Cross-linked Matrix Research Articles

Histone Deacetylase Inhibitors Attenuate Hepatic Fibrosis through Suppression of Group 2 Innate Lymphoid Cells and Type 2 Inflammation

Deposition of collagen and matrix proteins is essential for tissue repair and remodelling. Chronic liver diseases typically show excessive matrix protein deposition or crosslinking that leads to scar tissue, obstructs blood flow and disrupts liver functions, all characteristics of advanced liver damage in cirrhosis. There are no effective anti‐fibrotic therapies. Immunomodulatory mechanisms that contribute to fibrogenesis in chronic liver disease are not fully elucidated. Here we examine thioacetamide‐induced liver injury in mice, which develop progressive hepatic inflammation and fibrosis similar to clinical features of chronic human liver disease. We find that inhibitors of class I, but not class II, histone deacetylase (HDAC) enzymes suppress hepatic inflammation and fibrosis in this model. Inhibitors of class I HDACs attenuate accumulation and activation of group 2 innate lymphoid cells (ILC2), specifically interleukin (IL)‐33 (but not IL‐25) dependent CD45+/Lin−/Thy‐1+/ST2+/KLRG1int ILC2 cells, associated with type 2 inflammation that drives hepatic stellate cells to secrete excessive matrix proteins. Some HDAC inhibitors that are registered anti‐cancer drugs might be repurposed for treating chronic liver fibrosis.Support or Funding InformationZL acknowledges salary support from the Centre for Inflammation and Disease Research, University of Queensland. The National Health and Medical Research Council of Australia is acknowledged for a Career Development Fellowship to KS (1141131), a Senior Research Fellowship to MJS (1107914) and a Senior Principal Research Fellowship to DPF (1117017).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Dosimetric and chemical characteristics of Fricke gels based on PVA matrices cross-linked with glutaraldehyde

Fricke gel radiochemical sensors based on various matrices have been studied for decades as 3D dosimeters for radiotherapy. Despite their many appealing features, progressive aging and blurring of the signal have prevented the widespread use of these dosimeters, so far. We have addressed these shortcomings and hereby present our development of a Fricke gel based on a chemically cross-linked PVA matrix. We investigated the influence of several parameters of the polymeric matrix on sensitivity, diffusion coefficient and spontaneous oxidation of the proposed gel dosimeter. Based on these findings, we optimized the gel compositions. Our new gel formulation combines transparency, high sensitivity and simple production method, typical of gels based on natural polymers, with low diffusion coefficient and slow spontaneous oxidation typical of PVA gels made by freezing-thawing.

Repair of complex abdominal wall hernias with a cross-linked porcine acellular matrix: cross-sectional results of a Dutch cohort study

BackgroundThe use of synthetic mesh in potentially contaminated and contaminated incisional hernias may lead to a higher morbidity and mortality. Biological meshes may provide a solution, but since these meshes are rarely used, little is known about long-term results. The aim of this cohort study was to evaluate the long-term clinical efficacy and patient satisfaction following Permacol™ in complex abdominal wall hernia repair (CAWHR) patients in a cross-sectional fashion. Materials and methodsAll patients were operated for CAWHR with Permacol™ in the Netherlands between 2009 and 2012. The design was a multicenter cross-sectional cohort study. The STROCSS statement was followed. Patients were interviewed, underwent abdominal examination, and completed quality-of-life questionnaires. ClinicalTrials.gov Identifier NCT02166112. Research Registry Identifier researchregistry4713. ResultsSeventy-seven patients were seen in the outpatient clinic. Their hernias were classified as potentially contaminated in 25 patients (32.5%) and infected in 52 patients (67.5%). The mean follow-up was 22.2 ± 12.6 months. The most frequent postoperative complication was wound infection (n = 21; 27.3%), meshes had to be removed in five patients (6.5%). By the time of their visit to the outpatient clinic, 22 patients (28.6%) had a recurrence of whom ten (13%) had undergone reoperation. Thirty-nine patients (50.6%) had bulging of the abdominal wall. Quality-of-life questionnaires revealed that patients graded their health status with a mean 6.8 (± 1.8) out of 10 points. ConclusionBulging and recurrence are frequently observed in patients treated with Permacol™ for CAWHR. Considering both recurrence and bulging as undesirable outcomes of treatment, a total of 46 patients (59.7%) had an unfavorable outcome. Infection rates were high, but comparable with similar patient cohorts. Quality-of-life questionnaires revealed that patients were satisfied with their general health, but scored significantly lower on most quality-of-life modalities of the Short Form-36 questionnaire.

Microcellular natural rubber using supercritical CO2 technology

Microcellular natural rubber (NR) prepared using a supercritical CO2 technology is a promising alternative to replace traditional foaming agent due to environmental concern. Crucial parameters for the foaming process including CO2 saturation time (30, 60, 90, 120, 180) min, pressure (0, 8.5, 10.5, 12.5) MPa, temperature (45, 55, 65, 85) °C, and crosslinking characteristics of NR (pre-vulcanized time at 15 min and 30 min) were orderly conducted. The results obtained showed a decrement of average cell size (less than 10 μm), cell size distribution, and expansion ratio depending on an enhancement of saturation time and pressure. However, the increment of saturation temperature affected the increase in average cell size, cell size distribution, and expansion ratio. In case of the crosslinking behavior, an escalation of the pre-vulcanized time of rubber influenced the decrement in average cell size, cell size distribution and expansion ratio resulting from an elevation of matrix crosslinking.

Thrombospondin-2 regulates extracellular matrix production, LOX levels, and cross-linking via downregulation of miR-29

Collagen fibrillogenesis and crosslinking have long been implicated in extracellular matrix (ECM)-dependent processes such as fibrosis and scarring. However, the extent to which matricellular proteins influence ECM protein production and fibrillar collagen crosslinking has yet to be determined. Here we show that thrombospondin 2 (TSP2), an anti-angiogenic matricellular protein, is an important modulator of ECM homeostasis. Specifically, through a fractionated quantitative proteomics approach, we show that loss of TSP2 leads to a unique ECM phenotype characterized by a significant decrease in fibrillar collagen, matricellular, and structural ECM protein production in the skin of TSP2 KO mice. Additionally, TSP2 KO skin displays decreased lysyl oxidase (LOX), which manifests as an increase in fibrillar collagen solubility and decreased levels of LOX-mediated fibrillar collagen crosslinking. We show that these changes are indirectly mediated by miR-29, a major regulator of ECM proteins and LOX, as miR-29 expression is increased in the TSP2 KO. Altogether, these findings indicate that TSP2 contributes to ECM production and assembly by regulating miR-29 and LOX.

The use of glycerol as reactive solvent in the one-pot synthesis of antibacterial hybrid organic–inorganic coatings with photothermal activity

Hybrid organic–inorganic coatings showing photothermal activity and anti-bacterial properties were easily obtained by cross-linking of glycerol in presence of silane-coated silver NPs (Ag NPs). Ag NPs functionalized with aminosilane groups were prepared by reduction of AgNO3 with 3-aminopropyl trimethoxysilane (APTMS), by following a previously published procedure (dell’Erba et al., J Mater Sci 51:3817–3823, 2016), using glycerol as both reducing agent and solvent. Thermal treatment of these dispersions induced reaction between hydroxyl from glycerol and methoxysilane groups, producing a chemically resistant, cross-linked nanostructured network with covalently bonded Ag NPs. Control on the degree of glycerol release during synthesis enabled producing, in just one step, a cross-linked material with variable concentrations of Ag NPs. Tuning the annealing temperature and composition of the reactive samples allowed controlling the final concentration of NPs in the solid samples and the physicochemical properties of the coatings. Obtained materials showed an excellent chemical stability, bactericidal effect against Escherichia coli, and a significant photothermal effect. The simplicity of the procedure, the use of glycerol as monomer and solvent, and the high versatility of the strategy that enables the inclusion of different metals in a cross-linked matrix, make the synthetic strategy very promising for the development of materials with technological applications.

Non-Cross-Linked Collagen Mesh Performs Best in a Physiologic, Noncontaminated Rat Model.

Background. In laparoscopic incisional hernia repair, direct contact between the prosthesis and abdominal viscera is inevitable and may lead to adhesions. Despite the large variety of mesh prosthesis, little is known about their in vivo behavior. Biological meshes are considered to have many advantages, but due to their price they are rarely used. A rat model was used to assess biological and conventional synthetic meshes on their in vivo characteristics. Design. One-hundred twenty male Wistar rats were randomized into five groups of 24 rats. A mesh was implanted intraperitoneally and fixated with nonresorbable sutures. The following five meshes were implanted: Parietene (polypropylene), Permacol (cross-linked porcine acellular dermal matrix), Strattice (non-cross-linked porcine acellular dermal matrix), XCM Biologic (non-cross-linked porcine acellular dermal matrix), and Omyra Mesh (condensed polytetrafluoroethylene). The rats were sacrificed after 30, 90, or 180 days. Incorporation, shrinkage, adhesions, abscess formation, and histology were assessed for all meshes. Results. All animals thrived postoperatively. After 180 days, Permacol, Parietene, and Omyra Mesh had a significantly better incorporation than Strattice (P = .001, P = .019, and P = .037 respectively). After 180 days, Strattice had significantly fewer adhesions on the surface of the mesh than Parietene (P < .001), Omyra Mesh (P = .011), and Permacol (P = .027). After 30 days, Permacol had significantly stronger adhesions than Strattice (P = .030). However, this difference was not significant anymore after 180 days. After 180 days, there was significantly less shrinkage in Permacol than in Strattice (P = .001) and Omyra Mesh (P = .050). Conclusion. Based on incorporation, adhesions, mesh shrinkage, and histologic parameters, Strattice performed best in this experimental rat model.

Matrix crosslinking enhances macrophage adhesion, migration, and inflammatory activation.

Macrophages are versatile cells of the innate immune system that can adopt a variety of functional phenotypes depending on signals in their environment. In previous work, we found that culture of macrophages on fibrin, the provisional extracellular matrix protein, inhibits their inflammatory activation when compared to cells cultured on polystyrene surfaces. Here, we sought to investigate the role of matrix stiffness in the regulation of macrophage activity by manipulating the mechanical properties of fibrin. We utilize a photo-initiated crosslinking method to introduce dityrosine crosslinks to a fibrin gel and confirm an increase in gel stiffness through active microrheology. We observe that matrix crosslinking elicits distinct changes in macrophage morphology, integrin expression, migration, and inflammatory activation. Macrophages cultured on a stiffer substrate exhibit greater cell spreading and expression of αM integrin. Furthermore, macrophages cultured on crosslinked fibrin exhibit increased motility. Finally, culture of macrophages on photo-crosslinked fibrin enhances their inflammatory activation compared to unmodified fibrin, suggesting that matrix crosslinking regulates the functional activation of macrophages. These findings provide insight into how the physical properties of the extracellular matrix might control macrophage behavior during inflammation and wound healing.

PbI2 Initiated Cross-Linking and Integration of a Polymer Matrix with Perovskite Films: 1000 h Operational Devices under Ambient Humidity and Atmosphere and with Direct Solar Illumination

The instability of organic lead halide perovskites such as MAPbI3 under ambient conditions is a challenge, as it leads to degradation in device performance and has limited their long-term applicati...

Deep eutectic solvents as simultaneous plasticizing and crosslinking agents for starch

The aim of this work was to prepare deep eutectic solvents (DES) made with choline salts with α-hydroxylate anions and glycerol and apply them as starch plasticizers. Additionally, crosslinking potential of polyfunctional anions from the salts was investigated. Starch/DES premixtures were rheologically and thermally (DSC, TGA) analyzed. Thermoplastic starch (TPS)/DES films were prepared via thermocompression molding. Influence of choline salt to glycerol molar ratio, type of anion and compression parameters on mechanical, dynamic mechanical, thermal and sorption properties as well as structural morphology (XRD, FTIR analysis) was studied. DES containing citrate anion exhibited parallel crosslinking and plasticizing ability of polysaccharide matrix as applied techniques confirmed. The higher choline citrate (CCit) content in DES the higher tensile strength, more amorphous structure and lower sorption degree to CCit:G 1:6 M ratio. XRD revealed that TPS/CCit-based DES films did not retrograde even after one year of storage. The best compression parameters for studied systems were: 140 °C, 12 tons, 10 min.

Impact of uniaxial tensile fatigue on the evolution of microscopic and mesoscopic structure of carbon black filled natural rubber.

This investigation addresses the evolution of the microscopic and mesoscopic structures distribution, and micro-defects of carbon black (CB) filled natural rubber (NR) under uniaxial tensile condition during the fatigue process. NR was filled with three different grades of CB in order to understand the impact of the structural degree and specific surface areas of CB and fatigue degree on the Payne effect. It was found that the Payne effect was initially suppressed and then enhanced by increasing the degree of fatigue. The decrease of the storage modulus in the low strain area was attributed to the CB network destruction and the breakdown of the matrix cross-linking network in the early fatigue stage. However, by further increasing the degree of fatigue, the spatial rearrangement of CB aggregates with the orientation of molecular chains between adjacent CB aggregates will results in mechanical reinforcement before the appearance of micro-defects. Moreover, it has been demonstrated that the structural degree of CB has a stronger impact on the mesoscopic structures than the specific surface area of CB during the tensile fatigue process.

Copolymer Solid-State Electrolytes for 3D Microbatteries via Initiated Chemical Vapor Deposition.

Reliable integration of thin film solid-state polymer electrolytes (SPEs) with 3D electrodes is one major challenge in microbattery fabrication. We used initiated chemical vapor deposition (iCVD) to produce a series of nanoscale copolymer films comprising hydroxyethyl methacrylate and ethylene glycol diacrylate. Conformal copolymer coatings were applied to a variety of patterned 3D electrodes and subsequently converted into ionic conductors by lithium salt doping. Broad tunability in ionic conductivity was achieved by optimizing the copolymer cross-linking density and matrix polarity, resulting in a room-temperature conductivity of (6.1 ± 2.7) × 10-6 S cm-1, the highest value reported for conformal, nanoscale SPEs.

Mimicking Active Biopolymer Networks with a Synthetic Hydrogel.

Stiffening due to internal stress generation is of paramount importance in living systems and is the foundation for many biomechanical processes. For example, cells stiffen their surrounding matrix by pulling on collagen and fibrin fibers. At the subcellular level, molecular motors prompt fluidization and actively stiffen the cytoskeleton by sliding polar actin filaments in opposite directions. Here, we demonstrate that chemical cross-linking of a fibrous matrix of synthetic semiflexible polymers with thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) produces internal stress by induction of a coil-to-globule transition upon crossing the lower critical solution temperature of PNIPAM, resulting in a macroscopic stiffening response that spans more than 3 orders of magnitude in modulus. The forces generated through collapsing PNIPAM are sufficient to drive a fluid material into a stiff gel within a few seconds. Moreover, rigidified networks dramatically stiffen in response to applied shear stress featuring power law rheology with exponents that match those of reconstituted collagen and actomyosin networks prestressed by molecular motors. This concept holds potential for the rational design of synthetic materials that are fluid at room temperature and rapidly rigidify at body temperature to form hydrogels mechanically and structurally akin to cells and tissues.

Electrospun Nanobelt-Shaped Polymer Membranes for Fast and High-Sensitivity Detection of Metal Ions.

Until now, no polymer nanobelt-shaped materials have been developed as electrochemical, optical, and mass sensors. In this work, we first develop polymer nanobelt-shaped membranes for fast and high-sensitivity detection of metal ions, which are fabricated by a new nanobelt-based processing method with simultaneous zein matrix cross-linking and curcumin cross-linking. Their morphologies, optimal detection pH, ion selectivity, and ion detection sensitivity are systematically analyzed. The limits of detection of electrospun curcumin-loaded zein membranes with a detection time of 0.5 h are as follows: cross-linked nanobelt-shaped membranes (0.3 mg/L) < uncross-linked nanobelt-shaped membranes (1 mg/L) ≈ cross-linked nanofibrous membranes (1 mg/L) < uncross-linked nanofibrous membranes (3 mg/L). The cross-linked nanobelt-shaped membranes are also applied to detect Fe3+ in drinking water and environmental water. Finally, the mechanisms of Fe3+ detection by these membranes are studied and discussed. The results demonstrate that the difference of limit of detection is dependent on if the curcumin sensor is cross-linked or not and the membrane nanostructures (nanobelts or nanofibers). Cross-linking produces stable sensor molecules on the surface and therefore induces low limits of detection. Compared with nanofibers, nanobelts have a higher surface-to-volume ratio and can have more sensor molecules on their surfaces and therefore have lower limits of detection. In addition, the as-prepared membranes had good membrane storage stability (at least 3 months at room temperature). All of these results suggest that cross-linked electrospun nanobelt-shaped membranes by a new nanobelt-based processing method are ideal platforms for sensing. We believe that they will attract increasing attention in scientific and engineering fields such as materials, environmental, and food science.

Modulable properties of PVA/cellulose fiber composites.

Development of PVA/cellulose fiber composite material with modulable properties, obtained through the increase of reinforcement and heat treatments in order to optimize the composite in terms of mechanical, thermal, and degradation properties. The composite was designed selecting as matrix an experimental formulation based on water-soluble, biodegradable, polyvinyl alcohol (PVA) and microcrystalline cellulose (MCC), as reinforcement. Six different formulations, with increasing ratio of MCC content (from 0% to 55% w/w) in PVA, were developed and extruded by a co-rotating twin-screw extruder (TSA FSCM 21/40). Then, samples have been treated through two different thermal conditions (T1, T2) and characterized by scanning electron microscopy, tensile mechanical tests, thermogravimetric analysis, and water degradation tests to investigate, respectively, the influence of MCC ratios and heat treatment on morphological, mechanical, degradation, and thermal properties. The PVA/MCC composite exhibited a good stress-strain behavior as well as a close correlation between MCC content on tensile, thermal, and degradation properties. The second part of the results includes the analysis of the effects that the thermal treatments (T1, T2) had on the composite. In fact, thermal treatments have allowed improving the thermal and water stability as well as a significant improvement in the considered mechanical parameters due to a possible crosslinking of the PVA matrix. The present work shows how the properties of the PVA/MCC composite can become modular with the aim of extending its range of application as a new sustainable solution in the field of consumer products.

Freestanding organogels by molecular velcro of unsaturated amphiphiles.

A simple amphiphile, N-cardanyltaurine amide (NCT) with different degrees of cis-unsaturation in its tail resulted in the formation of strong organogels. Interestingly, this is in contrast to the commonly accepted notion that introducing unsaturation in alkyl chains enhances fluidity in lipid assemblies. The physico-chemical and first-principles DFT calculations confirmed the pegging of 'kinked' unsaturated side chains, where the hydrophobic interlocking as in Velcro fasteners leads to a network of cylindrical micelles, resulting in self-standing organogels. Textural profile analysis and spectroscopic details substantiated the dynamic assembly to resemble a 3D network of gelators rather than being a cross-linked or polymerized matrix of monomers.

Undervalued ubiquitous proteins

The role of ubiquitous proteins (UPs) and their corresponding enzymes have been underestimated in carcinogenesis as the focus of much research revolved around measuring mutations and/or other genetic epiphenomena as surrogate markers of cancer and cancer progression. Over the past three decades, the scientific community has come to realize that the concentration on microdissection of cancer cells without accounting for the neighborhood in which these cells reside, i.e., the stroma, fails to reflect the true nature of cancer biology. UPs are fundamental for cellular homeostasis and phylogenetic development as well as for the integrity of the cytoskeleton and for the stability of cells and tissues in regards to intercellular signaling, cell shape and mobility, apoptosis, wound healing, and cell polarity. Corresponding enzymes are used by microorganisms to gain entry into the host by degradation of UPs and play a role to cleave peptide bonds for killing disease-causing life forms along for the creation of the precancerous niche (PCN) during carcinogenesis, cancer invasion, and in metastasis. The language used by such proteins as well as their complementary enzymes with its influence on multiple pathways and the cross-linked extracellular matrix is incompletely understood. The role of UPs in the disruption of signaling homeostasis and resulting interference with crosstalk in carcinogenesis appears sufficiently delineated to warrant a much more refined examination of their qualitative and quantitative contribution to the development of cancer and cancer therapy.

Urinary transglutaminase 2 as a potent biomarker to predict interstitial fibrosis and tubular atrophy of kidney allograft during early posttransplant period in deceased donor kidney transplantation.

PurposeTransglutaminase type 2 (TG2) is an extracellular matrix crosslinking enzyme with a pivotal role in kidney fibrosis. We tested whether quantification of urinary TG2 may represent a noninvasive method to estimate the severity of kidney allograft fibrosis.MethodsWe prospectively collected urine specimens from 18 deceased donor kidney transplant recipients at 1-day, 7-day, 1-month, 3-month, and 6-month posttransplant. In addition, kidney allograft tissue specimens at 0-day and 6-month posttransplant were sampled to analyze the correlation of urinary TG2 and kidney allograft fibrosis.ResultsThirteen recipients had increased interstitial fibrosis and tubular atrophy (IFTA) scores at the 6-month protocol biopsy (IFTA group). The mean level of urinary TG2 in the IFTA group was higher compared to that of 5 other recipients without IFTA (no IFTA group). Conversely, the mean level of urinary syndecan-4 in the IFTA group was lower than levels in patients without IFTA. In the IFTA group, double immunofluorescent staining revealed that TG2 intensity was significantly upregulated and colocalizations of TG2/heparin sulfate proteoglycan and nuclear syndecan-4 were prominent, usually around tubular structures.ConclusionUrinary TG2 in early posttransplant periods is a potent biomarker for kidney allograft inflammation or fibrosis.

LOXL1 folding in exfoliation glaucoma.

Exfoliation syndrome (XFS) is an age-related disease defined by the deposition of aggregated fibrous material (XFM) in the peri-cellular space. Principal morbidity occurs in the eye, where XFM accumulates on the anterior ocular tissues. GWAS have found that certain genetic variants of lysyl oxidase-like 1 (LOXL1), a matrix cross-linking enzyme that is required for elastic fiber formation confer risk for the development of XFS, but are not a single causative factor as many genetically affected individuals do not develop XFS or subsequent glaucoma (XFG). We have found that XFG cells display defects in lysosomes, microtubules, autophagy, and mitochondria resembling defects found in cells from age-related syndromes, such as the main neurodegenerative diseases. In the majority of these diseases, the determining cellular factor is a protein containing intrinsically disordered regions (IDRs) and displaying a high propensity for aggregation. We have found that in XFG patient-derived cells, LOXL1 protein is actively subjected to autophagic clearance, suggesting that LOXL1 is undergoing aggregation. In silico analysis demonstrates that LOXL1's first 369 aa constitute an IDR with the highest disorder probability peak centering around the known risk positions. Experimentally, we have found over-expression of either unmodified LOXL1 or fluorescent chimeras preserving the well-structured N-terminus cause copious intracellular aggregation and that aggregation wanes when the high IDR peaks are deleted. Overall, our work suggests that XFS/G results from the aggregation of the LOXL1 protein coupled with a reduction of cellular proteostasis capabilities in aging, resulting in a chronic build-up of LOXL1-containing protein aggregates.

Removal of Europium from aqueous solution using Saccharomyces cerevisiae immobilized in glutaraldehyde cross-linked chitosan

ABSTRACTThe current study deals with the utility of Saccharomyces cerevisiae (yeast) immobilized in glutaraldehyde cross-linked chitosan matrix for the removal of Eu(III) from aqueous solution. The biosorbent was characterized using FT-IR, SEM-EDX, XRD, TGA, and XPS analysis. Experimental variables that influence the adsorption were studied and the concentration of Europium was determined by ion chromatography. At pH 5.0, the adsorption was spontaneous and endothermic in nature. The biosorbent gave a Langmuir adsorption capacity of 19.41 mg g−1 and followed pseudo second-order kinetics. The regeneration of biosorbent was achieved using potassium thiocyanate and the method showed good selectivity.