High density type I collagen gels for tissue engineering of whole menisci

This study investigates the potential of high density type I collagen gels as an injectable scaffold for tissue engineering of whole menisci, and compares these results with previous strategies using alginate as an injectable scaffold. Bovine meniscal fibrochondrocytes were mixed with collagen and injected into micro-computed tomography-based molds to create 10 and 20 mg ml^?1 menisci that were cultured for up to 4 weeks and compared with cultured alginate menisci. Contraction, histological, confocal microscopy, biochemical and mechanical analysis were performed to determine tissue development. After 4 weeks culture, collagen menisci had preserved their shape and significantly improved their biochemical and mechanical properties. Both 10 and 20 mg ml^?1 menisci maintained their DNA content while significantly improving the glycosaminoglycan and collagen content, at values significantly higher than the alginate controls. Collagen menisci matched the alginate control in terms of the equilibrium modulus, and developed a 3- to 6-fold higher tensile modulus than alginate by 4 weeks. Further fibrochondrocytes were able to reorganize the collagen gels into a more fibrous appearance similar to native menisci.     

Effects of hydroxyapatite on endothelial network formation in collagen/fibrin composite hydrogels in vitro and in vivo

Co-culture of endothelial cells (EC) and mesenchymal stem cells (MSC) results in robust vascular network formation in constrained 3-D collagen/fibrin (COL/FIB) composite hydrogels. However, the ability to form endothelial networks is lost when such gels are allowed to compact via cell-mediated remodeling. In this study, we created co-cultures of human EC and human MSC in both constrained and unconstrained COL/FIB matrices and systematically added nanoparticulate hydroxyapatite (HA, 0–20 mg ml⁻¹), a bone-like mineral that has been shown to have pro-vasculogenic effects. Constructs cultured for 7 days were assayed for gel compaction, vascular network formation, and mechanical properties. In vitro, robust endothelial network formation was observed in constrained COL/FIB constructs without HA, but this response was significantly inhibited by addition of 5, 10, or 20 mg ml⁻¹ HA. In unconstrained matrices, network formation was abolished in pure COL/FIB constructs but was rescued by 1.25 or 2.5 mg ml⁻¹ HA, while higher levels again inhibited vasculogenesis. HA inhibited gel compaction in a dose-dependent manner, which was not correlated to endothelial network formation. HA affected initial stiffness of the gels, but gel remodeling abrogated this effect. Subcutaneous implantation of COL/FIB with 0, 2.5 or 20 mg ml⁻¹ HA in the mouse resulted in increased perfusion at the implant site, with no significant differences between materials. Histology at day 7 showed both host and human CD31-stained vasculature infiltrating the implants. These findings are relevant to the design of materials and scaffolds for orthopedic tissue engineering, where both vasculogenesis and formation of a mineral phase are required for regeneration.     

In vitro cytotoxicity of porous silicon microparticles: Effect of the particle concentration,surface chemistry and size

We report here the in vitro cytotoxicity of mesoporous silicon (PSi) microparticles on the Caco-2 cells as a function of particle size fractions (1.2–75 μm), particle concentration (0.2–4 mg ml^?1) and incubation times (3, 11 and 24 h). The particle size (smaller PSi particles showed higher cytotoxicity) and the surface chemistry treatment of the PSi microparticles were considered to be the key factors regarding the toxicity aspects. These effects were significant after the 11 and 24 h exposure times, and were explained by cell–particle interactions involving mitochondrial disruption resulting from ATP depletion and reactive oxygen species production induced by the PSi surface. These events further induced an increase in cell apoptosis and consequent cell damage and cell death in a dose-dependent manner and as a function of the PSi particle size. These effects were, however, less pronounced with thermally oxidized PSi particles. Under the experimental conditions tested and at particle sizes >25 μm, the non-toxic threshold concentration for thermally hydrocarbonized and carbonized PSi particles was <2 mg ml^?1, and for thermally oxidized PSi microparticles was <4 mg ml^?1.     

Gene expression profile of mouse fibroblasts exposed to a biodegradable iron alloy for stents

Iron-based materials could constitute an interesting option for cardiovascular biodegradable stent applications due to their superior ductility compared to their counterparts – magnesium alloys. Since the predicted degradation rate of pure iron is considered slow, manganese (35% w/w), an alloying element for iron, was explored to counteract this problem through the powder metallurgy process (Fe–35 Mn). However, manganese presents a high cytotoxic potential; thus its effect on cells must first be established. Here, we established the gene expression profile of mouse 3T3 fibroblasts exposed to Fe–35 Mn degradation products in order to better understand cell response to potentially cytotoxic degradable metallic material (DMM). Mouse 3T3 cells were exposed to degradation products eluting through tissue culture insert filter (3 μm pore size) containing cytostatic amounts of 3.25 mg ml^?1 of Fe–35 Mn powder, 0.25 mg ml^?1 of pure Mn powder or 5 mg ml^?1 of pure iron powder for 24 h. We then conducted a gene expression profiling study from these cells. Exposure of 3T3 cells to Fe–35 Mn was associated with the up-regulation of 75 genes and down-regulation of 59 genes, while 126 were up-regulated and 76 down-regulated genes in the presence of manganese. No genes were found regulated for the iron powder. When comparing the GEP of 3T3 fibroblasts in the presence of Fe–35 Mn and Mn, 68 up-regulated and 54 down-regulated genes were common. These results were confirmed by quantitative RT-PCR for a subset of these genes. This GEP study could provide clues about the mechanism behind degradation products effects on cells of the Fe–35 Mn alloy and may help in the appraisal of its potential for DMM applications.     

Clinico-hematological and micronuclear changes induced by cypermethrin in broiler chicks: Their attenuation with vitamin E and selenium

This study was carried out on 90 one-day-old broiler chicks to know clinico-hematological alterations, DNA damage caused by cypermethrin (CY), and attenuation of toxic effects by vitamin E (Vit E) and selenium (Se). Birds were randomly divided into five equal groups. Groups 1–4 received CY (600 ml kg^?1 b.wt) daily for 30 days by crop tubing. In addition to CY, groups 2, 3 and 4 received Vit E (150 mg kg^?1 b.wt), Se (0.25 mg kg^?1 b.wt), and Vit E (150 mg kg^?1 b.wt)+Se (0.25 mg kg^?1 b.wt), respectively. Group 5 served as control. Birds were monitored twice daily for clinical signs. They were weighed and blood samples were collected at experimental days 10, 20 and 30 for hematological studies. CY-treated birds showed more prominent signs of toxicity compared to CY+Vit E, CY+Se and CY+Vit E+Se birds. Body weight in groups 1–3 was significantly (P<0.05) smaller at days 20 and 30 when compared with the control group. Significantly (P<0.001) higher numbers of micronuclei appeared in chicks treated with CY compared to CY+Vit E- and CY+Se-treated birds. Significantly decreased total erythrocyte counts (TEC), hemoglobin (Hb) concentration and packed cell volume (PCV) in all treated groups were recorded. Treated birds suffered from macrocytic hypochromic anemia. Leukocytosis in early stage and later leucopenia was seen in treated birds. It can be concluded that CY induces toxic effects in broilers chicks; however, these toxic effects can be ameliorated by Vit E or Se. Combination of Vit E and Se was more effective to ameliorate toxic effects of cypermethrin.     

Toxico-pathological changes induced by cypermethrin in broiler chicks: Their attenuation with Vitamin E and selenium

Ninety 1-day old broiler chicks of mixed gender (as hatched) procured from a local hatchery were randomly divided into five equal groups. All the treatments were given through crop tubing. Groups 1–4 received cypermethrin (CY) (600 mg kg^?1 b. wt.) daily for 30 days. In addition to CY (group 1), groups 2–4 received Vit E (150 mg kg^?1 b. wt.), Se (0.25 mg kg^?1 b. wt.), and Vit E (150 mg kg^?1 b. wt.)+Se (0.25 mg kg^?1 b. wt.), respectively. Group 5 served as control andreceived normal saline (2 ml kg^?1 b. wt.) for 30 days. Randomly selected six broiler chicks from each group were slaughtered at experimental days 10, 20 and 30 for the collection of serum/plasma and morbid tissues. Absolute organ weights were recorded. Total plasma proteins, fibrinogen and creatinine were significantly (P<0.05) increased while alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and urea decreased significantly (P<0.05) in CY-treated group when compared with the control group. Kidneys were swollen grossly in treated broiler chicks. In liver, necrosis of hepatocytes, cytoplasmic vacuolation, bile duct hyperplasia and mononuclear cellular infiltration were observed. In kidneys, necrosis of tubular epithelial cells, cytoplasmic vacuolation, cellular infiltration and atrophy of glomeruli were observed. Sub-arachnoid space was much dilated in CY-treated broiler chicks. It can be concluded that CY induces biochemical and histopathological alterations in broilers chicks; however, these toxic effects can be ameliorated by Vit E or Se. Combination of Vit E and Se was more effective in ameliorating toxic effects of cypermethrin in broilers chicks.     

Preventive effect of a galactoglucomannan (GGM) from Dendrobium huoshanense on selenium-induced liver injury and fibrosis in rats

This study was carried out to investigate the preventive effects of galactoglucomannan (GGM), a homogeneous polysaccharide from Dendrobium huoshanense, on liver injury and fibrosis induced by sodium selenite. Sprague–Dawley rats injected subcutaneously with sodium selenite at the dosage of 3.28 mg kg^?1 b. wt. were set as the model groups. Rats treated with sodium selenite at the dosage of 3.28 mg kg^?1 b. wt. and GGM at 50–200 mg kg^?1 b. wt. were set as the prevention groups. Biochemical and histological analysis showed that GGM significantly ameliorated selenite-induced liver injury and fibrosis in rats. Oral administration of GGM effectively attenuated the toxicity of selenite to liver tissue, which was judged both by the decreased activities of serum hepatic enzymes, including alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH), and by liver histopathological examination. Meanwhile, GGM also reduced the levels of H₂O₂ and malondialdehyde (MDA), elevated the levels of GSH, restored the fluidity of hepatic plasma membrane, and retained the activities of endogenous enzymes including superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST). The prevention of selenite-induced liver injury and fibrosis by GGM was further supported by the reduced expression of transforming growth factor-β1 (TGF-β1) and type I collagen. These results suggested that GGM may be developed into a novel antifibrotic agent for the prevention of liver injury and fibrosis.     

An explanation of the mineralization mechanism in osteoblasts induced by calcium hydroxide

Calcium hydroxide (Ca(OH)₂) has been broadly used in endodontics, including apexification to obtain apical closure by mineralization. However, the detailed mechanism of mineralization induced by Ca(OH)₂ is still unclear. This study focuses on the function of calcium and hydroxyl ions which dissociate from Ca(OH)₂ during the mineralization process. Though primary osteoblasts cultured in the medium without or with 0.025 mg ml^?1 Ca(OH)₂ did not show mineralization, they did exhibit mineralization when they were cultured with a higher concentration of Ca(OH)₂ (0.25 mg ml^?1). Mineralization induced in the presence of 0.25 mg ml^?1 Ca(OH)₂ was greater at pH 7.4 than at pH 8.5. The high mineralization activity observed under neutral conditions was caused by the prolonged activation of p38 and JNK. Hydroxyl ions did not have any effect on the mineralization. The results demonstrate that calcium ions dissociated from Ca(OH)₂ are critical for inducing the mineralization of osteoblasts.     

Control of cellular adhesiveness in an alginate-based hydrogel by varying peroxidase and H2O2 concentrations during gelation

An aqueous solution of alginate possessing phenolic hydroxyl (Alg-Ph) groups is gellable via a horseradish peroxidase (HRP)-catalyzed oxidative crosslinking reaction between Ph groups, consuming H₂O₂ as an electron acceptor. This study evaluates the effect of H₂O₂ and HRP concentrations on cellular adhesiveness and proliferation on the resultant enzymatically crosslinked Alg-Ph gels. After 4 h of seeding, 81.1% of L929 fibroblast cells adhere to an Alg-Ph hydrogel prepared with 1 U ml^?1 HRP and 1 mM H₂O₂. Increasing the concentration of H₂O₂ to 15 mM decreases the percentage of adhering cells to 28.4%. The cellular adhesion at this H₂O₂ concentration is increased to 82.6% by increasing the HRP concentration to 10 U ml^?1. The cells adhering to the Alg-Ph hydrogels with higher cellular adhesiveness establish a confluent monolayer during 168 h of culture. A cell sheet can then be harvested within 5 min of immersion in a medium containing alginate lyase at 1.0 mg ml^?1. The harvested cell sheet re-adhere, and the cells contained in the sheet proliferate after being transferred to another cell culture dish.     

The correlation of sodium iodide symporter and BRAFV600E mutation in classical variant papillary thyroid carcinoma

BRAF^V600E mutation was analyzed by real-time polymerase chain reaction in 96 consecutive cases with classical variant papillary thyroid cancer, and immunohistochemical staining of Na +/I − symporter (NIS) protein was evaluated. Localization (intracellular or membranous), density, and the intensity of cytoplasmic staining were characterized semiquantitatively. Extrathyroidal invasion, surgical margin positivity, and lymph node metastasis were compared with BRAF^V600E mutation and NIS expression. Eighty-eight patients who had at least 24-month follow-up were also included in survival analysis. BRAF^V600E mutation was determined in 78.1% (75/96) and functional NIS activity in 74% (71/96) of the cases. There were statistically significant differences in mean ages between BRAF^V600E mutation–positive (48.6) and BRAF^V600E mutation–negative cases (37.3; Levene test, P = .419; Student t test, P = .001). The surgical margin positivity (46.7%) and extrathyroidal extension percentage (54.7%) in the BRAF^V600E mutation–positive group were higher than the negative (28.6% and 33.3%, respectively) group, without statistical significance (P = .138 and P = .084, respectively). Functional NIS activity was higher in BRAF^V600E mutation–positive cases (78.1%) than mutation-negative ones (57.1%; P = .047). The possibility of moderate and intense cytoplasmic staining in BRAF^V600E mutation–positive cases (72%) was 6.3 times higher than the possibility of weak staining (28%) in the mutation-positive cases (95% confidence interval, 2.2-18.8; P = .001). Functional NIS expression is higher in patients with classical variant papillary thyroid cancer with BRAF^V600E mutation. However, the clinical features were not found to be associated with NIS expression. There may be different mechanisms determining the outcome of therapy.     

The inhibitory effect of polyvinylphosphonic acid on functional matrix metalloproteinase activities in human demineralized dentin

This study has examined the use of polyvinylphosphonic acid (PVPA) as a potential matrix metalloproteinase (MMP) inhibitor and how brief cross-linking of demineralized dentin matrix that did not affect its mechanical properties enhanced the anti-MMP activity of PVPA. The anti-MMP potential of five PVPA concentrations (100–3000 μg ml^–1) was initially screened using a rhMMP-9 colorimetic assay. Demineralized dentin beams were treated with the same five concentrations of PVPA to collagen and then aged for 30 days in a calcium- and zinc-containing medium. The changes in modulus of elasticity, loss of dry mass and dissolution of collagen peptides were measured via three-point bending, precision weighing and hydroxyproline assay, respectively. All tested PVPA concentrations were highly effective (P < 0.05) in inhibiting MMP-9. Ageing in the incubation medium did not significantly alter the modulus of elasticity of the five PVPA treatment groups. Conversely, aged dentin beams from the control group exhibited a significant decline in their modulus of elasticity (P < 0.05) over time. Mass loss from the dentin beams and the corresponding increase in hydroxyproline in the medium in the five PVPA treatment groups were significantly lower than for the control (P < 0.05). PVPA is a potent inhibitor of endogenous MMP activities in demineralized dentin. It may be used as an alternative to chlorhexidine to prevent collagen degradation within hybrid layers to extend the longevity of resin–dentin bonds.     

Encapsulation of fibroblasts causes accelerated alginate hydrogel degradation

Calcium-alginate hydrogel has been widely studied as a material for cell encapsulation for tissue engineering. At present, the effect that cells have on the degradation of alginate hydrogel is largely unknown. We have shown that fibroblasts encapsulated at a density of 7.5 × 10⁵ cells ml^?1 in both 2% and 5% w/v alginate remain viable for at least 60 days. Rheological analysis was used to study how the mechanical properties exhibited by alginate hydrogel changed during 28 days in vitro culture. Alginate degradation was shown to occur throughout the study but was greatest within the first 7 days of culture for all samples, which correlated with a sharp release of calcium ions from the construct. Fibroblasts were shown to increase the rate of degradation during the first 7 days when compared with acellular samples in both 2% and 5% w/v gels, but after 28 days both acellular and cell-encapsulating samples retained disc-shaped morphologies and gel-like spectra. The results demonstrate that although at an early stage cells influence the mechanical properties of encapsulating alginate, over a longer period of culture, the hydrogels retain sufficient mechanical integrity to exhibit gel-like properties. This allows sustained immobilization of the cells at the desired location in vivo where they can produce extracellular matrix and growth factors to expedite the healing process.     

Hydraulic permeability of multilayered collagen gel scaffolds under plastic compression-induced unidirectional fluid flow

Under conditions of free fluid flow, highly hydrated fibrillar collagen gels expel fluid and undergo gravity driven consolidation (self-compression; SC). This process can be accelerated by the application of a compressive stress (plastic compression; PC) in order to generate dense collagen scaffolds for tissue engineering. To define the microstructural evolution of collagen gels under PC, this study applied a two-layer micromechanical model that was previously developed to measure hydraulic permeability (k) under SC. Radially confined PC resulted in unidirectional fluid flow through the gel and the formation of a dense lamella at the fluid expulsion boundary which was confirmed by confocal microscopy of collagen immunoreactivity. Gel mass loss due to PC and subsequent SC were measured and applied to Darcy’s law to calculate the thickness of the lamella and hydrated layer, as well as their relative permeabilities. Increasing PC level resulted in a significant increase in mass loss fraction and lamellar thickness, while the thickness of the hydrated layer dramatically decreased. Permeability of lamella also decreased from 1.8 × 10^?15 to 1.0 × 10^?15 m² in response to an increase in PC level. Ongoing SC, following PC, resulted in a uniform decrease in mass loss and k with increasing PC level and as a function SC time. Experimental k data were in close agreement with those estimated by the Happel model. Calculation of average k values for various two-layer microstructures indicated that they each approached 10^?15–10^?14 m² at equilibrium. In summary, the two-layer micromechanical model can be used to define the microstructure and permeability of multi-layered biomimetic scaffolds generated by PC.     

The mechanical stress–strain properties of single electrospun collagen type I nanofibers

Knowledge of the mechanical properties of electrospun fibers is important for their successful application in tissue engineering, material composites, filtration and drug delivery. In particular, electrospun collagen has great potential for biomedical applications due to its biocompatibility and promotion of cell growth and adhesion. Using a combined atomic force microscopy (AFM)/optical microscopy technique, the single fiber mechanical properties of dry, electrospun collagen type I were determined. The fibers were electrospun from a 80 mg ml^?1 collagen solution in 1,1,1,3,3,3-hexafluro-2-propanol and collected on a striated surface suitable for lateral force manipulation by AFM. The small strain modulus, calculated from three-point bending analysis, was 2.82 GPa. The modulus showed significant softening as the strain increased. The average extensibility of the fibers was 33% of their initial length, and the average maximum stress (rupture stress) was 25 MPa. The fibers displayed significant energy loss and permanent deformations above 2% strain.     

Enhanced insulin secretion of physically crosslinked pancreatic β-cells by using a poly(ethylene glycol) derivative with oleyl groups

A polymeric crosslinker was developed to promote the formation of cellular spheroids. Our approach was based on the crosslinking of cell membrane using a polymeric crosslinker that worked via hydrophobic interaction. The crosslinker, a poly(ethylene glycol) derivative with oleyl groups as a hydrophobic group at both ends, was synthesized and characterized by gel permeation chromatography and Fourier-transform infrared spectroscopy. Cell culture experiments were then performed to confirm spheroid formation. The rat pancreatic islet β-cell line RIN, which possesses the ability to secrete insulin, was cultured with the crosslinker in a round-bottomed 96-well plate. The formation of a spheroid was achieved when the crosslinker was added to the cell suspension, especially in the absence of serum. The size of the spheroid decreased with time and with increasing crosslinker concentration, and depended on the number of cells plated in each well. The number of cells cultured with crosslinker was almost constant during 7 days and hardly proliferated in crosslinker concentrations of 0–2.5 mg ml^?1, while the number of cells showed a decrease in the 25 mg ml^?1 crosslinker concentration. It was shown that the insulin protein secretion in the spheroid cultured with crosslinker for 1 week was enhanced. The cell adhesion protein E-cadherin mRNA expression of the resulting spheroid was also enhanced. These results indicate that the promoted cell function was due to the cell–cell and cell–matrix interactions in the spheroid, suggesting that this polymeric crosslinker was useful for the formation of cell spheroids.     

c-Met expression and MET amplification in malignant pleural mesothelioma

c-Met is a receptor tyrosine kinase shown to be overexpressed in malignant pleural mesothelioma (MPM). Whereas MET mutations have been identified in 3%-16% of MPMs, MET amplification has recently been reported in a single epithelioid MPM. We studied c-Met expression and MET amplification in a large MPM cohort and correlated results with morphologic and clinical features. We report the first case of MET amplification in sarcomatoid MPM. MPMs from surgical pathology files (1989-2014) were reviewed. c-Met immunohistochemistry was performed. Staining intensity and distribution were multiplied (H-score). Staining localization (cytoplasmic and/or membranous) was noted. Fluorescence in situ hybridization was performed using probes for MET and centromere 7. One hundred forty-nine patients (median age, 68.0 years; interquartile range, 61-75) had epithelioid (n = 97), biphasic (n = 18), or sarcomatoid (n = 34) MPM. Median follow-up was 10.1 months (range, 0.1-222.5). One hundred thirty patients died of disease; 2 were alive with disease. c-Met was expressed in 147 MPMs. c-Met staining intensity, distribution, and H-score differed among the histologic subtypes (P = .015; P = .0001, and P = .0005, respectively), but none were predictive of survival. Epithelioid subtype had greater c-Met expression. MET amplification was identified in 1 sarcomatoid MPM and MET duplication in 1 epithelioid MPM; both had poor outcomes. Chromosome 7 aneusomy was observed in 54 of 144 (37.5%) MPMs and associated with decreased overall survival in sarcomatoid MPMs (hazard ratio = 2.81; 95% confidence interval, 1.21-6.51; P = .01). In conclusion, c-Met is expressed in MPM, with significant differences in expression among histologic subtypes. MET amplification is a rare event in MPM, making it an unlikely common pathogenesis for c-Met expression.     

Reduced hydraulic permeability of three-dimensional collagen scaffolds attenuates gel contraction and promotes the growth and differentiation of mesenchymal stem cells

Optimal scaffold characteristics are essential for the therapeutic application of engineered tissues. Hydraulic permeability (k) affects many properties of collagen gels, such as mechanical properties, cell–scaffold interactions within three dimensions (3D), oxygen flow and nutrient diffusion. However, the cellular response to 3D gel scaffolds of defined k values has not been investigated. In this study, unconfined plastic compression under increasing load was used to produce collagen gels with increasing solid volume fractions. The Happel model was used to calculate the resulting permeability values in order to study the interaction of k with gel mechanical properties and mesenchymal stem cell (MSC)-induced gel contraction, metabolism and differentiation in both non-osteogenic (basal medium) and osteogenic medium for up to 3 weeks. Collagen gels of fibrillar densities ranging from 0.3 to >4.1 wt.% gave corresponding k values that ranged from 1.00 to 0.03 μm². Mechanical testing under compression showed that the collagen scaffold modulus increased with collagen fibrillar density and a decrease in k value. MSC-induced gel contraction decreased as a direct function of decreasing k value. Relative to osteogenic conditions, non-osteogenic MSC cultures exhibited a more than 2-fold increase in gel contraction. MSC metabolic activity increased similarly under both osteogenic and non-osteogenic culture conditions for all levels of plastic compression. Under osteogenic conditions MSC differentiation and mineralization, as indicated by alkaline phosphatase activity and von Kossa staining, respectively, increased in response to an elevation in collagen fibrillar density and decreased gel permeability. In this study, gel scaffolds with higher collagen fibrillar densities and corresponding lower k values provided a greater potential for MSC differentiation and appear most promising for bone grafting purposes. Thus, cell–scaffold interactions can be optimized by defining the 3D properties of collagen scaffolds through k adjustment.     

Hemocompatibility evaluation of different silver nanoparticle concentrations employing a modified Chandler-loop in vitro assay on human blood

Due to their antibacterial effects, the use of silver nanoparticles (AgNPs) in a great variety of medical applications like coatings of medical devices has increased markedly in the last few years. However, blood in contact with AgNPs may induce adverse effects, thereby altering hemostatic functions. The objective of this study was to investigate the hemocompatibility of AgNPs in whole blood. Human whole blood (n = 6) was treated with different AgNPs concentrations (1, 3 and 30 mg l^?1) or with saline/blank solutions as controls before being circulated in an in vitro Chandler-loop model for 60 min at 37 °C. Before and after circulation, various hematologic markers were investigated. Based on the hematologic parameters measured, no profound changes were observed in the groups treated with AgNP concentrations of 1 or 3 mg l^?1. AgNP concentrations of 30 mg l^?1 induced hemolysis of erythrocytes and α-granule secretion in platelets, increased CD11b expression on granulocytes, increased coagulation markers thrombin–antithrombin-III complex, kallikrein-like and FXIIa-like activities as well as complementing cascade activation. Overall, we provide for the first time a comprehensive evaluation including all hematologic parameters required to reliably assess the hemocompatibility of AgNPs. We strongly recommend integrating these hemocompatibility tests to preclinical test procedures prior to in vivo application of new AgNP-based therapies.     

Low-density polypropylene meshes coated with resorbable and biocompatible hydrophilic polymers as controlled release agents of antibiotics

The application of bioactive meshes in abdominal surgery for the repair of hernias is an increasing clinical activity in a wide sector of the population. The main secondary effect is the appearance of infections from bacteria, specifically Staphylococcus aureus and S. epidermidis. This paper describes the development and application of low-density polypropylene meshes coated with a biocompatible and resorbable polymer as a controlled release system of the antibiotic vancomycin. The polymeric coating (a non-cross-linked copolymer of 2-hydroxyethyl methacrylate and 2-acrylamido-2-methylpropanesulfonic acid) has a thickness of 14–15 μm and contains 0.32 mg cm^?2 of the antibiotic vancomycin. The in vitro experiments demonstrate the excellent inhibitory character of the coated meshes loaded with the antibiotic, following the standard protocol of inhibition of halo in agar diffusion test. This inhibitory effect is maintained for a relatively long period (at least 14 days) with a low concentration of antibiotic. The acrylic polymer system regulates the release of the antibiotic with a rate of 24 μg h^?1, due to its slow dissolution in the medium. Experiments in vivo, based on the implantation of coated meshes, demonstrate that the system controls the infection in the animal (rabbits) for at least 30 days. The concentration of antibiotic in the blood stream of the rabbits was below the detection limit of the analytical technique (<1–2 μg ml^?1), which demonstrates that the antibiotic is released in the local area of the implant and remains concentrated at the implantation site, without diffusion to the blood stream. The systems can be applied to other medical devices and implants for the application of new-generation antibiotics in a controlled release and targeted applications.     

Periprosthetic tibial fractures in unicompartmental knee arthroplasty as a function of extended sagittal saw cuts: An experimental study

Periprosthetic tibial plateau fractures (TPF) are rare but represent a serious complication of unicompartmental knee arthroplasty (UKA). As TPFs usually occur perioperatively, these can be associated with extended sagittal saw cuts during surgery. The aim of the study was to evaluate TPF as a function of extended sagittal saw cuts. The hypothesis was that extended sagittal saw cuts reduce the loading capacity of the tibial plateau and increase the risk of periprosthetic TPF.In a randomised study, standardised cemented Oxford UKA tibial component implantation was performed in six matched, paired fresh-frozen tibiae. In group A, a regular preparation of the tibial plateau was performed, whereas in group B a standardised extended sagittal saw cut was made at the dorsal cortex of the tibia. All tibiae were fractured under standardised conditions and fracture patterns and fracture loads were analysed.In group A, tibiae fractured with a mean load of F_max = 3.9 (2.3–8.5) kN, whereas in group B fractures occurred at a mean load of F_max = 2.6 (1.1–5.0) kN. The difference was statistically significant (p < 0.05).Extended sagittal saw cuts in UKA weaken the tibial bone structure. Our results show that descendent extended sagittal saw cuts of 10° reduce fracture loads by about 30%. Surgeons should be aware of the potential pitfalls of an extended sagittal saw cut, as this can lead to reduced loading capacity of the tibial plateau and increase the risk of periprosthetic TPF.