Effect of Storage Conditions on the Integrity of Human Umbilical Cord Mesenchymal Stromal Cell-Derived Microvesicles.

We studied the effect of storage conditions on the safety of microvesicles produced by human multipotent umbilical cord mesenchymal stromal cells into the conditioned medium. It was found that microvesicles can be stored without serious degradation for up to 1 week at 4°Ð¡, but were almost completely destroyed during freezing and thawing cycles irrespective of the storage temperatures (-20°Ð¡, -70°Ð¡, or -196°Ð¡). Similar results were obtained for lyophilized medium conditioned by human multipotent umbilical cord mesenchymal stromal cells. Addition of a cryoprotectant (5-10% DMSO) followed by freezing and/or lyophilization preserved microvesicles at a nearly initial level. These findings indicate that during storage, microvesicles, being membrane structures, behave similar to living cells and require appropriate conditions for prolonged storage.

Comparative Analysis of Secretome of Human Umbilical Cord- and Bone Marrow-Derived Multipotent Mesenchymal Stromal Cells.

Production of cytokines and growth factors by cultured human umbilical cord tissue- and bone marrow-derived multipotent mesenchymal stromal cells was measured by multiplex analysis. In most cases, the concentrations of bioactive factors in the culture medium conditioned by umbilical cord-derived cells was ten- to hundred-times higher than in the medium conditioned by bone marrow-derived cells. These results suggest that both multipotent mesenchymal stromal cells from the umbilical cord and cell-free products can have more pronounced therapeutic effect in comparison with mesenchymal stromal cells obtained from "adult" sources.

Human Umbilical Cord Mesenchymal Stromal Cell-Derived Microvesicles Express Surface Markers Identical to the Phenotype of Parental Cells.

Production of microvesicles in culture of human umbilical cord multipotent mesenchymal stromal cells was studied and comparative analysis of the expression of some surface molecules (clusters of differentiation, CD) was performed. It was found that the mesenchymal stromal cells produce microvesicles in the amount sufficient for their detection by flow cytometry. Parallel analysis of the phenotypes of maternal mesenchymal stromal cells and secreted microvesicles revealed identical expression of surface molecules CD13, CD29, CD44, CD54, CD71, CD73, CD90, CD105, CD106, and HLA-I. The concentration of microvesicles in the conditioned medium was 17.9±4.6×106/ml; i.e. one cell produced ~40-50 (44.7±11.5) microvesicles over 2 days in culture.

Human Umbilical Cord Mesenchymal Stromal Cells Support Viability of Umbilical Cord Blood Hematopoietic Stem Cells but not the "Stemness" of Their Progeny in Co-Culture.

Cell-cell interactions and the ability of mesenchymal stromal cells to support the expansion of hematopoietic progenitor cells were studied in co-culture of human umbilical cord tissue-derived mesenchymal stromal cells and nucleated umbilical cord blood cells. It was found that hematopoietic stem cells from the umbilical cord blood are capable to adhere to mesenchymal stromal cells and proliferate during 3-4 weeks in co-culture. However, despite the formation of hematopoietic foci and accumulation of CD34+ and CD133+ cells in the adherent cell fraction, the ability of newly generated blood cells to form colonies in semi-solid culture medium was appreciably reduced. These findings suggest that human umbilical cord tissue-derived mesenchymal stromal cells display a weak capability to support the "stemness" of hematopoietic stem cell progeny despite long-term maintenance of their viability and proliferation.

Expression of Surface Molecules in Human Mesenchymal Stromal Cells Co-Cultured with Nucleated Umbilical Cord Blood Cells.

We studied the expression of different classes of surface molecules (CD13, CD29, CD40, CD44, CD54, CD71, CD73, CD80, CD86, CD90, CD105, CD106, CD146, HLA-I, and HLA-DR) in mesenchymal stromal cells from human umbilical cord and bone marrow during co-culturing with nucleated umbilical cord blood cells. Expression of the majority of surface markers in both types of mesenchymal stromal cells was stable and did not depend on the presence of the blood cells. Significant differences were found only for cell adhesion molecules CD54 (ICAM-1) and CD106 (VCAM-1) responsible for direct cell-cell contacts with leukocytes and only for bone marrow derived cells.

Human Umbilical Cord Blood Serum: Effective Substitute of Fetal Bovine Serum for Culturing of Human Multipotent Mesenchymal Stromal Cells.

Optimal conditions for culturing of multipotent mesenchymal stromal cells in the presence of pooled umbilical cord blood serum were determined. It was found that umbilical cord blood serum in a concentration range of 1-10% effectively supported high viability and proliferative activity of cells with unaltered phenotype and preserved multilineage differentiation capacity. The proposed approach allows avoiding the use of xenogenic animal sera for culturing of multipotent mesenchymal stromal cells and creates prerequisites for designing and manufacturing safe cellular and/or acellular products for medical purposes.

Changes in Cell Composition of Umbilical Cord Blood and Functional Activity of Hematopoietic Stem Cells during Cryogenic Storage and Repeated Freezing/Thawing Cycles.

We analyzed changes in cell composition of umbilical cord blood and functional activity of hematopoietic stem cells during cryogenic storage and after repeated freezing/thawing cycles. It was found that repeated freezing/thawing cycles performed according to the optimal programmable freezing protocol did not significantly affect viability and functional activity of hematopoietic stem cells. When fast freezing program was used, the cells completely lost their capacity to form colonies in semisolid medium, despite high viability parameters in the test with 7-AAD.

Isolation of Multipotent Mesenchymal Stromal Cells from Cryopreserved Human Umbilical Cord Tissue.

Umbilical cord stroma is an easily available, convenient, and promising source of multipotent mesenchymal stromal cells for regenerative medicine. Cryogenic storage of umbilical cord tissue provides more possibilities for further isolation of multipotent mesenchymal stromal cells for autologous transplantation or scientific purposes. Here we developed a protocol for preparation of the whole umbilical cord tissue for cryogenic storage that in combination with the previously described modified method of isolation of multipotent mesenchymal stromal cells allowed us to isolate cells with high proliferative potential, typical phenotype, and preserved differentiation potencies.

Optimized Protocol for Isolation of Multipotent Mesenchymal Stromal Cells from Human Umbilical Cord.

Extraembryonic tissues, in particular, umbilical cord stroma are promising sources of multipotent mesenchymal stromal cells for regenerative medicine. In recent years, methods for isolation of mesenchymal stromal cells from different compartments of the umbilical cords based on enzymatic disaggregation of the tissue or on tissue explants have been proposed. Here we propose a protocol of isolation of multipotent mesenchymal stromal cells from the whole umbilical cord that combines the advantages of each approach and ensures sufficient cell yield for further experimental and clinical applications. A combination of short-term incubation of tissue fragments on cold collagenase solution followed by their culturing in the form of explants significantly increased the yield of cells with high proliferative activity, typical pluripotent mesenchymal stromal cell phenotype, and preserved differentiation capacity.

Umbilical cord blood for autologous transfusion in the early postnatal ontogeny: analysis of cell composition and viability during long-term culturing.

Changes in cell composition and viability as well as the content and functional activity of hemopoietic progenitor cells were analyzed during long-term (up to 1 month at 4°C) storage of human umbilical cord blood cells. No significant quantitative changes in erythrocytes were found during this period. The total content and viability of leukocytes changed, which resulted in the prevalence of mononuclear cells (lymphocytes and monocytes). Analysis of functional activity of hemopoietic stem cells in semisolid culture revealed a decrease in the relative content of CFU during the first week of storage [corrected] and inability of cells to colony formation after 2 weeks.

Enrichment of umbilical cord blood mononuclears with hemopoietic precursors in co-culture with mesenchymal stromal cells from human adipose tissue.

We demonstrated the possibility of enrichment of umbilical cord blood mononuclear fraction with early non-differentiated precursors under conditions of co-culturing with mesenchymal stromal cells from the human adipose tissue. It was established that umbilical cord blood mononuclear cells adhered to mesenchymal stromal cell feeder and then proliferate and differentiate into hemopoietic cells. In comparison with the initial umbilical cord blood mononuclear fraction, the cell population obtained after 7-day expansion contained 2-fold more CFU and 33.4 ± 9.5 and 24.2 ± 11.2% CD34(+) and CD133(+) cells, respectively, which corresponds to enrichment of precursor cell population by 148 ± 60. The proposed scheme of expansion of hemopoietic cells from umbilical cord blood is economically expedient and can widely used in biology and medicine.

Mechano-chemical control of human endothelium orientation and size.

Human umbilical vein endothelial cells (EC) were grown on elastic silicone membranes subjected to cyclic stretch, simulating arterial wall motion. Stretching conditions (20% amplitude, 52 cycle/min) stimulated stress fiber formation and their orientation transversely to the strain direction. Cell bodies aligned along the same axis after the actin cytoskeleton. EC orientation response was inhibited by the adenylate cyclase activator, forskolin (10(-5) M), which caused stress fiber disassembly and the redistribution of F-actin to the cortical cytoplasm. Preoriented EC depleted of stress fibers by forskolin treatment retained their aligned state. Thus, stress fibers are essential for the process of EC orientation induced by repeated strain, but not for the maintenance of EC orientation. The monolayer formed by EC grown to confluence in conditions of intermittent strain consisted of uniform elongated cells and was resistant to deformation. In contrast, the monolayer assembled in stationary conditions was less compliant and exposed local denudations on initiation of stretching. When stretched in the presence of 10(-5) M forskolin it rapidly (3-4 h) reestablished integrity but gained a heterogeneous appearance since denuded areas were covered by giant cells. The protective effect of forskolin was because of the stimulation of EC spreading. This feature of forskolin was demonstrated while studying its action on EC spreading and repair of a scratched EC monolayer in conventional culture. Thus mechanical deformation and adenylate cyclase activity may be important factors in the control of endothelium morphology in human arteries.

Specific interaction of cultured human mesenchymal and hemopoietic stem cells under conditions of reduced oxygen content.

We studied the effect of reduced oxygen content (5%) on the phenotype and functional activity of cultured human mesenchymal stem cells. The expression of main immunophenotypic markers for mesenchymal stem cells (CD13, CD29, CD44, CD73, CD90, CD105, and HLA-I) remained practically unchanged under conditions of hypoxia. The expression of cell adhesion molecules (CD54 and CD106) increased during coculturing of mesenchymal stem cells and hemopoietic stem cells. These changes were accompanied by increased production of hemopoietins (interleukin-6 and interleukin-8) and enhanced colony-forming capacity of hemopoietic stem cells. Coculturing of mesenchymal stem cells and hemopoietic stem cells during hypoxia was followed by increased formation of hemopoietic islets and intensive production of interleukin-6, interleukin-8, and vascular endothelial growth factor (compared to cultures under normoxic conditions).

A monoclonal antibody, VM64, reacts with a 130 kDa glycoprotein common to platelets and endothelial cells: heterogeneity in antibody binding to human aortic endothelial cells.

A new monoclonal antibody (mAb), VM64, reacts with a common antigen on the surface of human platelets and vascular endothelial cells (EC). Under nonreduced conditions it recognized in immunoblotting a protein of 130 kDa both in platelets and EC. VM64 precipitated the same 130 kDa protein from the lysate of surface radioiodinated platelets. Electrophoretic mobility of this protein was not altered by reduction and differed from the bands precipitated by reference mAb against platelet glycoproteins (GP) Ia-IIa, Ib, IIb-IIIa and GMP130. VM64 binding to platelets and EC was specific and saturable. The number of binding sites on platelets was 9.9 +/- 3.5 x 10(3) per platelet and on the surface of EC monolayer -2.40 +/- 0.32 x 10(6) per cell. VM64 also binds to platelets from Glanzmann's thrombasthenia patients which lack GPIIb-IIIa. VM64 did not affect platelet aggregation induced by ADP, collagen, thrombin and ristocetin. In the monolayers of EC from umbilical vein and human aorta, VM64 stained the area at the periphery of the cells adjacent to the cell-cell boundaries. In preconfluent cultures preferential staining was observed at the active leading margins of the cells. Unlike EC cultures from umbilical vein, where all cells were positively stained, in aortic EC cultures some unstained or poorly stained cells were constantly present, indicating a heterogeneity of EC population related to the expression of VM64 antigen. The biochemical characteristics of VM64 antigen, its presence both on platelets and EC and typical distribution on the surface of EC suggested that this antigen is identical to PECAM (CD31) protein.

[Coculture of human endothelium and smooth muscle cells: functional heterogeneity of endothelial cells from zones with different susceptibility to atherosclerosis]. / Sovmestnoe kul'tivirovanie éndotelial'nykh i gladkomyshechnykh kletok aorty cheloveka: funktsional'naia geterogennost' éndoteliia v zonakh s razlichnoi predraspolozhennost'iu k aterosklerozu.

Using co-culture technique and 3H-thymidine radioautography we have studied effects of human aortic endothelial cells (EC), isolated separately from zones of low (LP) and high (HP) probability of atherosclerosis of grossly normal and atherosclerotic aortas, on 3H-thymidine incorporation by human intimal smooth muscle cells (SMCs). It was found that EC activity depended on a zone of probability, from which the cells were isolated, and on the degree of atherosclerotic lesion. The first-passage ECs from grossly normal LP zones inhibited 3H-thymidine incorporation, compared to control, incubated without Ecs, SMCs (63.5 +/- 27.5%). Cells from HP zones of the same vessels were less active or stimulated SMC proliferation (99.4 +/- 42.9%). EC cultures obtained from both LP and HP zones of atherosclerotic vessels had, as a rule, no effect or increased 3H-thymidine incorporation by SMCs (100.3 +/- 19.8 and 124.1 +/- 20.1%). In contrast to morphologically heterogeneous primary and first-passage cultures obtained from high seeding density, EC monolayers obtained with a split 1:10 were composed predominantly of small mononuclear cells. These cultures effectively inhibited SMC DNA synthesis independently of a zone of probability and a degree of atherosclerotic lesion of aorta (60.4 +/- 10.0 and 51.5 +/- 12.7%). The obtained data suggest that EC morphological heterogeneity is accompanied by functional changes of cells and may be involved in atherosclerotic plaque formation.

[Morphologic and functional characterization of human aortic endothelium. III. Growth in culture and colony formation at low seeding density]. / Morfologicheskie i funtsional'nye osobennosti éndoteliia aorty cheloveka. III. Rost v kul'ture i formirovanie kolonii pri nizkoi plotnosti posadki.

In human aortic endothelial cell (HAEC) cultures, obtained separately from aortic zones of low (LP) and high (HP) probability of atherosclerosis, proliferative characteristics of cells and HAEC ability to form colonies at clonal seeding density were studied. It has been found that the population doubling time is significantly higher in endothelial cell (EC) cultures from HP-zones, compared to that in cultures from LP-zones of the same vessels. In cultures from both LP- and HP-zones only a few percent of EC had a proliferative potential enough to form cell colonies. The number of formed colonies was always lower in EC cultures from HP-zones, and decreased depending on atherosclerotic lesions and cell donor age. The obtained data suggest that the decline of EC proliferative potential, mostly in HP-zones (even without visible signs of atherosclerotic lesions) is due to a decrease in the number of cells with a high mitotic activity, i.e. "cambial" cells.

[Damage to human endothelial cells by cholestane-3 beta,5 alpha,6 beta-triol and the protective effects of preparations that raise the intracellular level of cAMP]. / Povrezhdenie éndotelial'nykh kletok cheloveka kholestan-3 beta,5 al'fa,6 beta-triolom i zashchitnye éffekty preparatov, povyshaiushchikh vnutrikletochnyi uroven' tsAMF.

Effect of drugs, which are able to elevate the intracellular level of cAMP, on resistance of human umbilical vein endothelial cells (HUVEC) to cholestane-3 beta,5 alpha, 6 beta-triol (Triol)-induced injury was studied. Triol at a concentration of 62 microM caused death of 50% of cells after a 24 hour incubation. Addition of forskolin (10 microM), methylisobutylxantine (100 microM), or 8-Br-cAMP (100 microM) into the incubation medium prevented injury of HUVEC under these conditions. These findings indicate that endothelial resistance to the injury can be regulated by the adenylate cyclase system. A comparative study on Triol-induced injury of adult human aortic endothelial cells isolated separately from zones of low (LP) and high (HP) probability of atherosclerosis was also performed. In 7 cases endothelial cells isolated from the LP zones were more resistant to Triol-induced injury, in 2 cases the differences were not significant. The development of atherosclerotic lesion in HP zones is likely to be associated with a higher sensitivity of endothelial cells from these zones to different injuring agents.

[Induction of cell adhesion molecules, E-selectin, VCAM-1 and ICAM-1, in a co-culture of human endothelial and smooth muscle cells]. / Induktsiia molekul kletochnoi adgezii, E-selektina, VCAM-1 i ICAM-1 v sovmestnoi kul'ture éndotelial'nykh i gladkomyshechnykh kletok cheloveka.

Using immunofluorescence and flow cytometry, we studied the surface expression of cell adhesion molecules, E-selectin, VCAM-1 and ICAM-1, in human umbilical vein endothelial cells (HUVEC) co-cultured with human aortic intimal smooth muscle cells (SMC). It was found that inactivated HUVEC constitutively expressed only ICAM-1. After 3-4 h of co-culturing with SMC in the Transwell system we observed the appearance of E-selectin and VCAM-1, and the increase of ICAM-1 content on the cell surface. In all the cases, the maximum expression of these molecules (85-100% of positively stained cells) was detected within 18-24 h after co-culturing. Similar effect was exerted by SMC-conditioned culture medium, whose action well compared with that of a direct addition of interleukin-1 to EC at a concentration of 5-10 u/ml. The obtained data suggest that the cytokines secreted by SMC may participate in the regulation of endothelial cell adhesion molecule expression, and influence cell accumulation in sites of inflammation, immune disorders, etc.

[Morphological and functional study of human endothelium response to hyperthermia in vitro]. / Morfologicheskie i funktsional'nye osobennosti otveta éndoteliia cheloveka na gipertermiiu in vitro.

Effects of hyperthermia (+42.5 degrees C) on the endothelial monolayer organization, actin cytoskeleton and cell viability have been examined in culture of human aortic endothelial cells (EC). Short-lasting hyperthermia (1-4 hrs) provoked disappearance of stress fibers, redistribution of actin filaments to the area of cell-to-cell contacts, shape changes and reorganization of the monolayer. It also stimulated formation of intercellular contacts in a preconfluent EC culture. The cAMP content was elevated one hour after heat treatment and then lowered to negligible values (comparing to the basal cAMP level). Long-lasting hyperthermia (6-72 hrs) resulted in EC injury, and damage of endothelial monolayer accompanied by increased Chromium-51 release and almost complete blockade of [3H]-thymidine incorporation into DNA. Addition of cAMP elevating drugs (forskolin, 8-Br-cAMP or isobutylmethylxanthine) into the cell culture medium prevented heat-induced decrease in cAMP concentration, stimulated EC spreading, protected EC from injury, and promoted integrity of endothelial monolayers. Obtained results indicate that long-lasting hyperthermia can be regarded as an additional factor of endothelium injury involved in development of vascular pathology.