The Integrin Antagonist Cilengitide Activates αVβ3, Disrupts VE-Cadherin Localization at Cell Junctions and Enhances Permeability in Endothelial Cells

Cilengitide is a high-affinity cyclic pentapeptdic αV integrin antagonist previously reported to suppress angiogenesis by inducing anoikis of endothelial cells adhering through αVβ3/αVβ5 integrins. Angiogenic endothelial cells express multiple integrins, in particular those of the β1 family, and little is known on the effect of cilengitide on endothelial cells expressing αVβ3 but adhering through β1 integrins. Through morphological, biochemical, pharmacological and functional approaches we investigated the effect of cilengitide on αVβ3-expressing human umbilical vein endothelial cells (HUVEC) cultured on the β1 ligands fibronectin and collagen I. We show that cilengitide activated cell surface αVβ3, stimulated phosphorylation of FAK (Y397 and Y576/577), Src (S418) and VE-cadherin (Y658 and Y731), redistributed αVβ3 at the cell periphery, caused disappearance of VE-cadherin from cellular junctions, increased the permeability of HUVEC monolayers and detached HUVEC adhering on low-density β1 integrin ligands. Pharmacological inhibition of Src kinase activity fully prevented cilengitide-induced phosphorylation of Src, FAK and VE-cadherin, and redistribution of αVβ3 and VE-cadherin and partially prevented increased permeability, but did not prevent HUVEC detachment from low-density matrices. Taken together, these observations reveal a previously unreported effect of cilengitide on endothelial cells namely its ability to elicit signaling events disrupting VE-cadherin localization at cellular contacts and to increase endothelial monolayer permeability. These effects are potentially relevant to the clinical use of cilengitide as anticancer agent

Thin Polymer Brush Decouples Biomaterial's Micro-/Nano-Topology and Stem Cell Adhesion

Surface morphology and chemistry of polymers used as biomaterials, such as tissue engineering scaffolds, have a strong influence on the adhesion and behavior of human mesenchymal stem cells. Here we studied semicrystalline poly(ε-caprolactone) (PCL) substrate scaffolds, which exhibited a variation of surface morphologies and roughness originating from different spherulitic superstructures. Different substrates were obtained by varying the parameters of the thermal processing, i.e. crystallization conditions. The cells attached to these polymer substrates adopted different morphologies responding to variations in spherulite density and size. In order to decouple substrate topology effects on the cells, sub-100 nm bio-adhesive polymer brush coatings of oligo(ethylene glycol) methacrylates were grafted from PCL and functionalized with fibronectin. On surfaces featuring different surface textures, dense and sub-100 nm thick brush coatings determined the response of cells, irrespective to the underlying topology. Thus, polymer brushes decouple substrate micro-/nano-topology and the adhesion of stem cells

Effets de la plagiocéphalie posturale au cours des 12 premiers mois sur le développement psychomoteur à 4 ans des enfants nés très prématurément

International audienceAims: The link between deformational plagiocephaly and psychomotor development is a recurrent question in medical publications. Main publications concentrate on term infants, but there is a lack of data on the impact of deformational plagiocephaly on the long-term neurodevelopment of premature infants. We attempted to establish a possible relation between deformational plagiocephaly during the 1st year of life and the psychomotor score at 4 years in prematurely born infants. Other risk factors potentially impacting the psychomotor score were also studied.Material and methods: A retrospective study of the files of the children followed by the "Naître et Devenir Région PACA Ouest Corse Sud" healthcare network and included in the database allowed us to select a cohort of 594 infants born prematurely at under 33 weeks of gestational age. These children were developmentally evaluated during the 1st year of life and at 4 years or age using the "EVAL Mater" test. The "Naître et Devenir" network is following up infants born prematurely at under 33 weeks of gestation in the West Provence Alpes Côte d'Azur and South Corsica region, from discharge to 7 years. A group of 170 specially trained pediatricians follow these infants developmentally at term, 3, 6, 9, 12, 18, and 24 months of corrected age and 3, 4 5, 6, and 7 years. Data are collected in a specially designed database.Results: There was no significant link between deformational plagiocephaly during the 1st year of life and a pathological psychomotor score at age 4, but some risk factors were demonstrated: male gender, birth at under 28 weeks of gestational age, weight at birth under 1000g, having a Latal and Ferriero neuromotor score equal to or greater than 2 at 3 months of corrected age, and to a lesser extent having a prescription for physiotherapy during the 1st year.Conclusion: The research on deformational plagiocephaly in the full-term infant suggests a relation between deformational plagiocephaly and developmental delay predominantly on the motor side, with an increased rate of special needs services at school age. The question is raised of whether deformational plagiocephaly is the cause of the delay or an early sign of cerebral anomaly with an early motor delay in full-term infants. The results suggest that deformational plagiocephaly in the prematurely born infant may not be related to neurodevelopmental delay but simply to the extended time spent in the supine position because of the early birth associated with physiological hypotonia and axial extension. Other risk factors such as male gender, birth before 28 weeks of gestation, weight less than 1000g, a Latal and Ferriero neuromotor score greater than 2 at 3 months of corrected age, and having a prescription for physiotherapy during the 1st year of life are strongly related to delayed psychomotor development at age 4

Comparative study of surface chemical composition and oxide layer modification upon oxygen plasma cleaning and piranha etching on a novel low elastic modulus Ti25Nb21Hf alloy

Metals are widely employed for many biological artificial replacements, and it is known that the quality and the physical/chemical properties of the surface are crucial for the success of the implant. Therefore, control over surface implant materials and their elastic moduli may be crucial to avoid undesired effects. In this study, surface modification upon cleaning and activation of a low elastic modulus Ti alloy (Ti25Hf21Nb) was investigated. Two different methods, oxygen plasma (OP) cleaning and piranha (PI) solution, were studied and compared. Both surface treatments were effective for organic contaminant removal and to increase the Ti-oxide layer thickness rather than other metal-oxides present at the surface, which is beneficial for biocompatibility of the material. Furthermore, both techniques drastically increased hydrophilicity and introduced oxidation and hydroxylation (OH)-functional groups at the surface that may be beneficial for further chemical modifications. However, these treatments did not alter the surface roughness and bulk material properties. The surfaces were fully characterized in terms of surface roughness, wettability, oxide layer composition, and hydroxyl surface density through analytical techniques (interferometry, X-ray photoelectron spectroscopy (XPS), contact angle, and zinc complexation). These findings provide essential information when planning surface modifications for cleanliness, oxide layer thickness, and surface hydroxyl density, as control over these factors is essential for many applications, especially in biomaterials.Peer ReviewedPostprint (published version

Structural and Functional Characterization of IS679 and IS66-Family Elements

A new insertion sequence (IS) element, IS679 (2,704 bp in length), has been identified in plasmid pB171 of enteropathogenic Escherichia coli B171. IS679 has imperfect 25-bp terminal inverted repeats (IRs) and three open reading frames (ORFs) (here called tnpA, tnpB, and tnpC). A plasmid carrying a composite transposon (Tn679) with the kanamycin resistance gene flanked by an intact IS679 sequence and an IS679 fragment with only IRR (IR on the right) was constructed to clarify the transposition activity of IS679. A transposition assay done with a mating system showed that Tn679 could transpose at a high frequency to the F plasmid derivative used as the target. On transposition, Tn679 duplicated an 8-bp sequence at the target site. Tn679 derivatives with a deletion in each ORF of IS679 did not transpose, finding indicative that all three IS679 ORFs are essential for transposition. The tnpA and tnpC products appear to have the amino acid sequence motif characteristic of most transposases. A homology search of the databases found that a total of 25 elements homologous to IS679 are present in Agrobacterium, Escherichia, Rhizobium, Pseudomonas, and Vibrio spp., providing evidence that the elements are widespread in gram-negative bacteria. We found that these elements belong to the IS66 family, as do other elements, including nine not previously reported. Almost all of the elements have IRs similar to those in IS679 and, like IS679, most appear to have duplicated an 8-bp sequence at the target site on transposition. These elements have three ORFs corresponding to those in IS679, but many have a mutation(s) in an ORF(s). In almost all of the elements, tnpB is located in the −1 frame relative to tnpA, such that the initiation codon of tnpB overlaps the TGA termination codon of tnpA. In contrast, tnpC, separated from tnpB by a space of ca. 20 bp, is located in any one of three frames relative to tnpB. No common structural features were found around the intergenic regions, indicating that the three ORFs are expressed by translational coupling but not by translational frameshifting