Multipotent stromal cells (MSCs) are currently in clinical trials for a number of inflammatory diseases. Recent studies have demonstrated the ability of MSCs to attenuate inflammation in rodent models of acute lung injury (ALI) suggesting that MSCs may also be beneficial in treating ALI. To better understand how human MSCs (hMSCs) may act in ALI, the lungs of immunocompetent mice were exposed to lipopolysaccharide (LPS) and 4 hr later bone marrow derived hMSCS were delivered by oropharyngeal aspiration (OA). Administration of hMSCs significantly reduced the expression of pro-inflammatory cytokines, neutrophil counts and total protein in bronchoalveolar lavage. There was a concomitant reduction in pulmonary edema as indicated by a decrease in lung wet/dry weight ratio. The anti-inflammatory effects of hMSCs were not dependent on localization to the lung, as intraperitoneal administration of hMSCs also attenuated LPS-induced inflammation in the lung. Microarray analysis revealed significant induction of TNF--induced protein 6 (TSG-6) expression by hMSCs 12 hr after OA delivery to LPS-exposed lungs. Knockdown of TSG-6 expression in hMSCs by RNA interference abrogated most of their anti-inflammatory effects. In addition, intra-pulmonary delivery of recombinant human TSG-6 reduced LPS-induced inflammation in the lung. These results show that hMSCs recapitulate the observed beneficial effects of rodent MSCs in animal models of ALI and suggest that the anti-inflammatory properties of hMSCs in the lung are explained, at least in part, by activation of hMSCs to secrete TSG-6.
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Sex, Specimen part, Treatment
View SamplesHuman mesenchymal stem cells or multipotent stromal cells (MSCs) are of interest for clinical therapy, in part because of their capacity for proliferation and differentiation. However, results from clinical trials and in vitro models have been variable, possibly due to MSC heterogeneity and a lack of standardization between MSC in vitro expansion protocols. Here we defined changes in MSCs during expansion in vitro. In low density cultures, MSCs expand through distinct lag, exponential growth and stationary phases. We assayed cultures of passage 2 human MSCs from three donors at low density (50 cells/cm2) at about 5% confluence on Day 2 and after the cultures had expanded to about 70% confluence on Day 7. On Day 2 genes involved in cell division were up-regulated. On Day 7 genes for cell development were up-regulated. The variations between three donors were less than the variation within the expansion of MSCs from a single donor. The microarray data for selected genes were confirmed by real-time PCR, ELISA and FACScan. About 50% of cells at Day 2 were in S-phase compared to 10% at Day 7. The results demonstrated major differences in early and late stage cultures of MSCs that should be considered in using the cells in experiments and clinical applications.
Human multipotent stromal cells undergo sharp transition from division to development in culture.
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View SamplesHuman multipotent stromal cells readily form single-cell-derived colonies when plated at clonal densities. However, the colonies are heterogeneous because cells from a colony form new colonies that vary in size and differentiation potential when replated at clonal densities. The experiments here tested the hypothesis that cells in the inner regions of colonies are partially differentiated, but the differentiation is reversible. Cells were separately isolated from the dense inner (IN) regions and less-dense outer regions (OUT) of single-cell-derived colonies. Cells were then compared by assays of their transcriptomes and proteins, and for clonogenicity and differentiation. IN cells expressed fewer cell-cycle genes and higher levels of genes for extracellular matrix than the OUT cells. When transferred to differentiation medium, differentiation of the colonies occurred primarily in the IN regions. However, the IN cells were indistinguishable from OUT cells when replated at clonal densities and assayed for rates of propagation and clonogenicity. Also, colonies formed by IN cells were similar to colonies formed by OUT cells because they had distinct IN and OUT regions. Cultures of IN and OUT cells remained indistinguishable through multiple passages (30-75 population doublings), and both cells formed colonies that were looser and less dense as they were expanded. The results demonstrated that cells in the IN region of single-cell-derived colonies are partially differentiated, but the differentiation can be reversed by replating the cells at clonal densities.
Reversible commitment to differentiation by human multipotent stromal cells in single-cell-derived colonies.
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View SamplesQuantitative assays for human DNA and mRNA were used to examine the paradox that intravenously (IV) infused human multipotent stromal cells (hMSCs) can enhance tissue repair without significant engraftment. After 2 X 106 hMSCs were IV infused into mice, most of the cells were trapped as emboli in lung. The cells in lung disappeared with a half-life of about 24 hr but < 1,000 cells appeared in 6 other tissues. The hMSCs in lung up-regulated expression of multiple genes with a large increase in the anti-inflammatory protein TSG-6. After myocardial infarction, IV hMSCs but not hMSCs transduced with TSG-6 siRNA decreased inflammatory responses, reduced infarct size, and improved cardiac function. IV administration of recombinant TSG-6 also reduced inflammatory responses and reduced infarct size. The results suggest improvements in animal models and patients after IV infusions of MSCs are at least in part explained by activation of MSCs to secrete TSG-6.
Intravenous hMSCs improve myocardial infarction in mice because cells embolized in lung are activated to secrete the anti-inflammatory protein TSG-6.
Specimen part, Disease
View SamplesThe methodology for the repair of critical-sized or non-union bone lesions has unpredictable efficacy due in part to our incomplete knowledge of bone repair and the biocompatibility of bone substitutes. Although human mesenchymal stem cells (hMSCs) differentiate into osteoblasts, which promote bone growth, their ability to repair bone has been unpredictable. We hypothesized that given the multi-stage process of osteogenesis, hMSC-mediated repair might be maximal at a specific time-point of healing. Utilizing a mouse model of calvarial healing, we demonstrate that the osteo-repair capacity of hMSCs can be substantially augmented by treatment with an inhibitor of peroxisome-proliferator-activated-receptor-, but efficacy is confined to the rapid osteogenic phase. Upon entry into the bone-remodeling phase, hMSC retention signals are lost, resulting in truncation of healing. To solve this limitation, we prepared a scaffold consisting of hMSC-derived extracellular matrix (ECM) containing the necessary biomolecules for extended site-specific hMSC retention. When inhibitor-treated hMSCs were co-administered with ECM, they remained at the injury well into the remodeling phase of healing, which resulted in reproducible and complete repair of critical-sized defects in 3 weeks. These data suggest that hMSC-derived ECM and inhibitor-treated hMSCs could be employed at optimal times to substantially and reproducibly improve bone repair.
No associated publication
Sex, Age, Disease, Treatment
View SamplesTo study the gene expression changes in mesenchymal stem cells from bone marrow stroma (MSCs) during in vitro expansion (from low density), passage 1 MSC were grown in culture for 15 days with medium change every 2-3 days. Samples for microarrays were taken at day 5 (early log-phase), 10 (late log-phase) and 15 (stationary phase). The data was queried for expression changes in Wnt signaling molecules and cell surface markers. Several components of the canonical Wnt signaling pathway were expressed, including Dkk-1; Wnt-5a; alpha-catenin; beta-catenin; frizzled 1, 4, 6, and 7; disheveled; glycogen synthetase kinase 3 beta; and glycogen synthetase kinase 3 alpha. In addition, the expression of over 10 cell surface transcripts decreased and an almost equal number increased during expansion. The two of the transcripts with the largest decreases coded for proteins previously shown to be linked to cell motility and tumor progression: PODXL, and alpha6-integrin (CD49f). As the cultures expanded, the largest increase was for mRNA for the cell adhesion protein VCAM-1. To study the gene expression changes in more detail, real-time RT-PCR, RT-PCR, ELISAs, FACS, and western blotting were performed for additional MSC donors. The results demonstrated dramatic changes in the transcriptome of MSCs during in vitro expansion.
The Wnt signaling inhibitor dickkopf-1 is required for reentry into the cell cycle of human adult stem cells from bone marrow.
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View SamplesCanonical Wnt signaling controls proliferation and differentiation of osteogenic progenitor cells, and tumor-derived secretion of the Wnt antagonist Dickkopf-1 (Dkk1) is correlated with osteolyses and metastasis in many bone malignancies. However, the role of Dkk1 in the oncogenesis of primary osteosarcoma (OS) remains unexplored. Here, we over-expressed Dkk1 in the OS cell line MOS-J. Contrary to expectations, Dkk1 had autocrine effects on MOSJ cells in that it increased proliferation and resistance to metabolic stress in vitro. In vivo, Dkk1 expressing MOS-J cells formed larger and more destructive tumors than controls. These effects were attributed in part to up-regulation of the stress response enzyme and cancer stem cell marker aldehyde-dehydrogenase-1 (ALDH1) through Jun-N-terminal kinase signaling. This is the first report linking Dkk1 to tumor stress resistance, further supporting the targeting of Dkk1 not only to prevent and treat osteolytic bone lesions but also to reduce numbers of stress-resistant tumor cells.
An unexpected role for a Wnt-inhibitor: Dickkopf-1 triggers a novel cancer survival mechanism through modulation of aldehyde-dehydrogenase-1 activity.
Specimen part, Cell line
View SamplesWe hypothesized that social interactions, such as those involved in courtship and mating, would lead to assayable changes in gene expression that may have important effects on individual reproductive success and fitness through alterations in physiology or changes in nervous system function.
Mating alters gene expression patterns in Drosophila melanogaster male heads.
Sex, Age, Specimen part, Treatment
View SamplesWe hypothesized that social interactions, such as those involved in reproductive behaviors, would lead to immediate and assayable changes in gene expression that may have important effects on individual reproductive success and fitness through alterations in physiology or via short-term or long-term changes in nervous system function.
Socially-responsive gene expression in male Drosophila melanogaster is influenced by the sex of the interacting partner.
Sex, Age, Specimen part, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Sexually dimorphic genome-wide binding of retinoid X receptor alpha (RXRα) determines male-female differences in the expression of hepatic lipid processing genes in mice.
Sex, Age, Specimen part
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