Encapsulated bacteriophages in alginate-nanohydroxyapatite hydrogel as a novel delivery system to prevent orthopedic implant-associated infections.

An innovative delivery system based on bacteriophages-loaded alginate-nanohydroxyapatite hydrogel was developed as a multifunctional approach for local tissue regeneration and infection prevention and control. Bacteriophages were efficiently encapsulated, without jeopardizing phage viability and functionality, nor affecting hydrogel morphology and chemical composition. Bacteriophage delivery occurred by swelling-disintegration-degradation process of the alginate structure and was influenced by environmental pH. Good tissue response was observed following the implantation of bacteriophages-loaded hydrogels, sustaining their biosafety profile. Bacteriophages-loaded hydrogels did not affect osteoblastic cells' proliferation and morphology. A strong osteogenic and mineralization response was promoted through the implantation of hydrogels system with nanohydroxyapatite. Lastly, bacteriophages-loaded hydrogel showed excellent antimicrobial activity inhibiting the attachment and colonization of multidrug-resistant E. faecalis surrounding and within femoral tissues. This new local delivery approach could be a promising approach to prevent and control bacterial contamination during implantation and bone integration.

Effect of Splinting on Orthodontic Mini-Implant Tipping and Bone Histomorphometric Parameters: An In Vivo Animal Model Study.

This study aimed to address the stability of orthodontic mini-implants submitted to an immediate orthodontic functional load, in splinted or unsplinted conditions, further characterizing the histomorphometric parameters of the neighboring bone tissue, in an in vivo experimental model. Mini-implants (1.4 × 6.0 mm) were placed in the proximal tibia of New Zealand White rabbits and immediately loaded with a 150 g force. Tissue healing was characterized within 8 weeks. Microtomography was used to assess the mini-implants' tipping and bone histomorphometric indexes. Loaded implants were evaluated in splinted and unsplinted conditions, with data being compared to that of unloaded mini-implants with the Kruskal-Wallis nonparametric test, followed by Dunn's multiple comparison tests. The splinting of mini-implants submitted to immediate orthodontic loading significantly reduced the tipping to levels similar to those of unloaded mini-implants. Immediate loading further increased the histomorphometric indexes associated with bone formation at the peri-implant region, in both splinted and unsplinted conditions, with no significant differences between the tension and compression regions. Accordingly, within this experimental setting, splinting was found to lessen tipping and mini-implants' displacement, without affecting the increased bone formation at the peri-implant region, induced by a functional orthodontic load.

The Embryonic Chick Femur Organotypic Model as a Tool to Analyze the Angiotensin II Axis on Bone Tissue.

Activation of renin-angiotensin system (RAS) plays a role in bone deterioration associated with bone metabolic disorders, via increased Angiotensin II (AngII) targeting Angiotensin II type 1 receptor/Angiotensin II type 2 receptor (AT1R/AT2R). Despite the wide data availability, the RAS role remains controversial. This study analyzes the feasibility of using the embryonic chick femur organotypic model to address AngII/AT1R/AT2R axis in bone, which is an application not yet considered. Embryonic day-11 femurs were cultured ex vivo for 11 days in three settings: basal conditions, exposure to AngII, and modulation of AngII effects by prior receptor blockade, i.e., AT1R, AT2R, and AT1R + AT2R. Tissue response was evaluated by combining µCT and histological analysis. Basal-cultured femurs expressed components of RAS, namely ACE, AT1R, AT2R, and MasR (qPCR analysis). Bone formation occurred in the diaphyseal region in all conditions. In basal-cultured femurs, AT1R blocking increased Bone Surface/Bone Volume (BS/BV), whereas Bone Volume/Tissue Volume (BV/TV) decreased with AT2R or AT1R + AT2R blockade. Exposure to AngII greatly decreased BV/TV compared to basal conditions. Receptor blockade prior to AngII addition prevented this effect, i.e., AT1R blockade induced BV/TV, whereas blocking AT2R caused lower BV/TV increase but greater BS/BV; AT1R + AT2R blockade also improved BV/TV. Concluding, the embryonic chick femur model was sensitive to three relevant RAS research setups, proving its usefulness to address AngII/AT1R/AT2R axis in bone both in basal and activated conditions.

Effects of 660-nm and 780-nm Laser Therapy on ST88-14 Schwann Cells.

The aim of the present study was to evaluate the comparative effects of red (660-nm) and near-infrared (780-nm) low-level laser therapy (LLLT) on viability, mitochondrial activity, morphology and gene expression of growth factors on Schwann cells (SC). ST88-14 cells were grown in RPMI 1640 with 10 mM of HEPES, 2 mM of glutamine, 10% fetal bovine serum and 1% antibiotic-antimycotic solution at 37°C in humidified atmosphere of 5% CO2 . Cells were detached with trypsin and centrifugated at 231 g for 5 min at 10°C, and the pellet (8 × 104  cells/tube) was irradiated at the bottom of 50 ml polypropylene tube with a Twin-Laser system (660 and 780 nm, 40 mW, 1 mW cm-2 , 3.2 and 6.4 J, 80 and 160 J cm-2 with 80 and 160 s). After 1, 3 and 7 days, the analysis was performed. After irradiation, the SC increase mitochondrial activity, gene expression of the neural growth factors NGF and BDNF, and cell migration and increase the G2/M cells. SC showed neuronal morphology, normal F-actin cytoskeleton organization and positive labeling for S100. PBM increased metabolic activity, mitosis and gene expression when irradiated with red and infrared LLLT. An increase in cell migration was obtained when irradiated with infrared LLLT.

Defensins in the oral cavity: distribution and biological role.

The oral cavity outreaches as a particular environment in which there is a continuous interplay between bacteria, fungi and viruses, and the epithelial barrier. Among the innate mechanisms that aim to establish a regulated equilibrium between health and disease, natural antimicrobial peptides, especially those part of the defensins' family, have emerged as fundamental mediators. Their biological role is emphasized by the large number of expressed genes, as well as the multiplicity of the individual molecules present on biological tissues and fluids, in physiological and pathological conditions. Furthermore, the direct antimicrobial action, defensins may play a pivotal role in the orchestration of the innate response and contribute to the interplay between the innate and adaptive immunity. This review focuses on the specificities of defensins' structure, expression and biological role in the oral environment, enlightening their relevance in physiological and pathological conditions.

Bone Cells Dynamics during Peri-Implantitis: a Theoretical Analysis.

OBJECTIVES: The present manuscript aims a detailed characterization of the bone cells dynamics during physiological bone remodelling and, subsequently, to address the cellular and molecular mechanisms that play a fundamental role in the immune-inflammatory-induced uncoupled bone remodelling observed in peri-implantitis. RESULTS: An intimate relationship between the immune system and bone is acknowledged to be determinant for bone tissue remodelling and integrity. Due to the close interaction of immune and bone cells, the two systems share a number of surface receptors, cytokines, signalling pathways and transcription factors that are involved in mutual regulatory mechanisms. This physiological equilibrium is disturbed in pathological conditions, as verified in peri-implantitis establishment and development. Activation of the innate and adaptive immune response, challenged by the local bacterial infection, induces the synthesis of high levels of a variety of pro- and anti-inflammatory cytokines that disturb the normal functioning of the bone cells, by uncoupling bone resorption and formation, ending up with a net alveolar bone loss and subsequent implant failure. Most data points to an immune-inflammatory induced osteoclast differentiation and function, as the major underlying mechanism to the uncoupled bone resorption to bone formation. Further, the disturbed functioning of osteoblasts, reflected by the possible expression of a fibro-osteoblastic phenotype, may also play a role. CONCLUSIONS: Alveolar bone loss is a hallmark of peri-implantitis. A great deal of data is still needed on the cellular and humoral crosstalk in the context of an integrated view of the osteoimmunologic interplay occurring in the peri-implantitis environment subjacent to the bone loss outcome.

The 1st Baltic Osseointegration Academy and Lithuanian University of Health Sciences Consensus Conference 2016. Summary and Consensus Statements: Group I - Peri-Implantitis Aetiology, Risk Factors and Pathogenesis.

INTRODUCTION: The task of Group 1 was to review and update the existing data concerning aetiology, risk factors and pathogenesis of peri-implantitis. Previous history of periodontitis, poor oral hygiene, smoking and presence of general diseases have been considered among the aetiological risk factors for the onset of peri-implant pathologies, while late dental implant failures are commonly associated with peri-implantitis and/or with the application of incorrect biomechanical forces. Special interest was paid to the bone cells dynamics as part of the pathogenesis of peri-implantitis. MATERIAL AND METHODS: The main areas indagated by this group were as follows: influence of smoking, history of periodontitis and general diseases on peri-implantitis development, bio-mechanics of implant loading and its influence on peri-implant bone and cellular dynamics related to the pathogenesis of peri-implantitis. The systematic reviews and/or meta-analyses were registered in PROSPERO, an international prospective register of systematic reviews: http://www.crd.york.ac.uk/PROSPERO/. The literature in the corresponding areas of interest was screened and reported following the PRISMA (Preferred Reporting Item for Systematic Review and Meta-Analysis) Statement: http://www.prisma-statement.org/. Method of preparation of the systematic reviews, based on comprehensive search strategies, was discussed and standardized. The summary of the materials and methods employed by the authors in preparing the systematic reviews and/or meta-analyses is presented in Preface chapter. RESULTS: The results and conclusions of the review process are presented in the respective papers. One systematic review with meta-analysis, three systematic reviews and one theoretical analysis were performed. The group's general commentaries, consensus statements, clinical recommendations and implications for research are presented in this article.

Biomimetic mineralization on a macroporous cellulose-based matrix for bone regeneration.

The aim of this study is to investigate the biomimetic mineralization on a cellulose-based porous matrix with an improved biological profile. The cellulose matrix was precalcified using three methods: (i) cellulose samples were treated with a solution of calcium chloride and diammonium hydrogen phosphate; (ii) the carboxymethylated cellulose matrix was stored in a saturated calcium hydroxide solution; (iii) the cellulose matrix was mixed with a calcium silicate solution in order to introduce silanol groups and to combine them with calcium ions. All the methods resulted in a mineralization of the cellulose surfaces after immersion in a simulated body fluid solution. Over a period of 14 days, the matrix was completely covered with hydroxyapatite crystals. Hydroxyapatite formation depended on functional groups on the matrix surface as well as on the precalcification method. The largest hydroxyapatite crystals were obtained on the carboxymethylated cellulose matrix treated with calcium hydroxide solution. The porous cellulose matrix was not cytotoxic, allowing the adhesion and proliferation of human osteoblastic cells. Comparatively, improved cell adhesion and growth rate were achieved on the mineralized cellulose matrices.

Dental stem cells for craniofacial tissue engineering.

This article focuses on the biological characterization and discussion of the potential application of oral-derived adult stem cells for craniofacial tissue engineering applications. The authors reviewed experimental (in vitro and in vivo) and clinical reports regarding the isolation, characterization, modulation, and translational clinical application of human precursor cell populations derived from postnatal dental tissues. Five different human dental stem/progenitor cell populations have been isolated and characterized. These postnatal populations present mesenchymal stem cell-like characteristics and enjoy forceful capabilities regarding the differentiation into odontogenic/osteogenic lineages, supporting evidence--in preclinical and clinical trials--for the regeneration of oral/dental tissues.

Advances in the Aetiophatogenesis of Sjögren's Syndrome: a Literature Review.

OBJECTIVES: The purpose of present paper is to review and critically address the recent advances on the aetiopathogenesis of the Sjögren's syndrome, taking into account the attained clinical features, with particular relevance given to the oral involvement. MATERIAL AND METHODS: A comprehensive review of the available literature between 1970 and 2012, regarding to the aetiopathogenesis and clinical findings related to Sjögren's syndrome was conducted. Eligible studies were identified by searching the electronic literature PubMed, Medline, Embase, and ScienceDirect databases for relevant reports (last search update January 2012), combining the MESH heading term "Sjögren's syndrome", with the words "salivary glands, xerostomia, xerophtalmia, aetiology". The authors checked the references of the selected articles to identify additional eligible publications and contacted the authors, if necessary. RESULTS: This article addresses a large number of the recent advances in the aetiopathogenesis of the disease, taking into account the attained clinical features of both local and systemic nature. Detailed mechanisms of the hypothesized influence of viral infections, genetic and hormonal factors, and the relevance of the altered glandular homeostasis are critically discussed with particular relevance given to the local and systemic involvement of Sjögren's syndrome. CONCLUSIONS: The increasing number of data published recently on the aetiophatogenesis of Sjögren's syndrome strengthens the hypothesis that this condition, as all autoimmune diseases, is a multifactor disorder. Genetic predisposition, hormonal and environmental factors are thought to be implicated.

Diagnostic Approaches to Sjögren's syndrome: a Literature Review and Own Clinical Experience.

OBJECTIVES: The purpose of present paper is to critically address the recent advances on diagnostic procedures of Sjögren's syndrome, taking into account the attained local and systemic features of the disease. MATERIAL AND METHODS: A comprehensive review of the available literature regarding to the diagnostic approaches to Sjögren's syndrome was conducted. Eligible studies were identified by searching the electronic literature PubMed, Medline, Embase, and ScienceDirect databases for relevant reports (last search update January 2012) combining the MESH heading term "Sjögren's syndrome", with the words "diagnosis, diagnostic procedures, salivary gland function, ocular tests, histopathology, salivary gland imaging, serology". The authors checked the references of the selected articles to identify additional eligible publications and contacted the authors, if necessary. RESULTS: Presented article addresses the established diagnostic criteria for Sjögren's syndrome and critically evaluates the most commonly used diagnostic procedures, presenting data from author's own clinical experience. Diagnostic criteria for Sjögren's syndrome are required both by healthcare professionals and patients, namely in order to provide a rational basis for the assessment of the symptoms, establish an individual disease prognosis, and orientate the therapeutic intervention. CONCLUSIONS: Sjögren's syndrome is quite a common autoimmune disease of which the diagnosis and treatment are not easily established. Due to its systemic involvement, it can exhibit a wide range of clinical manifestations that contribute to confusion and delay in diagnosis. The use of proper diagnostic modalities will help to reduce the time to diagnosis and preserve the health and quality of life of patients with Sjögren's syndrome.

Surface properties and osteoblastic cytocompatibility of two blasted and Acid-etched titanium implant systems with distinct microtopography.

OBJECTIVES: The aim of this study is to compare two commercially available screw-type sandblasted and acid-etched (SLA) Ti implant systems from Eckermann Laboratorium S.L., with similar geometry and distinct microtopography, regarding surface properties and osteoblastic cytocompatibility. MATERIAL AND METHODS: Implant I (referred as a conventional SLA system) and Implant II (a system patented as Eckcyte(®)) were characterized for macro and microtopograpphy, surface roughness and chemical composition. For the cytocompatibility studies, human bone marrow osteoblastic cells were seeded over the implants' surface, and the cell response was assessed for cell adhesion and proliferation, alkaline phosphatase (ALP) activity and matrix mineralization. RESULTS: Implant I presented a rough surface with irregularly shaped and sized cavities among flatter-appearing areas, whereas Implant II exhibited a homogeneous rough microporous surface. Compared to Implant I, Implant II presented higher Ra values (0.8 [SD 0.008] µm and 1.21 [SD 0.15] µm, respectively, P < 0.05) and also increased values of Rz, Rt and Rsm, a more negative value of Rsk, and similar RKu values. XPS showed the expected presence of Ti, O, C and N; Al, Si, F, P and Ca were detected in low concentrations. Implant II exhibited significantly lower Al levels. Both implants supported the adhesion, proliferation and differentiation of osteoblastic cells. Implant II showed a thicker fibrilar cell layer and an earlier onset and more abundant matrix mineralization. CONCLUSIONS: The homogeneous rough and microporous surface of Implant II is most probably a main contributor for its improved cell response.