Microfluidic traction force microscopy to study mechanotransduction in angiogenesis.

The formation of new blood vessels from existing vasculature, angiogenesis, is driven by coordinated endothelial cell migration and matrix remodelling in response to local signals. Recently, a growing body of evidence has shown that mechanotransduction, along with chemotransduction, is a major regulator of angiogenesis. Mechanical signals, such as fluid shear stress and substrate mechanics, influence sprouting and network formation, but the mechanisms behind this relationship are still unclear. Here, we present cellular traction forces as possible effectors activated by mechanosensing to mediate matrix remodelling, and encourage the use of traction force microscopy to study mechanotransduction in angiogenesis. We also suggest that deciphering the response of endothelial cells to mechanical signals could reveal an optimal angiogenic mechanical environment, and provide insight into development, wound healing, the initiation and growth of tumours, and new strategies for tissue engineering. This article is protected by copyright. All rights reserved

Endothelial Differentiation of Human Stem Cells Seeded onto Electrospun Polyhydroxybutyrate/Polyhydroxybutyrate-Co-Hydroxyvalerate Fiber Mesh

Tissue engineering is based on the association of cultured cells with structural matrices and the incorporation of signaling molecules for inducing tissue regeneration. Despite its enormous potential, tissue engineering faces a major challenge concerning the maintenance of cell viability after the implantation of the constructs. The lack of a functional vasculature within the implant compromises the delivery of nutrients to and removal of metabolites from the cells, which can lead to implant failure. In this sense, our investigation aims to develop a new strategy for enhancing vascularization in tissue engineering constructs. This study's aim was to establish a culture of human adipose tissue-derived stem cells (hASCs) to evaluate the biocompatibility of electrospun fiber mesh made of polyhydroxybutyrate (PHB) and its copolymer poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHB-HV) and to promote the differentiation of hASCs into the endothelial lineage. Fiber mesh was produced by blending 30% PHB with 70% PHB-HV and its physical characterization was conducted using scanning electron microscopy analysis (SEM). Using electrospinning, fiber mesh was obtained with diameters ranging 300 nm to 1.3 µm. To assess the biological performance, hASCs were extracted, cultured, characterized by flow cytometry, expanded and seeded onto electrospun PHB/PHB-HV fiber mesh. Various aspects of the cells were analyzed in vitro using SEM, MTT assay and Calcein-AM staining. The in vitro evaluation demonstrated good adhesion and a normal morphology of the hASCs. After 7, 14 and 21 days of seeding hASCs onto electrospun PHB/PHB-HV fiber mesh, the cells remained viable and proliferative. Moreover, when cultured with endothelial differentiation medium (i.e., medium containing VEGF and bFGF), the hASCs expressed endothelial markers such as VE-Cadherin and the vWF factor. Therefore, the electrospun PHB/PHB-HV fiber mesh appears to be a suitable material that can be used in combination with endothelial-differentiated cells to improve vascularization in engineered bone tissues

A review of mathematical models for the formation of vascular networks

Two major mechanisms are involved in the formation of blood vasculature: vasculogenesis and angiogenesis. The former term describes the formation of a capillary-like network from either a dispersed or a monolayered population of endothelial cells, reproducible also in vitro by specific experimental assays. The latter term describes the sprouting of new vessels from an existing capillary or post-capillary venule. Similar mechanisms are also involved in the formation of the lymphatic system through a process generally called lymphangiogenesis. A number of mathematical approaches have been used to analyse these phenomena. In this article, we review the different types of models, with special emphasis on their ability to reproduce different biological systems and to predict measurable quantities which describe the overall processes. Finally, we highlight the advantages specific to each of the different modelling approaches. The research that led to the present paper was partially supported by a grant of the group GNFM of INdA

R. P. Dom H. Leclercq, O. S. B. Les Martyrs, t. IV, Juifs, Sarrasins et Iconoclastes

Vailhé Siméon. R. P. Dom H. Leclercq, O. S. B. Les Martyrs, t. IV, Juifs, Sarrasins et Iconoclastes. In: Échos d'Orient, tome 9, n°58, 1906. pp. 184-186

Kléopas Koikylidès : Βίος καὶ πολιτεία τοῦ ὁσίου πατρὸς ἡμῶν Σάββα

Vailhé Siméon. Kléopas Koikylidès : Βίος καὶ πολιτεία τοῦ ὁσίου πατρὸς ἡμῶν Σάββα. In: Échos d'Orient, tome 9, n°58, 1906. p. 191

Pour l'union des Églises

Vailhé Siméon. Pour l'union des Églises. In: Échos d'Orient, tome 14, n°86, 1911. pp. 48-51

1° Henri Levantin : Quarante ans d'autonomie au Liban, Dans les Études ; 2° Le Moutasarrifat ou gouvernement autonome du Liban. Dans la Revue de l'Orient chrétien.

Vailhé Siméon. 1° Henri Levantin : Quarante ans d'autonomie au Liban, Dans les Études ; 2° Le Moutasarrifat ou gouvernement autonome du Liban. Dans la Revue de l'Orient chrétien.. In: Échos d'Orient, tome 6, n°39, 1903. pp. 158-159

H. Gelzer : Pergamon unter Byzantinern und Osmanen. Aus dem Anhang zu den Abhandlungen der Kœnigl. preuss. Akademie der Wissentschaften vom Iahre 1903.

Vailhé Siméon. H. Gelzer : Pergamon unter Byzantinern und Osmanen. Aus dem Anhang zu den Abhandlungen der Kœnigl. preuss. Akademie der Wissentschaften vom Iahre 1903.. In: Échos d'Orient, tome 7, n°45, 1904. pp. 122-123