RESUMEN
Vasculogenic mesenchymal tumor (VMT), a primitive mesenchymal neoplasm enriched by various-sized atypical vessels, is a new entity that develops in mediastinal germ cell tumors (GCTs) with yolk sac tumor (YST) components after chemotherapy. Notably, patients with VMT in the residual GCT have increased risk of developing sarcomas or hematopoietic malignancies. Here, we report a late-teenage male patient with residual teratoma and high-grade VMT after chemotherapy for a mediastinal mixed GCT, including YST. Whole-exome sequencing revealed biallelic inactivation of TP53 and extensive copy number alterations that suggested whole-genome doubling. The biopsy tissue of the mixed GCT before chemotherapy exhibited overlapping genetic alterations to those in the VMT. Immunohistochemical analyses of the VMT showed that the abnormal vessels were positive for cytokeratin, glypican 3, EZH2, and IMP3. The findings that VMT inherits the genetic alterations of pre-existing mixed GCT and exhibits a partly YST-like immunophenotype might contribute to its clinical aggressiveness.
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Tumor del Seno Endodérmico , Neoplasias del Mediastino , Neoplasias de Células Germinales y Embrionarias , Teratoma , Neoplasias Testiculares , Adolescente , Humanos , Masculino , Mediastino/patología , Secuenciación del Exoma , Teratoma/genética , Teratoma/patología , Neoplasias del Mediastino/genética , Tumor del Seno Endodérmico/patología , Neoplasias Testiculares/patologíaRESUMEN
Autoimmune polyendocrine syndrome (APS) is one of the life-threatening immune-related adverse events (irAEs). We firstly report a case of APS induced by adjuvant nivolumab therapy. Clinicians should be aware of the potential risks of developing severe irAEs when applying adjuvant immunotherapy.
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Diabetes Mellitus Tipo 1 , Poliendocrinopatías Autoinmunes , Enfermedades de la Tiroides , Hormona Adrenocorticotrópica/efectos adversos , Hormona Adrenocorticotrópica/deficiencia , Diabetes Mellitus Tipo 1/inducido químicamente , Diabetes Mellitus Tipo 1/tratamiento farmacológico , Enfermedades del Sistema Endocrino , Enfermedades Genéticas Congénitas , Humanos , Hipoglucemia , Nivolumab/efectos adversos , Poliendocrinopatías Autoinmunes/inducido químicamente , Enfermedades de la Tiroides/inducido químicamenteRESUMEN
Basal cell carcinoma is the most common type of skin cancer, and surgical excision with clear margins is the standard of care. Surgical margins are determined based on risk factors (high or low risk) for recurrence according to the National Comprehensive Cancer Network and Japanese basal cell carcinoma guidelines. The clarity of the clinical tumor border (well-defined or poorly defined) is considered a risk factor, and significant discrepancies in the judgment of clinical tumor borders among dermato-oncologists may occur. Therefore, we analyzed the dermato-oncologists' concordance in judging the clinical tumor border of basal cell carcinoma. Forty-seven dermato-oncologists (experts: 37; young trainees: 10) participated in this study. The datasets of clinical and dermoscopic photographs of 79 Japanese cases of head and neck basal cell carcinoma were used to determine the concordance in the judgment of clinical tumor border. The probability of the border that was selected more often was used to calculate the rater agreement rate for each dataset. Correct judgment was defined as a more frequently selected border, and the concordance rate of clarity of clinical tumor border for each dermato-oncologist was calculated based on the definition of the correct judgment. A median concordance rate of 85% or higher for all dermato-oncologists was predefined as an acceptable rate for clinical use. Of the 79 datasets, rater agreement rates were 80-100%, 60-79%, and 51-59% for 55, 19, and five datasets, respectively. The median concordance rate for all dermato-oncologists was 86% (interquartile range: 82-89%). There was no significant difference in the concordance rate between the experts and the trainees (median, 87% vs. 85.5%; p = 0.58). The concordance rates of dermato-oncologists for all datasets were relatively high and acceptable for clinical use.
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Carcinoma Basocelular , Neoplasias de Cabeza y Cuello , Neoplasias Cutáneas , Carcinoma Basocelular/patología , Carcinoma Basocelular/cirugía , Humanos , Japón , Juicio , Márgenes de Escisión , Neoplasias Cutáneas/diagnóstico , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/cirugíaRESUMEN
BACKGROUND: Basal cell carcinoma (BCC) is the most common skin cancer. While Mohs micrographic surgery is commonly accepted for BCC treatment, surgical excision with free margins is widely considered the best treatment modality for BCCs in Japan. However, little is known about the predictors of the invasion levels of BCCs. OBJECTIVE: To investigate the optimization of deep surgical margins by identifying factors significantly influencing the invasion levels of facial BCCs. METHODS: The tumor invasion level was defined as the deepest part of a tumor. Tumor thickness was measured from the top of the granular layer to the deepest extension of the tumor or from the ulcer base overlying the deepest point of invasion in ulcerated lesions. Factors independently associated with tumor thickness and invasion level were identified by multivariate analysis. Six variables were tested: age, sex, anatomical region (nose, orbit, others), histologic pattern (aggressive, non-aggressive), presence of pigmentation, and diameter. RESULTS: We included 718 cases of facial BCCs involving 705 Japanese patients. The most frequent anatomical region and histologic pattern were the nose and nodular pattern, respectively. Only tumor diameter showed a correlation with tumor thickness (ß = 0.377, P < 0.001). Tumor diameter (AOR = 71.189, 95 % CI: 11.420-430.931, P = 0.01) and the following anatomical regions showed correlations with the invasion level: nose/others: AOR=2.769, 95 % CI: 1.235-6.493, P = 0.01; orbit/others: AOR=6.369, 95 % CI: 2.728-15.429, P < 0.001; orbit/nose: AOR=2.300, 95 % CI: 1.056-4.984, P = 0.04. CONCLUSIONS: This study serves as a guide for optimizing deep surgical margins and planning surgery for facial BCCs considering independently associated factors.
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Carcinoma Basocelular/cirugía , Procedimientos Quirúrgicos Dermatologicos/métodos , Neoplasias Faciales/cirugía , Márgenes de Escisión , Neoplasias Cutáneas/cirugía , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma Basocelular/diagnóstico , Carcinoma Basocelular/patología , Procedimientos Quirúrgicos Dermatologicos/estadística & datos numéricos , Cara , Neoplasias Faciales/diagnóstico , Neoplasias Faciales/patología , Femenino , Humanos , Japón , Masculino , Persona de Mediana Edad , Invasividad Neoplásica , Planificación de Atención al Paciente , Pronóstico , Estudios Retrospectivos , Piel/patología , Neoplasias Cutáneas/diagnóstico , Neoplasias Cutáneas/patología , Carga Tumoral , Adulto JovenRESUMEN
Vitiligo is an autoimmune disorder resulting from the destruction of melanocytes. Several reports indicate the association between vitiligo and treatment response in advanced melanoma during immunotherapy. It has not been investigated, however, if an increase of vitiligo while on treatment with anti-programmed death 1 (PD-1) antibodies is associated with more durable responses. The aim of this study is to evaluate the correlation between the vitiligo dynamics and clinical efficacy of anti-PD-1 antibodies. This study included advanced melanoma patients who were treated with nivolumab or pembrolizumab and developed vitiligo thereafter. Correlation between vitiligo expansion (defined as an increase of lesion size at two separate time points at least 4 weeks apart) as well as vitiligo extent (body surface area [BSA] affected) and clinical efficacy based on response rate, progression-free survival and overall survival was assessed. We retrospectively reviewed 29 patients. The median time from the initiation of anti-PD-1 antibody to vitiligo onset was 4.3 months in patients who showed a response and 5.5 months in patients who showed no response (P = 0.31). Twelve patients showed vitiligo expansion, and in nine of these patients, vitiligo increased to grade 2 (covering ≥ 10% BSA). Vitiligo expansion and grade 2 vitiligo showed no improvement in treatment response (P = 0.59 and 0.25) but were associated with prolonged progression-free survival (P = 0.019 and 0.04). Grade 2 vitiligo also showed a trend for prolonged overall survival (P = 0.07). Trend of expansion and larger vitiligo extent may be predictive factors of prolonged survival during anti-PD-1 antibody in melanoma patients.
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Inhibidores de Puntos de Control Inmunológico/efectos adversos , Melanoma/tratamiento farmacológico , Neoplasias Cutáneas/tratamiento farmacológico , Vitíligo/diagnóstico , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Monoclonales Humanizados/administración & dosificación , Anticuerpos Monoclonales Humanizados/efectos adversos , Relación Dosis-Respuesta a Droga , Esquema de Medicación , Femenino , Humanos , Inhibidores de Puntos de Control Inmunológico/administración & dosificación , Masculino , Melanoma/diagnóstico , Melanoma/inmunología , Melanoma/mortalidad , Persona de Mediana Edad , Estadificación de Neoplasias , Nivolumab/administración & dosificación , Nivolumab/efectos adversos , Pronóstico , Receptor de Muerte Celular Programada 1/antagonistas & inhibidores , Receptor de Muerte Celular Programada 1/inmunología , Supervivencia sin Progresión , Estudios Retrospectivos , Índice de Severidad de la Enfermedad , Piel/inmunología , Piel/patología , Neoplasias Cutáneas/diagnóstico , Neoplasias Cutáneas/inmunología , Neoplasias Cutáneas/mortalidad , Vitíligo/inducido químicamente , Vitíligo/inmunologíaRESUMEN
Intra-bone marrow injection is a novel strategy for hematopoietic stem cell transplantation. Here, we investigated whether ex vivo culture of cord blood hematopoietic stem/progenitor cells influences their reconstitution in bone marrow after intra-bone marrow transplantation. Freshly isolated AC133(+) cells or cells derived from AC133(+) cells cultured with cytokines (stem cell factor, flt-3 ligand, and thrombopoietin) for 5 days were injected into the bone marrow of the left tibia in irradiated NOD/SCID mice. In the bone marrow of the injected left tibia, the engraftment levels of human CD45(+) cells at 6 weeks after transplantation did not differ considerably between transplantation of noncultured and cytokine-cultured cells. However, the migration and distribution of transplanted cells to the bone marrow of other, noninjected bones were extremely reduced for cytokine-treated cells compared with noncultured cells. Similar findings were observed for engraftment of CD34(+) cells. Administration of granulocyte colony-stimulating factor to mice after transplantation induced the migration of cytokine-cultured cells to the bone marrow of previously aspirated bone but not to other intact bones. These data suggest that ex vivo manipulation of hematopoietic progenitor/stem cells significantly affects their migration properties to other bone marrow compartments after intra-bone marrow transplantation. Our data raise a caution for future clinical applications of the intra-bone marrow transplantation method using ex vivo-manipulated hematopoietic stem cells.
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Trasplante de Células Madre Hematopoyéticas , Células Madre Hematopoyéticas/citología , Antígeno AC133 , Animales , Antígenos CD/metabolismo , Células de la Médula Ósea/citología , Células de la Médula Ósea/metabolismo , Trasplante de Médula Ósea , Técnicas de Cultivo de Célula , Movimiento Celular , Trasplante de Células Madre de Sangre del Cordón Umbilical , Glicoproteínas/metabolismo , Supervivencia de Injerto , Células Madre Hematopoyéticas/metabolismo , Humanos , Ratones , Ratones Endogámicos NOD , Ratones SCID , Péptidos/metabolismo , Trasplante HeterólogoAsunto(s)
Melanoma , Neoplasias Cutáneas , Humanos , Proteínas Proto-Oncogénicas B-raf/genética , Melanoma/tratamiento farmacológico , Melanoma/genética , Melanoma/patología , Neoplasias Cutáneas/tratamiento farmacológico , Neoplasias Cutáneas/genética , Inhibidores de Proteínas Quinasas/uso terapéutico , Inhibidores de Proteínas Quinasas/farmacología , Quinasas de Proteína Quinasa Activadas por Mitógenos/genética , Mutación , Línea Celular Tumoral , Proteínas de la Membrana/genética , GTP Fosfohidrolasas/genética , Melanoma Cutáneo MalignoRESUMEN
BACKGROUND: Due to resistance and immune-related adverse events (irAE) some melanoma patients require ipilimumab after nivolumab therapy. However, little is known about the result of this switching. OBJECTIVE: Investigate the outcome of ipilimumab switching in Japanese patients. METHODS: We retrospectively collected 60 patients who were treated with ipilimumab after nivolumab from 9 institutes in Japan. Information of the primary tumor, treatment, response, irAE), and survival was collected. RESULTS: In our cohort, acral lentiginous and mucosal melanoma accounted for 53% of the cases. The most common reason for initiating ipilimumab was disease progression (93%). Median interval from the last nivolumab administration to first ipilimumab administration was 29days. Only 38% of patients completed 4 injections of ipilimumab. The best overall response was 3.6%. IrAE occurred in 78% of patients and 70% of those were of grade 3/4 (G3/4) and 31% of patients experienced 2 or more irAEs. An within interval of 28days or less between the last nivolumab administration and ipilimumab administration was correlated with the development of G3/4 pyrexia and 3 or more irAEs, but irAE occurrence did not affect survival. Multivariate analysis showed that endocrine irAE (relative risk=0.22, P=0.015) and skin irAE (relative risk=2.78, P=0.048) were significant factors associated with survival. CONCLUSION: In our study, the response ratio to ipilimumab after nivolumab was unsatisfactory and associated with a high frequency of severe irAEs. As there are few second-line treatment options for patients with BRAF wild-type advanced melanoma after nivolumab failure, patients should be closely monitored if ipilimumab is initiated.
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Antineoplásicos Inmunológicos/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Melanoma/tratamiento farmacológico , Neoplasias Cutáneas/tratamiento farmacológico , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Monoclonales/uso terapéutico , Progresión de la Enfermedad , Supervivencia sin Enfermedad , Sustitución de Medicamentos/efectos adversos , Sustitución de Medicamentos/métodos , Femenino , Humanos , Ipilimumab/uso terapéutico , Japón , Masculino , Melanoma/inmunología , Melanoma/mortalidad , Persona de Mediana Edad , Nivolumab , Estudios Retrospectivos , Neoplasias Cutáneas/inmunología , Neoplasias Cutáneas/mortalidad , Insuficiencia del TratamientoRESUMEN
We describe a patient with low-titer cold agglutinin disease (CAD) who developed mixed-type autoimmune hemolytic anemia (AIHA) and idiopathic thrombocytopenia following chicken pox infection. At least 1 year before admission to hospital, the patient had mild hemolytic anemia associated with low-titer cold agglutinins. A severe hemolytic crisis and thrombocytopenia (Evans' syndrome) occurred several days after infection with chicken pox, and the patient was referred to our hospital. Serological findings revealed the presence of both cold agglutinins and warm-reactive autoantibodies against erythrocytes, and the diagnosis was mixed-type AIHA. Following steroid therapy, the hemoglobin (Hb) level and platelet count improved. The patient was closely followed over a 10-year period with recurrent documented hemolysis after viral or bacterial infections. Warm-reactive autoantibodies have not been detected in the last 2 years, and only the immunoglobulin M anti-I cold agglutinins with a low titer and wide thermal amplitude have remained unchanged. Therefore, the patient has received at least 10 mg prednisolone daily to maintain a Hb level of 10 g/dL. To the best of our knowledge, no adult case of low-titer CAD that has evolved into mixed-type AIHA and Evans' syndrome after chicken pox infection has been previously reported in the literature.
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Anemia Hemolítica Autoinmune/tratamiento farmacológico , Antiinflamatorios/administración & dosificación , Varicela , Prednisolona/administración & dosificación , Trombocitemia Esencial/tratamiento farmacológico , Anemia Hemolítica Autoinmune/sangre , Anemia Hemolítica Autoinmune/complicaciones , Anemia Hemolítica Autoinmune/etiología , Autoanticuerpos/sangre , Varicela/sangre , Varicela/etiología , Femenino , Estudios de Seguimiento , Hemoglobinas/análisis , Humanos , Inmunoglobulina M/sangre , Persona de Mediana Edad , Recuento de Plaquetas , Síndrome , Trombocitemia Esencial/sangre , Trombocitemia Esencial/etiologíaRESUMEN
Histone acetylation controls the expression of specific genes in eukaryotic cells. We investigated the role of histone deacetylases (HDACs) in the differentiation of human erythroid cells, using pharmacological approaches. When CD36+ erythroid precursor cells, generated from CD34+ cells with stem cell factor, flt-3 ligand, thrombopoietin, interleukin-3, interleukin-6, and erythropoietin, were cultured with an HDAC inhibitor FK228 (depsipeptide) at a specified dose in the presence of erythropoietin, their differentiation was inhibited, as determined by the expression of CD45 and glycophorin A. Addition of the same dose of FK228 to cultures did not affect the growth of CD36+ cells. Regardless of the presence or absence of FK228, cultured CD36+ cells displayed similar proliferation kinetics. Analysis of acetylated histones revealed that FK228 upregulated the acetylation status of histones H3 and H4 in CD36+ cells. The inhibition of CD36+ cell differentiation was restored by removal of FK228 from the culture, indicating that the modification of CD36+ cell differentiation by FK228 is reversible. Furthermore, interference with histone deacetylation by FK228 inhibited the generation of CD36+ erythroid cells from CD34+ hematopoietic progenitor cells. Our results indicate the possible involvement of HDACs in human erythropoiesis, especially the regulation of erythroid cell differentiation.
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Diferenciación Celular/fisiología , Células Eritroides/metabolismo , Histona Desacetilasas/fisiología , Acetilación/efectos de los fármacos , Antígenos CD36/análisis , Diferenciación Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Depsipéptidos/farmacología , Células Eritroides/citología , Células Eritroides/efectos de los fármacos , Eritropoyetina/farmacología , Citometría de Flujo , Glicoforinas/análisis , Histona Desacetilasas/metabolismo , Histonas/metabolismo , Humanos , Antígenos Comunes de Leucocito/análisis , Factores de TiempoRESUMEN
Interleukin (IL)-4 and IL-10 have a wide variety of activities in the immune system. We re-evaluated the action of IL-4 and IL-10 on human blood monocytes, myeloid dendritic cell (DC1) precursors, using a serum-free culture system. Both IL-4 and IL-10 inhibited the survival of CD14+ monocytes supported by granulocyte-macrophage colony-stimulating factor in a dose-dependent manner. When IL-4 and IL-10 were combined, they had synergistic effects at low doses and induced a profound suppression of CD14+ monocyte survival. When the optimal timing was determined, the exposure to IL-4 and IL-10 for the initial 2 days was essential for suppression of survival of CD14+ monocytes. Annexin V/propidium iodide staining indicates that the suppression of CD14+ monocyte survival induced by IL-4 and IL-10 results from apoptosis. Tumor necrosis factor-alpha and lipopolysaccharide abrogated the effects of IL-4 and IL-10 on CD14+ monocytes, albeit incompletely. Thus, IL-4 in synergy with IL-10 negatively regulates the survival of DC1 precursor monocytes by inducing their apoptosis, which is modulated by factors such as tumor necrosis factor-alpha and lipopolysaccharide. Our data suggest the primary activities of IL-4 and IL-10 in DC1-mediated immune responses.
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Antineoplásicos/farmacología , Supervivencia Celular , Factor Estimulante de Colonias de Granulocitos y Macrófagos/farmacología , Interleucina-10/farmacología , Interleucina-4/farmacología , Monocitos , Apoptosis , Técnicas de Cultivo de Célula , Células Dendríticas , Relación Dosis-Respuesta a Droga , HumanosAsunto(s)
Procedimientos de Cirugía Plástica , Cuero Cabelludo , Arterias , Humanos , Cuero Cabelludo/cirugía , Piel , Colgajos QuirúrgicosAsunto(s)
Anticuerpos Monoclonales Humanizados/efectos adversos , Antineoplásicos Inmunológicos/efectos adversos , Neoplasias Pulmonares/tratamiento farmacológico , Penfigoide Ampolloso/inducido químicamente , Anciano de 80 o más Años , Humanos , Pierna , Neoplasias Pulmonares/patología , Masculino , Penfigoide Ampolloso/diagnóstico , Penfigoide Ampolloso/inmunología , Índice de Severidad de la Enfermedad , Piel/efectos de los fármacos , Piel/inmunología , Piel/patologíaAsunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Trastorno del Sistema de Conducción Cardíaco/inducido químicamente , Imidazoles/efectos adversos , Oximas/efectos adversos , Piridonas/efectos adversos , Pirimidinonas/efectos adversos , Anciano de 80 o más Años , Trastorno del Sistema de Conducción Cardíaco/diagnóstico , Trastorno del Sistema de Conducción Cardíaco/fisiopatología , Electrocardiografía , Femenino , Sistema de Conducción Cardíaco/efectos de los fármacos , Sistema de Conducción Cardíaco/fisiopatología , Ventrículos Cardíacos/efectos de los fármacos , Ventrículos Cardíacos/fisiopatología , Humanos , Melanoma/tratamiento farmacológico , Neoplasias Cutáneas/tratamiento farmacológicoAsunto(s)
Antineoplásicos Inmunológicos/uso terapéutico , Dermoscopía , Neoplasias Intestinales/tratamiento farmacológico , Melanoma/tratamiento farmacológico , Melanoma/patología , Nivolumab/uso terapéutico , Neoplasias Cutáneas/tratamiento farmacológico , Neoplasias Cutáneas/patología , Anciano , Biopsia , Femenino , Humanos , Neoplasias Intestinales/patología , Melanoma Cutáneo MalignoRESUMEN
OBJECTIVE: Although the anticancer activities of histone deacetylase (HDAC) inhibitors have been studied, a role for HDAC in normal hematopoiesis has not been clearly defined. Previous studies have shown that the potent HDAC inhibitor FK228 stimulates interleukin (IL)-3-mediated erythropoiesis. Here, we examined whether the widely used valproic acid (VPA) affects megakaryopoiesis as well as erythropoiesis. MATERIALS AND METHODS: CD34(+) cells were incubated in serum-free or serum-containing cultures with cytokines, with or without VPA. RESULTS: In the serum-free cultures containing IL-3+stem cell factor (SCF), VPA significantly increased generation of CD61(+)GPA(-) megakaryocytic and a CD61(+)GPA(+) mixture of megakaryocytic and erythroid precursors from CD34(+) hematopoietic precursors at a pharmacological concentration (100 microg/mL). The increase in generation of megakaryocytic and erythroid precursors by VPA was confirmed by replating cultured cells with thrombopoietin+SCF and erythropoietin+SCF, respectively. VPA was as potent as FK228. In cultures with granulocyte-macrophage colony-stimulating factor+SCF, where CD61(-)GPA(+) erythroid precursors were mostly developed, VPA mainly enhanced the generation of CD61(-)GPA(+) erythroid precursors. In serum-containing cultures, only low numbers of CD61(+) or GPA(+) cells were developed with IL-3+SCF. Nevertheless, a substantial number of these cells were generated with VPA. Furthermore, these stimulating effects of VPA were observed by incubating CD34(+) cells from patients with myelodysplastic syndrome. Quantitative reverse transcription polymerase chain reaction showed that VPA enhanced GATA-2, but not GATA-1, messenger RNA expression with IL-3+SCF. CONCLUSIONS: These results indicate a novel role for VPA in enhancing the potential of IL-3 to stimulate megakaryopoiesis as well as erythropoiesis and suggest a new therapeutic approach of epigenetic therapy for hematological disease.
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Células Precursoras Eritroides/metabolismo , Eritropoyesis/efectos de los fármacos , GABAérgicos/farmacología , Interleucina-3/farmacología , Megacariocitos/metabolismo , Trombopoyesis/efectos de los fármacos , Ácido Valproico/farmacología , Antígenos CD34 , Células Precursoras Eritroides/citología , Eritropoyetina/farmacología , Factor de Transcripción GATA1/metabolismo , Factor de Transcripción GATA2/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Integrina beta3/metabolismo , Megacariocitos/citología , Síndromes Mielodisplásicos/tratamiento farmacológico , Síndromes Mielodisplásicos/metabolismo , ARN Mensajero/metabolismo , Células Madre , Trombopoyetina/farmacologíaRESUMEN
Hepatic stellate cells are believed to play a key role in the development of liver fibrosis. Several studies have reported that bone marrow cells can give rise to hepatic stellate cells. We hypothesized that hepatic stellate cells are derived from hematopoietic stem cells. To test this hypothesis, we generated chimeric mice by transplantation of clonal populations of cells derived from single enhanced green fluorescent protein (EGFP)-marked Lin(-)Sca-1(+)c-kit(+)CD34(-) cells and examined the histology of liver tissues obtained from the chimeric mice with carbon tetrachloride (CCl(4))-induced injury. After 12 weeks of CCl(4) treatment, we detected EGFP(+) cells in the liver, and some cells contained intracytoplasmic lipid droplets. Immunofluorescence analysis demonstrated that 50% to 60% of the EGFP(+) cells were negative for CD45 and positive for vimentin, glial fibrillary acidic protein, ADAMTS13, and alpha-smooth muscle actin. Moreover, EGFP(+) cells isolated from the liver synthesized collagen I in culture. These phenotypes were consistent with those of hepatic stellate cells. The hematopoietic stem cell-derived hepatic stellate cells seen in male-to-male transplants revealed only one Y chromosome. Our findings suggest that hematopoietic stem cells contribute to the generation of hepatic stellate cells after liver injury and that the process does not involve cell fusion.