RESUMEN
Hematopoiesis is a dynamic process in which blood cells are continuously generated from hematopoietic stem cells (HSCs). The regulatory mechanisms controlling HSC fate have been studied extensively over the past several decades. Although many protein-coding genes have been shown to regulate hematopoietic differentiation, additional levels of HSC regulation are not well studied. Advances in deep sequencing have revealed many new classes of regulatory noncoding RNAs (ncRNAs), such as enhancer RNAs and antisense ncRNAs. Functional analysis of some of these ncRNAs has provided insights into the molecular mechanisms that regulate hematopoietic development and disease. In this review, we summarize recent advances in our understanding of functional regulatory ncRNAs associated with hematopoietic self-renewal and differentiation, as well as those dysregulated ncRNAs involved in hematologic malignancies.
Asunto(s)
Hematopoyesis/genética , ARN no Traducido , Animales , Biomarcadores , Proliferación Celular/genética , Elementos de Facilitación Genéticos , Células Eritroides/patología , Células Madre Hematopoyéticas/fisiología , Humanos , Linfocitos/patología , Linfocitos/fisiología , Células Mieloides/patología , Células Mieloides/fisiología , ARN sin Sentido , ARN Largo no CodificanteRESUMEN
A genome-wide association study was carried out in 1020 case subjects with recurrent early-onset major depressive disorder (MDD) (onset before age 31) and 1636 control subjects screened to exclude lifetime MDD. Subjects were genotyped with the Affymetrix 6.0 platform. After extensive quality control procedures, 671 424 autosomal single nucleotide polymorphisms (SNPs) and 25 068 X chromosome SNPs with minor allele frequency greater than 1% were available for analysis. An additional 1 892 186 HapMap II SNPs were analyzed based on imputed genotypic data. Single-SNP logistic regression trend tests were computed, with correction for ancestry-informative principal component scores. No genome-wide significant evidence for association was observed, assuming that nominal P<5 × 10(-8) approximates a 5% genome-wide significance threshold. The strongest evidence for association was observed on chromosome 18q22.1 (rs17077540, P=1.83 × 10(-7)) in a region that has produced some evidence for linkage to bipolar-I or -II disorder in several studies, within an mRNA detected in human brain tissue (BC053410) and approximately 75 kb upstream of DSEL. Comparing these results with those of a meta-analysis of three MDD GWAS data sets reported in a companion article, we note that among the strongest signals observed in the GenRED sample, the meta-analysis provided the greatest support (although not at a genome-wide significant level) for association of MDD to SNPs within SP4, a brain-specific transcription factor. Larger samples will be required to confirm the hypothesis of association between MDD (and particularly the recurrent early-onset subtype) and common SNPs.
Asunto(s)
Trastorno Depresivo Mayor/genética , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Polimorfismo de Nucleótido Simple/genética , Adulto , Anciano , Mapeo Cromosómico , Europa (Continente) , Femenino , Frecuencia de los Genes , Genotipo , Humanos , Modelos Logísticos , Masculino , Análisis por Micromatrices/métodos , Persona de Mediana Edad , Recurrencia , Factores Sexuales , Factor de Transcripción Sp4/genéticaRESUMEN
Side-population (SP) analysis identifies precursor cells in normal and malignant tissues. Cells with this phenotype have increased resistance to many cytotoxic agents, and may represent a primary drug-resistant population in malignant diseases. To discover whether drug-resistant malignant SP cells are nonetheless sensitive to immune-mediated killing, we first established the presence of a malignant CD5(+)CD19(+) SP subset in the blood of 18/21 subjects with B-cell chronic lymphocytic leukemia (B-CLL). We examined the fate of these cells in six of these individuals who received autologous human CD40 ligand and interleukin-2 (hCD40L/IL-2) gene-modified tumor cells as part of a tumor vaccine study. Vaccinated patients showed an increase in B-CLL-reactive T cells followed by a corresponding decline in circulating CD5(+)CD19(+) SP cells. T-cell lines and clones generated from vaccinated patients specifically recognized B-CLL SP tumor cells. Elimination of SP cells is likely triggered by their increased expression of target antigens, such as receptor for hyaluronan-mediated motility (RHAMM), after stimulation of the malignant cells by hCD40L, as CD8(+) RHAMM-specific T cells could be detected in the peripheral blood of immunized patients and were associated with the decline in B-CLL SP cells. Hence, malignant B cells with a primary drug-resistant phenotype can be targeted by T- cell-mediated effector activity after immunization of human subjects.
Asunto(s)
Ligando de CD40/inmunología , Vacunas contra el Cáncer/inmunología , Leucemia Linfocítica Crónica de Células B/terapia , Linfocitos T Citotóxicos/inmunología , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2 , Transportadoras de Casetes de Unión a ATP/fisiología , Adulto , Anciano , Antígenos CD19/análisis , Antígenos CD5/análisis , Resistencia a Antineoplásicos , Proteínas de la Matriz Extracelular/genética , Femenino , Humanos , Receptores de Hialuranos/genética , Inmunización , Leucemia Linfocítica Crónica de Células B/inmunología , Masculino , Persona de Mediana Edad , Proteínas de Neoplasias/fisiología , Vidarabina/análogos & derivados , Vidarabina/farmacologíaRESUMEN
Hematopoietic stem cells (HSC) continuously replenish the blood and immune systems. Their activity must be sustained throughout life to support optimal immune responses. It has been thought that stem cells may be somewhat protected from age because of their perpetual requirement to replenish the blood, however studies over the past 10 years have revealed dramatic changes in HSC function and phenotype with respect to age. When the number of HSC within murine bone marrow is measured, an increase in concentration and absolute number of HSC within the bone marrow is observed as the animal ages, paralleled with increased homogeneity of stem cell marker expression. Results from transplantation studies demonstrate that although there is a decline in hematopoietic output on a per-cell basis, the increase in number provides sufficient, yet abnormal, blood production throughout the lifespan of the animal. HSC may play a role in immunosenescence through cell-fate decisions leading to an overproduction of myeloid cells and an underproduction of lymphocytes. When examining gene expression of aged HSC, recent studies have highlighted several key factors contributing to increased inflammation, stress response and genomic instability. Here, we will review the general phenotype observed with aging of the hematopoietic system, focusing on the HSC, and compile recent expression profiling efforts that have examined HSC aging.
Asunto(s)
Senescencia Celular , Células Madre Hematopoyéticas/fisiología , Animales , Ligamiento Genético , Inestabilidad Genómica , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/metabolismo , Humanos , Sistema Inmunológico/citología , Sistema Inmunológico/fisiología , Pliegue de ProteínaRESUMEN
Stem cells have an extensive capacity to proliferate, differentiate and self-renew. In many mammals, including humans, an adult stem cell subpopulation termed the "side population" (SP) has been identified. SP cells can rapidly efflux lipophilic fluorescent dyes to produce a characteristic profile based on fluorescence-activated flow cytometric analysis. Previous studies have demonstrated SP cells in bone marrow obtained from patients with acute myeloid leukemia, suggesting that these cells might be candidate leukemic stem cells, and recent studies have found a SP of tumor progenitor cells in human solid tumors. These new data indicate that the ability of malignant SP cells to expel anticancer drugs may directly improve their survival and sustain their clonogenicity during exposure to cytostatic drugs, allowing disease recurrence when therapy is withdrawn. Identification of a tumor progenitor population with intrinsic mechanisms for cytostatic drug resistance might also provide clues for improved therapeutic intervention.
Asunto(s)
Neoplasias/patología , Células Madre Neoplásicas/patología , Transportadoras de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/fisiología , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Proliferación Celular , Supervivencia Celular , Resistencia a Antineoplásicos , Citometría de Flujo , Regulación Neoplásica de la Expresión Génica , Humanos , Neoplasias/tratamiento farmacológico , Neoplasias/genética , Células Madre Neoplásicas/efectos de los fármacos , Células Madre Neoplásicas/fisiologíaRESUMEN
A subset of stem cells, termed the "side population" (SP), has been identified in several tissues in mammalian species. These cells maintain a high efflux capability for antimitotic drugs. We have investigated whether functionally equivalent stem cells also may be detected in human cancers. We initially examined primary tumor cells from 23 patients with neuroblastoma and cell lines derived from a range of other tumors. A distinct SP was found in neuroblastoma cells from 15 of 23 patients (65%). The SP was capable of sustained expansion ex vivo and showed evidence for asymmetric division, generating both SP and non-SP progeny. These cells also expressed high levels of ABCG2 and ABCA3 transporter genes and had a greater capacity to expel cytotoxic drugs, such as mitoxantrone, resulting in better survival. A SP also was detected in breast cancer, lung cancer, and glioblastoma cell lines, suggesting that this phenotype defines a class of cancer stem cells with inherently high resistance to chemotherapeutic agents that should be targeted during the treatment of malignant disease.
Asunto(s)
Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Transportadoras de Casetes de Unión a ATP/biosíntesis , Adulto , Antígenos de Superficie/análisis , Antineoplásicos/farmacología , Bencimidazoles/farmacocinética , Línea Celular Tumoral , Supervivencia Celular , Niño , Preescolar , Resistencia a Antineoplásicos , Femenino , Citometría de Flujo , Colorantes Fluorescentes/farmacocinética , Expresión Génica , Humanos , Lactante , Masculino , Persona de Mediana Edad , Mitoxantrona/farmacología , Células Madre Neoplásicas/efectos de los fármacos , Neuroblastoma/tratamiento farmacológico , Neuroblastoma/metabolismo , Neuroblastoma/patología , Proteínas Proto-Oncogénicas c-kit/biosíntesisRESUMEN
The past 5 years have witnessed an explosion of interest in using adult-derived stem cells for cell and gene therapy. This has been driven by a number of findings, in particular, the possibility that some adult stem cells can differentiate into non-autologous cell types, and also the discovery of multipotential stem cells in adult bone marrow. These discoveries suggested a quasi-alchemical nature of cells derived from adult organs, thus raising new and exciting therapeutic possibilities. Recent data, however, argue against the whole idea of stem cell 'plasticity', and bring into question the therapeutic strategies based upon this concept. Here, we will review the current state of knowledge in the field and discuss some of the clinical implications.
Asunto(s)
Diferenciación Celular , Fusión Celular , Macrófagos/citología , Células Madre/citología , Adulto , Animales , HumanosRESUMEN
Bone marrow contains many cell types, including stroma, vascular cells, adipocytes, osteoblasts and osteoclasts, as well as mesenchymal stem cells and hematopoietic stem cells. It was previously thought that cells within bone marrow solely functioned to regenerate cells within the marrow, as well as all circulating hematopoietic cells in peripheral blood. Recent reports, however, suggest that marrow-derived cells can also regenerate other cell types, including cardiac muscle, liver cell types, neuronal and non-neuronal cell types of the brain, as well as endothelial cells and osteoblasts. These multiple cell types could have originated from either of the stem cell populations within bone marrow or potentially other precursors. Therefore, it is not entirely clear whether each of these distinct cell lineages has a true progenitor within marrow or whether the marrow contains a multipotent population of cells that has been set aside during embryogenesis for postnatal repair and remodeling of a variety of tissues. It is clear, however, that directing the fate of bone marrow-derived progenitors (ie toward hematopoietic, vascular or cardiac cell fates) can only be accomplished if the phenotype of the stem cells is defined, and their homing and differentiation programs are elucidated. Much work is focused on these issues, wherein lie the key to harnessing the potential of adult stem cells for autologous cell and gene therapy.
Asunto(s)
Células de la Médula Ósea , Regeneración , Células Madre/citología , Adulto , Animales , Diferenciación Celular , Endotelio Vascular/citología , Terapia Genética/métodos , Trasplante de Células Madre Hematopoyéticas/métodos , Células Madre Hematopoyéticas , Humanos , Músculo Liso Vascular/citologíaRESUMEN
The concept that ostensibly tissue-specific stem cells can give rise to cells of heterologous lineages has gained support from studies using purified hematopoietic stem cells and sensitive donor-cell tracking methods. The ability to exploit these findings in clinical settings will probably depend on new insights into the mechanisms by which such stem cells or their progeny migrate to sites of organ damage and differentiate to cell types competent to participate in tissue regeneration.
Asunto(s)
Células Madre/fisiología , Animales , Diferenciación Celular , Linaje de la Célula , Predicción , Hematopoyesis , Células Madre Hematopoyéticas/fisiología , Humanos , Músculo Esquelético/fisiología , Neuronas/fisiologíaRESUMEN
The hematopoietic stem cell underlying acute myeloid leukemia (AML) is controversial. Flow cytometry and the DNA-binding dye Hoechst 33342 were previously used to identify a distinct subset of murine hematopoietic stem cells, termed the side population (SP), which rapidly expels Hoechst dye and can reconstitute the bone marrow of lethally irradiated mice. Here, the prevalence and pathogenic role of SP cells in human AML were investigated. Such cells were found in the bone marrow of more than 80% of 61 patients and had a predominant CD34(low/-) immunophenotype. Importantly, they carried cytogenetic markers of AML in all 11 cases of active disease examined and in 2 out of 5 cases in complete hematological remission. Comparison of daunorubicin and mitoxantrone fluorescence emission profiles revealed significantly higher drug efflux from leukemic SP cells than from non-SP cells. Three of 28 SP cell transplants generated overt AML-like disease in nonobese diabetic--severe combined immunodeficient mice. Low but persistent numbers of leukemic SP cells were detected by molecular and immunological assays in half of the remaining mice. Taken together, these findings indicate that SP cells are frequently involved in human AML and may be a target for leukemic transformation. They also suggest a mechanism by which SP cells could escape the effects of cytostatic drugs and might eventually contribute to leukemia relapse. (Blood. 2001;98:1166-1173)
Asunto(s)
Leucemia Mieloide/patología , Células Madre/patología , Enfermedad Aguda , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Animales , Antibióticos Antineoplásicos/farmacocinética , Antineoplásicos/farmacocinética , Bencimidazoles/farmacocinética , Separación Celular , Niño , Preescolar , Daunorrubicina/farmacocinética , Resistencia a Medicamentos , Femenino , Humanos , Inmunofenotipificación , Lactante , Leucemia Mieloide/tratamiento farmacológico , Leucocitos Mononucleares , Masculino , Ratones , Ratones Endogámicos NOD , Persona de Mediana Edad , Mitoxantrona/farmacocinética , Síndromes Mielodisplásicos/tratamiento farmacológico , Síndromes Mielodisplásicos/patología , Trasplante de Neoplasias , Neoplasias Primarias Secundarias , Trasplante de Células Madre , Células Madre/efectos de los fármacos , Células Tumorales Cultivadas/efectos de los fármacos , Células Tumorales Cultivadas/trasplanteRESUMEN
Recent discoveries have demonstrated the extraordinary plasticity of tissue-derived stem cells, raising fundamental questions about cell lineage relationships and suggesting the potential for novel cell-based therapies. We have examined this phenomenon in a potential reciprocal relationship between stem cells derived from the skeletal muscle and from the bone marrow. We have discovered that cells derived from the skeletal muscle of adult mice contain a remarkable capacity for hematopoietic differentiation. Cells prepared from muscle by enzymatic digestion and 5 day in vitro culture were harvested and introduced into each of six lethally irradiated recipients together with distinguishable whole bone marrow cells. Six and twelve weeks later, all recipients showed high-level engraftment of muscle-derived cells representing all major adult blood lineages. The mean total contribution of muscle cell progeny to peripheral blood was 56%, indicating that the cultured muscle cells generated approximately 10- to 14-fold more hematopoietic activity than whole bone marrow. Although the identity of the muscle-derived hematopoietic stem cells is still unknown, they may be identical to muscle satellite cells, some of which lack myogenic regulators and could respond to hematopoietic signals. We have also found that stem cells in the bone marrow can contribute to cardiac muscle repair and neovascularization after ischemic injury. We transplanted highly purified bone marrow stem cells into lethally irradiated mice that subsequently were rendered ischemic by coronary artery occlusion and reperfusion. The engrafted stem cells or their progeny differentiated into cardiomyocytes and endothelial cells and contributed to the formation of functional tissue.
Asunto(s)
Células de la Médula Ósea/citología , Hematopoyesis/fisiología , Músculo Esquelético/citología , Células Madre/citología , Factores de Edad , Animales , Trasplante de Médula Ósea , Diferenciación Celular , Linaje de la Célula , Trasplante de Células , Células Cultivadas/trasplante , Supervivencia de Injerto , Células Madre Hematopoyéticas/citología , Humanos , Ratones , Ratones Endogámicos C57BL , Desarrollo de Músculos , Músculo Esquelético/crecimiento & desarrollo , Isquemia Miocárdica/terapia , Daño por Reperfusión Miocárdica/terapia , Miocardio/patología , Neovascularización Fisiológica , Especificidad de Órganos , Quimera por Radiación , Trasplante de Células MadreRESUMEN
Myocyte loss in the ischemically injured mammalian heart often leads to irreversible deficits in cardiac function. To identify a source of stem cells capable of restoring damaged cardiac tissue, we transplanted highly enriched hematopoietic stem cells, the so-called side population (SP) cells, into lethally irradiated mice subsequently rendered ischemic by coronary artery occlusion for 60 minutes followed by reperfusion. The engrafted SP cells (CD34(-)/low, c-Kit(+), Sca-1(+)) or their progeny migrated into ischemic cardiac muscle and blood vessels, differentiated to cardiomyocytes and endothelial cells, and contributed to the formation of functional tissue. SP cells were purified from Rosa26 transgenic mice, which express lacZ widely. Donor-derived cardiomyocytes were found primarily in the peri-infarct region at a prevalence of around 0.02% and were identified by expression of lacZ and alpha-actinin, and lack of expression of CD45. Donor-derived endothelial cells were identified by expression of lacZ and Flt-1, an endothelial marker shown to be absent on SP cells. Endothelial engraftment was found at a prevalence of around 3.3%, primarily in small vessels adjacent to the infarct. Our results demonstrate the cardiomyogenic potential of hematopoietic stem cells and suggest a therapeutic strategy that eventually could benefit patients with myocardial infarction.
Asunto(s)
Endotelio Vascular/citología , Trasplante de Células Madre Hematopoyéticas , Células Madre Hematopoyéticas/fisiología , Isquemia Miocárdica/fisiopatología , Miocardio/citología , Regeneración/fisiología , Animales , Médula Ósea/efectos de la radiación , Endotelio Vascular/metabolismo , Humanos , Inmunohistoquímica , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Infarto del Miocardio/patología , Isquemia Miocárdica/patología , Isquemia Miocárdica/terapia , Miocardio/metabolismo , beta-Galactosidasa/metabolismoRESUMEN
After embryonic development, the vast majority of cells are differentiated and all organs are in place. Growth of the organism then ensues and continues until adulthood, whereupon cell division largely ceases. In some tissues, notably the bone marrow, skin, and gut, cell proliferation continues throughout life to replace cells lost by attrition. This regeneration is fueled by rare, long-lived, and largely quiescent stem cells that give rise to committed progenitors, which in turn generate large numbers of fully differentiated cells. Mounting evidence suggests that such cells can significantly contribute to tissue repair and regeneration in adults and may therefore prove beneficial for autologous cell and gene therapies. This review focuses on the potential of adult stem cells to give rise to hematopoietic and vascular cells. We discuss evidence that a highly purified population of adult stem cells, termed SP cells, serves as a hematopoietic progenitor and can contribute to vascular regeneration after injury. We also discuss the potential relationship of these cells to the embryonic hemangioblast.
Asunto(s)
Vasos Sanguíneos/embriología , Hematopoyesis , Células Madre Hematopoyéticas/fisiología , Adulto , Factores de Crecimiento Endotelial/análisis , Endotelio Vascular/citología , Endotelio Vascular/embriología , Humanos , Músculo Liso Vascular/citología , Músculo Liso Vascular/embriología , Factor A de Crecimiento Endotelial VascularRESUMEN
A novel Hoechst 33342 dye efflux assay was recently developed that identifies a population of hematopoietic cells termed side population (SP) cells. In the bone marrow of multiple species, including mice and primates, the SP is composed primarily of CD34(-) cells, yet has many of the functional properties of hematopoietic stem cells (HSCs). This report characterizes SP cells from human umbilical cord blood (UCB). The SP in unfractionated UCB was enriched for CD34(+) cells but also contained a large population of CD34(-) cells, many of which were mature lymphocytes. SP cells isolated from UCB that had been depleted of lineage-committed cells (Lin(-) UCB) contained CD34(+) and CD34(-) cells in approximately equivalent proportions. Similar to previous descriptions of human HSCs, the CD34(+)Lin(-) SP cells were CD38(dim)HLA-DR(dim)Thy-1(dim)CD45RA(-)CD71(-) and were enriched for myelo-erythroid precursors. In contrast, the CD34(-)Lin(-) SP cells were CD38(-)HLA-DR(-)Thy-1(-)CD71(-) and failed to generate myelo-erythroid progeny in vitro. The majority of these cells were CD7(+)CD11b(+)CD45RA(+), as might be expected of early lymphoid cells, but did not express other lymphoid markers. The CD7(+)CD34(-)Lin(-) UCB SP cells did not proliferate in simple suspension cultures but did differentiate into natural killer cells when cultured on stroma with various cytokines. In conclusion, the human Lin(-) UCB SP contains both CD34(+) multipotential stem cells and a novel CD7(+)CD34(-)Lin(-) lymphoid progenitor. This observation adds to the growing body of evidence that CD34(-) progenitors exist in humans.
Asunto(s)
Sangre Fetal , Células Madre Hematopoyéticas , Linfocitos , Animales , Antígenos CD34 , Antígenos CD7 , Bencimidazoles , Diferenciación Celular , Linaje de la Célula , Colorantes Fluorescentes , Células Madre Hematopoyéticas/citología , Humanos , Linfocitos/citología , RatonesRESUMEN
We have discovered that cells derived from the skeletal muscle of adult mice contain a remarkable capacity for hematopoietic differentiation. Cells prepared from muscle by enzymatic digestion and 5-day in vitro culture were harvested, and 18 x 10(3) cells were introduced into each of six lethally irradiated recipients together with 200 x 10(3) distinguishable whole bone marrow cells. After 6 or 12 weeks, all recipients showed high-level engraftment of muscle-derived cells representing all major adult blood lineages. The mean total contribution of muscle cell progeny to peripheral blood was 56 +/- 20% (SD), indicating that the cultured muscle cells generated approximately 10- to 14-fold more hematopoietic activity than whole bone marrow. When bone marrow from one mouse was harvested and transplanted into secondary recipients, all recipients showed high-level multilineage engraftment (mean 40%), establishing the extremely primitive nature of these stem cells. We also show that muscle contains a population of cells with several characteristics of bone marrow-derived hematopoietic stem cells, including high efflux of the fluorescent dye Hoechst 33342 and expression of the stem cell antigens Sca-1 and c-Kit, although the cells lack the hematopoietic marker CD45. We propose that this population accounts for the hematopoietic activity generated by cultured skeletal muscle. These putative stem cells may be identical to muscle satellite cells, some of which lack myogenic regulators and could be expected to respond to hematopoietic signals.
Asunto(s)
Hematopoyesis , Células Madre Hematopoyéticas/fisiología , Músculo Esquelético/citología , Animales , Bencimidazoles/metabolismo , Trasplante de Médula Ósea , Células Cultivadas , Citometría de Flujo , Antígenos Comunes de Leucocito/análisis , Ratones , Ratones Endogámicos C57BL , Músculo Esquelético/inmunologíaAsunto(s)
Antígenos CD34/análisis , Células Madre Hematopoyéticas/citología , Animales , Antígenos Ly/análisis , Biomarcadores , Diferenciación Celular , Trasplante de Células Madre Hematopoyéticas , Células Madre Hematopoyéticas/inmunología , Humanos , Inmunofenotipificación , Leucaféresis , Antígenos Comunes de Leucocito/análisis , RatonesRESUMEN
OBJECTIVE: To identify breed, age, sex, physical findings, history, and outcome of treatment in horses and other equids with enterolithiasis. DESIGN: Retrospective study. ANIMALS: 900 equids with enterolithiasis. PROCEDURE: Medical records from equids with enterolithiasis admitted between 1973 and 1996 were reviewed. Data on signalment, history, physical examination and clinicopathologic findings, surgical findings, and outcome were compiled from records and from telephone interviews with owners. Sex and breed predilections were determined by comparison of the study population with the general hospital population of equids during the same time period. RESULTS: Equids with enterolithiasis represented 15.1% of patients admitted for treatment colic, and 27.5% of patients undergoing celiotomy for treatment of colic. Arabian and Arabian crosses, Morgans, American Saddlebreds, and donkeys were significantly overrepresented, and Thoroughbreds, Standardbreds, warmbloods, and stallions were significantly underrepresented in the study population, compared with the hospital population. The mean age of equids with enterolithiasis was 11.4 years. The most common historic findings were signs of intermittent colic (33.3%) and passage of enteroliths in the feces (13.5%). Physical examination findings were similar to those found in equids with other forms of nonstrangulating large colon obstructive disease. Fifteen percent (131) developed gastrointestinal tract rupture caused by an enterolith that necessitated euthanasia. Short-term and 1-year survival rates for equids undergoing celiotomy for treatment of enterolithiasis and recovering from anesthesia were excellent (96.2 and 92.5%, respectively), and postoperative complications were uncommon. Recurrence of enterolithiasis was identified in 7.7% of the study population. CLINICAL IMPLICATIONS: Results indicated that shortterm and 1-year survival rates for equids undergoing surgery for enterolithiasis are excellent. Identification of signalment, history, and management factors may help identify equids with a high risk for development of enterolithiasis.
Asunto(s)
Cálculos/veterinaria , Equidae , Enfermedades de los Caballos/epidemiología , Enfermedades Intestinales/veterinaria , Factores de Edad , Animales , Cruzamiento , Cálculos/epidemiología , Cálculos/etiología , Cólico/epidemiología , Cólico/etiología , Cólico/veterinaria , Dieta/veterinaria , Femenino , Enfermedades de los Caballos/etiología , Caballos , Enfermedades Intestinales/epidemiología , Enfermedades Intestinales/etiología , Masculino , Peritonitis/epidemiología , Peritonitis/etiología , Peritonitis/veterinaria , Complicaciones Posoperatorias/epidemiología , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/veterinaria , Recurrencia , Estudios Retrospectivos , Rotura Espontánea/epidemiología , Rotura Espontánea/etiología , Rotura Espontánea/veterinaria , Factores SexualesRESUMEN
We previously described a method for isolating murine hematopoietic stem cells capable of reconstituting lethally irradiated recipients, which depends solely on dual-wavelength flow cytometric analysis of murine bone marrow cells stained with the fluorescent DNA-binding dye Hoechst 33342. This method, which appears to rely on the differential ability of stem cells to efflux the Hoechst dye, defines an extremely small and homogeneous population of cells (termed SP cells). We show here that dual-wavelength analysis of Hoechst dye-stained human, rhesus and miniature swine bone marrow cells reveals a small, distinct population of cells that efflux the dye in a manner identical to murine SP cells. Like the murine SP cells, both human and rhesus SP cells are primarily CD34-negative and lineage marker-negative. In vitro culture studies demonstrated that rhesus SP cells are highly enriched for long-term culture-initiating cells (LTC-ICs), an indicator of primitive hematopoietic cells, and have the capacity for differentiation into T cells. Although rhesus SP cells do not initially possess any hematopoietic colony-forming capability, they acquire the ability to form colonies after long-term culture on bone marrow stroma, coincident with their conversion to a CD34-positive phenotype. These studies suggest the existence of a hitherto unrecognized population of hematopoietic stem cells that lack the CD34 surface marker classically associated with primitive hematopoietic cells.