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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hemangioma is a benign tumor of infancy whose hallmark is rapid growth during the first year of life followed by slow regression during early childhood. The proliferating phase is characterized by abundant immature endothelial cells, the involuting phase by prominent endothelial-lined vascular channels and endothelial apoptosis, and the involuted phase by few remaining capillary-like vessels surrounded by loose fibrofatty tissue. Nothing is known about the mechanisms that contribute to the adipogenesis during this spontaneous regression. We postulated that mesenchymal stem cells (MSCs) reside in the tumor and preferentially differentiate into adipocytes. To test this hypothesis, we isolated MSCs from 14 proliferating and five involuting hemangiomas by taking advantage of the well known selective adhesion of MSCs to bacteriologic dishes. These hemangioma-derived MSCs (Hem-MSCs) are similar to MSCs obtained from human bone marrow, expressing the cell surface markers SH2 (CD105), SH3, SH4, CD90, CD29, smooth muscle alpha-actin, and CD133 but not the hematopoietic markers CD45 and CD14 or the hematopoietic/endothelial markers CD34, CD31, and kinase insert domain receptor (KDR). Hem-MSCs exhibited multilineage differentiation with robust adipogenic potential that correlated with the proliferating phase. The numbers of adipogenic Hem-MSCs were higher in proliferating-phase than in involuting-phase tumors and higher than in normal infantile skin. Furthermore, Hem-MSCs exhibited a random pattern of X-chromosomal inactivation, indicating that these cells are not clonally derived. In summary, we have identified MSCs as a novel cellular constituent in infantile hemangioma. These MSCs may contribute to the adipogenesis during hemangioma involution.
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PMID:Mesenchymal stem cells and adipogenesis in hemangioma involution. 1645 30

Endothelial progenitor cells (EPCs) contribute to blood vessel formation in ischemic and tumorous tissues, but comprise only a small population in circulation. We attempted to immortalize putative EPCs from human cord blood. Human CD34+ cord blood cells were cultured in the presence of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF), and transfected with a retroviral vector encoding the simian virus 40 large T (SV40T) antigen. This resulted in the immortalization of cord blood cells, leading to the establishment of several cell lines. One of these lines, HYCEC-1, exhibited a phenotype characteristic of the endothelial lineage, including expression of von Willebrand factor and VEGF receptor-2 (VEGFR-2/KDR/Flk-1) and uptake of acetylated-low density lipoprotein. Flow cytometric analysis revealed that HYCEC-1 cells were strongly positive for CD31 and CD146, moderately positive for CD144, weakly positive for CD133 and CD34, and negative for CD14 and CD45. HYCEC-1 cells formed capillary-like structures on basement matrix gel in vitro. Upon transplantation into the ischemic hind limb of nude rats, HYCEC-1 cells efficiently participated in neovascularization and augmented blood flow. The immortalized HYCEC-1 cells are suggested to be a class of EPCs that can efficiently participate in postnatal neovasculogenesis in the ischemic hind limb, and may also be a useful tool for studying tumor vessel formation.
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PMID:Postnatal neovascularization by endothelial progenitor cells immortalized with the simian virus 40T antigen gene. 1652 29

Circulating endothelial precursor cells (CEP) are interesting candidates for the treatment of ischemic diseases and for tumor targeting/imaging. We isolated a homogeneous population of CEP from CD34(+)/CD133(-) cells of peripheral blood that can be expanded easily on collagen-type-I coated plastic. CEP displayed a phenotype of mature endothelial cells (vWF, CD31, CD34, VEGF-R2, CD105, CD146) similar to that of cord-blood CEP and umbilical vein endothelial cells. They bound UEA-1 lectin, incorporated acetylated LDL and formed tube-like structures with capillary lumens in vitro. Weibel-Palade bodies were observed by electron microscopy. After 40-60 cell population doublings, CEP cultures underwent a terminal growth arrest, had shorter telomeres, up-regulated cell cycle inhibitory proteins, such as p21(CIP1) and stained positive for senescence-associated-beta galactosidase. During the whole expansion period CEP retained their endothelial phenotype and a normal karyotype. CEP had the capacity to home to ischemic tissue in vivo after systemic injection in nude rats. The convenient expandability, the homogenous phenotype, the functional cellular senescence program, the regular karyotype and the homing capacity to ischemic myocardium suggest autologous CEP cultures as a safe and promising tool for cell-based therapeutic approaches in targeting ischemic tissue and tumors.
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PMID:CD34+/CD133- circulating endothelial precursor cells (CEP): characterization, senescence and in vivo application. 1669 11

Until recently, it was generally accepted that vascularization of tumors arises exclusively from endothelial sprouting. Whether circulating bone marrow-derived endothelial progenitor cells (EPC) participate in the progression of non-small cell lung cancer (NSCLC) has not yet been evaluated. EPCs labeled with CD34, CD133, and vascular endothelial growth factor receptor-2 (VEGFR2) antibodies were counted by flow cytometry in the peripheral blood of 53 NSCLC patients. Furthermore, by means of a quantitative reverse transcription-PCR approach, we measured VEGFR2, CD133, CD34, and VE-cadherin mRNA in the peripheral blood samples of the same patient population. EPCs in tumor samples were identified by confocal microscopy using CD31, CD34, CD133, and VEGFR2 antibodies. Although immunofluorescent labeling of microvessels made clear that incorporation of EPCs is a rare phenomenon in NSCLC tissue (9 of 22 cases), circulating EPC levels before therapeutic intervention were increased in NSCLC patients (P < 0.002, versus healthy controls), and high pretreatment circulating EPC numbers correlated with poor overall survival (P < 0.001). Furthermore, in the subgroup of responders to treatment, the posttreatment EPC numbers in the peripheral blood were significantly lower compared with nonresponding patients. Interestingly, pretreatment mRNA levels of CD133, VE-cadherin, and CD34 were not significantly increased in NSCLC patients, whereas VEGFR2 expression was increased by 80-fold. Moreover, posttreatment VEGFR2 mRNA level in the peripheral blood was significantly higher in the subgroup of nonresponding patients when compared with posttreatment level of patients responding to antitumor therapy. Circulating levels of bone marrow-derived EPCs are significantly increased in NSCLC patients and correlate with clinical behavior.
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PMID:Identification and clinical significance of circulating endothelial progenitor cells in human non-small cell lung cancer. 1684 85

Infantile hemangiomas are composed of endothelial cells (ECs), endothelial progenitor cells (EPCs), as well as perivascular and hematopoietic cells. Our hypothesis is that hemangioma-derived EPCs (HemEPCs) differentiate into the mature ECs that comprise the major compartment of the tumor. To test this, we isolated EPCs (CD133(+)/Ulex europeus- I(+)) and mature ECs (CD133(-)/Ulex europeus-I(+)) from proliferating hemangiomas and used a previously described property of hemangioma-derived ECs (HemECs), enhanced migratory activity in response to the angiogenesis inhibitor endostatin, to determine if HemEPCs share this abnormal behavior. Umbilical cord blood-derived EPCs (cbEPCs) were analyzed in parallel as a normal control. Our results show that HemEPCs, HemECs, and cbEPCs exhibit increased adhesion, migration, and proliferation in response to endostatin. This angiogenic response to endostatin was consistently expressed by HemEPCs over several weeks in culture, whereas HemECs and cbEPCs shifted toward the mature endothelial response to endostatin. Similar mRNA-expression patterns among HemEPCs, HemECs, and cbEPCs, revealed by microarray analyses, provided further indication of an EPC phenotype. This is the first demonstration that human EPCs, isolated from blood or from a proliferating hemangioma, are stimulated by an angiogenesis inhibitor. These findings suggest that EPCs respond differently from mature ECs when exposed to angiogenic or antiangiogenic signals.
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PMID:Endothelial progenitor cells from infantile hemangioma and umbilical cord blood display unique cellular responses to endostatin. 1686 44

The Notch signaling pathway is required in both nonneoplastic neural stem cells and embryonal brain tumors, such as medulloblastoma, which are derived from such cells. We investigated the effects of Notch pathway inhibition on medulloblastoma growth using pharmacologic inhibitors of gamma-secretase. Notch blockade suppressed expression of the pathway target Hes1 and caused cell cycle exit, apoptosis, and differentiation in medulloblastoma cell lines. Interestingly, viable populations of better-differentiated cells continued to grow when Notch activation was inhibited but were unable to efficiently form soft-agar colonies or tumor xenografts, suggesting that a cell fraction required for tumor propagation had been depleted. It has recently been hypothesized that a small population of stem-like cells within brain tumors is required for the long-term propagation of neoplastic growth and that CD133 expression and Hoechst dye exclusion (side population) can be used to prospectively identify such tumor-forming cells. We found that Notch blockade reduced the CD133-positive cell fraction almost 5-fold and totally abolished the side population, suggesting that the loss of tumor-forming capacity could be due to the depletion of stem-like cells. Notch signaling levels were higher in the stem-like cell fraction, providing a potential mechanism for their increased sensitivity to inhibition of this pathway. We also observed that apoptotic rates following Notch blockade were almost 10-fold higher in primitive nestin-positive cells as compared with nestin-negative ones. Stem-like cells in brain tumors thus seem to be selectively vulnerable to agents inhibiting the Notch pathway.
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PMID:Notch pathway inhibition depletes stem-like cells and blocks engraftment in embryonal brain tumors. 1688 40

We investigated in vitro the properties of selected populations of cancer stem-like cells defined as tumorospheres that were obtained from human glioblastoma. We also assessed their potential and capability of differentiating into mature cells of the central nervous system. In vivo, their tumorigenicity was confirmed after transplantation into the brain of non-obese diabetic/severe combined immunodeficient (NOD-SCID) mice. The angiogenic potential of tumorospheres and glioblastoma-derived cells grown as adherent cells was revealed by evaluating the release of angiogenic factors such as vascular endothelial growth factor and CXCL12 by ELISA, as well as by rat aortic ring assay. The proliferative response of tumorospheres in the presence of CXCL12 was observed for the first time. Multidrug resistance-associated proteins 1 and 3 as well as other molecules conferring multidrug resistance were higher when compared with primary adherent cells derived from the same tumor. Finally, we obtained cells from the tumor developing after grafting that clearly expressed the putative neural stem cell marker CD133 as shown by FACS analysis and also nestin and CXCR4. The cells' positivity for glial fibrillary acidic protein was very low. Moreover these cells preserved their angiogenic potential. We conclude that human glioblastoma could contain tumor cell subsets with angiogenic and chemoresistance properties and that this chemoresistance potential is highly preserved by immature cells whereas the angiogenic potential is, to a higher extent, a property of mature cells. A better understanding of the features of these cell subsets may favor the development of more specifically targeted therapies.
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PMID:Glioblastoma-derived tumorospheres identify a population of tumor stem-like cells with angiogenic potential and enhanced multidrug resistance phenotype. 1698 Nov 97

Postnatal vasculogenesis, the process by which vascular committed bone marrow stem cells or endothelial precursor cells (EPC) migrate, differentiate, and incorporate into the nacent endothelium contributing to physiological and pathological neovascularization, has stimulated much interest. Its contribution to tumor nonvascularization, wound healing, and revascularization associated with skeletal and cardiac muscles ischaemia is established. We evaluated the mobilization of EPCs in response to musculoskeletal trauma. Blood from patients (n = 15) following AO type 42a1 closed diaphyseal tibial fractures was analyzed for CD34 and AC133 cell surface marker expression. Immunomagnetically enriched CD34+ mononuclear cell (MNC(CD34+)) populations were cultured and examined for phenotypic and functional vascular endothelial differentiation. Circulating MNC(CD34+) levels increased sevenfold by day 3 postinjury. Circulating MNC(AC133+) increased 2.5-fold. Enriched MNC(CD34+) populations from day 3 samples in culture exhibited cell cluster formation with sprouting spindles. These cells bound UEA-1 and incorporated fluorescent DiI-Ac-LDL intracellularily. Our findings suggest a systemic provascular response is initiated in response to musculoskeletal trauma. Its therapeutic manipulation may have implications for the potential enhancement of fracture healing.
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PMID:Mobilization of endothelial precursor cells: systemic vascular response to musculoskeletal trauma. 1700 4

Mounting evidence suggests that gliomas are comprised of differentiated tumor cells and brain tumor stem cells (BTSCs). BTSCs account for a fraction of total tumor cells, yet are apparently the sole cells capable of tumor initiation and tumor renewal. BTSCs have been identified as the CD133-positive fraction of human glioma, whereas their CD133-negative daughter cells have limited proliferative ability and are not tumorogenic. It is well established that the bulk tumor mass escapes immune surveillance by multiple mechanisms, yet little is known about the immunogenicity of the CD133-positive fraction of the tumor mass. We investigated the immunogenicity of CD133-positive cells in two human astrocytoma and two glioblastoma multiforme samples. Flow cytometry analyses revealed that the majority of CD133-positive cells do not express detectable MHC I or natural killer (NK) cell activating ligands, which may render them resistant to adaptive and innate immune surveillance. Incubating CD133-positive cells in interferon gamma (INF-gamma) significantly increased the percentage of CD133-positive cells that expressed MHC I and NK cell ligands. Furthermore, pretreatment of CD133-positive cells with INF-gamma rendered them sensitive to NK cell-mediated lysis in vitro. There were no consistent differences in immunogenicity between the CD133-positive and CD133-negative cells in these experiments. We conclude that CD133-posistive and CD133-negative glioma cells may be similarly resistant to immune surveillance, but that INF-gamma may partially restore their immunogenicity and potentiate their lysis by NK cells.
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PMID:Expression of MHC I and NK ligands on human CD133+ glioma cells: possible targets of immunotherapy. 1707 37

Understanding of the differentiation profile of brain tumor stem cells (BTSCs), the key ones among tumor cell population, through comparison with neural stem cells (NSCs) would lend insight into the origin of glioma and ultimately yield new approaches to fight this intractable disease. Here, we cultured and purified BTSCs from surgical glioma specimens and NSCs from human fetal brain tissue, and further analyzed their cellular biological behaviors, especially their differentiation property. As expected, NSCs differentiated into mature neural phenotypes. In the same differentiation condition, however, BTSCs exhibited distinguished differences. Morphologically, cells grew flattened and attached for the first week, but gradually aggregated and reformed floating tumor sphere thereafter. During the corresponding period, the expression rate of undifferentiated cell marker CD133 and nestin in BTSCs kept decreasing, but 1 week later, they regained ascending tendency. Interestingly, the differentiated cell markers GFAP and beta-tubulinIII showed an expression change inverse to that of undifferentiated cell markers. Taken together, BTSCs were revealed to possess a capacity to resist differentiation, which actually represents the malignant behaviors of glioma.
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PMID:Differentiation profile of brain tumor stem cells: a comparative study with neural stem cells. 1708 99


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