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Romeo Cecchelli

Publications and source records attributed to Romeo Cecchelli.

7 recordsLinked to original sources
PubMed2005

Induction of blood-brain barrier properties in cultured brain capillary endothelial cells: comparison between primary glial cells and C6 cell line.

The communication between glial cells and brain capillary endothelial cells is crucial for a well-differentiated blood-brain barrier (BBB). It has been suggested that in vitro primary glial cells (GCs) be replaced by the glial C6 cell line to standardise the model further. This study compares directly the structural and functional differentiation of bovine brain capillary endothelial cells (BBCECs) induced by co-culture with rat primary GCs or C6 cells, for the first time. Trans-endothelial electrical resistance (TEER) measurements showed that under no condition were C6 cells able to reproduce TEER values as high as in the presence of GCs. At the same time, permeability of the BBCECs to both radioactive sucrose and FITC-inulin was 2.5-fold higher when cells were co-cultured with C6 than with GCs. Furthermore, immunocytochemistry studies showed different cell morphology and less developed tight junction pattern of BBCECs co-cultured with C6 toward GCs. Additionally, studies on P-glycoprotein (P-gp) showed much lower P-gp presence and activity in BBCECs co-cultured with C6 than GCs. Both VEGF mRNA expression and protein content were dramatically increased when compared with GCs, suggesting that VEGF could be one of the factors responsible for higher permeability of BBB. Our results clearly indicate that, in the presence of the glial C6 cell line, BBCECs did not differentiate as well as in the co-culture with primary GCs at both structural and functional levels.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Mouse syngenic in vitro blood-brain barrier model: a new tool to examine inflammatory events in cerebral endothelium.

Although cerebral endothelium disturbance is commonly observed in central nervous system (CNS) inflammatory pathologies, neither the cause of this phenomenon nor the effective participation of blood-brain barrier (BBB) in such diseases are well established. Observations were mostly made in vivo using mouse models of chronic inflammation. This paper presents a new mouse in vitro model suitable for the study of underlying mechanistic events touching BBB functions during CNS inflammatory disturbances. This model consists of a coculture with both primary cell types isolated from mice. Mouse brain capillary endothelial cell (MBCEC)s coming from brain capillaries are in culture with their in vivo partners and form differentiated monolayers that retain endothelial markers and numerous phenotypic properties of in vivo cerebral endothelium, such as: (1) peripheral distribution of tight junction proteins (occludin, claudin-5, claudin-3 and JAM-1); (2) high trans-endothelium electrical resistance value; (3) attenuated paracellular flux of sucrose and inulin; (4) P-gp expression; (5) no MECA-32 expression. Furthermore, this endothelium expresses cell adhesion molecules described in vivo and shows intracellular cell adhesion molecule-1 and vascular cell adhesion molecule-1 upregulation under lipopolysaccharide-treatment. Therefore, this well-differentiated model using autologous cells appears as a suitable support to reconstitute pathological in vitro BBB model.

Animals↗
PubMed2005

VEGF-induced BBB permeability is associated with an MMP-9 activity increase in cerebral ischemia: both effects decreased by Ang-1.

After cerebral ischemia, angiogenesis, by supplying for the deficient perfusion, may be a beneficial process for limiting neuronal death and promoting tissue repair. In this study, we showed that the combination of Ang-1 and vascular endothelial growth factor (VEGF) provides a more adapted therapeutic strategy than the use of VEGF alone. Indeed, we showed on a focal ischemia model that an early administration of VEGF exacerbates ischemic damage, because of its effects on blood-brain barrier (BBB) permeability. In contrast, a coapplication of Ang-1 and VEGF leads to a significant reduction of the ischemic and edema volumes by 50% and 42%, respectively, in comparison with VEGF-treated mice. We proposed that Ang-1 blocks the BBB permeability effect of VEGF in association with a modulation of matrix metalloproteinase (MMP) activity. Indeed, we showed on both ischemic in vivo and BBB in vitro models that VEGF enhances BBB damage and MMP-9 activity and that Ang-1 counteracts both effects. However, we also showed a synergic angiogenic effect of Ang-1 and VEGF in the brain. Taken together, these results allow to propose that, in cerebral ischemia, the combination of Ang-1 and VEGF could be used early to promote the formation of mature neovessels without inducing side effects on BBB permeability.

Angiopoietin-1↗
PubMed2004

Down-regulation of caveolin-1 in glioma vasculature: modulation by radiotherapy.

Primary brain tumors, particularly glioblastomas (GB), remain a challenge for oncology. An element of the malignant brain tumors' aggressive behavior is the fact that GB are among the most densely vascularized tumors. To determine some of the molecular regulations occuring at the brain tumor endothelium level during tumoral progression would be an asset in understanding brain tumor biology. Caveolin-1 is an essential structural constituent of caveolae that has been implicated in mitogenic signaling, oncogenesis, and angiogenesis. In this work we investigated regulation of caveolin-1 expression in brain endothelial cells (ECs) under angiogenic conditions. In vitro, brain EC caveolin-1 is down-regulated by angiogenic factors treament and by hypoxia. Coculture of brain ECs with tumoral cells induced a similar down-regulation. In addition, activation of the p42/44 MAP kinase is demonstrated. By using an in vivo brain tumor model, we purified ECs from gliomas as well as from normal brain to investigate possible regulation of caveolin-1 expression in tumoral brain vasculature. We show that caveolin-1 expression is strikingly down-regulated in glioma ECs, whereas an increase of phosphorylated caveolin-1 is observed. Whole-brain radiation treatment, a classical way in which GB is currently being treated, resulted in increased caveolin-1 expression in tumor isolated ECs. The level of tumor cells spreading around newly formed blood vessels was also elevated. The regulation of caveolin-1 expression in tumoral ECs may reflect the tumoral vasculature state and correlates with angiogenesis kinetics.

Angiogenic Proteins↗
PubMed2003

Protective effect of glial cells against lipopolysaccharide-mediated blood-brain barrier injury.

Numerous infections of the central nervous system are characterized by altered blood-brain barrier (BBB) functions leading to brain damage. To study the mechanisms that cause BBB disruption in these pathologies, we used an in vitro BBB model consisting of a coculture of brain capillary endothelial cells and glial cells. When these endothelial cells were submitted alone to lipopolysaccharide (LPS), added in the luminal compartment, a huge increase in the paracellular permeability of the monolayer was observed. As glial cells surrounding the brain capillaries are of prime importance in specifying at least some cellular properties, we investigated whether glial cells would be able to modulate this endothelial cell response to LPS. When endothelial cells were incubated with LPS added luminally, in the presence of glial cells, LPS surprisingly had no effect on the endothelial cell monolayer permeability, suggesting a protective effect of glial cells on the LPS-mediated injury. As in our experiments, the endotoxin does not interact with the glial cell population. This protective effect suggests a close communication between cerebral endothelial cells and brain parenchymal cells. In our coculture model, the glial cell population is a mixture of astrocytes, oligodendrocytes, and microglial cells. Further experiments performed with purified astrocytes showed that microglial cells or oligodendrocytes, or both, are essential for the complete protection of the endothelial cell monolayer integrity. All these results are direct evidence for a modulatory effect of glial cells on brain capillary endothelial cell response in the pathogenesis of endotoxemia.

Animals↗
PubMed2002

Lessons from CADASIL.

Vascular dementia (VaD) includes several different vascular mechanisms and changes in the brain. Among VaD, CADASIL is an inherited angiopathy caused by mutations in the Notch3 gene. The pathological hallmark of CADASIL is a granular osmiophilic material deposit (GOM) that is not only found in the brain, but also in the peripheral vascular tree. Consequently, a window into the brain was opened from a strictly neurological disease with tremendous consequences thanks to a skin biopsy. The latter was and continues to be used as a diagnostic tool for CADASIL, despite an immunohistochemical test that is now available. The skin biopsy first used as a diagnostic tool revealed the existence of numerous other VaDs presenting systemic vascular changes. Later, skin biopsy became a research tool, and a morphological skin vessel change classification was proposed on 300 patients. Interestingly, similar skin vessel lesions appear to be related to the same biological modifications. In addition, an early destruction of the medial muscle cells was noticed in 74% of cases. Because vascular smooth muscle cells secrete a powerful endothelial permeability factor (VEGF), their destruction could lead to a decrease in vascular permeability. Cocultures of endothelial cells with vascular muscle cells showed that their presence doubled vascular permeability. Thus, alteration or the loss of vascular muscle cells likely results in hypopermeability, in addition to vessel wall hypotonia and a watershed hypoperfusion. The wealth of information brought forth by knowledge of CADASIL provided new tools for research and clues for understanding the consequences of vascular impairments in dementia.

Dementia, Multi-Infarct↗