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Human mesenchymal stem cells (MSCs) are known for their prostaglandin E2 (PGE2)-mediated immunosuppressive function but the precise molecular mechanisms underlying PGE2 biosynthesis during inflammation have not been completely elucidated. In this study, we have investigated the involvement of PGE2 pathway members in PGE2 production by bone marrow (BM)-MSCs in response to inflammatory stimuli, and their role in immunosuppression mediated by BM-MSCs. We found that IFN-γ and TNF-α increased cyclooxygenase (COX)-2 expression but not that of prostaglandin E synthase (PGES), or PGE2 production. On the other hand, the toll like receptor 3 (TLR3) stimulant poly(I:C) increased expression of both COX-2 and PGES, resulting in a significant increase in PGE2 levels. This effect was reversed upon COX-2 inhibition with indomethacin or PGES downregulation by siRNA. Reduced PGE2 levels decreased MSC’s capacity to inhibit hPBMC proliferation. In addition, administration of MSCs with inhibited PGES expression into mice with graft-versus-host disease (GVHD) did not reduce mortality. In summary, the present study reveals that upregulation of PGES via TLR3 is critical for BM-MSCs-mediated immunosuppression by PGE2 secretion via the COX-2/PGE2 pathway. These results provide a basis for understanding the molecular mechanisms underlying the PGE2-mediated immunosuppressive properties of MSCs. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effect of cell density on the proliferation activity of human mesenchymal stem cells (MSCs) derived from adipose tissue (AT-MSCs) over time in culture. Passage #4 (P4) and #12 (P12) AT-MSCs from two donors were plated at a density of 200 (culture condition 1, CC1) or 5000 (culture condition 2, CC2) cells cm−2. After 7 days of incubation, P4 and P12 AT-MSCs cultured in CC1 were thin and spindle-shaped, whereas those cultured in CC2 had extensive cell-to-cell contacts and an expanded cell volume. In addition, P4 and P12 AT-MSCs in CC1 divided more than three times, while those in CC2 divided less than once on average. Flow cytometric analysis using 5(6)-carboxyfluorescein diacetate N-succinimidyl ester dye showed that the fluorescence intensity of AT-MSCs was lower in CC1 than in CC2. Furthermore, expression of proliferation-associated genes, such as CDC45L, CDC20A and KIF20A, in P4 AT-MSCs was higher in CC1 than in CC2, and this difference was also observed in P12 AT-MSCs. These data demonstrated that cell culture density affects the proliferation activity of MSCs, suggesting that it is feasible to design a strategy to prepare suitable MSCs using specific culture conditions. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

To evaluate the optimal timing of mesenchymal stem cell (MSC) transplantation following stroke, rats were transplanted with MSCs at 1 (D1), 4 (D4), and 7 days (D7) after middle cerebral artery occlusion (MCAo). Rats in the D1 group showed a better functional recovery than those in the D4 or D7 groups after MCAo. MSCs preferentially migrated to the cortex in the D1 group, while the MSCs in the D4 or D7 groups preferentially migrated to the striatum. Interestingly, the level of monocyte chemotactic protein-1 (MCP-1) in the cortex was highest at 1 day after MCAo, while the level of stromal cell-derived factor-1 (SDF-1) in the striatum was lowest at 1 day after MCAo and then increased over time. The pattern of MCP-1 and SDF-1 level changes according to the time after MCAo was consistent with in vivo and in vitro migration patterns of MSCs. The results suggest that an earlier MSC transplantation is associated with a better functional recovery after stroke, which could be explained by the preferential migration of MSCs to the cortex in the early transplantation group. The time-dependent differential expression of MCP-1 and SDF-1 between ischemic regions seemed to mediate the differential migration of MSCs. Highest level of MCP-1 at one day of stroke may induce preferential migration of MSCs to the cortex, then better functional improvement. [ABSTRACT FROM AUTHOR]

Neurologic complications are serious complications after hematopoietic stem cell transplantation (HSCT) and significantly contribute to morbidity and mortality. The purpose of this study was to investigate the clinical features and prognosis in pediatric patients who had neurologic complications after allogeneic HSCT. We retrospectively reviewed the medical records of children and adolescents (19 years old or younger) who underwent allogeneic HSCT at our institution from 2000 to 2012. A total of 383 patients underwent 430 allogeneic transplantations. Among them, 73 episodes of neurologic complications occurred in 70 patients. The cumulative incidence of neurologic complications at day 400 was 20.0%. Almost two thirds of the episodes (63.0%, 46 of 73) occurred within 100 days after transplantation. Calcineurin inhibitor–related neurotoxicity was observed as the most common cause of neurotoxicity (47.9%, 35 of 73) and was significantly associated with earlier onset neurologic complications, seizure, and tremor. It also showed a significant association with lower probability of headache, abnormality of cranial nerve, and neurologic sequelae. In a multivariate analysis, days to neutrophil engraftment after HSCT, extensive chronic graft-versus-host disease (GVHD) and the existence of neurologic sequelae were identified as risk factors for mortality in patients who had neurologic complications (hazard ratio [HR], 1.08; 95% confidence interval [CI], 1.02 to 1.15; P = .011; HR, 5.98; 95% CI, 1.71 to 20.90; P = .005; and HR, 4.37; 95% CI, 1.12 to 17.05; P = .034, respectively). However, there was no significant difference in the 5-year overall survival between the patients who had neurologic complications without sequelae and the patients who did not have any neurologic complications (57.3% versus 61.8%, P = .906). In conclusion, we found that the major significant risk factors for mortality in pediatric recipients with neurologic complications were the existence of neurologic sequelae and extensive chronic GVHD. [ABSTRACT FROM AUTHOR]

No abstract available [ABSTRACT FROM AUTHOR]

Previous studies conducted cell expansion ex vivo using low initial plating densities for optimal expansion and subsequent differentiation of mesenchymal stem cells (MSCs). However, MSC populations are heterogeneous and culture conditions can affect the characteristics of MSCs. In this study, differences in gene expression profiles of adipose tissue (AT)-derived MSCs were examined after harvesting cells cultured at different densities. AT-MSCs from three different donors were plated at a density of 200 or 5,000 cells/cm2. After 7 days in culture, detailed gene expression profiles were investigated using a DNA chip microarray, and subsequently validated using a reverse transcription polymerase chain reaction (RT-PCR) analysis. Gene expression profiles were influenced primarily by the level of cell confluence at harvest. In MSCs harvested at ∼90% confluence, 177 genes were up-regulated and 102 genes down-regulated relative to cells harvested at ∼50% confluence (P<0.05, FC>2). Proliferation-related genes were highly expressed in MSCs harvested at low density, while genes that were highly expressed in MSCs harvested at high density (∼90% confluent) were linked to immunity and defense, cell communication, signal transduction and cell motility. Several cytokine, chemokine and growth factor genes involved in immunosuppression, migration, and reconstitution of damaged tissues were up-regulated in MSCs harvested at high density compared with MSCs harvested at low density. These results imply that cell density at harvest is a critical factor for modulating the specific gene-expression patterns of heterogeneous MSCs. [ABSTRACT FROM AUTHOR]

To overcome the limitations of allogeneic hematopoietic stem cell transplantation (HSCT), we conducted a study to identify a strategy for enhancing hematopoietic stem cell (HSC) engraftment during HSCT. Co-transplantation experiments with mesenchymal stem cells (MSCs) derived from adult human tissues including bone marrow (BM), adipose tissue (AT), and umbilical cord blood (CB) were conducted. We showed that AT-MSCs and CB-MSCs enhanced the engraftment of HSCs as effectively as BM-MSCs in NOD/SCID mice, suggesting that AT-MSCs and CB-MSCs can be used as alternative stem cell sources for enhancing the engraftment and homing of HSCs. CB-MSCs derived from different donors showed different degrees of efficacy in enhancing the engraftment of HSCs. The most effective CB-MSCs showed higher proliferation rates and secreted more MCP-1, RANTES, EGF, and VEGF. Our results suggest that AT-MSCs and CB-MSCs could be alternative stem cell sources for co-transplantation in HSCT. Furthermore, in terms of MSCs’ heterogeneity, characteristics of each population of MSCs are considerable factors for selecting MSCs suitable for co-transplantation with HSC. [ABSTRACT FROM AUTHOR]

Abstract: Mesenchymal stem cells (MSCs), which evoke only minimal immune reactivity, may have anti-inflammatory and immunomodulatory effects. In this study, we conducted a comparative analysis of the immunomodulatory properties of MSCs derived from adult human tissues including bone marrow (BM), adipose tissues (AT), umbilical cord blood (CB), and cord Wharton’s jelly (WJ). Using a multiple cytokine detection assay, we showed that there were no significant differences in levels of secreted factors from non-stimulated MSCs. We compared the immunosuppressive effect of BM-MSCs, AT-MSCs, CB-MSCs, and WJ-MSCs on phytohemagglutinin-induced T-cell proliferation. AT-MSCs, CB-MSCs, and WJ-MSCs effectively suppressed mitogen-induced T-cell proliferation as effectively as did BM-MSCs. Levels of interferon (IFN)-γ and tumor necrosis factor (TNF)-α secreted from activated T-cells increased over time, but these levels were significantly reduced when cocultured with each type of MSCs. In addition, the expression of hepatocyte growth factor, IL-10, transforming growth factor-β1, cyclooxygenase (COX)-1, and COX-2 were unchanged in MSCs treated with IFN-γ and/or TNF-α, while indoleamine 2,3-dioxygenase (IDO) expression increased. IFN-γ and/or TNF-α produced by activated T-cells were correlated with induction of IDO expression by MSCs, which, in turn, suppressed T-cell proliferation. These findings suggest that MSCs derived from AT, CB, or WJ could be substituted for BM-MSCs for treatment of allogeneic conflicts. [Copyright &y& Elsevier]

Abstract: Mesenchymal stem cells (MSCs), which are adherent stromal cells of a nonhematopoietic origin, have the ability to give rise to various differentiated cell types. MSCs regulate localization, self-renewal and differentiation of hematopoietic stem cells (HSCs) due to MSCs'' secretion of cytokines and growth factors, the cell-to-cell interactions and the influence of the extracellular matrix proteins. Using RT-PCR analysis, we examined the expression levels of cytokines and growth factors from MSCs and their differentiated cell types, including osteoblasts, adipocytes and endothelial cells. Cytokine and growth factor genes, including IL-6, IL-8, IL-11, IL-12, IL-14, IL-15, LIF, G-CSF, GM-CSF, M-SCF, FL and SCF, were found to be expressed in the MSCs. In contrast, there was no IL-1α, IL-1β, or IL-7 expression observed. The IL-12, IL-14, G-CSF, and GM-CSF mRNA expression levels either disappeared or decreased after the MSCs differentiated into osteoblasts, adipocytes, and endothelial cells. Among the differentiated cells derived from MSCs, osteoblasts, adipocytes, and endothelial cells expressed the osteopontin, aP2, and the VEGFR-2 gene, respectively. These profiles could help determine future clinical applications of MSCs and their derivatives for cell therapy. [Copyright &y& Elsevier]