Publications by authors named "Joseph Hemmerle"

54 Publications

Deficiency of the SMOC2 matricellular protein impairs bone healing and produces age-dependent bone loss.

Sci Rep 2020 09 9;10(1):14817. Epub 2020 Sep 9.

Developmental Biology and Stem Cells Department, Institute of Genetics and of Molecular and Cellular Biology (IGBMC), 1 rue Laurent Fries, BP 10142, 67404, Illkirch, France.

Secreted extracellular matrix components which regulate craniofacial development could be reactivated and play roles in adult wound healing. We report a patient with a loss-of-function of the secreted matricellular protein SMOC2 (SPARC related modular calcium binding 2) presenting severe oligodontia, microdontia, tooth root deficiencies, alveolar bone hypoplasia, and a range of skeletal malformations. Turning to a mouse model, Smoc2-GFP reporter expression indicates SMOC2 dynamically marks a range of dental and bone progenitors. While germline Smoc2 homozygous mutants are viable, tooth number anomalies, reduced tooth size, altered enamel prism patterning, and spontaneous age-induced periodontal bone and root loss are observed in this mouse model. Whole-genome RNA-sequencing analysis of embryonic day (E) 14.5 cap stage molars revealed reductions in early expressed enamel matrix components (Odontogenic ameloblast-associated protein) and dentin dysplasia targets (Dentin matrix acidic phosphoprotein 1). We tested if like other matricellular proteins SMOC2 was required for regenerative repair. We found that the Smoc2-GFP reporter was reactivated in adjacent periodontal tissues 4 days after tooth avulsion injury. Following maxillary tooth injury, Smoc2 mutants had increased osteoclast activity and bone resorption surrounding the extracted molar. Interestingly, a 10-day treatment with the cyclooxygenase 2 (COX2) inhibitor ibuprofen (30 mg/kg body weight) blocked tooth injury-induced bone loss in Smoc2 mutants, reducing matrix metalloprotease (Mmp)9. Collectively, our results indicate that endogenous SMOC2 blocks injury-induced jaw bone osteonecrosis and offsets age-induced periodontal decay.
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http://dx.doi.org/10.1038/s41598-020-71749-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7481257PMC
September 2020

Functionalization of PTFE Materials Using a Combination of Polydopamine and Platelet-Rich Fibrin.

J Surg Res 2020 07 13;251:254-261. Epub 2020 Mar 13.

Institut National de la Santé et de la Recherche Médicale, UMR_S 1121, Strasbourg, France.

Background: The diaphragm, which forms a physical barrier between the thoracic and the abdominal cavities, is also the major part of the respiratory system. Congenital diaphragmatic hernia (CDH) is a malformation of that partition muscle. Expanded polytetrafluoroethylene (e-PTFE), a synthetic nondegradable biomaterial, is currently used for the repair of diaphragm defects. Indeed, this hydrophobic biomaterial does not promote rapid and dense cell colonization. Surface modifications are needed to favor or even guide cellular responses.

Materials And Methods: In this context, we present here a practical and effective way of functionalization of the e-PTFE material. We investigated, by using electron microscopy, the coating with PRF (Platelet-Rich Fibrin) of PDA (Polydopamine) treated e-PTFE implant material.

Results: We demonstrate that this straightforward chemical functionalization with PDA increases the hydrophilicity of e-PTFE and thus improves tissue integration. Then, we demonstrated that whatever the contact time between PRF and e-PTFE and the centrifugation speed, the PDA coating on the e-PTFE biomaterial promotes further biological events like cell adhesion and spreading.

Conclusions: Our findings clearly show that this composite coating (chemically by using PDA + biologically by using PRF) method of e-PTFE is a simple, interesting and promising way to favor tissular integration of such biomaterials.
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http://dx.doi.org/10.1016/j.jss.2019.11.014DOI Listing
July 2020

Technical Quality of Root Canal Filling in Preclinical Training at Strasbourg University Using Two Teaching Protocols.

Eur J Dent 2019 Oct 31;13(4):521-526. Epub 2019 Dec 31.

Department of Endodontic and Conservative Dentistry, Faculty of Dental Medicine, Strasbourg University, Strasbourg, France.

Objectives:  The aim of this study was to compare two teaching protocols according to the technical quality of root canal therapy (RCT) and the procedural errors occurred in preclinical training.

Materials And Methods:  Two different groups of students were concerned. The first one (G1) performed a crown-down technique to shape the root canal systems and cold lateral condensation technique to fill them. The second one (G2) performed a step-down technique without initial manual scouting to shape the root canal systems, and cold hydraulic condensation technique, to fill them. G2 used clinical operative microscope to check the access cavity preparation.

Statistical Analysis:  The quality of RCTs and procedural errors were recorded and analyzed using chi-squared test and -test.

Results:  Four hundred sixty-eight root canals from 152 maxillary molars were treated by the G1 students: 46.6% canals were judged as acceptable. Four hundred sixty-nine root canals from 152 mandibular molars were treated by G1: 58.8% canals were judged as acceptable. Five hundred fifteen root canals from 156 maxillary molars were treated by G2 students: 84.1% canals were judged as acceptable. Four hundred ninety-three root canals from 156 mandibular molars were treated by G2: 90.9% canals were judged as acceptable. Among the errors, the incidence of "ledges" and "fractured instruments" was statistically significant in G1 compared with G2, both on maxillary and on mandibular molars.

Conclusions:  The molar RCTs performed by G2, who got benefit from the new teaching protocol, resulted in a better quality of root filling and in fewer procedural errors compared with the molar RCTs performed by G1.
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http://dx.doi.org/10.1055/s-0039-1698848DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6938450PMC
October 2019

Effectiveness of Etching by Three Acids on the Morphological and Chemical Features of Dentin Tissue.

J Contemp Dent Pract 2019 Aug 1;20(8):915-919. Epub 2019 Aug 1.

INSERM UMR_S 1121, Biomaterials and Bioengineering, Strasbourg, France.

Aim: The purpose of this study was to evaluate the microscopic and chemical effects of phosphoric acid gel, phosphoric acid liquid, and polyacrylic acid application for 15 seconds (s) on coronal dentin.

Materials And Methods: Twelve extracted teeth were selected. Three etching acids were used to prepare the dentin surfaces. Scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDX) were used to analyze the chemical and morphological changes of the dentinal surfaces, including the depth of demineralization. Collected data were statistically analyzed by the one-way analysis of variance test.

Results: Dentin etched with phosphoric acid gel or liquid showed greater peritubular dentin dissolution, including complete removal of the smear layer. In addition, there were many silica particles on the dentin etched by phosphoric acid gel 37%. The dentin that was etched with 25% polyacrylic acid for 15 seconds showed no smear layer removal. Chemical analysis (EDX) showed that dental surfaces etched with phosphoric acid liquid 37% for 15 seconds showed the strongest mineral dissolution at the calcium surface, with a calcium content of 5.25%. On the other hand, EDX analysis of the dental surface etched with 25% polyacrylic acid showed more surface enrichment in calcium (17.19%).

Conclusion: Although phosphoric acid (gel or liquid) 37% cleans the dental surface, phosphoric acid gel precipitates silica particles on the etched dentin surface. These particles cannot be removed by rinsing off this acid. The application of polyacrylic acid for 15 seconds does not noticeably demineralized dentin, nor remove the smear layer.

Clinical Significance: The clinician should use phosphoric acid (gel or liquid) to clean dental surfaces to prepare them for the bonding process. The low demineralizing effects of the polyacrylic acid permits its use near the pulp.
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August 2019

Effect of etching the coronal dentin with the rubbing technique on the microtensile bond strength of a universal adhesive system.

Dent Med Probl 2019 Oct-Dec;56(4):343-348

Inserm UMR_S 1121, Biomaterials and Bioengineering, University of Strasbourg, France.

Background: The adhesion of composite resins to the dentin substrate is influenced by the treatment of the smear layer. While etch-and-rinse systems require dentin to be conditioned with phosphoric acid, self-etching systems preserve the smear layer by incorporating it into the adhesive layer.

Objectives: The objective of this study was to evaluate the influence of etching with the rubbing technique on the microtensile bond strength (μTBS) of a universal adhesive to dentin.

Material And Methods: Eighteen extracted teeth were selected. Two etch-and-rinse techniques (with and without rubbing) and a self-etching technique were used to bond the dentin surfaces with a universal adhesive system. After 24 h, the bonded samples were prepared for the μTBS testing. The specimens were loaded with a tensile force at a crosshead speed of 0.5 mm/min until failure. The scanning electron microscope (SEM) analyses were used to reveal the failure modes. The data were statistically analyzed with the one-way analysis of variance (ANOVA) and χ2 tests.

Results: The etch-and-rinse system with rubbing produced significantly lower bond strength (42.11 ±9.26 MPa,) than the etch-and-rinse system without rubbing (47.30 ±8.12 MPa) and significantly higher bond strength than the self-etching system (38.07 ±9.49 MPa).

Conclusions: Under the conditions of this study, dentin etched with phosphoric acid for 3 s in the etchandrinse mode with the rubbing technique for a universal adhesive system decreases the μTBS of the composite to dentin.
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http://dx.doi.org/10.17219/dmp/111697DOI Listing
January 2020

Microscopic and Chemical Assessments of the Filling Ability in Oval-Shaped Root Canals Using Two Different Carrier-Based Filling Techniques.

Eur J Dent 2019 May 1;13(2):166-171. Epub 2019 Oct 1.

Department of Endodontics, Faculty of Dental Medicine, Strasbourg University, Strasbourg, France.

Objectives: The aim of this study was to assess the filling ability in oval-shaped canals using two different carrier-based filling techniques.

Materials And Methods: Twenty-four human mandibular premolars with one oval canal were selected. Canals were shaped using WaveOne Gold Primary and ProGlider. Samples were divided into two groups and filled as follows: Thermafil and GuttaCore. The proportions of gutta-percha-filled areas (GPFAs), sealer-filled areas (SFAs), and void areas (VA), at 2 and 5 mm, were analyzed using optical numeric microscope, scanning electron microscope, and energy-dispersive X-ray.

Statistical Analysis: Data were compared by Kruskal-Wallis one-way analysis of variance on ranks, with statistical significance set at α = 0.05.

Results: At 2 and 5 mm distances from the apex, this study discloses no statistically different filling ability for the two techniques. Concerning each sample treated using both filling systems, the presence of tags was visualized. At working length (WL)-5, and WL-2, the maximum tag penetration depth for the GuttaCore group into the dentinal tubules was, respectively, 96 μm and 48 μm, whereas the values in the thermafil group were 109 μm, and 55 μm, respectively.

Conclusions: Our results clearly show that Thermafil and GuttaCore can fill oval-shaped canals in appropriate way. Furthermore, we can state that the GuttaCore obturator allows to preserve the same filling ability than Thermafil obturator, in view of the fact that there was no difference, in terms of GPFA, SFA, and VA between the two different carrier-based obturation techniques.
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http://dx.doi.org/10.1055/s-0039-1695661DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6777156PMC
May 2019

Polydopamine Functionalization: A Smart and Efficient Way to Improve Host Responses to e-PTFE Implants.

Front Chem 2019 9;7:482. Epub 2019 Jul 9.

Institut National de la Santé et de la Recherche Médicale, UMR_S 1121, Strasbourg, France.

Among the different materials used as protheses for the treatment of Congenital Diaphragmatic Hernia, expanded polytetrafluoroethylene (e-PTFE) plays a leading role owing to its mechanical properties as explained in the first part of this review. However, this material is poorly cell adhesive, which is expected for its contact on the abdominal face, but should display specific tissue adhesion on its thoracic exposed faced. A side specific functionalization method is hence required. The deposition of a nanosized polydopamine film on PTFE is known to be possible but immersion of the e-PTFE membrane in an aerated dopamine solution leads to a functionalization not only on both faces of the membrane but also in its porous volume. The fact that polydopamine also forms at the water/air interface has allowed to transfer a polydopamine film on only one face of the e-PTFE membrane. The deposition method and applications of such Janus like membranes are reviewed in the second part of the review.
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http://dx.doi.org/10.3389/fchem.2019.00482DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6629787PMC
July 2019

A New Homozygous Missense Mutation Responsible for a Milder Phenotype of Skeletal Dysplasia With Amelogenesis Imperfecta.

Front Genet 2019 28;10:504. Epub 2019 May 28.

Faculté de Chirurgie Dentaire, Université de Strasbourg, Strasbourg, France.

Amelogenesis imperfecta (AI) is a heterogeneous group of rare inherited diseases presenting with enamel defects. More than 30 genes have been reported to be involved in syndromic or non-syndromic AI and new genes are continuously discovered (Smith et al., 2017). Whole-exome sequencing was performed in a consanguineous family. The affected daughter presented with intra-uterine and postnatal growth retardation, skeletal dysplasia, macrocephaly, blue sclerae, and hypoplastic AI. We identified a homozygous missense mutation in exon 11 of (NM_001300842.2: c.908C>T; p.Pro303Leu) segregating with the disease phenotype. We found that transcripts were expressed in the epithelium of the developing mouse tooth, bones undergoing ossification, and in vertebrae. Our results revealed that SLC10A7 is overexpressed in patient fibroblasts. Patient cells display altered intracellular calcium localization suggesting that SLC10A7 regulates calcium trafficking. Mutations in this gene were previously reported to cause a similar syndromic phenotype, but with more severe skeletal defects (Ashikov et al., 2018;Dubail et al., 2018). Therefore, phenotypes resulting from a mutation in can vary in severity. However, AI is the key feature indicative of mutations in patients with skeletal dysplasia. Identifying this important phenotype will improve clinical diagnosis and patient management.
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http://dx.doi.org/10.3389/fgene.2019.00504DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6546871PMC
May 2019

Electrochemistry on Stretchable Nanocomposite Electrodes: Dependence on Strain.

ACS Nano 2018 Sep 12;12(9):9223-9232. Epub 2018 Sep 12.

Department of Chemical Engineering , University of Michigan , Ann Arbor , Michigan 48109-2136 , United States.

Stretchable nanocomposite conductors are essential for engineering of bio-inspired deformable electronics, human-machine interfaces, and energy storage devices. While the effect of strain on conductivity for stretchable conductors has been thoroughly investigated, the strain dependence of multiple other electrical-transport processes and parameters that determine the functionalities and biocompatibility of deformable electrodes has received virtually no attention. The constancy of electrochemical parameters at electrode-fluid interfaces such as redox potentials, impedances, and charge-transfer rate constants on strain is often tacitly assumed. However, it remains unknown whether these foundational assumptions actually hold true for deformable electrodes. Furthermore, it is also unknown whether the previously used charge-transport circuits describing electrochemical processes on rigid electrodes are applicable to deformable electrodes. Here, we investigate the validity of the strain invariability assumptions for an elastic composite electrode based on gold nanoparticles (AuNPs). A comprehensive model of electrode reactions that accurately describes electrochemical processes taking place on nanocomposite electrodes for ferro-/ferricyanide electrochemicals pair at different strains is developed. Unlike rigid gold electrodes, the model circuit for stretchable electrodes is comprised of two parallel impedance segments describing (a) diffusion and redox processes taking place on the open surface of the composite electrode and (b) redox processes that occur in nanopores. AuNPs forming the open-surface circuit support the redox process, whereas those forming the nanopores only increase the double-layer capacitance. The redox potential was found to be strain-independent for tensile deformations as high as 40%. Other parameters, however, display strong strain dependence, exemplified by the 2-2.5 and 27 times increases of active area of the open and nanopore surface area, respectively, after application of 40% strain. Gaining better understanding of the strain-dependent and -independent electrochemical parameters enables both fundamental and practical advances in technologies based on deformable electrodes.
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http://dx.doi.org/10.1021/acsnano.8b03962DOI Listing
September 2018

Boric Acid as an Efficient Agent for the Control of Polydopamine Self-Assembly and Surface Properties.

ACS Appl Mater Interfaces 2018 Mar 15;10(9):7574-7580. Epub 2017 Sep 15.

Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 1121 , 11 rue Humann , 67085 Strasbourg Cedex , France.

The deposition of polydopamine (PDA) films on surfaces, a versatile deposition method with respect to the nature of the used substrate, is unfortunately accompanied by deposition of insoluble precipitates in solution after a prolonged oxidation time of dopamine solutions. Therefore, there is evident interest to find methods able to stop the deposition of PDA on surfaces and to simultaneously control the self-assembly of PDA in solution to get stable colloidal aggregates. In addition to proposed methods relying on the use of polymers like poly(vinyl alcohol) and proteins like human serum albumin, we show herein that boric acid is an efficient adjuvant that is simultaneously able to stop the self-assembly of PDA in solution as well as on surfaces and to change the adhesive properties of the resulting PDA coatings.
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http://dx.doi.org/10.1021/acsami.7b08356DOI Listing
March 2018

Control of Surface-Localized, Enzyme-Assisted Self-Assembly of Peptides through Catalyzed Oligomerization.

Langmuir 2017 08 7;33(33):8267-8276. Epub 2017 Aug 7.

Université de Strasbourg, CNRS, Institut Charles Sadron UPR 22, 23 rue du Loess, F-67034 Strasbourg Cedex, France.

Localized self-assembly allowing both spatial and temporal control over the assembly process is essential in many biological systems. This can be achieved through localized enzyme-assisted self-assembly (LEASA), also called enzyme-instructed self-assembly, where enzymes present on a substrate catalyze a reaction that transforms noninteracting species into self-assembling ones. Very few LEASA systems have been reported so far, and the control of the self-assembly process through the surface properties represents one essential step toward their use, for example, in artificial cell mimicry. Here, we describe a new type of LEASA system based on α-chymotrypsin adsorbed on a surface, which catalyzes the production of (KL)OEt oligopeptides from a KLOEt (K: lysine; L: leucine; OEt ethyl ester) solution. When a critical concentration of the formed oligopeptides is reached near the surface, they self-assemble into β-sheets resulting in a fibrillar network localized at the interface that can extend over several micrometers. One significant feature of this process is the existence of a lag time before the self-assembly process starts. We investigate, in particular, the effect of the α-chymotrypsin surface density and KLOEt concentration on the self-assembly kinetics. We find that the lag time can be finely tuned through the surface density in α-chymotrypsin and KLOEt concentration. For a given surface enzyme concentration, a critical KLOEt concentration exists below which no self-assembly takes place. This concentration increases when the surface density in enzyme decreases.
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http://dx.doi.org/10.1021/acs.langmuir.7b01532DOI Listing
August 2017

Retinoic Acid Excess Impairs Amelogenesis Inducing Enamel Defects.

Front Physiol 2016 6;7:673. Epub 2017 Jan 6.

Developmental Biology and Stem Cells Department, Institute of Genetics and Molecular and Cellular Biology (IGBMC)Illkirch, France; Centre National de la Recherche Scientifique, UMR 7104Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U 964Illkirch, France; Université de StrasbourgIllkirch, France; Faculté de Chirurgie Dentaire, Université de StrasbourgStrasbourg, France.

Abnormalities of enamel matrix proteins deposition, mineralization, or degradation during tooth development are responsible for a spectrum of either genetic diseases termed or acquired enamel defects. To assess if environmental/nutritional factors can exacerbate enamel defects, we investigated the role of the active form of vitamin A, retinoic acid (RA). Robust expression of RA-degrading enzymes and in developing murine teeth suggested RA excess would reduce tooth hard tissue mineralization, adversely affecting enamel. We employed a protocol where RA was supplied to pregnant mice as a food supplement, at a concentration estimated to result in moderate elevations in serum RA levels. This supplementation led to severe enamel defects in adult mice born from pregnant dams, with most severe alterations observed for treatments from embryonic day (E)12.5 to E16.5. We identified the enamel matrix proteins (), (), and () as target genes affected by excess RA, exhibiting mRNA reductions of over 20-fold in lower incisors at E16.5. RA treatments also affected bone formation, reducing mineralization. Accordingly, craniofacial ossification was drastically reduced after 2 days of treatment (E14.5). Massive RNA-sequencing (RNA-seq) was performed on E14.5 and E16.5 lower incisors. Reductions in (a key transcriptional regulator of bone and enamel differentiation) and its targets were observed at E14.5 in RA-exposed embryos. RNA-seq analysis further indicated that bone growth factors, extracellular matrix, and calcium homeostasis were perturbed. Genes mutated in human AI () were reduced in expression at E16.5. Our observations support a model in which elevated RA signaling at fetal stages affects dental cell lineages. Thereafter enamel protein production is impaired, leading to permanent enamel alterations.
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http://dx.doi.org/10.3389/fphys.2016.00673DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5217128PMC
January 2017

Enamel and dental anomalies in latent-transforming growth factor beta-binding protein 3 mutant mice.

Eur J Oral Sci 2017 02;125(1):8-17

Faculté de Chirurgie Dentaire, Université de Strasbourg, Strasbourg, France.

Latent-transforming growth factor beta-binding protein 3 (LTBP-3) is important for craniofacial morphogenesis and hard tissue mineralization, as it is essential for activation of transforming growth factor-β (TGF-β). To investigate the role of LTBP-3 in tooth formation we performed micro-computed tomography (micro-CT), histology, and scanning electron microscopy analyses of adult Ltbp3-/- mice. The Ltbp3-/- mutants presented with unique craniofacial malformations and reductions in enamel formation that began at the matrix formation stage. Organization of maturation-stage ameloblasts was severely disrupted. The lateral side of the incisor was affected most. Reduced enamel mineralization, modification of the enamel prism pattern, and enamel nodules were observed throughout the incisors, as revealed by scanning electron microscopy. Molar roots had internal irregular bulbous-like formations. The cementum thickness was reduced, and microscopic dentinal tubules showed minor nanostructural changes. Thus, LTBP-3 is required for ameloblast differentiation and for the formation of decussating enamel prisms, to prevent enamel nodule formation, and for proper root morphogenesis. Also, and consistent with the role of TGF-β signaling during mineralization, almost all craniofacial bone components were affected in Ltbp3-/- mice, especially those involving the upper jaw and snout. This mouse model demonstrates phenotypic overlap with Verloes Bourguignon syndrome, also caused by mutation of LTBP3, which is hallmarked by craniofacial anomalies and amelogenesis imperfecta phenotypes.
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http://dx.doi.org/10.1111/eos.12328DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5260799PMC
February 2017

New insight in the biological integration of polytetrafluoroethylene from an explant used for diaphragm repair.

J Biomater Appl 2017 Jan 11;31(6):844-850. Epub 2016 Nov 11.

1 Institut National de la Santé et de la Recherche Médicale, UMR_S 1121, Strasbourg, France.

Congenital diaphragmatic hernia is a severe disease requiring diaphragm replacement mostly with expanded polytetrafluoroethylene. Unfortunately, the recurrence rate is high due to prosthesis failure with significant morbidity for the child. To provide a better understanding of the integration and possible failure processes of the biomaterial implanted in humans, we conducted electron microscopical and mechanical assessments on a prosthesis explant from a child with congenital diaphragmatic hernia presenting a recurrence. Our findings show a major penetration of connective tissue into the expanded polytetrafluoroethylene on the rough side, whereas the smooth side presents few tissue colonization. This penetration is more important in the central area (area A) with large collagen bundles and layers, in comparison to the peripheral areas without prosthesis failure (area B), where few extracellular matrix is produced. The connective tissue penetrates the prosthesis in depth. In contrast, the peripheral areas with prosthesis failure (area C) show very few cells and extracellular matrix, with an oriented organization in comparison to areas A and B. Obviously, the forces applied on the implanted material modulate the cellular behavior of the newly developed tissues. Atomic force microscopic measurements of the biomaterials' surfaces may explain some cellular behaviors according to areas with or without failure.
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http://dx.doi.org/10.1177/0885328216676757DOI Listing
January 2017

Aberration-Corrected Transmission Electron Microscopic Study of the Central Dark Line Defect in Human Tooth Enamel Crystals.

Microsc Microanal 2016 10 15;22(5):1047-1055. Epub 2016 Sep 15.

3UMET,Bâtiment C6,Université de Lille 1-Sciences et Technologies,59650 Villeneuve d'Ascq,France.

Angstrom resolution images of human tooth enamel (HTE) crystallites were obtained using aberration-corrected high-resolution transmission electron microscopy and atomic-resolution scanning transmission electron microscopy in the modes of bright field, annular dark field, and high-angle annular dark-field. Images show that the central dark line (CDL) defect observed around the center of the HTE crystals is a site for caries formation in the HTE and has a thickness of ~0.2 nm. Results also suggest that the CDL goes through one of the OH- planes.
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http://dx.doi.org/10.1017/S1431927616011648DOI Listing
October 2016

Computed Tomographic Study of the Pediatric Diaphragmatic Growth: Application to the Treatment of Congenital Diaphragmatic Hernia.

Eur J Pediatr Surg 2017 Apr 11;27(2):177-180. Epub 2016 Apr 11.

Department of Pediatric Surgery, Hôpitaux Universitaires de Strasbourg, Strasbourg, Alsace, France.

 The prosthesis commonly used for the treatment of congenital diaphragmatic hernia (CDH) lacks elasticity to replace the diaphragm's mechanical properties and does not follow the natural growth of the child treated.  To determine the appropriate properties required for the prostheses, a CT study on healthy patients was conducted.  Two methods of diaphragmatic surface analysis are assessed: the diaphragmatic surface is either estimated using surface 2D estimations (method 1), or calculated using length measures on thoracoabdominal CT scans from children (method 2). Patients are divided into two groups depending on their age: group 1:  = 9; median age: 2.0 months (0.1-9.5); group 2:  = 9; median age: 182.6 months (158.5-235.5). Growth factor between the two groups is calculated and the two methods are statistically compared.  The ratio group 2/group 1 of the diaphragmatic surfaces was 4.3 ± 0.2 on the left side and 4.0 ± 0.2 on the right side for method 1, and 5.1 ± 0.2 on the left side and 5.1 ± 0.3 on the right side for method 2. The difference in the median values between both methods is statistically significant for both the left and right sides ( = 0.022 and  = 0.002, respectively). Hence, the two methods cannot be used exchangeably.  The treatment of CDH with large defect remains a challenge because of the high incidence of hernia recurrence probably due to prosthesis defect; thus it is important to estimate the diaphragmatic surface precisely. We aim to develop a prosthesis material that can be commonly used and found a mean diaphragmatic growth factor of approximately 4 to 5 from early childhood to adolescence.
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http://dx.doi.org/10.1055/s-0036-1582242DOI Listing
April 2017

Airway administration of a highly versatile peptide-based liposomal construct for local and distant antitumoral vaccination.

Int J Pharm 2015 Dec 18;496(2):1047-56. Epub 2015 Nov 18.

Equipe de Biovectorologie, Laboratoire de Conception et Application de Molécules Bioactives, UMR 7199CNRS/Université de Strasbourg, Faculté de Pharmacie, 74 route du Rhin, 67401 Illkirch Cedex, France. Electronic address:

With the discovery of tumor-associated antigens such as ErbB2, vaccination is considered as a promising strategy to prevent the development of cancer or treat the existing disease. Among routes of immunization, the respiratory route provides the opportunity to develop non-invasive approach for vaccine delivery. In the current study, this administration route was used in order to investigate the potency of a highly versatile di-epitopic liposomal construct to exhibit local or distant antitumoral efficiency after prophylactic or therapeutic vaccination in mice. Well-characterized liposomes, containing the ErbB2 (p63-71) TCD8(+) and HA (p307-319) TCD4(+) peptide epitopes and the Pam2CAG adjuvant, were formulated and administered into the airway of naïve BALB/c mice. The nanoparticle vaccine candidate induced local and specific systemic immune response, as measured by immune cell infiltration and chemokine and cytokine production in BALF or lung tissue, and by spleen T-cell activation ex vivo, respectively. This potent immune response resulted in an efficient antitumor activity against both lung and solid s.c. tumors. Interestingly, the antitumor efficacy was observed after both prophylactic and therapeutic vaccinations, which are the most judicious ones to fight cancer. Our data showed an undeniable interest of liposomal peptide-based vaccines in antitumor vaccination by the respiratory route, opening new perspectives for cancer treatment.
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http://dx.doi.org/10.1016/j.ijpharm.2015.11.027DOI Listing
December 2015

Generating and characterizing the mechanical properties of cell-derived matrices using atomic force microscopy.

Methods 2016 Feb 9;94:85-100. Epub 2015 Oct 9.

Inserm U1109, MN3T, Strasbourg F-67200, France; Université de Strasbourg, Strasbourg F-67000, France; LabEx Medalis, Université de Strasbourg, Strasbourg F-67000, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg F-67000, France. Electronic address:

Mechanical interaction between cells and their surrounding extracellular matrix (ECM) controls key processes such as proliferation, differentiation and motility. For many years, two-dimensional (2D) models were used to better understand the interactions between cells and their surrounding ECM. More recently, variation of the mechanical properties of tissues has been reported to play a major role in physiological and pathological scenarios such as cancer progression. The 3D architecture of the ECM finely tunes cellular behavior to perform physiologically relevant tasks. Technical limitations prevented scientists from obtaining accurate assessment of the mechanical properties of physiologically realistic matrices. There is therefore a need for combining the production of high-quality cell-derived 3D matrices (CDMs) and the characterization of their topographical and mechanical properties. Here, we describe methods that allow to accurately measure the young modulus of matrices produced by various cellular types. In the first part, we will describe and review several protocols for generating CDMs matrices from endothelial, epithelial, fibroblastic, muscle and mesenchymal stem cells. We will discuss tools allowing the characterization of the topographical details as well as of the protein content of such CDMs. In a second part, we will report the methodologies that can be used, based on atomic force microscopy, to accurately evaluate the stiffness properties of the CDMs through the quantification of their young modulus. Altogether, such methodologies allow characterizing the stiffness and topography of matrices deposited by the cells, which is key for the understanding of cellular behavior in physiological conditions.
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http://dx.doi.org/10.1016/j.ymeth.2015.09.012DOI Listing
February 2016

Polydopamine Films from the Forgotten Air/Water Interface.

J Phys Chem Lett 2014 Oct 24;5(19):3436-40. Epub 2014 Sep 24.

†Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 1121, 11 rue Humann, 67085 Strasbourg Cedex, France.

The formation of polydopamine under mild oxidation conditions from dopamine solutions with mechanical agitation leads to the formation of films that can functionalize all kinds of materials. In the absence of stirring of the solution, we report the formation of polydopamine films at the air/water interface (PDA A/W) and suggest that it arises from an homogeneous nucleation process. These films grow two times faster than in solution and can be deposited on hydrophilic or hydrophobic substrates by the Langmuir-Schaeffer technique. Thanks to this new method, porous and hydrophobic materials like polytetrafluoroethylene (PTFE) membranes can be completely covered with a 35 nm thick PDA A/W film after only 3h of reaction. Finally the oxidation of a monomer followed by a polymerization in water is not exclusive to polydopamine since we also transferred polyaniline functional films from the air/water interface to solid substrates. These findings suggest that self-assembly from a solution containing hydrophilic monomers undergoing a chemical transformation (here oxidation and oligomerization) could be a general method to produce films at the liquid/air interface.
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http://dx.doi.org/10.1021/jz501842rDOI Listing
October 2014

Priming cells for their final destination: microenvironment controlled cell culture by a modular ECM-mimicking feeder film.

Biomater Sci 2015 Sep;3(9):1302-11

Institut National de la Santé et de la Recherche Médicale, INSERM Unité 1121, Biomaterials and Bioengineering, 11 rue Humann, 67085 Strasbourg Cedex, France.

Mammalian cell culture is the starting point in many research studies focusing on biomedical applications. However, researchers have little control over the standardized cell microenvironment parameters. Here a modular ECM-mimicking surface coating for cell culture environment is designed. This substrate is a new and versatile thin film obtained by spin-coating of concentrated gelatin crosslinked by transglutaminase. It can be modified with respect to the biochemical and biophysical needs of the final cell destination, i.e. it delivers loaded multi-growth factors and serum components and allows for cell culture in a serum-free culture medium. Also, a well-known cell behavior modulator, the substrate stiffness, is controlled exogenously by addition of nanoparticles. In addition to growth factors, antimicrobial agents such as natural peptides are added to the substrate for limiting the repeated addition of antimicrobial agents to the culture medium and to prevent the increase of resistant bacterial strains in the culture environment. Finally, this substrate contains simultaneously ECM components, growth factors, stiffening elements and antimicrobial agents. It provides a favorable microenvironment and sterile conditions. It is a free-of-maintenance system, as cells will grow without addition of serum or antimicrobial cocktails. This low cost and easy-to-use substrate could emerge as a new standard for cell culture.
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http://dx.doi.org/10.1039/c5bm00172bDOI Listing
September 2015

Bioactive Seed Layer for Surface-Confined Self-Assembly of Peptides.

Angew Chem Int Ed Engl 2015 Aug 15;54(35):10198-201. Epub 2015 Jul 15.

Institut Charles Sadron, CNRS-UPR 22, 23 rue du Loess, 67034 Strasbourg Cedex (France).

The design and control of molecular systems that self-assemble spontaneously and exclusively at or near an interface represents a real scientific challenge. We present here a new concept, an active seed layer that allows to overcome this challenge. It is based on enzyme-assisted self-assembly. An enzyme, alkaline phosphatase, which transforms an original peptide, Fmoc-FFY(PO4 (2-) ), into an efficient gelation agent by dephosphorylation, is embedded in a polyelectrolyte multilayer and constitutes the "reaction motor". A seed layer composed of a polyelectrolyte covalently modified by anchoring hydrogelator peptides constitutes the top of the multilayer. This layer is the nucleation site for the Fmoc-FFY peptide self-assembly. When such a film is brought in contact with a Fmoc-FFY(PO4 (2-) ) solution, a nanofiber network starts to form almost instantaneously which extents up to several micrometers into the solution after several hours. We demonstrate that the active seed layer allows convenient control over the self-assembly kinetics and the geometric features of the fiber network simply by changing its peptide density.
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http://dx.doi.org/10.1002/anie.201504761DOI Listing
August 2015

Correction: Multivalency: influence of the residence time and the retraction rate on rupture forces measured by AFM.

J Mater Chem B 2015 Apr 9;3(15):3098. Epub 2015 Mar 9.

Université de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Villers-lès-Nancy, F-54600, France.

Correction for 'Multivalency: influence of the residence time and the retraction rate on rupture forces measured by AFM' by Jalal Bacharouche et al., J. Mater. Chem. B, 2015, 3, 1801-1812.
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http://dx.doi.org/10.1039/c5tb90039eDOI Listing
April 2015

Multivalency: influence of the residence time and the retraction rate on rupture forces measured by AFM.

J Mater Chem B 2015 Mar 26;3(9):1801-1812. Epub 2015 Jan 26.

Université de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Villers-lès-Nancy, F-54600, France.

The Bell-Evans theory relative to rupture forces between non-covalently interacting molecules predicts that the rupture force increases linearly with the logarithm of the force loading rate. Here we investigate by force spectroscopy performed with an atomic force microscope (AFM) the rupture forces between surfaces covered by β-cyclodextrin (β-CD) molecules and AFM tips coated with adamantane (AD) groups. The β-CD molecules are either deposited through a self-assembled monolayer (SAM) or grafted on poly(allylamine hydrochloride) chains (PAH-CD) that are adsorbed on the substrate. The AD groups are fixed covalently on the AFM tip through either a one-AD or a four-AD platform linked to the tip though a PEO chain. It is found that while the rupture forces between AFM tips covered with tetravalent AD molecules and SAM-CD surfaces do not exceed twice those found with tips covered by monovalent AD molecules, the rupture forces increase by a factor of 20 on PAH-CD substrates for a tetravalent AD covered tip compared to a monovalent one. Thus, there seems to exist a synergistic effect between the molecule multivalence and the polymeric nature of the CD-covered substrate. As found in the literature, we observe an increase of the intensity of the rupture forces between the AD-covered AFM tip and the β-CD covered substrate with the contact time over timescales up to several seconds. Finally, we find that when the host-guest system involves the multivalency of the AD guest and/or the polymeric nature of the host the mean rupture force decreases with the loading rate in contrast to what is predicted by the Bell-Evans theory. We tentatively explain this "anti-Bell-Evans" behavior by the possibility of rebinding during the rupture process. This effect should have important implications in the understanding of forces at the cellular level.
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http://dx.doi.org/10.1039/c4tb01261eDOI Listing
March 2015

A new biomimetic route to engineer enzymatically active mechano-responsive materials.

Chem Commun (Camb) 2015 Apr;51(26):5622-5

ICS (UPR22-CNRS), 23 rue du Loess, 67034, Strasbourg, France.

Using modified β-galactosidase covalently linked to cross-linked polyelectrolyte multilayers (PEM), catalytically active materials have been designed. Their enzymatic activity can be modulated, partially in a reversible way, simply by stretching. This strategy, based on enzyme conformational changes, constitutes a new tool for the development of biocatalytic mechano-responsive materials.
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http://dx.doi.org/10.1039/c5cc00329fDOI Listing
April 2015

Mutations in the latent TGF-beta binding protein 3 (LTBP3) gene cause brachyolmia with amelogenesis imperfecta.

Hum Mol Genet 2015 Jun 10;24(11):3038-49. Epub 2015 Feb 10.

Department of Medical Genetics, University of Antwerp and Antwerp University Hospital, Prins Boudewijnlaan 43, Edegem 2650, Belgium.

Inherited dental malformations constitute a clinically and genetically heterogeneous group of disorders. Here, we report on four families, three of them consanguineous, with an identical phenotype, characterized by significant short stature with brachyolmia and hypoplastic amelogenesis imperfecta (AI) with almost absent enamel. This phenotype was first described in 1996 by Verloes et al. as an autosomal recessive form of brachyolmia associated with AI. Whole-exome sequencing resulted in the identification of recessive hypomorphic mutations including deletion, nonsense and splice mutations, in the LTBP3 gene, which is involved in the TGF-beta signaling pathway. We further investigated gene expression during mouse development and tooth formation. Differentiated ameloblasts synthesizing enamel matrix proteins and odontoblasts expressed the gene. Study of an available knockout mouse model showed that the mutant mice displayed very thin to absent enamel in both incisors and molars, hereby recapitulating the AI phenotype in the human disorder.
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http://dx.doi.org/10.1093/hmg/ddv053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4424950PMC
June 2015

Cell Alignment Driven by Mechanically Induced Collagen Fiber Alignment in Collagen/Alginate Coatings.

Tissue Eng Part C Methods 2015 Sep 17;21(9):881-8. Epub 2015 Mar 17.

1 Institut National de la Santé et de la Recherche Médicale , UMR-S 1121, "Biomaterials and Bioengineering", Strasbourg, France .

For many years it has been a major challenge to regenerate damaged tissues using synthetic or natural materials. To favor the healing processes after tendon, cornea, muscle, or brain injuries, aligned collagen-based architectures are of utmost interest. In this study, we define a novel aligned coating based on a collagen/alginate (COL/ALG) multilayer film. The coating exhibiting a nanofibrillar structure is cross-linked with genipin for stability in physiological conditions. By stretching COL/ALG-coated polydimethylsiloxane substrates, we developed a versatile method to align the collagen fibrils of the polymeric coating. Assays on cell morphology and alignment were performed to investigate the properties of these films. Microscopic assessments revealed that cells align with the stretched collagen fibrils of the coating. The degree of alignment is tuned by the stretching rate (i.e., the strain) of the COL/ALG-coated elastic substrate. Such coatings are of great interest for strategies that require aligned nanofibrillar biological material as a substrate for tissue engineering.
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http://dx.doi.org/10.1089/ten.TEC.2014.0479DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4553373PMC
September 2015

Reversible biomechano-responsive surface based on green fluorescent protein genetically modified with unnatural amino acids.

Chem Commun (Camb) 2015 Jan;51(1):232-5

ICS (UPR22-CNRS), 23 rue du Loess, 67034, Strasbourg, France.

GFP has been genetically modified at two specific positions of its molecular architecture. These modifications allow its covalent attachment onto PEG brushes grafted on functionalized silicone surfaces. The stretching of this material leads to a reversible decrease of the fluorescence intensity due to stretch-induced forces applying on GFP molecules.
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http://dx.doi.org/10.1039/c4cc07486fDOI Listing
January 2015

The laminin response in inflammatory bowel disease: protection or malignancy?

PLoS One 2014 27;9(10):e111336. Epub 2014 Oct 27.

Inserm U1109, MNT3 team, Strasbourg, France; Université de Strasbourg, Strasbourg, France; LabEx Medalis, Université de Strasbourg, Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Strasbourg, France.

Laminins (LM), basement membrane molecules and mediators of epithelial-stromal communication, are crucial in tissue homeostasis. Inflammatory Bowel Diseases (IBD) are multifactorial pathologies where the microenvironment and in particular LM play an important yet poorly understood role in tissue maintenance, and in cancer progression which represents an inherent risk of IBD. Here we showed first that in human IBD colonic samples and in murine colitis the LMα1 and LMα5 chains are specifically and ectopically overexpressed with a concomitant nuclear p53 accumulation. Linked to this observation, we provided a mechanism showing that p53 induces LMα1 expression at the promoter level by ChIP analysis and this was confirmed by knockdown in cell transfection experiments. To mimic the human disease, we induced colitis and colitis-associated cancer by chemical treatment (DSS) combined or not with a carcinogen (AOM) in transgenic mice overexpressing LMα1 or LMα5 specifically in the intestine. We demonstrated that high LMα1 or LMα5 expression decreased susceptibility towards experimentally DSS-induced colon inflammation as assessed by histological scoring and decrease of pro-inflammatory cytokines. Yet in a pro-oncogenic context, we showed that LM would favor tumorigenesis as revealed by enhanced tumor lesion formation in both LM transgenic mice. Altogether, our results showed that nuclear p53 and associated overexpression of LMα1 and LMα5 protect tissue from inflammation. But in a mutation setting, the same LM molecules favor progression of IBD into colitis-associated cancer. Our transgenic mice represent attractive new models to acquire knowledge about the paradoxical effect of LM that mediate either tissue reparation or cancer according to the microenvironment. In the early phases of IBD, reinforcing basement membrane stability/organization could be a promising therapeutic approach.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0111336PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4210184PMC
December 2015

Evidence of noncentrosymmetry of human tooth hydroxyapatite crystals.

Chemistry 2014 Jun 29;20(23):6849-52. Epub 2014 Apr 29.

Institut für Physikalische Chemie, Johannes-Gutenberg-Universität, Mainz Welderweg11, 55099 Mainz (Germany).

Herein, we investigate human single hydroxyapatite crystals (enamel and dentine) by convergent-beam electron diffraction (CBED) and automated electron-diffraction tomography (ADT). The CBED pattern shows the absence of the mirror plane perpendicular to the c axis leading to the P63 space group instead of the P63 /m space group considered for larger-scale crystals, this is confirmed by ADT. This experimental evidence is of prime importance for understanding the morphogenesis and the architectural organization of calcified tissues.
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http://dx.doi.org/10.1002/chem.201402275DOI Listing
June 2014

Nanosized films based on multicharged small molecules and oppositely charged polyelectrolytes obtained by simultaneous spray coating of interacting species.

Langmuir 2013 Nov 13;29(47):14536-44. Epub 2013 Nov 13.

Centre National de la Recherche Scientifique (CNRS), Institut Charles Sadron (UPR 22) , 23 rue du Loess, 67034 Strasbourg Cedex, France.

Simultaneous spraying of polyelectrolytes and small multicharged molecules of opposite charges onto a vertical substrate leads to continuous buildups of organic films. Here, we investigate the rules governing the buildup of two such systems: poly(allylamine hydrochloride)/sodium citrate (PAH/citrate) and PAH/sulfated α-cyclodextrin (PAH/CD-S). Special attention is paid to the film growth rate as a function of the spraying rate ratio of the two constituents. This parameter was varied by increasing the spraying rate of one of the constituents while maintaining constant that of the other. For PAH/CD-S systems, whatever the constituent (PAH or CD-S) whose spraying rate was kept fixed, the film growth rate first increases and passes through a maximum before decreasing when the spraying rate of the other constituent is increased. For PAH/citrate, the film growth rate reaches a plateau value when the spraying rate of citrate is increased while that of PAH is maintained constant, whereas when the spraying rate of citrate is maintained constant and that of PAH is increased, a behavior similar to that of PAH/CD-S is observed. The composition of PAH/CD-S sprayed films determined by X-ray photoelectron spectroscopy is independent of the spraying rate ratio of the two constituents and corresponds to one allylamine for one sulfate group. For PAH/citrate, by increasing the PAH/citrate spraying rate ratio, the carboxylic/nitrogen ratio in the film increases and tends to 1. There is thus always a deficit of carboxylic groups (COO(-) + COOH) with respect to amines (NH2 + NH3(+)). Yet, the ratio (COO(-)/NH3(+)) is always close to 1, ensuring exact charge compensation. The film morphology determined by atomic force microscopy is granular for PAH/CD-S and is smooth and liquid-like for PAH/citrate. A model based on strong (respectively weak) interactions between PAH and CD-S (respectively citrate) is proposed to explain these features.
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http://dx.doi.org/10.1021/la403580dDOI Listing
November 2013
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