RESUMO
Endothelial progenitor cell (EPC) nomenclature remains ambiguous and there is a general lack of concordance in the stem cell field with many distinct cell subtypes continually grouped under the term "EPC." It would be highly advantageous to agree on standards to confirm an endothelial progenitor phenotype and this should include detailed immunophenotyping, potency assays, and clear separation from hematopoietic angiogenic cells which are not endothelial progenitors. In this review, we seek to discourage the indiscriminate use of "EPCs," and instead propose precise terminology based on defining cellular phenotype and function. Endothelial colony forming cells and myeloid angiogenic cells are examples of two distinct and well-defined cell types that have been considered EPCs because they both promote vascular repair, albeit by completely different mechanisms of action. It is acknowledged that scientific nomenclature should be a dynamic process driven by technological and conceptual advances; ergo the ongoing "EPC" nomenclature ought not to be permanent and should become more precise in the light of strong scientific evidence. This is especially important as these cells become recognized for their role in vascular repair in health and disease and, in some cases, progress toward use in cell therapy. Stem Cells Translational Medicine 2017;6:1316-1320.
Assuntos
Células Progenitoras Endoteliais/citologia , Animais , Terapia Baseada em Transplante de Células e Tecidos/métodos , Humanos , Neovascularização Fisiológica/fisiologia , Terminologia como AssuntoRESUMO
B cell development is often depicted as a linear process initiating in the fetus and continuing postnatally. Using a PU.1 hypomorphic mouse model, we found that B-1 and B-2 lymphopoiesis occurred in distinct fetal and adult waves differentially dependent on the Sfpi1 14 kB upstream regulatory element. The initial wave of fetal B-1 development was absent in PU.1 hypomorphic mice, while subsequent fetal and adult waves emerged. In contrast, B-2 lymphopoiesis occurred in distinct fetal and adult waves. Whole-transcriptome profiling of fetal and adult B cell progenitors supported the existence of three waves of B-1 and two waves of B-2 development and revealed that the network of transcription factors governing B lineage specification and commitment was highly divergent between B-1 and B-2 progenitors. These findings support the view that the B-1 and B-2 lineages are distinct and provide a genetic basis for layering of immune system development.
Assuntos
Subpopulações de Linfócitos B/imunologia , Redes Reguladoras de Genes/imunologia , Linfopoese/imunologia , Animais , Linhagem da Célula/imunologia , Feto/imunologia , Perfilação da Expressão Gênica/métodos , Camundongos , Células Precursoras de Linfócitos B/imunologia , Fatores de Transcrição/imunologiaRESUMO
Host responses to chemotherapy can induce resistance mechanisms that facilitate tumor regrowth. To determine the contribution of bone marrow-derived cells (BMDCs), we exposed tumor-bearing mice to chemotherapeutic agents and evaluated the influx and contribution of a genetically traceable subpopulation of BMDCs (vascular endothelial-cadherin-Cre-enhanced yellow fluorescent protein [VE-Cad-Cre-EYFP]). Treatment of tumor-bearing mice with different chemotherapeutics resulted in a three- to 10-fold increase in the influx of VE-Cad-Cre-EYFP. This enhanced influx was accompanied by a significant increase in angiogenesis. Expression profile analysis revealed a progressive change in the EYFP population with loss of endothelial markers and an increase in mononuclear markers. In the tumor, 2 specific populations of VE-Cad-Cre-EYFP BMDCs were identified: Gr1âº/CD11b⺠and Tie2high/platelet endothelial cell adhesion moleculelow cells, both located in perivascular areas. A common signature of the EYFP population that exits the bone marrow is an increase in Notch. Inducible inactivation of Notch in the EYFP⺠BMDCs impaired homing of these BMDCs to the tumor. Importantly, Notch deletion reduced therapy-enhanced angiogenesis, and was associated with an increased antitumor effect of the chemotherapy. These findings revealed the functional significance of a specific population of supportive BMDCs in response to chemotherapeutics and uncovered a new potential strategy to enhance anticancer therapy.
Assuntos
Células da Medula Óssea/fisiologia , Carcinoma Pulmonar de Lewis/tratamento farmacológico , Cisplatino/farmacologia , Neoplasias Colorretais/tratamento farmacológico , Paclitaxel/farmacologia , Receptor Notch1/fisiologia , Animais , Antígenos CD/metabolismo , Antineoplásicos/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Células da Medula Óssea/citologia , Caderinas/metabolismo , Carcinoma Pulmonar de Lewis/genética , Neoplasias Colorretais/genética , Resistencia a Medicamentos Antineoplásicos/fisiologia , Neoplasias Mamárias Animais/tratamento farmacológico , Neoplasias Mamárias Animais/genética , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Nus , Camundongos Transgênicos , Receptor Notch1/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
B-1 B cells have been proposed to be preferentially generated from fetal progenitors, but this view is challenged by studies concluding that B-1 production is sustained throughout adult life. To address this controversy, we compared the efficiency with which hematopoietic stem cells (HSCs) and common lymphoid progenitors (CLPs) from neonates and adults generated B-1 cells in vivo and developed a clonal in vitro assay to quantify B-1 progenitor production from CLPs. Adult HSCs and CLPs generated fewer B-1 cells in vivo compared with their neonatal counterparts, a finding corroborated by the clonal studies that showed that the CLP compartment includes B-1- and B-2-specified subpopulations and that the former cells decrease in number after birth. Together, these data indicate that B-1 lymphopoiesis is not sustained at constant levels throughout life and define a heretofore unappreciated developmental heterogeneity within the CLP compartment.
Assuntos
Linfócitos B/citologia , Medula Óssea/fisiologia , Células-Tronco Hematopoéticas/citologia , Células Progenitoras Linfoides/citologia , Linfopoese/imunologia , Fatores Etários , Animais , Células Clonais , Sistema Imunitário/crescimento & desenvolvimento , Contagem de Linfócitos , CamundongosRESUMO
Vascular endothelial growth factor (VEGF) is essential for developmental and pathological angiogenesis. Here we show that in the absence of any pathological insult, autocrine VEGF is required for the homeostasis of blood vessels in the adult. Genetic deletion of vegf specifically in the endothelial lineage leads to progressive endothelial degeneration and sudden death in 55% of mutant mice by 25 weeks of age. The phenotype is manifested without detectable changes in the total levels of VEGF mRNA or protein, indicating that paracrine VEGF could not compensate for the absence of endothelial VEGF. Furthermore, wild-type, but not VEGF null, endothelial cells showed phosphorylation of VEGFR2 in the absence of exogenous VEGF. Activation of the receptor in wild-type cells was suppressed by small molecule antagonists but not by extracellular blockade of VEGF. These results reveal a cell-autonomous VEGF signaling pathway that holds significance for vascular homeostasis but is dispensable for the angiogenic cascade.
Assuntos
Comunicação Autócrina , Endotélio Vascular/metabolismo , Homeostase , Transdução de Sinais , Fator A de Crescimento do Endotélio Vascular/metabolismo , Animais , Apoptose , Vasos Sanguíneos/citologia , Hipóxia Celular , Sobrevivência Celular , Células Cultivadas , Cobalto/toxicidade , Cruzamentos Genéticos , Ecocardiografia , Endotélio Vascular/citologia , Camundongos , Camundongos Mutantes , Camundongos Transgênicos , Modelos Biológicos , Fosforilação , RNA Mensageiro/metabolismo , Telemetria , Fatores de Tempo , Fator A de Crescimento do Endotélio Vascular/genética , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
The mannose 6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2r), a member of the IGF axis of growth factors, is a negative regulator of cell growth and a putative tumor suppressor gene. Regulation of M6P/IGF2r levels is critical in breast physiology; low expression is associated with various aspects of breast cancer. We have found that ionizing radiation induces the rapid expression of M6P/IGF2r in a dose-dependent manner in MCF7 human breast cancer cells. We show that this increase is mediated, at least in part, by a stabilization of M6P/IGF2r transcripts by radiation in both ER positive (MCF7 and T47D) and ER negative (MDA-MB-231) breast cancer cell lines. It is probable, therefore, that posttranscriptional dysregulation of M6P/IGF2r is a contributing mechanism in breast cancer development and breast cancer response to therapy. This is a novel find that underscores the importance of posttranscriptional control of radiation-induced gene expression-a phenomenon that has often been paradigmatically attributed to transcriptional control.
Assuntos
Neoplasias da Mama/radioterapia , Regulação da Expressão Gênica/efeitos da radiação , Manosefosfatos/genética , Receptor IGF Tipo 2/genética , Transcrição Gênica/efeitos da radiação , Northern Blotting , Relação Dose-Resposta à Radiação , Citometria de Fluxo , Humanos , Manosefosfatos/metabolismo , Processamento Pós-Transcricional do RNA , RNA Mensageiro/metabolismo , Radiação Ionizante , Receptor IGF Tipo 2/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células Tumorais Cultivadas/metabolismo , Células Tumorais Cultivadas/efeitos da radiaçãoRESUMO
The risk for hepatocellular carcinoma (HCC) development is significantly heightened in the atomic bomb survivors, but the mechanism is unclear. We have previously reported finding a radiation dose-dependent increase in HCCs with TP53 mutations from the survivors. We now show that, in the same HCC samples, the frequency of 3'-untranslated region (3'UTR) mutations in M6P/IGF2R, a candidate HCC tumor suppressor gene, decreases with dose (P = 0.0091), implying a radiation dose-dependent negative selection of cells harboring such mutations. The fact that they were in the 3'UTR implicates changes in transcript stability rather than in protein function as the mechanism. Moreover, these M6P/IGF2R 3'UTR mutations and the TP53 mutations detected previously were mutually exclusive in most of the tumors, suggesting two independent pathways to HCC development, with the TP53 pathway being more favored with increasing radiation dose than the M6P/IGF2R pathway. These results suggest that tumors attributable to radiation may be genotypically different from tumors of other etiologies and hence may provide a way of distinguishing radiation-induced cancers from "background" cancers--a shift from the current paradigm.
Assuntos
Carcinoma Hepatocelular/epidemiologia , Carcinoma Hepatocelular/genética , Neoplasias Hepáticas/epidemiologia , Neoplasias Hepáticas/genética , Neoplasias Induzidas por Radiação/epidemiologia , Neoplasias Induzidas por Radiação/genética , Guerra Nuclear/estatística & dados numéricos , Receptor IGF Tipo 2/genética , Carga Corporal (Radioterapia) , Análise Mutacional de DNA , Relação Dose-Resposta à Radiação , Predisposição Genética para Doença/epidemiologia , Predisposição Genética para Doença/genética , Humanos , Incidência , Japão/epidemiologia , Masculino , Manosefosfatos/genética , Mutação , Doses de Radiação , Medição de Risco/métodos , Fatores de Risco , Sobreviventes/estatística & dados numéricosRESUMO
The concept of an Endothelial Progenitor Cell (EPC) that participates in adult angiogenesis is less than a decade old, yet it has received a great deal of attention due to its potential for cell-based clinical therapies in many pathologies. However, controversy remains as to the identity of this bone marrow-derived cell type and its ability to give rise to new endothelium in the adult. Reports on the contribution of EPCs to new vessels in ischemic tissue or tumors vary widely, ranging from 80-90% to negligible. As researchers hone their ability to identify, isolate, and expand these cells by their markers and functionality, mounting evidence suggests that they might constitute multiple, but related cell types. At least two general phenotypes have emerged from studies of bone marrow-derived cells contributing to angiogenesis: one that incorporates into the endothelial wall directly contributing to vascular expansion and another that is able to home to neovessels, but it locates behind the endothelial wall. Nonetheless, experimental evidence indicates that this second cell type supports the viability of newly formed vessels and thus it is equally relevant to neovascular growth. As our understanding of neovascularization in pathologic states expands, a more clear definition of the multiple cellular components required for the process will shed light into new models of therapeutic intervention. The identification of a cell type that could be isolated, expanded and infused into a patient would be very useful for promoting angiogenesis in ischemia, myocardial infarct and other pathologies.
Assuntos
Endotélio/citologia , Células-Tronco/citologia , Adulto , Animais , Humanos , Modelos BiológicosRESUMO
Results of this study indicate a radioprotective effect of peroxiredoxin-I. Peroxiredoxin-I is an antioxidant that scavenges hydroperoxides, whereas reactive oxygen species are the main mediators of ionizing radiation toxicity. We hypothesized that peroxiredoxin-I might be induced by cellular exposure to radiation and act to protect them against its cytotoxic effects. Western blot and Northern blot analyses were used to assess peroxiredoxin-I protein and mRNA expression. Rat C6 glioma cells were engineered to overexpress sense or antisense human peroxiredoxin-I using retroviral vectors. Clonogenic cell survival was used to assess radiosensitivities of the engineered cells. Ionizing radiation induced peroxiredoxin-I protein and mRNA expression in human HT29 colon cancer and rat C6 glioma cells in a dose- and time-dependent manner over a 24 hr period. To determine the effect of peroxiredoxin-I on radiation responses, C6 glioma cells were engineered to overexpress sense or antisense human peroxiredoxin-I. In clonogenic assays, cells overexpressing peroxiredoxin-I were more radioresistant. Cells transduced with antisense peroxiredoxin-I were marginally more sensitive to radiation toxicity. Irradiation can induce peroxiredoxin-I expression, and the increased peroxiredoxin-I may protect cells from further radiation damage. These results suggest that protection by peroxiredoxin-I may play an important role in the survival of glioma and colon cancer cells in patients undergoing radiation therapy.