The effects of erythritol air-polishing powder on microbiologic and clinical outcomes during supportive periodontal therapy: Six-month results of a randomized controlled clinical trial.

OBJECTIVES To characterize the physical characteristics of a new low abrasive erythritol powder (EPAP) and to evaluate its influence on the clinical and microbiologic parameters over a period of 6 months in patients undergoing supportive periodontal therapy (SPT). METHOD AND MATERIALS Prior to the clinical application, the particle size and abrasion level of EPAP were compared to glycine air-polishing powder (GPAP) ex vivo. Subsequently, 40 chronic periodontitis patients previously enrolled in SPT were randomly assigned into two groups for the treatment with subgingival EPAP or repeated scaling and root planing (SRP). At baseline (BL), bleeding on probing positive (BOP+) sites with probing pocket depth (PPD) of ≥ 4 mm but no detectable calculus were defined as study sites. During SPT, these sites were either treated by EPAP or SRP at BL, 3, and 6 months (3M, 6M). When indicated, additional SRP was provided. Plaque Index, BOP, PPD, clinical attachment level (CAL), and subgingival plaque were evaluated at BL and 6M. RESULTS EPAP yielded lower abrasiveness and smaller particle sizes when compared to GPAP. In 38 patients completing the study, EPAP and SRP resulted in significant reductions of BOP% (EPAP, 40.45%; SRP, 42.53%), PPD (EPAP, -0.67; SRP, -0.68), and increase of CAL (EPAP, 0.48; SRP, 0.61) while at 6M no statistically significant between-group differences were observed (P > .05). Microbiologic evaluation revealed minor shifts in the composition of the subgingival biofilm without influence on periodontopathogenic bacteria. CONCLUSION The subgingival use of EPAP by means of an air-polishing device may be considered safe and may lead to comparable clinical and microbiologic outcomes to those obtained with SRP. CLINICAL RELEVANCE The subgingival use of EPAP appears to represent a promising modality for the removal of subgingival biofilm during SPT.

The benefits of one-dimensional detectors for high-pressure powder X-ray diffraction

High-pressure powder X-ray diffraction is a fundamental technique for investigating structural responses to externally applied force. Synchrotron sources and two-dimensional detectors are required. In contrast to this conventional setup, high-resolution beamlines equipped with one-dimensional detectors could offer much better resolved peaks but cannot deliver accurate structure factors because they only sample a small portion of the Debye rings, which are usually inhomogeneous and spotty because of the small amount of sample. In this study, a simple method to overcome this problem is presented and successfully applied to solving the structure of an L-serine polymorph from powder data. A comparison of the obtained high-resolution high-pressure data with conventional data shows that this technique, providing up to ten times better angular resolution, can be of advantage for indexing, for lattice parameter refinement, and even for structure refinement and solution in special cases.

Novel MesoPorous BioGlass/silk scaffold containing adPDGF-B and adBMP7 for the repair of periodontal defects in beagle dogs

AIM The local delivery of growth factors via gene therapy has gained tremendous awareness in recent years due to their sustained growth factor delivery to target tissues. The aim of this study was to fabricate and investigate a scaffold able to release growth factors via gene therapy for the repair of periodontal tissues. MATERIALS AND METHODS Novel mesoporous bioglass (MBG)/silk fibrin scaffold combined with BMP7 and/or PDGF-B adenovirus was fabricated and tested in vitro for cell migration, proliferation and differentiation. Furthermore, acute-type buccal dehiscence periodontal defects (mesiodistal width × depth: 5 × 5 mm) were created on the buccal portion of the maxillary premolars in five normal male beagle dogs (12 months old, 15.0 ± 2.0 kg) and histologically examined for periodontal regeneration following implantation of the following five groups: (1) no scaffold, (2) MBG/silk scaffold alone, (3) scaffold + adPDGF-B, (4) scaffold + adBMP7, (5) scaffold + adPDGF-b + adBMP7. RESULTS In vitro findings demonstrated that adPDGF-B was able to rapidly recruit periodontal ligament (PDL) cells over sixfold more effectively than adBMP7, whereas adBMP7 was more able to induce osteoblast differentiation of PDL cells. In vivo findings demonstrate that scaffolds loaded with adPDGF-B were able to partially regenerate the periodontal ligament while adBMP7 scaffolds primarily improved new bone formation. The combination of both adPDGF-B and adBMP7 synergistically promoted periodontal regeneration by allowing up to two times greater regeneration of the periodontal ligament, alveolar bone and cementum when compared to each adenovirus used alone. CONCLUSIONS Although both PDGF-B and BMP7 are individually capable of promoting periodontal regeneration to some degree, their combination synergistically promotes wound healing in acute-type buccal dehiscence periodontal defects when delivered simultaneously. This study demonstrates the promise for successful delivery of low-cost, effective growth factor delivery via gene therapy for the treatment of periodontal defects.

Intervertebral Disc Repair using Fleece-Membrane Composite Silk Material and Genipin-enhanced Fibrin Hydrogel

Introduction: Treating low back pain (LBP) has become an increasing challenge, as it is one of the main factors causing pain and is accompanied by high costs for the individual and the society. LBP can be caused by trauma of the intervertebral disc (IVD) or IVD degeneration. In the case of disc herniation the inner gelatinous part of the IVD, called nucleus pulposus, is pressed through the fibrous, annulus fibrosus that forms the outer part of the IVD. Today’s gold standard for treatment is extensive surgery as removal of the IVD and fusion of the vertebrae. In order to find a more gentle way to treat LBP and restore the native IVD we use a novel silk fleece-membrane composite from genetically modified silk worms whose silk contains a growth factor (GDF-6) that is associated with pushing stem cells towards a disc like phenotype (1). By combining it with a genipin-enhanced fibrin hydrogel we tested its suitability in organ culture on prior injured bovine IVD in our custom built two-degree of freedom bioreactor to mimic natural loading conditions. Material & Methods: Bovine IVDs of 12-17 months old animals were isolated by first removing all surrounding tissue followed by cutting out the IVDs as previously described (2). Culturing of discs occurred in high glucose Dulbecco's Modified Eagle Medium (HG-DMEM) supplemented with 5% serum as previously described (2). On the next day injury was induced using a 2mm biopsy punch (Polymed, Switzerland). The formed cavity was filled with (0.4%) genipin-enhanced human based fibrin hydrogel (35-55mg/mL human fibrinogen, Baxter, Austria) and sealed with a silk fleece-membrane composite (Spintec Engineering, Germany). Different culture conditions were applied: free swelling, static diurnal load of 0.2MPa for 8h/d and complex loading at 0.2MPa compression combined with ± 2° torsion at 0.2Hz for 8h/d (2). After 14 days of culture cell activity was determined with resazurin assay. Additionally, glycosaminoglycan (dimethyl-methylene blue), DNA (Hoechst) and collagen content (hydroxy- proline) were determined. Finally, real-time qPCR of major IVD marker and inflammation genes was performed to judge integrity of IVDs. Results: The fibrin hydrogel is able to keep the silk seal in place throughout the 14 days of in organ culture under all conditions. Additionally, cell activity showed optimistic results and we could not confirm negative effects of the repaired discs regarding overexpression of inflammation markers. Conclusions: The genipin-enhanced fibrin hydrogel in combination with the silk fleece- membrane composite seems to be a promising approach for IVD repair. Currently we assess the capability of GDF-6 incorporated in our silk composites on human mesenchymal stem cells and later on in organ culture. References 1. Clarke LE, McConnell JC, Sherratt MJ, Derby B, Richardson SM, Hoyland JA. Growth differentiation factor 6 and transforming growth factor-beta differentially mediate mesenchymal stem cell differentiation, composition and micromechanical properties of nucleus pulposus constructs. Arthritis Res Ther 2014, Mar 12;16(2):R67. 2. Chan SC, Gantenbein-Ritter B. Preparation of intact bovine tail intervertebral discs for organ culture. J Vis Exp 2012, Feb 2;60(60):e3490. Acknowledgements. This work is funded by the Gebert Rüf Foundation, project number GRS-028/13.

Repair of Annulus fibrosus with Genipin-enhanced Fibrin Hydrogel and silk membrane- fleece

Introduction Low back pain is often caused by a trauma causing disc herniation and /or disc degeneration. Although there are some promising approaches for nucleus pulposus repair, the inner tissue of the intervertebral disc (IVD) so far no treatment or repair is available for annulus fibrosus (AF) injuries. Here we aimed to develop a new method to seal and repair AF injuries by using a silk fleece composite and a genipin enhanced hydrogel. Methods Bovine (b) IVDs were harvested under aseptic conditions and kept in free swelling conditions for 24h in high-glucose DMEM containing 5% bovine serum for equilibration (1). A circular 2mm biopsy punch (Polymed Medical Center, Switzerland) was used to form a reproducible defect in the AF. For filling the defect and keeping the silk composite in place a human-derived fibrin gel (Baxter Tisseel, Switzerland) enhanced with 4.2mg/ml of the cross linker genipin (Wako Chemicals GmbH, Germany) was used. The silk composite consists of a mesh- and a membrane side (Spintec Engineering GmbH, Germany); the membrane is facing outwards to form a seal. bIVDs were cultured in vitro for 14 days either under dynamic load in a custom-built bioreactor under physiological conditions (0.2MPa load and ±2° torsion at 0.2Hz for 8h/day) or static diurnal load of 0.2MPa (2). At the end of culture discs were checked for seal failure, disc height, metabolic activity, cell death by necrosis (LDH assay), DNA content and glycosaminoglycan content. Results Silk composite maintained its position throughout the 14 days of culture under loaded conditions. Although repaired discs performed slightly lower in cell activity, DNA and GAG content were in the range of the control. Also LDH resulted in similar values compared to control discs (Fig 1). Height loss in repaired discs was in the same range as for static diurnal loaded control samples. For dynamically loaded samples the decrease was comparable to the injured, unrepaired discs. Fig 1 LDH of repaired discs compared to control disc after 24h in free swelling conditions for equilibration and first three loading cycles. Conclusions Silk-genipin-fibrin reinforced hydrogel is a promising approach to close AF defects as tested by two degree of freedom loading. In further experiments cytocompatibility of genipin has to be investigated. References 1. Chan SC, Gantenbein-Ritter B. Preparation of intact bovine tail intervertebral discs for organ culture. J Vis Exp 2012, Feb 2;60(60):e3490. 2. Walser J, Ferguson SJ, Gantenbein-Ritter B. Design of a mechanical loading device to culture intact bovine caudal motional segments of the spine under twisting motion. In: Davies J, editors. Replacing animal models: a practical guide to creating and using biomimetic alternatives. Chichester, UK: John Wiley & Sons, Ltd.; 2012. p. 89-105. Acknowledgements This project is funded by the Gerbert Rüf Stiftung project # GRS-028/13 and the Swiss National Science Project SNF #310030_153411.

Genetically engineered silk and genipin-enhanced fibrin hydrogel for annulus fibrosus repair

INTRODUCTION: Around 80% of people are affected by low back pain at least once in their life, often caused by trauma provoking intervertebral disc (IVD) herniation and/or IVD degeneration. Apart from some promising approaches for nucleus pulposus repair, so far no treatment or repair is available for the outer fibrous tissue, annulus fibrosus (AF). We aimed for sealing and repairing an AF injury in a bovine IVD organ culture model in vitro over 14 days under different loading conditions. For this purpose, a silk fleece composite from Bombyx mori silk was combined with genipin-enhanced fibrin hydrogel [1]. METHODS: Bovine IVDs of 12-17 months old animals were isolated by first removing all surrounding tissue, followed by cutting out the IVDs [2]. Culturing of discs occurred in high glucose Dulbecco's Modified Eagle Medium (HG-DMEM) supplemented with 5% serum as previously described. On the next day, injury was induced using a 2mm biopsy punch (Polymed, Switzerland). The formed cavity was filled with (0.4%) genipin-enhanced human based fibrin hydrogel (35- 55mg/mL human fibrinogen, Baxter, Austria) and sealed with a silk fleece-membrane composite (Spintec Engineering, Germany). Different culture conditions were applied: free swelling, static diurnal load of 0.2MPa for 8h/d and complex loading at 0.2MPa compression combined with ± 2° torsion at 0.2Hz for 8h/d. Complex loading was applied by a custom built 2 degree of freedom bioreactor [3]. After 14 days of culture cell activity was determined with resazurin assay. Additionally, glycosaminoglycan (dimethyl-methylene blue), DNA (Hoechst) and collagen content (hydroxy-proline) were determined. Finally, real-time qPCR of major IVD marker genes was performed. RESULTS: The silk seal closing the injury site could successfully withstand the forces of all three loading conditions with no misplacement over the two weeks’ culture. Nevertheless, disc height of the repaired discs did not significantly differ from the injured group. The disc phenotype could be maintained as demonstrated by biochemical analysis of gene expression, cell activity, DNA-, collagen- and GAG content. The silk itself was evaluated to be highly biocompatible for hMSC, as revealed by cytotoxicity assays. DISCUSSION & CONCLUSIONS: The silk can be considered a highly-elastic and biocompatible material for AF closure and the genipin-enhanced fibrin hydrogel has also good biomechanical properties. However, the cyto-compatibility of genipin seems rather poor and other hydrogels and/or cross-linkers should be looked into. REFERENCES: 1 C.C. Guterl et al. (2014) Characterization of Mechanics and Cytocompatibility of Fibrin Genipin Annulus Fibrosus Sealant with the Addition of Cell Adhesion Molecules, Tissue Eng Part A 2 S.C. Chan, B. Gantenbein-Ritter (2012) Preparation of intact bovine tail intervertebral discs for organ culture, J Vis Exp 3 B Gantenbein et al. (2015) Organ Culture Bioreactors - Platforms to Study Human Intervertebral Disc Degeneration and Regenerative Therapy, Curr Stem Cell Res Ther [epub ahead of print] ACKNOWLEDGEMENTS: This project is supported by the Gebert Rüf Stiftung project # GRS-028/13.

Tomorrow’s Silk Road: Assessing an EU-China Free Trade Agreement

The Centre for European Policy Studies (CEPS) is an independent policy research institute in Brussels. Its mission is to produce sound policy research leading to constructive solutions to the challenges facing Europe. The views expressed in this book are entirely those of the authors and should not be attributed to CEPS or any other institution with which they are associated or to the European Union. This book, commissioned by the Foreign Trade Association, aims to provide an independent and in-depth contribution on the status of bilateral economic exchanges and persistent trade barriers between the European Union and China. A second objective is to encourage a frank and open dialogue, based on a scientific evaluation and without prejudice, of the possibility of a preferential trade agreement between the two sides. The study was carried out by CEPS, in cooperation with the World Trade Institute at the University of Bern.