Outcomes of adults with invasive meningococcal disease with reduced penicillin susceptibility in Auckland 2004-2017.

PURPOSE: The purpose of this study was to assess the clinical outcomes of adults with invasive meningococcal disease (IMD) and to compare the outcomes of patients with IMD caused by a penicillin susceptible isolate (minimum inhibitory concentration (MIC) ≤ 0.06 mg/L) with patients with IMD caused by an isolate with reduced penicillin susceptibility (MIC > 0.06 mg/L). We also assessed the outcomes of patients with IMD caused by an isolate with reduced penicillin susceptibility who were treated exclusively with intravenous (IV) benzylpenicillin. METHODS: Retrospective study of all culture positive IMD in adult patients (age ≥ 15 years) in the Auckland region from 2004 to 2017. RESULTS: One hundred and thirty-nine patients were included; 94 had penicillin susceptible isolates (88 cured, 6 died), and 45 had an isolate with reduced penicillin susceptibility (41 cured, 1 possible relapse, 3 died). The median benzylpenicillin/ceftriaxone treatment duration was 3 days for both groups. There was no difference in the patient outcomes of both groups. Eighteen patients with IMD caused by an isolate with reduced penicillin susceptibility received benzylpenicillin alone and were cured. CONCLUSIONS: This study provides further support to existing data that has shown that short duration IV beta-lactam treatment is effective for IMD in adults. Only a small number of patients with meningitis caused by an isolate with reduced penicillin susceptibility received benzylpenicillin alone, limiting its evaluation. For Neisseria meningitidis meningitis, we recommend ceftriaxone as empiric treatment and as definitive treatment when this is caused by an isolate with reduced penicillin susceptibility.

Merged testing for colorectal cancer syndromes and re-evaluation of genetic variants improve diagnostic yield: Results from a nationwide prospective cohort.

Approximately 5% of patients with colorectal cancer (CRC) have a Mendelian predisposition for the disease. Identification of the disease-causing genetic variant enables carrier testing and tailored cancer prevention within affected families. To determine the panorama and genetic variation of Mendelian CRC syndromes among referrals at the cancer genetics clinics in Sweden, 850 patients clinically selected for CRC genetic investigation were included in a prospective study that tested for all major hereditary polyposis and nonpolyposis CRC conditions. Genetically defined syndromes were diagnosed in 11% of the patients. Lynch syndrome was predominant (n = 73) followed by familial adenomatous polyposis (n = 12) and MUTYH-associated polyposis (n = 8); the latter of which two patients presented with CRC before polyposis was evident. One patient with a history of adolescent-onset CRC and polyposis had biallelic disease-causing variants diagnostic for constitutional mismatch repair deficiency syndrome. Post-study review of detected variants of unknown clinical significance (n = 129) resulted in the reclassification of variants as likely benign (n = 59) or as diagnostic for Lynch syndrome (n = 2). Our results reveal the panorama of Mendelian CRC syndromes at the cancer genetics clinics in Sweden and show that unified testing for polyposis and nonpolyposis CRC conditions as well as regular reexamination of sequence data improve the diagnostic yield.

Monocytes and pyrophosphate promote mesenchymal stem cell viability and early osteogenic differentiation.

Pyrophosphate-containing calcium phosphate implants promote osteoinduction and bone regeneration. The role of pyrophosphate for inflammatory cell-mesenchymal stem cell (MSC) cross-talk during osteogenesis is not known. In the present work, the effects of lipopolysaccharide (LPS) and pyrophosphate (PPi) on primary human monocytes and on osteogenic gene expression in human adipose-derived MSCs were evaluated in vitro, using conditioned media transfer as well as direct effect systems. Direct exposure to pyrophosphate increased nonadherent monocyte survival (by 120% without LPS and 235% with LPS) and MSC viability (LDH) (by 16-19% with and without LPS). Conditioned media from LPS-primed monocytes significantly upregulated osteogenic genes (ALP and RUNX2) and downregulated adipogenic (PPAR-γ) and chondrogenic (SOX9) genes in recipient MSCs. Moreover, the inclusion of PPi (250 µM) resulted in a 1.2- to 2-fold significant downregulation of SOX9 in the recipient MSCs, irrespective of LPS stimulation or culture media type. These results indicate that conditioned media from LPS-stimulated inflammatory monocytes potentiates the early MSCs commitment towards the osteogenic lineage and that direct pyrophosphate exposure to MSCs can promote their viability and reduce their chondrogenic gene expression. These results are the first to show that pyrophosphate can act as a survival factor for both human MSCs and primary monocytes and can influence the early MSC gene expression. Graphical abstract.

The MIC distribution of dalbavancin differs between different coagulase-negative staphylococci.

Background: CoNS constitute a significant part of the human microbiota of skin and mucous membranes. They can cause nosocomial infections, and have shown decreased susceptibility to several antibiotics. The few remaining treatment options include (lipo)glycopeptides such as dalbavancin. However, there is a lack of knowledge concerning whether susceptibility to lipoglycopeptides varies between different species of CoNS. Objectives: To determine the susceptibility to dalbavancin in different species of CoNS. Methods: We investigated 480 bacterial isolates from 10 CoNS species: Staphylococcus epidermidis, Staphylococcus capitis, Staphylococcus caprae, Staphylococcus haemolyticus, Staphylococcus lugdunensis, Staphylococcus warneri, Staphylococcus pettenkoferi, Staphylococcus hominis, Staphylococcus sciuri and Staphylococcus simulans. The isolates were randomly selected from different sources of infection, including blood isolates, as well as deep and superficial infections. Antibiotic susceptibility was tested with the gradient test method. Results: There was a statistically significant difference (ANOVA; P < 0.0001) in the MIC distribution for dalbavancin between different CoNS species. S. sciuri was the least susceptible species, with 90% of the isolates having an MIC value for dalbavancin above the EUCAST breakpoint of 0.125 mg/L. The lowest MIC90 values were seen for S. capitis, S. simulans and S. caprae (all 0.032 mg/L). Conclusions: This study demonstrated a difference in dalbavancin susceptibility between different CoNS species, suggesting that species-specific breakpoints for CoNS should be further investigated.

Evaluation of Clinical Performance of Ponto Implantation Using a Minimally Invasive Surgical Technique-A Prospective Multicenter Study.

OBJECTIVE: To investigate the clinical outcomes of bone-anchored hearing implant surgery using the MONO procedure. STUDY DESIGN: Multicenter, multinational, single-arm, prospective trial with a 12-month follow-up. SETTING: Seven European university hospitals from the United Kingdom, Sweden, Denmark, and The Netherlands. PATIENTS: Fifty-one adult patients requiring surgical intervention for bone conduction hearing. INTERVENTION: Bone-anchored hearing implant surgery using the MONO procedure. MAIN OUTCOME MEASURES: The primary endpoint assessed implant usability 3 months after surgery. Implant status, soft tissue reactions, pain and numbness, postoperative events, and sound processor usage were assessed at all follow-up visits. Hearing-related quality of life was evaluated using the Glasgow Benefit Inventory (GBI). RESULTS: At 3 months, 94.2% of the implant/abutment complexes provided reliable anchorage for sound processor usage. No severe intraoperative complications occurred. Sixty-nine percent of surgeries were performed under local anesthesia, with surgery lasting 10 minutes on average. Four implants were lost due to trauma (n = 2), spontaneous loss of osseointegration (n = 1), or incomplete insertion (n = 1). Adverse soft tissue reactions occurred in 2.6% of visits, with a maximum Holgers grade of 3 (n = 1) and grade 2 (n = 5) across patients. Hearing-related quality of life at 3 months improved in 96% of patients. CONCLUSION: The MONO procedure provides a safe and efficient surgical technique for inserting bone-anchored hearing implants with few and minor intra- and postoperative complications.

Osseointegration of titanium with an antimicrobial nanostructured noble metal coating.

Nanometer scale surface features on implants and prostheses can potentially be used to enhance osseointegration and may also add further functionalities, such as infection resistance, to the implant. In this study, a nanostructured noble metal coating consisting of palladium, gold and silver, never previously used in bone applications, was applied to machined titanium screws to evaluate osseointegration after 6 and 12 weeks in rabbit tibiae and femurs. Infection resistance was confirmed by in vitro adhesion test. A qualitatively and quantitatively similar in vivo bone response was observed for the coated and uncoated control screws, using histology, histomorphometry and electron microscopy. The bone-implant interface analysis revealed an extensive bone formation and direct bone-implant contact. These results demonstrate that the nanostructured noble metal coating with antimicrobial properties promotes osseointegration and may therefore be used to add extra implant functionality in the form of increased resistance to infection without the use of antibiotics. FROM THE CLINICAL EDITOR: The authors of this paper demonstrate that nanostructured noble metal coating of implants and prostheses used in orthopedic procedures promotes osseointegration and may be used to add extra implant functionality in the form of increased resistance to infection without the use of antibiotics.

Legitimizing user knowledge in mental health services: Epistemic (in)justice and barriers to knowledge integration.

Including the voices and knowledge of service users is essential for developing recovery-oriented and evidence-based mental health services. Recent studies have however, suggested that challenges remain to the legitimization of user knowledge in practice. To further explore such challenges, a co-production study was conducted by a team of researchers and representatives from user organizations in Sweden. The aim of the study was to explore the barriers and facilitators to the legitimacy of user knowledge, as a central factor in sustainably implementing user influence in mental health practice. A series of workshops, with representatives of mental health services and user organizations were conducted by the research team to explore these issues. The analysis built on the theoretical framework of epistemic injustice, and the underlying aspects, testimonial, hermeneutic and participation-based injustice, were utilized as a framework for a deductive analysis. Results suggest that this is a useful model for exploring the complex dynamics related to the legitimacy of user knowledge in mental health systems. The analysis suggests that the legitimacy of user knowledge is related to the representativeness of the knowledge base, the systematic formulation of this knowledge in applicable methods, access to resources and positions within the mental health system and participation in the process of integrating this knowledge-base in mental health contexts. Legitimizing user knowledge in practice additionally challenges mental health systems to support readiness for change in working environments and to address the power and role issues that these changes involve.

Midkine and pleiotrophin have bactericidal properties: preserved antibacterial activity in a family of heparin-binding growth factors during evolution.

Antibacterial peptides of the innate immune system combat pathogenic microbes, but often have additional roles in promoting inflammation and as growth factors during tissue repair. Midkine (MK) and pleiotrophin (PTN) are the only two members of a family of heparin-binding growth factors. They show restricted expression during embryogenesis and are up-regulated in neoplasia. In addition, MK shows constitutive and inflammation-dependent expression in some non-transformed tissues of the adult. In the present study, we show that both MK and PTN display strong antibacterial activity, present at physiological salt concentrations. Electron microscopy of bacteria and experiments using artificial lipid bilayers suggest that MK and PTN exert their antibacterial action via a membrane disruption mechanism. The predicted structure of PTN, employing the previously solved MK structure as a template, indicates that both molecules consist of two domains, each containing three antiparallel beta-sheets. The antibacterial activity was mapped to the unordered C-terminal tails of both molecules and the last beta-sheets of the N-terminals. Analysis of the highly conserved MK and PTN orthologues from the amphibian Xenopus laevis and the fish Danio rerio suggests that they also harbor antibacterial activity in the corresponding domains. In support of an evolutionary conserved function it was found that the more distant orthologue, insect Miple2 from Drosophila melanogaster, also displays strong antibacterial activity. Taken together, the findings suggest that MK and PTN, in addition to their earlier described activities, may have previously unrealized important roles as innate antibiotics.

Assessment of Temporal Bone Thickness for Implantation of a New Active Bone-Conduction Transducer.

OBJECTIVE: To investigate the minimum bone thickness in adults and children in the area of the skull affected by implantation of a new bone conduction device in patients without known medical history that indicates anatomical malformations. STUDY DESIGN: Retrospective, non-interventional study on computer tomography (CT) scans on file at a university medical center. STUDY METHODS: A digital model of the new bone conduction implant was virtually implanted in 3D reconstructions of temporal bones based on 197 CT scans, 132 from adults and 65 from children (evenly distributed in five different age groups). The bone thickness was measured in a total of 11 designated positions; five measurement points for the transducer (recess area), and six for the fixation screws, corresponding to three different positions for the fixation band holding the implant in place (screw area). RESULTS: The minimum bone thickness in the combined recess and screw area for adults was 5.55 ±â€Š1.46 mm, with a 95% CI of 5.30 to 5.80 mm. For children, the thickness was 4.34 ±â€Š2.29 mm (95% CI: 3.77-4.91 mm), increasing from 1.92 mm (0-4 yr) to 6.41 mm (12-14 yr). For all ages, the bone in the recess area was generally thicker compared with the screw area.With an implantation depth of 3 mm the transducer fitted in all of the adult temporal bones (100%) and 99.2% (131/132) of the adults had a bone thickness of at least 2.7 mm in all six measured screw positions. In all children from the age of 5 the transducer fitted at an implantation depth of 3 mm, and in all children from the age of 9, the fixation screws fitted at a depth of 2.7 mm. In all CT scans except for a 6-month-old child the new bone conduction device could be implanted in at least one of the fixation band positions analyzed. CONCLUSIONS: In adults and many children without known medical history that indicates anatomical malformations, the average minimum bone thickness was thicker than both the maximum transducer depth of 3 mm and the 2.7 mm bone involvement of the osseointegrating fixation screws. The results indicate implant fit of the new bone conduction implant in all adult patients. The risks of compromising the sigmoid sinus and the dura as considered with larger implants are thus significantly reduced. Preoperative planning with CT would still be recommended for children below 9 years old.

Antimicrobial Peptide-Functionalized Mesoporous Hydrogels.

Antimicrobial peptides (AMPs) are seen as a promising replacement to conventional antibiotics for the prevention of skin wound infections. However, due to the short half-life of AMPs in biological environments, such as blood, their use in clinical applications has been limited. The covalent immobilization of AMPs onto suitable substrates is an effective solution to create contact-killing surfaces with increased long-term stability. In this work, an antimicrobial peptide, RRPRPRPRPWWWW-NH2 (RRP9W4N), was covalently attached to amphiphilic and ordered mesoporous Pluronic F127 hydrogels made of cross-linked lyotropic liquid crystals through 1-ethyl-3-(3-(dimethylamino)propyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) chemistry. The AMP-hydrogels showed high antibacterial activity against Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, methicillin-resistant S. aureus (MRSA), and multidrug-resistant Escherichia coli for up to 24 h. Furthermore, the AMP-hydrogels did not present any toxicity to human fibroblasts. The AMPs retained their antimicrobial activity up to 48 h in human blood serum, which is a significant increase in stability compared to when used in dissolved state. A pilot in vivo rat model showed 10-100× less viable counts of S. aureus on AMP-hydrogels compared with control hydrogels during the first 3 days of infection. Studies performed on human whole blood showed that blood coagulated more readily in the presence of AMP-hydrogels as compared to hydrogels without AMPs, indicating potential hemostatic activity. Overall, the results suggest that the combination of amphiphilic hydrogels with covalently bonded AMPs has potential to be used as antibacterial wound dressing material to reduce infections and promote hemostatic activity as an alternative to antibiotics or other antimicrobial agents, whose use should be restricted.

Integrin and chemokine receptor gene expression in implant-adherent cells during early osseointegration.

The mechanisms of early cellular recruitment and interaction to titanium implants are not well understood. The aim of this study was to investigate the expression of pro-inflammatory cytokines, chemokines and adhesion markers during the first 24 h of implantation. Anodically oxidized and machined titanium implants were inserted in rat tibia. After 3, 12, and 24 h the implants were unscrewed and analyzed with quantitative polymerase chain reaction. Immunohistochemistry and scanning electron microscopy revealed different cell types, morphology and adhesion at the two implant surfaces. A greater amount of cells, as indicated by higher expression of small subunit ribosomal RNA (18S), was detected on the oxidized surface. Higher expression of CXC chemokine receptor-4 (at 12 h) and integrins, alphav (at 12 h), beta1 (at 24 h) and beta2 (at 12 and 24 h) was detected at the oxidized surfaces. Significantly higher tumor necrosis factor-alpha (at 3 h) and interleukin-1beta (at 24 h) expression was demonstrated for the machined surface. It is concluded that material surface properties rapidly modulate the expression of receptors important for the recruitment and adhesion of cells which are crucial for the inflammatory and regenerative processes at implant surfaces in vivo.

Synthesis of 2'-([1,2,3]triazol-1-yl)-2'-deoxyadenosines.

A reliable and efficient protocol for the synthesis of 2 '-([1,2,3]triazol-1-yl)-2 '-deoxyadenosine derivatives from vidarabine is presented. Vidarabine was converted to 2'-azido-2'-deoxy-3',5-O-(tetraisopropyldisiloxane-1,3-diyl)-adenosine. This azide was used as the starting material for the Cu(I)-catalyzed parallel synthesis of 1,2,3-triazoles using a variety of alkynes. The reactions proceeded in good yield and gave almost exclusively the 1,4-disubstituted 1,2,3-triazoles.

Staphylococcal biofilm gene expression on biomaterials - A methodological study.

The combination of increased healthcare access, universal aging, and infallible therapy demands, synergistically drive the need for the development of biomaterial technologies that mitigate the challenge of biomaterial-associated infections (BAI). Staphylococcus epidermidis and Staphylococcus aureus account for the majority of BAI due to their ability to accumulate in adherent multilayered biofilm. This investigation details the development of gene expression assays to evaluate the genetic processes of attachment, accumulation, maturation, and dispersal phases of biofilms on biomaterials in vitro, while abiding by the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines. The biofilm formation of S. epidermidis on polyurethane (PU) central venous catheters and S. aureus on machined titanium (Ti) was examined in terms of gene expression at early and late time points. The results provided insight into how each stage of biofilm formation is orchestrated over time on these biomaterials in vitro. Furthermore, the results suggested that mechanical RNA extraction, organic solvents, elimination of genomic DNA, and preamplification are advisable strategies to implement for biofilm gene expression analysis. It is concluded that this method can be employed for the assessment of biofilm-biomaterial interactions at the molecular level. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3400-3412, 2017.

Site-specific gene expression analysis of implant-near cells in a soft tissue infection model - Application of laser microdissection to study biomaterial-associated infection.

Analysis of the implant-tissue interface is important for an understanding of the cellular response to biomaterials with different surface characteristics. However, inaccessibility to the site has restricted the detailed evaluation of the tissue surrounding the implant. Laser microdissection enables the isolation of specific cells and tissues for subsequent DNA, RNA, or protein analysis. The present experimental study employed laser microdissection to analyze tissue-specific differences in gene expression in cells around infected or control titanium implants 72 h after subcutaneous implantation in a rat model. Three different tissue zones located 0-800 µm away from the implant-tissue interface were analyzed. Implant sites challenged with a dose of 106  CFU Staphylococcus epidermidis demonstrated higher gene expression of selected markers for inflammation (TNF-α, IL-6), cell recruitment (MCP-1, IL-8, IL-8 R), infection (TLR2), and tissue remodeling (MMP-9) compared with control implants. Furthermore, the gene expression analysis of the three extracted tissue zones revealed marked spatial differences, depending on the distance to the implant. Control implants continuously induced higher cell gene expression in the implant-tissue interface compared with cells 200-800 µm away from the implant, whereas the sites inoculated with S. epidermidis resulted in high gene expression further away from the implant as well. In conclusion, this study demonstrates that laser microdissection is an interesting tool, revealing both gene- and site-specific gene expression patterns in the implant-tissue interface. The technique provides an opportunity for detailed molecular dissection of the biological events related to the implant but occurring at different distances from the implant. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2210-2217, 2017.

A novel soft tissue model for biomaterial-associated infection and inflammation - bacteriological, morphological and molecular observations.

Infection constitutes a major risk for implant failure, but the reasons why biomaterial sites are more vulnerable than normal tissue are not fully elucidated. In this study, a soft tissue infection model was developed, allowing the analysis of cellular and molecular responses in each of the sub-compartments of the implant-tissue interface (on the implant surface, in the surrounding exudate and in the tissue). Smooth and nanostructured titanium disks with or without noble metal chemistry (silver, gold, palladium), and sham sites, were inoculated with Staphylococcus epidermidis and analysed with respect to number of viable bacteria, number, viability and gene expression of host cells, and using different morphological techniques after 4 h, 24 h and 72 h. Non-infected rats were controls. Results showed a transient inflammatory response at control sites, whereas bacterial administration resulted in higher recruitment of inflammatory cells (mainly polymorphonuclear), higher, continuous cell death and higher gene expression of tumour necrosis factor-alpha, interleukin-6, interleukin-8, Toll-like receptor 2 and elastase. At all time points, S. epidermidis was predominantly located in the interface zone, extra- and intracellularly, and lower levels were detected on the implants compared with surrounding exudate. This model allows detailed analysis of early events in inflammation and infection associated to biomaterials in vivo leading to insights into host defence mechanisms in biomaterial-associated infections.

Role of nanostructured gold surfaces on monocyte activation and Staphylococcus epidermidis biofilm formation.

The role of material surface properties in the direct interaction with bacteria and the indirect route via host defense cells is not fully understood. Recently, it was suggested that nanostructured implant surfaces possess antimicrobial properties. In the current study, the adhesion and biofilm formation of Staphylococcus epidermidis and human monocyte adhesion and activation were studied separately and in coculture in different in vitro models using smooth gold and well-defined nanostructured gold surfaces. Two polystyrene surfaces were used as controls in the monocyte experiments. Fluorescent viability staining demonstrated a reduction in the viability of S. epidermidis close to the nanostructured gold surface, whereas the smooth gold correlated with more live biofilm. The results were supported by scanning electron microscopy observations, showing higher biofilm tower formations and more mature biofilms on smooth gold compared with nanostructured gold. Unstimulated monocytes on the different substrates demonstrated low activation, reduced gene expression of pro- and anti-inflammatory cytokines, and low cytokine secretion. In contrast, stimulation with opsonized zymosan or opsonized live S. epidermidis for 1 hour significantly increased the production of reactive oxygen species, the gene expression of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), IL-6, and IL-10, as well as the secretion of TNF-α, demonstrating the ability of the cells to elicit a response and actively phagocytose prey. In addition, cells cultured on the smooth gold and the nanostructured gold displayed a different adhesion pattern and a more rapid oxidative burst than those cultured on polystyrene upon stimulation. We conclude that S. epidermidis decreased its viability initially when adhering to nanostructured surfaces compared with smooth gold surfaces, especially in the bacterial cell layers closest to the surface. In contrast, material surface properties neither strongly promoted nor attenuated the activity of monocytes when exposed to zymosan particles or S. epidermidis.

The influence of bone type on the gene expression in normal bone and at the bone-implant interface: experiments in animal model.

BACKGROUND: Studies on the biological processes in different bone types and the reaction of different bone types to biomaterials are often hindered because of the difficulties in sampling procedures and lack of sensitive techniques. PURPOSE: The purpose was to assess the suitability of quantitative polymerase chain reaction (qPCR) for investigation of the biological differences between cortical and trabecular bone types and their responses to biomaterials. MATERIALS AND METHODS: Gene expression of selected markers in rat bone samples from different locations was evaluated. Samples were harvested by trephines from the trabecular femoral epiphysis, cortico-trabecular proximal tibial metaphysic, and the cortical distal tibial metaphysis. Gene expression was also evaluated at the surfaces of anodically oxidized implants retrieved from cortical and trabecular sites after 3 days of implantation. mRNA in the bone samples and in the tissue associated with the implant surfaces was extracted and quantified using qPCR. Tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), alkaline phosphatase (ALP), osteocalcin (OC), tartrate-resistant acid phosphatase (TRAP), cathepsin K (CATK), and 18S ribosomal subunits (18S) were analyzed. RESULTS: In the bone samples, higher expression of ALP, OC, TRAP, and CATK was found in femoral epiphysis compared to proximal or distal tibial metaphysis, indicating a higher turnover in the trabecular bone. On the other hand, TNF-α and IL-1ß showed higher expression in both tibia sites compared with the femur site, which suggests higher inflammatory potential in the cortical bone. In response to the oxidized implants trabecular bone expressed a higher level of IL-1ß, whereas the implants in cortical bone were associated with higher expression of ALP and OC. CONCLUSION: There are biological differences between cortical and trabecular bone types, both in the normal steady-state condition and in response to biomaterials. Such differences can be characterized and discriminated quantitatively using a sensitive technique such as qPCR.

Human embryonic mesodermal progenitors highly resemble human mesenchymal stem cells and display high potential for tissue engineering applications.

Adult stem cells, such as human mesenchymal stem cells (hMSCs), show limited proliferative capacity and, after long-term culture, lose their differentiation capacity and are therefore not an optimal cell source for tissue engineering. Human embryonic stem cells (hESCs) constitute an important new resource in this field, but one major drawback is the risk of tumor formation in the recipients. One alternative is to use progenitor cells derived from hESCs that are more lineage restricted but do not form teratomas. We have recently derived a cell line from hESCs denoted hESC-derived mesodermal progenitors (hES-MPs), and here, using genome-wide microarray analysis, we report that the process of hES-MPs derivation results in a significantly altered expression of hESC characteristic genes to an expression level highly similar to that of hMSCs. However, hES-MPs displayed a significantly higher proliferative capacity and longer telomeres. The hES-MPs also displayed lower expression of HLA class II proteins before and after interferon-gamma treatment, indicating that these cells may somewhat be immunoprivileged and potentially used for HLA-incompatible transplantation. The hES-MPs are thus an appealing alternative to hMSCs in tissue engineering applications and stem-cell-based therapies for mesodermal tissues.

In vivo evaluation of noble metal coatings.

A nanotopographic noble metal (Ag, Au, Pd) coating has been applied on commercial urinary catheters and used in more than 80,000 patients, with good clinical results. We have previously evaluated the biocompatibility of different variations of this coating, showing high cellular viability and function in vitro. However, the reasons for good clinical and preclinical behavior are not known. This in vivo study aimed to investigate the soft tissue peri-implant reaction to five coatings with systematically altered noble metal ratios after 1, 3, and 21 days of implantation in rats. The results show that coatings of silver only, or silver with medium amounts of gold and low-medium palladium content were superior to other tested coatings. Such surfaces were during the first days after implantation associated with a decreased recruitment of inflammatory cells to implant close exudates, a lower percentage of neutrophils, higher cell viability, and lower production of monocyte chemoattractant protein-1 (MCP-1), compared to the other coatings and uncoated silicone (PDMS) control. In contrast, the addition of higher concentrations of gold and palladium to silver induced a thicker soft tissue capsule. Coatings with high concentration of palladium induced the thickest fibrouscapsule after 21 days of implantation. The study demonstrates that by varying the noble metal ratio at implant surfaces it is possible to modulate inflammation and fibrosis in soft tissue.

In vivo gene expression in response to anodically oxidized versus machined titanium implants.

A quantitative polymerase chain reaction technique (qPCR) in combination with scanning electron microscopy was applied for the evaluation of early gene expression response and cellular reactions close to titanium implants. Anodically oxidized and machined titanium miniscrews were inserted in rat tibiae. After 1, 3, and 6 days the implants were unscrewed and the surrounding bone was retrieved using trephines. Both the implants and bone were analyzed with qPCR. A greater amount of cells, as indicated with higher expression of 18S, was detected on the oxidized surface after 1 and 6 days. Significantly higher osteocalcin (at day 6), alkaline phosphatase (at days 3 and 6), and cathepsin K (at day 3) expression was demonstrated for the oxidized surface. Higher expression of tumor necrosis factor-alpha (at day 1) and interleukin-1beta (at days 1 and 6) was detected on the machined surfaces. SEM revealed a higher amount of mesenchymal-like cells on the oxidized surface. The results show that the rapid recruitment of mesenchymal cells, the rapid triggering of gene expression crucial for bone remodeling and the transient nature of inflammation, constitute biological mechanisms for osseointegration, and high implant stability associated with anodically oxidized implants.