" fiber, a reorganization of its spongy matrix occurs, which leads to the formation of microfibrills, followed by a reduction of the diameter of the fiber. The durability of an artificial fiber depends on the degree of stretching and on the substructure of the microfibrills. The model process of artificial fibers preparation reproduces to the great detail the natural process of spider web spinning. Future applications of this model include production of biomaterials with unique properties.