Revisiting the multiple roles of T-cadherin in health and disease.

As a non-canonical member of cadherin superfamily, T-cadherin was initially described as a molecule involved in homophilic recognition in the nervous and vascular systems. The ensuing decades clearly demonstrated that T-cadherin is a remarkably multifunctional molecule. It was validated as a bona fide receptor for both: LDL exerting adverse atherogenic action and adiponectin mediating many protective metabolic and cardiovascular effects. Motivated by the latest progress and accumulated data unmasking important roles of T-cadherin in blood vessel function and tissue regeneration, here we revisit the original function of T-cadherin as a guidance receptor for the growing axons and blood vessels, consider the recent data on T-cadherin-induced exosomes' biogenesis and their role in myocardial regeneration and revascularization. The review expands upon T-cadherin contribution to mesenchymal stem/stromal cell compartment in adipose tissue. We also dwell upon T-cadherin polymorphisms (SNP) and their possible therapeutic applications. Furthermore, we scrutinize the molecular hub of insulin and adiponectin receptors (AdipoR1 and AdipoR2) conveying signals to their downstream targets in quest for defining a putative place of T-cadherin in this molecular circuitry.

Secretome of Multipotent Mesenchymal Stromal Cells as a Promising Treatment and for Rehabilitation of Patients with the Novel Coronaviral Infection.

As a rule, coronavirus infections are mild in healthy adults and do not require special approaches to treatment. However, highly pathogenic strains, particularly the recently isolated SARS-CoV2, which causes COVID-19 infection, in about 15% of cases lead to severe complications, including acute respiratory distress syndrome, which causes high patient mortality. In addition, a common complication of COVID-19 is the development of pulmonary fibrosis. Why is the novel coronavirus so pathogenic? What new treatments can be proposed to speed up the recovery and subsequent rehabilitation of the organism? In 2020, over 34 000 scientific articles were published on the structure, distribution, pathogenesis, and possible approaches to the treatment of infection caused by the novel SARS-CoV2 coronavirus. However, there are still no definitive answers to these questions, while the number of the diseased is increasing daily. One of the comprehensive approaches to the treatment of the consequences of the infection is the use of multipotent human mesenchymal stromal cells and products of their secretion (secretome). Acting at several stages of the development of the infection, the components of the secretome can suppress the interaction of the virus with endothelial cells, regulate inflammation, and stimulate lung tissue regeneration, preventing the development of fibrosis. The results of basic and clinical research on this topic are summarized, including our own experimental data, indicating that cell therapy approaches can be successfully applied to treat patients with COVID-19.

Extracellular Matrix in the Regulation of Stem Cell Differentiation.

Extracellular matrix (ECM) proteins fill the space between cells in multicellular organisms, contributing to the structure of organs and tissues. The mechanical properties of ECM are well studied. At present, the role of individual ECM components and the three-dimensional tissue-specific matrices in the regulation of cell functional activity, proliferation, migration, acquisition of a specialized phenotype and its maintenance is intensively studied. In this review, we described main ECM structural proteins, enzymes, and extracellular vesicles and present the data on the participation of ECM components in the regulation of stem cell differentiation and self-maintenance, as well as approaches to the modeling of stem cells microenvironment using decellularized ECM.

Serotonin Modulates Differently the Functional Properties of Damaged and Intact Motoneurons in the Frog Spinal Cord.

When studying a preparation of the isolated spinal cord segment of an adult frog, damaged and intact lumbar motoneurons were found to differ significantly in the membrane potential, input resistance and the action potential properties (amplitude, duration, fast and medium phases of the afterhyperpolarization, and the frequency of spikes). Serotonin (5-HT) reduced the amplitude of afterpolarization and increased the frequency of the spikes of the intact neurons, while in the damaged motoneurons, 5-HT increased the amplitude of afterpolarization and had no effect on the frequency of discharges.

Presynaptic serotonin 5-HT1B/D receptor-mediated inhibition of glycinergic transmission to the frog spinal motoneurons.

Endogenous monoamine 5-hydroxytryptamine (5-HT, serotonin) is a phylogenetically ancient neurotransmitter present in vertebrates. The functions of 5-HT in central nervous system are intensively studied; however, the presynaptic effects of 5-HT in frog spinal motoneurons are practically unexplored. We have previously shown that 5-HT decreases the frequency of glycinergic miniature inhibitory postsynaptic potentials (mIPSPs), but does not affect the frequency of GABAergic mIPSPs and increases the frequency of glutamatergic postsynaptic potentials. In the present study, using pharmacological methods and intracellular recordings in motoneurons from an adult frog's isolated spinal cord, we aimed to identify the 5-HT receptor subtype responsible for inhibiting the release of glycine. Аn agonist of 5-HT1A and 5-HT7 receptors, 8-OH-DPAT, and a selective agonist of 5-HT2 receptors, α-Ме-5-НТ, did not show any significant effect on inhibitory transmission, indicating that 5-HT1A, 5-HT2, and 5-HT7 receptors are not involved in the modulation of glycine release in the adult frog spinal cord. An agonist of 5-HT1B/D receptors sumatriptan decreased the frequency (but not the amplitude) of glycinergic mIPSPs similar to 5-HT. An antagonist of 5-HT1,2 receptors, methysergide, abolished the effect of sumatriptan. Together our results suggest that 5-HT inhibits the release of glycine by activation of 5-HT1B/D receptors.

[PRESYNAPTIC SEROTONERGIC MODULATION OF SPONTANEOUS AND MINIATURE SYNAPTIC ACTIVITY IN THE FROG LUMBAR MOTONEURONS].

In this study we investigated the effect of 5-HT on the spontaneous and miniature synaptic activity in lumbar motoneurons from isolated frog spinal cord using intracellular recording. 5-HT increased the frequency of the spontaneous and miniature postsynaptic potentials (mPSPs). The effect of 5-HT on different subpopulations of mPSPs was multidirectional: it increased the frequency of glutamatergic excitatoty mPSP by 18 % and decreased the frequency of glycinergic inhibitory mPSP by 28 %, but had no effect on the frequency of GABAergic inhibitory mPSP. The amplitude and kinetic parameters of any subpopulation of mPSPs did not change. The data obtained show that 5-HT regulates the probability of glutamate and glycine release from presynaptic terminals ending at the frog spinal motoneurons. 5-HT shifts the ba- lance between synaptic excitation and inhibition in the spinal neural network toward excitation. Thus, 5-HT participates in control of motor output and provides its facilitation.

[Therapeutic potential of human mesenchymal stromal cells secreted components: a problem with standartization].

Regenerative medicine approaches, such as replacement of damaged tissue by ex vivo manufactured constructions or stimulation of endogenous reparative and regenerative processes to treat different diseases, are actively developing. One of the major tools for regenerative medicine are stem and progenitor cells, including multipotent mesenchymal stem/stromal cells (MSC). Because the paracrine action of bioactive factors secreted by MSC is considered as a main mechanism underlying MSC regenerative effects, application of MSC extracellular secreted products could be a promising approach to stimulate tissue regeneration; it also has some advantages compared to the injection of the cells themselves. However, because of the complexity of composition and multiplicity of mechanisms of action distinguished the medicinal products based on bioactive factors secreted by human MSC from the most of pharmaceuticals, it is important to develop the approaches to their standardization and quality control. In the current study, based on the literature data and guidelines as well as on our own experimental results, we provided rationalization for nomenclature and methods of quality control for the complex of extracellular products secreted by human adipose-derived MSC on key indicators, such as "Identification", "Specific activity" and "Biological safety". Developed approaches were tested on the samples of conditioned media contained products secreted by MSC isolated from subcutaneous adipose tissue of 30 donors. This strategy for the standardization of innovative medicinal products and biomaterials based on the bioactive extracellular factors secreted by human MSC could be applicable for a wide range of bioactive complex products, produced using the different types of stem and progenitor cells.

[THE INHIBITORY EFFECT OF GLYCINE AND GABA ON MONOSYNAPTIC EPSPs IN THE FROG SPTNAL MOTONFUCTYNMR].

In this research we have studied the inhibitory effect of glycine and GABA on the monosynaptic EPSPs induced by microstimulation of presynaptic fibers close to the frog lumbar motoneurones. Monosynaptic EPSPs had two components mediated by AMPA/KA (78%) and NMDA (22%) receptors. Both inhibitory mediators considerably decreased EPSP's decay time by 33.4 +/- 4.0% (n = 18) for glycine and by 40.2 +/- 3.6% (n = 18) for GABA. The decrease of EPSP's decay time was reduced after blockade ofNMDA receptors by AP5. The time characteristics were recovered in the normal saline. Glycine and GABA inhibited NMDA component of EPSPs to a greater extent than AMPA/KA component. It was confirmed by our previous data about the predominant inhibitory effect of glycine and GABA on responses induced by NMDA (as compared with AMPA and KA) application to motoneurone membrane.

[Hygienic evaluation of contemporary light sources].

The article covers problems of illumination hygiene and electromagnetic safety of workers using contemporary light sources. The authors present results of experimental studies of electromagnetic environment in energy-efficient lamps.

[Inhibitory regulation of glutamate receptors in the frog motoneuron].

The interaction of exogenously applied excitatory (glutamate and their agonists NMDA, AMPA, kainate) and inhibitory (glycine and GABA) amino acid effects was studied intracellularly in the motoneurones of the isolated frog spinal cord. During simultaneous glycine or GABA bath applications GLU-, AMPA-, KA- and NMDA-evoked responses were, respectively, decreased up to 45.8 +/- 2.9% (n = 12) and 67.8 +/- 3.9% (n = 16), 13.9 +/- 4.3% (n = 9) and 32.1 +/- 8.3% (n = 12), 36.8 +/- 8.2% (n = 7) and 48.0 +/- 11.8% (n = 6), 7.7 +/- 3.5% (n = 9) and 18.1 +/- 3.8% (n = 14) from the control. Sequential applications of EAA after glycine or GABA as well as the applications of EAA-agonist and glycine (GABA) mixture demonstrated similar results. The decrease of EAA-responses by glycine and GABA was abolished by selective GlyR antagonist strychnine (1 microM) and the selective GABAR antagonist SR95531 (gabazine, 20 MM), respectively. The data revealed differences in inhibitory effect of glycine and GABA on the excitation responses mediated by different types of glutamate receptors in the frog motoneurones: the predominant inhibitory effect of glycine and GABA on NMDA-responses and weak inhibitory effect on KA- and GLU-responses. Inhibitory effect of glycine was twice as much as that of GABA at the same concentration.

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.

Mesenchymal stem cells in tissue growth and repair.

It has been established in the recent several decades that stem cells play a crucial role in tissue renewal and regeneration. Mesenchymal stem cells (MSCs) are part of the most important population of adult stem cells. These cells have hereby been identified for the very first time and subsequently isolated from bone marrow stroma. Bone marrow-derived MSCs have been believed to play the role of a source of cells for the renewal and repair of connective tissues, including bone, cartilage and adipose tissues. Cells similar to bone marrow-derived MSCs have now been identified in all postnatal tissues. Data on the distribution and function of MSCsin vivocollected using novel approaches pertaining to the identification of MSCsin situ, to their isolation from tissues, and finally to the determination of their biological properties have enabled successful revision of the role of MSCs in various organs and tissues. This review summarizes our own, as well as others', data concerning the role of MSCs in the regulation processes of tissue repair and regeneration. In our opinion, MSCs provide the connection between the blood-vascular, immune, endocrine, and nervous systems and tissue-specific stem cells in the body.

[The contribution of glycine and GABA(A) receptors to generation of the inhibitory postsynaptic potentials in the frog spinal cord motoneurones].

The contribution of glycine and GABA(A) receptors to generation of the inhibitory postsynaptic potentials (IPSPs) evoked by microstimulation of the inhibitory fibers was studied intracellularly in the motoneurones of the isolated frog spinal cord. IPSPs were isolated by bloking EPSPs with kynurenate or CNQX and AP-5. The reversion under the small depolarising current (1-10) nA was used for the identification of IPSPs. The selective GlyR antagonist strychnine (1-5 microM) reduced the amplitude of IPSPs by a factor of 4.7 on the average in all studied motoneurones, while the selective GABA(A)R antagonist bicuculline (50-70 microM)--only by a factor of 1.6 and had no effect in 44% of motoneurones. Sequential applications of strychnine and bicuculline completely blocked the IPSPs. The results suggest that postsynaptic inhibition in the frog motoneurones is mediated by glycine (predominantly) and GABA(A) (to a smaller extent) receptors. It is possible the GABA(A) receptors are partly extrasynaptic.

[Viability and angiogenic activity of mesenchymal stromal cells from adipose tissue and bone marrow in hypoxia and inflammation in vitro].

Adult progenitor stromal cells derived from adipose tissue (ADSC) and bone marrow (BMDSC) hold great promise for use in cell-based therapy of ischemic diseases. Both cell lines secrete a various number of angiogenic cytokines which are regulated by hypoxia and improve vascularization of ischemic tissues being injected in damaged muscle or intravenously. However, such factors as low oxygen level and inflammation may impair the viability and functional activity of these cells after delivery to the ischemic area. We directly compared the reactions of ADSCs and BMDSCs to hypoxic and inflammatory conditions in vitro. Cultured ADSCs and BMDSCs from Balb/c mice were cultivated for 48 h under 1% O2 (hypoxia), 20% O2 (normoxia) or in the presence of inflammatory cytokines. Cell viability analyzed by annexin V-PE binding and 7AAD storage (flow cytometry), and by quantitative TUNEL showed no decrease under hypoxic condition. But cell apoptotic rates significantly increased (up to 70 %) under inflammatory condition. Inflammatory cytokines did not stimulate gene expression of angiogenic growth factors. Otherwise, gene expression profiles of angiogenesis-related cytokines showed activation of pro-angiogenic and suppression of anti-angiogenic factors in the cells under hypoxic condition. In general this effect was higher for ADSCs than for BMDSCs. Using in vitro and in vivo models of angiogenesis we have demonstrated that incubation under hypoxic condition increases stromal cells ability to stimulate blood vessels growth.

[Mechanism of stimulation of angiogenesis in ischemic myocardium with the help of adipose tissue stromal cells].

Stromal cells from subcutaneous adipose tissue (adipose derived stromal cells - ASCs) are perspective for cell therapy of ischemic states because of ability to stimulate growth of vessels. For the elucidation of mechanisms of angiogenic action of ASCs we used the model of co-cultivation of ASCs with cells isolated from postnatal hearts (fraction of cardiomyocutes - CMC). CMC fraction contained mature cardiomyocytes, endothelial and progenitor cells. On the 2-nd day spontaneously beating colonies of CMC with growing from them CD31-positive capillary-like structures were formed in CMC culture. Observed structures were unstable and came apart after 5 days of cultivation. At co-cultivation of CMC with ASCs formation of stable ramified CD31-positive structures was observed. Using the method of co-cultivation of CMC with mitomycin C treated ASCs and the method of immune magnetic depletion for removal of epithelial cells from the CMC fraction we found that ASCs stimulates formation of capillary like structure at the account of secretion of angiogenic factors, stabilization of forming CD31-positive structures at the account of intercellular contacts and stimulation of endothelial differentiation of progenitor cells present in CMC fraction.

[Left ventricular heart aneurism--a new source of resident cardiac stem cells].

In the past few years it has been established that the heart contains a reservoir of stem and progenitor cells that have the ability to differentiate in vitro and in vivo toward vascular and cardiac lineages and that show cardiac regeneration potential in vivo following injection into the infracted myocardium. The aim of the present study was to characterize cardiac stem cells in the tissue of chronic left ventricular aneurism. It was shown that human c-kit positive cells were scattered in fibrous, muscle and adipose parts of aneurism tissue. C-kit positive cells localized mainly in fibrous tissue nearby large vessels, however, c-kit positive cells did not express endothelial, smooth muscle or cardiomyocyte cell markers. Co-localization experiments demonstrated that all c-kit positive cells were of non-hematopoietic origin, since they did not express markers such as CD34 and CD45. Majority of c-kit positive cells expressed MDR1, but showed no proliferation activity (Ki67). It thus appears that aneurism tissue could be an alternative source of autologous cardiac stem cells. However, their regeneration capacity should be further explored.

Differences in the activation of inhibitory motoneuron receptors in the frog Rana ridibunda by GABA and glycine and their interaction.

Intracellular recording of potentials was used in isolated spinal cord segments from the frog Rana ridibunda to compare the inhibitory effects of GABA and glycine on the motoneuron membrane. At equal concentrations, the response (a change in membrane potential) to application of glycine was 1.5-2 times greater than the response to GABA in terms of amplitude, and EC(50) values were 0.75 and 1.57 mM, respectively. The response to simultaneous application of GABA and glycine averaged 79.1 +/- 2.4% (n = 19) of the sum of the individual responses and 130.1 +/- 1.5% (n = 19) of the glycine response (partial occlusion). Preliminary application of glycine decreased the GABA response by 85.3 +/- 0.2% (n = 10), while preapplication of GABA decreased the glycine response by only 52.9 +/- 0.3% (n = 11). The glycine and GABA responses were specifically suppressed by strychnine and bicuculline. These results provide evidence that as in mammals, amphibian motoneurons have both glycine (predominantly) and GABA(A) receptors; they also show that asymmetrical cross inhibition can occur.

Nonviral transfection of adipose tissue stromal cells: an experimental study.

Delivery of plasmid DNA and interfering RNA into adipose tissue stromal cells was carried out by the methods of lipofection, calcium phosphate method, and by electroporation. The percent of transfected cells after delivery of plasmid DNA by the calcium phosphate method and lipofection was 0 and 15%, respectively, vs. more than 50% after electroporation. Similar results were obtained for delivery of short-strand RNA into cells. These data indicate that electroporation is the most effective method of nonviral transfection of adipose tissue stromal cells.