Human 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 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 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 SamplesSenescence of stromal fibroblasts has been linked to establishment of cancer associated fibroblasts (CAF) and aging-associated increase of tumors. However, in clinically occurring carcinomas, density and proliferation of CAFs are frequently increased rather than decreased. We previously showed that genetic deletion or down-modulation of the canonical Notch effector CSL/RBP-J? in skin dermal fibroblasts is sufficient for CAF activation with consequent development of multifocal keratinocyte tumors. We now show that CSL deletion or knockdown induces senescence of primary fibroblasts derived from dermis, oral mucosa, breast and lung. CSL functions in these cells as a constitutive direct repressor of multiple senescence- and CAF-effector genes. At the same time, it physically interacts with p53, repressing its activity, and p53 activation provides a failsafe mechanism against compromised CSL function. Concomitant loss of CSL and p53 overcomes fibroblast senescence, enhances expression of CAF effector genes and, in vivo, promotes tumour and stromal cell expansion. Together, the findings support a CAF activation/stromal evolution model under convergent CSL/p53 control. Overall design: Human Dermal Fibroblasts were transfected with two different siRNA against CSL in parallel with a control siRNA. Total RNA was extracted 3 days post-transfection, followed by RNA-Seq analysis.
Combined CSL and p53 downregulation promotes cancer-associated fibroblast activation.
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View SamplesSenescence of stromal fibroblasts has been linked to establishment of cancer associated fibroblasts (CAF) and aging-associated increase of tumors. However, in clinically occurring carcinomas, density and proliferation of CAFs are frequently increased rather than decreased. We previously showed that genetic deletion or down-modulation of the canonical Notch effector CSL/RBP-J-kappa in skin dermal fibroblasts is sufficient for CAF activation with consequent development of multifocal keratinocyte tumors. We now show that CSL deletion or knockdown induces senescence of primary fibroblasts derived from dermis, oral mucosa, breast and lung. CSL functions in these cells as a constitutive direct repressor of multiple senescence- and CAF-effector genes. At the same time, it physically interacts with p53, repressing its activity, with p53 activation providing a failsafe mechanism against compromised CSL function. Concomitant loss of CSL and p53 overcomes fibroblasts senescence, enhances CAF effector gene expression and, in vivo, promotes stromal and cancer cell expansion. Together, these findings support a CAF activation/stromal evolution model under convergent CSL/p53 control.
Combined CSL and p53 downregulation promotes cancer-associated fibroblast activation.
Specimen part
View SamplesMaize is highly sensitive to short term flooding and submergence. We aimed to discover genetic variation for submergence tolerance in maize and elucidate the genetic basis of submergence tolerance through transcriptional profiling of contrasting genotypes. A diverse set of maize nested association mapping (NAM) founder lines were screened, and two highly tolerant (Mo18W and M162W) and sensitive (B97 and B73) genotypes were identified. Transcriptome analysis was performed on these inbreds to provide genome level insights into the molecular responses to submergence. Overall design: RNA deep sequencing of shoot tissue from four inbreds (B73, B97, Mo18W and M162W) in three conditions 24h control (non-submerged), 24h submerged and 72h submerged.
Genetic and molecular characterization of submergence response identifies Subtol6 as a major submergence tolerance locus in maize.
Specimen part, Cell line, Subject
View SamplesPapillomaviruses (PVs) are able to induce papillomas, premalignant lesions, and carcinomas in a wide variety of species. PVs are classified first based on their host and tissue tropism and then their genomic diversities. A laboratory mouse papillomavirus, MmuPV1 (formerly MusPV), naturally infects NMRI-Foxn1nu/Foxn1nu (nude; T cell deficient) mice. C57BL/6J wild-type mice were not susceptible to MmuPV1 infection; however, immunocompetent, alopecic, S/RV/Cri-ba/ba (bare) mice developed small papillomas at injection sites that regressed. NMRI-Foxn1nu and B6.Cg-Foxn1nu but not NU/J-Foxn1nu mice were susceptible to MmuPV1 infection. B6 congenic strains, but not other congenic strains carrying the same allelic mutations, that lack B- and T-cells, but not B-cells alone, were susceptible to infection, indicating that mouse strain and T-cell deficiency are critical to tumor formation. Although lesions initially observed were exophytic papillomas around the muzzle, exophytic papillomas on the tail and condylomas of the vaginal lining could be induced by experimental infections. On the dorsal skin, locally invasive, poorly differentiated tumors developed with features similar to human trichoblastomas. Transcriptome analysis revealed significant differences between the normal skin in these anatomic sites and in papillomas versus trichoblastomas. The primarily dysregulated genes involved molecular pathways associated with cancer, cellular development, cellular growth and proliferation, cell morphology, and connective tissue development and function. Surprisingly, few of the genes commonly associated with basal cell carcinoma or squamous cells carcinoma were dramatically dysregulated.
Immune status, strain background, and anatomic site of inoculation affect mouse papillomavirus (MmuPV1) induction of exophytic papillomas or endophytic trichoblastomas.
Specimen part
View SamplesThe motor neurons innervating the muscles of facial expression are organized into somatotopic hindbrain clusters termed subnuclei. Each of the medial, intermediate, dorsolateral, and lateral subnuclei gives rise to a specific branch of the facial motor nerve (cranial nerve VII). How subnucleus-specific gene expression could mediate the accurate development of facial nerve projections was not well understood.
Etv1 Controls the Establishment of Non-overlapping Motor Innervation of Neighboring Facial Muscles during Development.
Sex, Specimen part
View SamplesThe entorhinal cortex of the mouse seems to be sensitive to molecular mechanisms that have been linked to the pathology of Alzheimer's disease. In this microarray study we are interested in comparing the expression profile of the left versus the right EC of the mouse, in order to understand if there is a significant difference in gene expression that might reveal any insights into the differential activation of these areas.
Molecular drivers and cortical spread of lateral entorhinal cortex dysfunction in preclinical Alzheimer's disease.
Age, Specimen part
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