An organotypic oral mucosal infection model to study host-pathogen interactions.

Early in vitro oral mucosal infection models (OMMs) failed to consider the suitability of the model environment to represent the host immune response. Denture stomatitis (DS) is mediated by Candida albicans, but the role of Staphylococcus aureus remains uncertain. A collagen hydrogel-based OMM containing HaCaT and HGF cell types was developed, characterised and employed to study of tissue invasion and pro-inflammatory cytokine production in response to pathogens. Models formed a robust epithelium. Despite their inflammatory baseline, 24-h infection with C. albicans, and/or S. aureus led to tissue invasion, and significantly upregulated IL-6 and IL-8 production by OMMs when compared to the unstimulated control. No significant difference in IL-6 or IL-8 production by OMMs was observed between single and dual infections. These attributes indicate that this newly developed OMM is suitable for the study of DS and could be implemented for the wider study of oral infection.

Prognostic Role of CD68+ and CD163+ Tumour-Associated Macrophages and PD-L1 Expression in Oral Squamous Cell Carcinoma: A Meta-Analysis.

Background: Oral squamous cell carcinoma (OSCC) is a common malignant cancer in humans. An abundance of tumour associated macrophages (TAMs) create an immunosuppressive tumour microenvironment (TME). TAM markers (CD163 and CD68) are seen to serve as prognostic factors in OSCC. PD-L1 has seen to widely modulate the TME but its prognostic significance remains controversial. The aim of this meta-analysis is to evaluate the prognostic role of CD163+, CD68+ TAMs and PD-L1 in OSCC patients. Methods: Searches in PubMed, Scopus and Web of Science were performed; 12 studies were included in this meta-analysis. Quality assessment of included studies was performed according to REMARK guidelines. Risk of bias across studies was investigated according to the rate of heterogeneity. Meta-analysis was performed to investigate the association of all three biomarkers with overall survival (OS). Results: High expression of CD163+ TAMs were associated with poor overall survival (HR = 2.64; 95% Cl: [1.65, 4.23]; p < 0.0001). Additionally, high stromal expression of CD163+ TAMs correlated with poor overall survival (HR = 3.56; 95% Cl: [2.33, 5.44]; p < 0.00001). Conversely, high CD68 and PD-L1 expression was not associated with overall survival (HR = 1.26; 95% Cl: [0.76, 2.07]; p = 0.37) (HR = 0.64; 95% Cl: [0.35, 1.18]; p = 0.15). Conclusion: In conclusion, our findings indicate CD163+ can provide prognostic utility in OSCC. However, our data suggests CD68+ TAMs were not associated with any prognostic relevance in OSCC patients, whereas PD-L1 expression may prove to be a differential prognostic marker dependent on tumour location and stage of progression.

Atrial fibrillation in Middle Eastern Arabs and South Asians: a scoping review.

Most of the published literature on Atrial fibrillation (AF) originates from the northern hemisphere and mainly involves Caucasian patients, with limited studies in certain ethnicities and races. This scoping review was conducted to collect and summarize the pertinent evidence from the published scientific literature on AF in South Asians and Middle Eastern Arabs. MEDLINE, Embase and CENTRAL databases were included in our search. After screening 8995 records, 55 studies were selected; 42 from the Middle East and 13 from South Asia. Characteristics of the included studies were tabulated, and their data were summarized for study design, setting, enrolment period, sample size, demographics, prevalence or incidence of AF, co-morbidities, risk factors, AF types and symptoms, management, outcomes, and risk determinants. Identified literature gaps included a paucity of community or population-based studies that are representative of these two ethnicities/races. In addition, studies that addressed ethnic/racial in-equality and access to treatment were lacking. Our study underscores the urgent need to study cardiovascular disorders, particularly AF, in South Asians and Middle Eastern Arabs as well as in other less represented ethnicities and races.

Atypical Mesenchymal Stromal Cell Responses to Topographic Modifications of Titanium Biomaterials Indicate Cytoskeletal- and Genetic Plasticity-Based Heterogeneity of Cells.

Titanium (Ti) is widely used as a biomaterial for endosseous implants due to its relatively inert surface oxide layer that enables implanted devices the ability of assembling tissue reparative components that culminate in osseointegration. Topographic modifications in the form of micro- and nanoscaled structures significantly promote osseointegration and enhance the osteogenic differentiation of adult mesenchymal stromal cells (MSCs). While the biological mechanisms central to the differential responses of tissues and cells to Ti surface modifications remain unknown, adhesion and morphological adaptation are amongst the earliest events at the cell-biomaterial interface that are highly influenced by surface topography and profoundly impact the regulation of stem cell fate determination. This study correlated the effects of Ti topographic modifications on adhesion and morphological adaptation of human MSCs with phenotypic change. The results showed that modified Ti topographies precluded the adhesion of a subset of MSCs while incurring distinct morphological constraints on adherent cells. These effects anomalously corresponded with a differential expression of stem cell pluripotency and Wnt signalling-associated markers on both modified surfaces while additionally differing between hydrophobic and hydrophilic surface modifications-though extent of osteogenic differentiation induced by both modified topographies yielded similarly significant higher levels of cellular mineralisation in contrast to polished Ti. These results suggest that in the absence of deposited proteins and soluble factors, both modified topographies incur the selective adhesion of a subpopulation of progenitors with relatively higher cytoskeletal plasticity. While the presence of deposited proteins and soluble factors does not significantly affect adherence of cells, nanotopographic modifications enhance expression of pluripotency markers in proliferative conditions, which are conversely overridden by both modified topographies in osteogenic inductive conditions. Further deciphering the mechanisms underlying cellular selectivity and Ti topographic responsiveness will improve our understanding of stem cell heterogeneity and advance the potential of MSCs in regenerative medicine.

Development and characterization of a 3D oral mucosa model as a tool for host-pathogen interactions.

The aim of this study was to (i) design, develop and validate a practical and physiologically relevant reconstituted in vitro oral mucosa tissue model and (ii) to assess its applicability in in vitro host-pathogen interactions with C. albicans and S. aureus. Co-culture organotypic constructions were created by incorporating specific numbers of keratinocytes (NOK-si) onto cellularised, collagen gel scaffolds containing human gingival fibroblasts incubated in KGM media and cultured for 14 days. The detection of the appropriate oral mucosa/epithelial structure was evaluated by histology (hematoxylin and eosin (HE), periodic acid-Schiff (P.A.S.) and Picrosirius red), and immunocytochemistry (cytokeratin 13, cytokeratin 14, Ki-67 and collagen IV) compared to a normal human gingiva. The morphology of the reconstituted tissue was analyzed by Transmission Electron Microscopy. To further quantitate tissue damage, lactate dehydrogenase (LDH) was measured in the tissue supernatant. NOK-si grown upon a gingival scaffold provided an organotypic model in an in vitro setting and exhibited structural characteristics typically associated with normal oral mucosa. Immunocytochemistry revealed the detection of epithelial cytokeratins 13 and 14, Col IV and Ki-67 in the reconstituted oral mucosa model. Infection was detected after 8 h and 16 h. This study presents an in vitro cellularised, organotypic model of reconstituted oral mucosa, which enables close control and characterization of its structure and differentiation over a mid-length period of time in culture.

When another assessment attempt is bad for progress.

This article was migrated. The article was marked as recommended. The history and current practice of resit tests are briefly reviewed. The evidence supporting resits and also the problems associated with resits are evaluated. In addition, the financial implications of resits for both students and institutions are explored, along with the need to ensure assessments establish currency of ability and are a reflection of the long-term capability of students. Although resit outcomes are typically capped at the passing score we argue that they still afford an unfair advantage. We conclude that where resit opportunities are provided then they should have higher pass marks than first sit attempts. However, we recommend that the stress of high stakes exams, and thus resits, should be avoided. Consequently, a case is made for an alternative to resits whereby multiple lower stakes assessment results are aggregated.

Angoff anchor statements: setting a flawed gold standard?

This article was migrated. The article was marked as recommended. The Angoff standard setting method depends fundamentally on the conceptualisation of an anchor statement. The precise wording and consequent interpretation of anchor statements varies in practice. Emphasis is often placed on standard setting judges' perceptions of difficulty for a candidate subgroup. The current review focusses on the meaning of anchor statements and argues that when determining the required standard of performance it is more appropriate to consider: (1) what it is important to achieve, and not how difficult it is to achieve it; (2) what all candidates should achieve, and not what a subgroup of candidates would achieve. In summary, current practice should be refined by using an anchor statement which refers to estimating the 'minimum acceptable performance by every candidate' for each item being tested, and then requiring each judge to score the relevant aspects of importance which could then be combined to derive a cut-score.

Making progression and award decisions.

This article was migrated. The article was marked as recommended. It is incumbent on medical schools to show, both to regulatory bodies and to the public at large, that their graduating students are "fit for purpose" as doctors. Since students graduate by virtue of passing assessments, it is vital that schools quality assure their assessment procedures, standards and outcomes. An important part of this quality assurance process is how progression and award decisions are made. This begins with developing clear evidence-based policies and processes that ensure assessments are effective, relevant, fair, robust and secure. Assessment is a series of processes primarily designed to enable judgements to be made as to whether a student has, or has not, met the standard required for the outcomes at that stage. This article will provide a clear rationale and guidance for establishing robust processes for making progression and award decisions.

The regulation of bone turnover in ameloblastoma using an organotypic in vitro co-culture model.

Ameloblastoma is a rare, odontogenic neoplasm with benign histopathology, but extensive, local infiltrative capacity through the bone tissue it originates in. While the mechanisms of ameloblastoma invasion through the bone and bone absorption are largely unknown, recent investigations have indicated a role of the osteoprotegerin/receptor activator of nuclear factor kappa-B ligand regulatory mechanisms. Here, we present results obtained using a novel in vitro organotypic tumour model, which we have developed using tissue engineering techniques. Using this model, we analysed the expression of genes involved in bone turnover and detected a 700-fold increase in receptor activator of nuclear factor kappa-B ligand levels in the co-culture models with ameloblastoma cells cultured with bone cells. The model described here can be used for gene expression studies, as a basis for drug testing or for a more tailored platform for testing of the behaviour of different ameloblastoma tumours in vitro.

Poly(propylene glycol) and urethane dimethacrylates improve conversion of dental composites and reveal complexity of cytocompatibility testing.

OBJECTIVES: To determine the effects of various monomers on conversion and cytocompatibility of dental composites and to improve these properties without detrimentally affecting mechanical properties, depth of cure and shrinkage. METHODS: Composites containing urethane dimethacrylate (UDMA) or bisphenol A glycidyl methacrylate (Bis-GMA) with poly(propylene glycol) dimethacrylate (PPGDMA) or triethylene glycol dimethacrylate (TEGDMA) were characterized using the following techniques: conversion (FTIR at 1 and 4mm depths), depth of cure (BS EN ISO 4049:2009 and FTIR), shrinkage (BS EN ISO 17304:2013 and FTIR), strength and modulus (biaxial flexural test) and water sorption. Cytocompatibility of composites and their liquid phase components was assessed using three assays (resazurin, WST-8 and MTS). RESULTS: UDMA significantly improved conversion, BFS and depth of cure compared to Bis-GMA, without increasing shrinkage. UDMA was cytotoxic at lower concentrations than Bis-GMA, but extracts of Bis-GMA-containing composites were less cytocompatible than of those containing UDMA. PPGDMA improved conversion and depth of cure compared to TEGDMA, without detrimentally affecting shrinkage. TEGDMA was shown by all assays to be highly toxic. Resazurin, but not WST-8 and MTS, suggested that PPGDMA exhibited improved cytocompatibility compared to TEGDMA. SIGNIFICANCE: The use of UDMA and PPGDMA results in composites with excellent conversion, depth of cure and mechanical properties, without increasing shrinkage. Composites containing UDMA appear to be slightly more cytocompatible than those containing Bis-GMA. These monomers may therefore improve the material properties of dental restorations, particularly bulk fill materials. The effect of diluent monomer on cytocompatibility requires further investigation.

Titanium phosphate glass microcarriers induce enhanced osteogenic cell proliferation and human mesenchymal stem cell protein expression.

In this study, we have developed 50- to 100-µm-sized titanium phosphate glass microcarriers (denoted as Ti5) that show enhanced proliferation of human mesenchymal stem cells and MG63 osteosarcoma cells, as well as enhanced human mesenchymal stem cell expression of bone differentiation markers, in comparison with commercially available glass microspheres at all time points. We also demonstrate that these microcarriers provide superior human mesenchymal stem cell proliferation with conventional Dulbecco's Modified Eagle medium than with a specially developed commercial stem cell medium. The microcarrier proliferative capacity is revealed by a 24-fold increase in MG63 cell numbers in spinner flask bioreactor studies performed over a 7-day period, versus only a 6-fold increase in control microspheres under the same conditions; the corresponding values of Ti5 and control microspheres under static culture are 8-fold and 7-fold, respectively. The capability of guided osteogenic differentiation is confirmed by ELISAs for bone morphogenetic protein-2 and osteopontin, which reveal significantly greater expression of these markers, especially osteopontin, by human mesenchymal stem cells on the Ti5 microspheres than on the control. Scanning electron microscopy and confocal laser scanning microscopy images reveal favorable MG63 and human mesenchymal stem cell adhesion on the Ti5 microsphere surfaces. Thus, the results demonstrate the suitability of the developed microspheres for use as microcarriers in bone tissue engineering applications.

Biological effects of soft denture reline materials on L929 cells in vitro.

Soft denture reline materials have been developed to help patients when their oral mucosa is damaged or affected due to ill-fitting dentures or post-implant surgery. Although reports have indicated that these materials leach monomers and other components that do affect their biocompatibility, there is little information on what cell molecules may be implicated in these material/tissue interactions. The biocompatibility of six soft liners (Ufi Gel P, Sofreliner S, Durabase Soft, Trusoft, Softone and Coe Comfort) was evaluated using a mouse fibroblast cell line, L929. Within 2 h of material disc preparation, each of the materials was exposed by direct contact to L929 cells for periods of 24 and 48 h. The effect of this interaction was assessed by alamarBlue assay (for cell survival). The expression of integrin α5ß1 and transforming growth factor ß1 was also assessed using plate assays such as enzyme-linked immunosorbent assay. Trusoft, Softone and Coe Comfort showed significantly reduced cell survival compared with the other soft lining materials at each incubation period. Furthermore, there were significant differences with these same materials in the expression of both integrin α5ß1 and transforming growth factor ß1. Soft liner materials may affect cell viability and cellular proteins that have important roles in wound healing and the preservation of cell viability and function in the presence of environmental challenges and stresses.

Tissue engineering in dentistry.

OBJECTIVES: of this review is to inform practitioners with the most updated information on tissue engineering and its potential applications in dentistry. DATA: The authors used "PUBMED" to find relevant literature written in English and published from the beginning of tissue engineering until today. A combination of keywords was used as the search terms e.g., "tissue engineering", "approaches", "strategies" "dentistry", "dental stem cells", "dentino-pulp complex", "guided tissue regeneration", "whole tooth", "TMJ", "condyle", "salivary glands", and "oral mucosa". SOURCES: Abstracts and full text articles were used to identify causes of craniofacial tissue loss, different approaches for craniofacial reconstructions, how the tissue engineering emerges, different strategies of tissue engineering, biomaterials employed for this purpose, the major attempts to engineer different dental structures, finally challenges and future of tissue engineering in dentistry. STUDY SELECTION: Only those articles that dealt with the tissue engineering in dentistry were selected. CONCLUSIONS: There have been a recent surge in guided tissue engineering methods to manage periodontal diseases beyond the traditional approaches. However, the predictable reconstruction of the innate organisation and function of whole teeth as well as their periodontal structures remains challenging. Despite some limited progress and minor successes, there remain distinct and important challenges in the development of reproducible and clinically safe approaches for oral tissue repair and regeneration. Clearly, there is a convincing body of evidence which confirms the need for this type of treatment, and public health data worldwide indicates a more than adequate patient resource. The future of these therapies involving more biological approaches and the use of dental tissue stem cells is promising and advancing. Also there may be a significant interest of their application and wider potential to treat disorders beyond the craniofacial region. CLINICAL SIGNIFICANCE: Considering the interests of the patients who could possibly be helped by applying stem cell-based therapies should be carefully assessed against current ethical concerns regarding the moral status of the early embryo.

Electrophoretic deposition of gentamicin-loaded bioactive glass/chitosan composite coatings for orthopaedic implants.

Despite their widespread application, metallic orthopaedic prosthesis failure still occurs because of lack of adequate bone-bonding and the incidence of post-surgery infections. The goal of this research was to develop multifunctional composite chitosan/Bioglass coatings loaded with gentamicin antibiotic as a suitable strategy to improve the surface properties of metallic implants. Electrophoretic deposition (EPD) was applied as a single-step technology to simultaneously deposit the biopolymer, bioactive glass particles, and the antibiotic on stainless steel substrate. The microstructure and composition of the coatings were characterized using SEM/EDX, XRD, FTIR, and TGA/DSC, respectively. The in vitro bioactivity of the coatings was demonstrated by formation of hydroxyapatite after immersion in simulated body fluid (SBF) in a short period of 2 days. High-performance liquid chromatography (HPLC) measurements indicated the release of 40% of the loaded gentamicin in phosphate buffered saline (PBS) within the first 5 days. The developed composite coating supported attachment and proliferation of MG-63 cells up to 10 days. Moreover, disc diffusion test showed improved bactericidal effect of gentamicin-loaded composite coatings against S. aureus compared to control non-gentamicin-loaded coatings.

The Relationship between Biofilm and Physical-Chemical Properties of Implant Abutment Materials for Successful Dental Implants.

The aim of this review was to investigate the relationship between biofilm and peri-implant disease, with an emphasis on the types of implant abutment surfaces. Individuals with periodontal disease typically have a large amount of pathogenic microorganisms in the periodontal pocket. If the individuals lose their teeth, these microorganisms remain viable inside the mouth and can directly influence peri-implant microbiota. Metal implants offer a suitable solution, but similarly, these remaining bacteria can adhere on abutment implant surfaces, induce peri-implantitis causing potential destruction of the alveolar bone near to the implant threads and cause the subsequent loss of the implant. Studies have demonstrated differences in biofilm formation on dental materials and these variations can be associated with both physical and chemical characteristics of the surfaces. In the case of partially edentulous patients affected by periodontal disease, the ideal type of implant abutments utilized should be one that adheres the least or negligible amounts of periodontopathogenic bacteria. Therefore, it is of clinically relevance to know how the bacteria behave on different types of surfaces in order to develop new materials and/or new types of treatment surfaces, which will reduce or inhibit adhesion of pathogenic microorganisms, and, thus, restrict the use of the abutments with indication propensity for bacterial adhesion.

Bone formation controlled by biologically relevant inorganic ions: role and controlled delivery from phosphate-based glasses.

The role of metal ions in the body and particularly in the formation, regulation and maintenance of bone is only just starting to be unravelled. The role of some ions, such as zinc, is more clearly understood due to its central importance in proteins. However, a whole spectrum of other ions is known to affect bone formation but the exact mechanism is unclear as the effects can be complex, multifactorial and also subtle. Furthermore, a significant number of studies utilise single doses in cell culture medium, whereas the continual, sustained release of an ion may initiate and mediate a completely different response. We have reviewed the role of the most significant ions that are known to play a role in bone formation, namely calcium, zinc, strontium, magnesium, boron, titanium and also phosphate anions as well as copper and its role in angiogenesis, an important process interlinked with osteogenesis. This review will also examine how delivery systems may offer an alternative way of providing sustained release of these ions which may effect and potentiate a more appropriate and rapid tissue response.

Titanium phosphate glass microspheres for bone tissue engineering.

We have demonstrated the successful production of titanium phosphate glass microspheres in the size range of ∼10-200 µm using an inexpensive, efficient, easily scalable process and assessed their use in bone tissue engineering applications. Glasses of the following compositions were prepared by melt-quench techniques: 0.5P2O5-0.4CaO-(0.1-x)Na2O-xTiO2, where x=0.03, 0.05 and 0.07 mol fraction (denoted as Ti3, Ti5 and Ti7 respectively). Several characterization studies such as differential thermal analysis, degradation (performed using a novel time lapse imaging technique) and pH and ion release measurements revealed significant densification of the glass structure with increased incorporation of TiO2 in the glass from 3 to 5 mol.%, although further TiO2 incorporation up to 7 mol.% did not affect the glass structure to the same extent. Cell culture studies performed using MG63 cells over a 7-day period clearly showed the ability of the microspheres to provide a stable surface for cell attachment, growth and proliferation. Taken together, the results confirm that 5 mol.% TiO2 glass microspheres, on account of their relative ease of preparation and favourable biocompatibility, are worthy candidates for use as substrate materials in bone tissue engineering applications.

Osteochondral tissue engineering: scaffolds, stem cells and applications.

Osteochondral tissue engineering has shown an increasing development to provide suitable strategies for the regeneration of damaged cartilage and underlying subchondral bone tissue. For reasons of the limitation in the capacity of articular cartilage to self-repair, it is essential to develop approaches based on suitable scaffolds made of appropriate engineered biomaterials. The combination of biodegradable polymers and bioactive ceramics in a variety of composite structures is promising in this area, whereby the fabrication methods, associated cells and signalling factors determine the success of the strategies. The objective of this review is to present and discuss approaches being proposed in osteochondral tissue engineering, which are focused on the application of various materials forming bilayered composite scaffolds, including polymers and ceramics, discussing the variety of scaffold designs and fabrication methods being developed. Additionally, cell sources and biological protein incorporation methods are discussed, addressing their interaction with scaffolds and highlighting the potential for creating a new generation of bilayered composite scaffolds that can mimic the native interfacial tissue properties, and are able to adapt to the biological environment.

Viscoelastic and biological performance of low-modulus, reactive calcium phosphate-filled, degradable, polymeric bone adhesives.

The aim of this study was to investigate the effect of reactive mono- and tricalcium phosphate addition on the mechanical, surface free energy, degradation and cell compatibility properties of poly(lactide-co-propylene glycol-co-lactide) dimethacrylate (PPGLDMA) thin films. Dry composites containing up to 70 wt.% filler were in a flexible rubber state at body temperature. Filler addition increased the initial strength and Young's modulus and reduced the elastic and permanent deformation under load. The polymer had high polar surface free energy, which might enable greater spread upon bone. This was significantly reduced by filler addition but not by water immersion for 7 days. The samples exhibited reduced water sorption and associated bulk degradation when compared with previous work with thicker samples. Their cell compatibility was also improved. Filler raised water sorption and degradation but improved cell proliferation. The materials are promising bone adhesive candidates for low-load-bearing areas.

Structural characterization and physical properties of P2O5-CaO-Na2O-TiO2 glasses by Fourier transform infrared, Raman and solid-state magic angle spinning nuclear magnetic resonance spectroscopies.

Phosphate-based glasses have been investigated for tissue engineering applications. This study details the properties and structural characterization of titanium ultra-phosphate glasses in the 55(P(2)O(5))-30(CaO)-(25-x)(Na(2)O)-x(TiO(2)) (0≤x≤5) system, which have been prepared via melt-quenching techniques. Structural characterization was achieved by a combination of X-ray diffraction (XRD), and solid-state nuclear magnetic resonance, Raman and Fourier transform infrared spectroscopies. Physical properties were also investigated using density, degradation and ion release studies; additionally, differential thermal analysis was used for thermal analysis of these glasses. The results show that with the addition of TiO(2) the density and glass transition temperature increased whereas the degradation and ion release properties are decreased. From XRD data, TiP(2)O(7) and CaP(2)O(6) were detected in 3 and 5 mol.% TiO(2)-containing glasses. Magic angle spinning nuclear magnetic resonance results confirmed that as TiO(2) is incorporated into the glass; the amount of Q(3) increases as the amount of Q(2) consequently decreases, indicating increasing polymerization of the phosphate network. Spectroscopy results also showed that the local structure of glasses changes with increasing TiO(2) content. As TiO(2) is incorporated into the glass, the phosphate connectivity increases, indicating that the addition of TiO(2) content correlates unequivocally with an increase in glass stability.