RESUMEN

Mesenchymal stem cells (MSC) represent a promising therapeutic approach in many diseases in view of their potent immunomodulatory properties, which are only partially understood. Here, we show that the endothelium is a specific and key target of MSC during immunity and inflammation. In mice, MSC inhibit activation and proliferation of endothelial cells in remote inflamed lymph nodes (LNs), affect elongation and arborization of high endothelial venules (HEVs) and inhibit T-cell homing. The proteomic analysis of the MSC secretome identified the tissue inhibitor of metalloproteinase-1 (TIMP-1) as a potential effector molecule responsible for the anti-angiogenic properties of MSC. Both in vitro and in vivo, TIMP-1 activity is responsible for the anti-angiogenic effects of MSC, and increasing TIMP-1 concentrations delivered by an Adeno Associated Virus (AAV) vector recapitulates the effects of MSC transplantation on draining LNs. Thus, this study discovers a new and highly efficient general mechanism through which MSC tune down immunity and inflammation, identifies TIMP-1 as a novel biomarker of MSC-based therapy and opens the gate to new therapeutic approaches of inflammatory diseases.

Asunto(s)

Células Endoteliales/metabolismo , Ganglios Linfáticos/citología , Linfocitos/fisiología , Células Madre Mesenquimatosas/fisiología , Inhibidor Tisular de Metaloproteinasa-1/metabolismo , Inhibidores de la Angiogénesis , Animales , Técnicas de Transferencia de Gen , Vectores Genéticos , Inflamación , Trasplante de Células Madre Mesenquimatosas , Células Madre Mesenquimatosas/metabolismo , Ratones , Inhibidor Tisular de Metaloproteinasa-1/administración & dosificación , Inhibidor Tisular de Metaloproteinasa-1/genética , Inhibidor Tisular de Metaloproteinasa-1/farmacología

RESUMEN

Recently, we found that mutation of the C-terminus of transcription factor hexamethylene bisacetamide-inducible protein 1 (HEXIM1) in mice leads to abnormalities in cardiovascular development because of aberrant vascular endothelial growth factor (VEGF) expression. HEXIM1 regulation of some genes has also been shown to be positive transcription elongation factor b (P-TEFb) dependent. However, it is not known whether HEXIM1 regulates VEGF in the mammary gland. We demonstrate that HEXIM1 regulates estrogen-induced VEGF transcription through inhibition of estrogen receptor-alpha recruitment to the VEGF promoter in a P-TEFb-independent manner in MCF-7 cells. Under hypoxic conditions, HEXIM1 inhibits estrogen-induced hypoxia-inducible factor-1 alpha (HIF-1alpha) protein expression and recruitment of HIF-1alpha to the hypoxia-response element in the VEGF promoter. In the mouse mammary gland, increased HEXIM1 expression decreased estrogen-driven VEGF and HIF-1alpha expression. Conversely, a mutation in the C-terminus of HEXIM1 (HEXIM1(1-312)) led to increased VEGF and HIF-1alpha expression and vascularization in mammary glands of heterozygous HEXIM1(1-312) mice when compared with their wild-type littermates. In addition, HEXIM1(1-312) mice have a higher incidence of carcinogen-induced mammary tumors with increased vascularization, suggesting an inhibitory role for HEXIM1 during angiogenesis. Taken together, our data provide evidence to suggest a novel role for HEXIM1 in cancer progression.

Asunto(s)

Células Epiteliales/metabolismo , Regulación de la Expresión Génica , Glándulas Mamarias Animales/metabolismo , Proteínas de Unión al ARN/metabolismo , Factor A de Crecimiento Endotelial Vascular/genética , Factor A de Crecimiento Endotelial Vascular/metabolismo , Animales , Carcinógenos/toxicidad , Hipoxia de la Célula/efectos de los fármacos , Línea Celular Tumoral , Células Epiteliales/efectos de los fármacos , Células Epiteliales/patología , Estradiol/farmacología , Receptor alfa de Estrógeno/metabolismo , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Glándulas Mamarias Animales/irrigación sanguínea , Glándulas Mamarias Animales/efectos de los fármacos , Glándulas Mamarias Animales/patología , Neoplasias Mamarias Experimentales/inducido químicamente , Neoplasias Mamarias Experimentales/metabolismo , Neoplasias Mamarias Experimentales/patología , Neoplasias Mamarias Experimentales/fisiopatología , Ratones , Mutación , Neovascularización Patológica/metabolismo , Neovascularización Fisiológica , Factor B de Elongación Transcripcional Positiva/metabolismo , Regiones Promotoras Genéticas/genética , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/genética , Elementos de Respuesta , Factores de Transcripción

RESUMEN

The embryonic avian heart is an important model for studying cardiac developmental biology. The mechanisms that govern the development of a four-chambered heart from a peristaltic heart tube are largely unknown due in part to a lack of adequate imaging technology. Due to the small size and rapid motion of the living embryonic avian heart, an imaging system with high spatial and temporal resolution is required to study these models. Here, an optical coherence tomography (OCT) system using a buffered Fourier Domain Mode Locked (FDML) laser is applied for ultrahigh-speed non-invasive imaging of embryonic quail hearts at 100,000 axial scans per second. The high scan rate enables the acquisition of high temporal resolution 2D datasets (195 frames per second or 5.12 ms between frames) and 3D datasets (10 volumes per second). Spatio-temporal details of cardiac motion not resolvable using previous OCT technology are analyzed. Visualization and measurement techniques are developed to non-invasively observe and quantify cardiac motion throughout the brief period of systole (less than 50 msec) and diastole. This marks the first time that the preseptated embryonic avian heart has been imaged in 4D without the aid of gating and the first time it has been viewed in cross section during looping with extremely high temporal resolution, enabling the observation of morphological dynamics of the beating heart during systole.