RESUMO
BACKGROUND: In the developing cerebral cortex, Radial Glia (RG) multipotent neural stem cell, among other functions, differentiate into astrocytes and serve as a scaffold for blood vessel development. After some time, blood vessel Endothelial Cells (ECs) become associated with astrocytes to form the neurovascular Blood-Brain Barrier (BBB) unit. OBJECTIVE: Since little is known about the mechanisms underlying bidirectional RG-ECs interactions in both vascular development and astrocyte differentiation, this study investigated the impact of interactions between RG and ECs mediated by secreted factors on EC maturation and gliogenesis control. METHODS: First, we demonstrated that immature vasculature in the murine embryonic cerebral cortex physically interacts with Nestin positive RG neural stem cells in vivo. Isolated Microcapillary Brain Endothelial Cells (MBEC) treated with the conditioned medium from RG cultures (RG-CM) displayed decreased proliferation, reduction in the protein levels of the endothelial tip cell marker Delta-like 4 (Dll4), and decreased expression levels of the vascular permeability associated gene, plasmalemma vesicle-associated protein-1 (PLVAP1). These events were also accompanied by increased levels of the tight junction protein expression, zonula occludens-1 (ZO-1). RESULTS: Finally, we demonstrated that isolated RG cells cultures treated with MBEC conditioned medium promoted the differentiation of astrocytes in a Vascular Endothelial Growth Factor-A (VEGF-A) dependent manner. CONCLUSION: These results suggest that the bidirectional interaction between RG and ECs is essential to induce vascular maturation and astrocyte generation, which may be an essential cell-cell communication mechanism to promote BBB establishment.
Assuntos
Astrócitos/citologia , Barreira Hematoencefálica/citologia , Diferenciação Celular/fisiologia , Células Endoteliais/citologia , Animais , Encéfalo/citologia , Encéfalo/metabolismo , Permeabilidade Capilar/fisiologia , Células Cultivadas , Camundongos , Células-Tronco Neurais/citologia , Neurogênese/fisiologiaRESUMO
The urogenital ridge (which includes the gonad and attached mesonephros) has proved to be a unique system to analyze the role of vascularization in morphogenesis of an internal organ. During the period of vascularization, development of the testis and ovary diverge morphologically. Time-lapse imaging of the gonad provides novel insights into the mechanisms that incorporate vasculature into an organ at the stage when structural organization of the tissue is initiated. Moreover, the divergent development of the testis and ovary provides a basis of comparison to correlate vascular development with the sex specific morphological development of the tissue. We are currently incorporating different cellular markers in this analysis to simultaneously image the endothelium and other cells in the organ. As far as we know, this is the first system for imaging vascular development in an organ undergoing extensive epithelial morphogenesis (Coveney et al., 2008). We are optimistic that this work will lead to further insights into the interwoven processes of cell differentiation and paracrine signaling that transform a common bipotential primordium to the highly specialized testis or ovary.
Assuntos
Diagnóstico por Imagem , Endotélio Vascular/crescimento & desenvolvimento , Gônadas/crescimento & desenvolvimento , Sistema Urogenital/anatomia & histologia , Sistema Urogenital/irrigação sanguínea , Fatores de Crescimento do Endotélio Vascular/fisiologia , Ovário/crescimento & desenvolvimento , Testículo/crescimento & desenvolvimentoRESUMO
The urogenital ridge (which includes the gonad and attached mesonephros) has proved to be a unique system to analyze the role of vascularization in morphogenesis of an internal organ. During the period of vascularization, development of the testis and ovary diverge morphologically. Time-lapse imaging of the gonad provides novel insights into the mechanisms that incorporate vasculature into an organ at the stage when structural organization of the tissue is initiated. Moreover, the divergent development of the testis and ovary provides a basis of comparison to correlate vascular development with the sex specific morphological development of the tissue. We are currently incorporating different cellular markers in this analysis to simultaneously image the endothelium and other cells in the organ. As far as we know, this is the first system for imaging vascular development in an organ undergoing extensive epithelial morphogenesis (Coveney et al., 2008). We are optimistic that this work will lead to further insights into the interwoven processes of cell differentiation and paracrine signaling that transform a common bipotential primordium to the highly specialized testis or ovary.(AU)