Quantification Of Inflammation Research Articles

Ex vivo magnetic resonance elastography of the small bowel in Crohn's disease.

Conventional magnetic resonance enterography is limited in differentiating active inflammation and fibrosis in lesions of Crohn's disease (CD), thus providing a restricted basis for therapeutic decision making. Magnetic resonance elastography (MRE) is an emerging imaging tool that differentiates soft tissues on the basis of their viscoelastic properties. The aim of this study was to demonstrate the feasibility of MRE in assessing the viscoelastic properties of small bowel samples and quantifying differences in viscoelastic properties between healthy ileum and ileum affected by CD. Twelve patients (median age: 48 years) were prospectively enrolled in this study between September 2019 and January 2021. Patients of the study group (n=7) underwent surgery for terminal ileal CD, while patients of the control group (n=5) underwent segmental resection of healthy ileum. MRE of ileal tissue samples of surgical specimens from both groups was performed in a compact tabletop MRI scanner. Penetration rate (a in m/s) and shear wave speed (c in m/s) were determined as markers of viscosity and stiffness for vibration frequencies f of 1,000, 1,500, 2,000, 2,500, and 3,000 Hz. Additionally, damping ratio γ was deduced, and frequency-independent viscoelastic parameters were calculated using the viscoelastic spring-pot model. Penetration rate a was significantly lower in CD-affected ileum compared to healthy ileum for all vibration frequencies (P<0.05). Consistently, damping ratio γ was higher in CD-affected ileum, averaged over all frequencies (healthy: 0.58±0.12, CD: 1.04±0.55, P=0.03), as well as at 1,000 and 1,500 Hz individually (P<0.05). Spring-pot-derived viscosity parameter η was also significantly reduced in CD-affected tissue (2.62±1.37 versus 10.60±12.60 Pa·s, P=0.02). No significant difference was found for shear wave speed c between healthy and diseased tissue at any frequency (P>0.05). MRE of surgical small bowel specimens is feasible, allowing determination of viscoelastic properties and reliable quantification of differences in viscoelastic properties between healthy and CD-affected ileum. Thus, the results presented here are an important prerequisite for future studies investigating comprehensive MRE mapping and exact histopathological correlation including characterization and quantification of inflammation and fibrosis in CD.

Exosomes Isolated from Cardiosphere‐Derived Cells Attenuate Disease Severity in Experimental Autoimmune Myocarditis

ObjectiveMyocarditis is a leading cause of heart failure and sudden cardiac death in children and young adults. Current therapies are limited to supportive care, motivating a search for novel therapeutics. Cardiosphere‐derived cells (CDCs) are cardiac progenitor‐stromal cells that have demonstrated therapeutic bioactivity in multiple inflammatory disease models. This effect is largely mediated through exosomes secreted by CDCs. We hypothesize that CDC exosomes are salutary in experimental autoimmune myocarditis (EAM) and exert their therapeutic effect via modulation of T lymphocytes.MethodsEAM was induced by injecting Lewis rats with purified cardiac myosin and complete Freund’s adjuvant. Animals underwent randomization to receive intravenous CDC exosomes or a vehicle control. Non‐immunized littermates served as healthy controls. Phenotyping included assessment of cardiac function (left ventricular ejection fraction, LVEF) by echocardiography, electrical abnormalities by electrocardiography (EKG), and quantification of inflammation by histology and flow cytometry. In vitro polarization of naïve CD4+ T cells was conducted to assess the effect of CDC exosomes on cytokine production and proliferation.ResultsOn day 28, animals with EAM exhibited significant functional decline, compared to healthy controls (LVEF: 59.2 ± 3.6% versus 80.0 ± 0.7%, p&lt;0.001), while animals receiving exosomes were partially protected (LVEF: 67.8 ± 2.1%, p=0.003 vs. EAM + vehicle, Figure 1B). Similarly, EAM animals receiving vehicle developed repolarization abnormalities on EKG, with significant QTc interval prolongation, compared to healthy controls (QTc: 238.7 ± 5.0 ms versus 189.1 ± 7.3 ms, p=0.004), while animals receiving exosomes had normal QTc intervals (188.2 ± 16.5 ms, p=0.004 vs. EAM + vehicle, Figure 1C). Cardiac histology revealed decreased inflammation in the exosome group (median severity: vehicle: 4, exosome: 1.5, Figure 2A). Analysis of leukocytes in the blood and spleen showed a decrease in total T lymphocytes in the exosome group, but an increase in the proportion of regulatory T cells within the T lymphocyte population (Figure 2B). In vitro, differentiated CD4+ T cells preferentially expressed IL‐10 and IFN‐γ after exosome exposure (8.5‐ and 7.3‐fold increase over control, respectively). Lastly, induced regulatory T cells proliferate more rapidly following exosome exposure (cells dividing beyond three generations: 57% in exosome group versus 18% in control group), while proliferation rates were not significantly different for conventional effector T cells.ConclusionExosomes secreted by CDCs improve the disease manifestations of EAM, with underlying upregulation of IL‐10 and IFN‐γ, factors that are known to be protective in murine models of EAM. Furthermore, exosome exposure preferentially increases proliferation of regulatory T cells, which are major producers of IL‐10. Our findings are consistent with the notion that a multiplicative amplification of IL‐10 production may explain the salutary effects of CDC exosomes in vivo.Support or Funding InformationA.A. is supported by an institutional training grant (T32HL116273)Functional and Electrocardiographic ChangesFigure 1Inflammatory Profile in Heart, Blood, and SpleenFigure 2

Towards Quantification of Inflammation in Atherosclerotic Plaque in the Clinic \u2013 Characterization and Optimization of Fluorine-19 MRI in Mice at 3\u2009T

Fluorine-19 (19F) magnetic resonance imaging (MRI) of injected perfluorocarbons (PFCs) can be used for the quantification and monitoring of inflammation in diseases such as atherosclerosis. To advance the translation of this technique to the clinical setting, we aimed to 1) demonstrate the feasibility of quantitative 19F MRI in small inflammation foci on a clinical scanner, and 2) to characterize the PFC-incorporating leukocyte populations and plaques. To this end, thirteen atherosclerotic apolipoprotein-E-knockout mice received 2 × 200 µL PFC, and were scanned on a 3 T clinical MR system. 19F MR signal was detected in the aortic arch and its branches in all mice, with a signal-to-noise ratio of 11.1 (interquartile range IQR = 9.5–13.1) and a PFC concentration of 1.15 mM (IQR = 0.79–1.28). Imaging flow cytometry was used on another ten animals and indicated that PFC-labeled leukocytes in the aortic arch and it branches were mainly dendritic cells, macrophages and neutrophils (ratio 9:1:1). Finally, immunohistochemistry analysis confirmed the presence of those cells in the plaques. We thus successfully used 19F MRI for the noninvasive quantification of PFC in atherosclerotic plaque in mice on a clinical scanner, demonstrating the feasibility of detecting very small inflammation foci at 3 T, and advancing the translation of 19F MRI to the human setting.

Quantification of Inflammation Following Nd:YAG Laser Capsulotomy and Assessing the Anti-inflammatory Effects of Nepafenac 0.1% and Betamethasone 0.1%

ABSTRACT Purpose: To quantify the intraocular inflammation, measured using laser flare photometry (LFP), after Nd:YAG capsulotomy and compare the effects of different topical anti-inflammatory regimes. Methods: A single-center, prospective, randomized controlled study, which included 90 eyes of 90 patients with visually significant posterior capsular opacification. In all patients, Nd:YAG capsulotomy was done and was then randomized into three groups: (A) Topical betamethasone 0.1%; (B) Topical nepafenac 0.1%; and (C) Control group: did not receive any anti-inflammatory agent post capsulotomy. Results: There was a significant increase in the mean LFP values 2 h following laser capsulotomy (p < 0.001) and then declined gradually and came back to pre-laser values by 2 weeks in all three groups. The mean LFP values, central macular thickness, and best corrected visual acuity were comparable among groups. None developed central macular edema. Conclusion: Intraocular inflammation following Nd:YAG capsulotomies is minimal and transient. Routine use of prophylactic anti-inflammatory agents may be avoided.

Phytochemical Investigation and Screening for Inflammatory Bowel Disease Activity of Ethanolic Extract of Kariyat

Objectives: The present study investigates the protective effect of Kariyat against Indomethacin and Acetic Acid induced Inflammatory Bowel Disease in male wistar rats. Material Method: HPTLC and GC-MS investigations indicated presence of steroid, phenols, terpenoid, alkaloids, saponine, flavonoids. IBD was induced by administration of Indomethacin (7.5mg/kg b.w. S.c.), Acetic Acid (4% v/v). Two different models used to induce IBD named Indomethacin induces enter colitis and Acetic Acid induces enter colitis in case of Indomethacin induces enter colitis the compromises 5 groups (n=6), normal, control, standard treated (Prednisolone 2mg/kg p.o.), KEE treated (100 mg/kg b.w.), KEE treated (200 mg/kg b.w.) in case of Acetic Acid induces colitis the compromises 5 groups (n=6), normal, control, standard treated (Prednisolone 2mg/kg p.o.), KEE treated (100mg/kg b.w.), KEE treated(200mg/kg b.w.). After treatment of 7 days animals were sacrificed and colon was isolated for macroscopic and microscopic studies. Quantification of inflammation was done by using myeloperoxidase assay (MPO), Lactate dehydrogenase (LDH), Lipid peroxidase (LPO). Result: Evaluation based on macroscopic features showed significantly lower score values for drug treated and standard drug treated groups compared to the disease control groups. Histological examination of disease control group showed massive necrosis of the mucosa and sub mucosa. Drug treated group showed mild lesions, regeneration and inflammatory reaction. The Prednisolone treated group showed suppressed inflammatory reaction. The results observed from MPO, LDH and LPO assays showed significant improvement of disease with extract treated groups compared to disease control group. Histopathological examination of Kariyat treated group revealed less damage compared to Indomethacin and Acetic Acid Induced group. Conclusion: Kariyat have shown to be effective in Indomethacin and Acetic Acid induced colitis in rats, which has protected the animals against experimentally induced disease because of its antioxidant and anti-inflammatory activity.

Skeletal, cardiac, and respiratory muscle function and histopathology in the P448Lneo\u2212 mouse model of FKRP-deficient muscular dystrophy

BackgroundFukutin-related protein (FKRP) mutations are the most common cause of dystroglycanopathies known to cause both limb girdle and congenital muscular dystrophy. The P448Lneo− mouse model has a knock-in mutation in the FKRP gene and develops skeletal, respiratory, and cardiac muscle disease.MethodsWe studied the natural history of the P448Lneo− mouse model over 9 months and the effects of twice weekly treadmill running. Forelimb and hindlimb grip strength (Columbus Instruments) and overall activity (Omnitech Electronics) assessed skeletal muscle function. Echocardiography was performed using VisualSonics Vevo 770 (FujiFilm VisualSonics). Plethysmography was performed using whole body system (ADInstruments). Histological evaluations included quantification of inflammation, fibrosis, central nucleation, and fiber size variation.ResultsP448Lneo− mice had significantly increased normalized tissue weights compared to controls at 9 months of age for the heart, gastrocnemius, soleus, tibialis anterior, quadriceps, and triceps. There were no significant differences seen in forelimb or hindlimb grip strength or activity monitoring in P448Lneo− mice with or without exercise compared to controls. Skeletal muscles demonstrated increased inflammation, fibrosis, central nucleation, and variation in fiber size compared to controls (p < 0.05) and worsened with exercise. Plethysmography showed significant differences in respiratory rates and decreased tidal and minute volumes in P448Lneo− mice (p < 0.01). There was increased fibrosis in the diaphragm compared to controls (p < 0.01). Echocardiography demonstrated decreased systolic function in 9-month-old mutant mice (p < 0.01). There was increased myocardial wall thickness and mass (p < 0.001) with increased fibrosis in 9-month-old P448Lneo− mice compared to controls (p < 0.05). mRNA expression for natriuretic peptide type A (Nppa) was significantly increased in P448Lneo− mice compared to controls at 6 months (p < 0.05) and for natriuretic peptide type B (Nppb) at 6 and 9 months of age (p < 0.05).ConclusionsFKRP-deficient P448Lneo− mice demonstrate significant deficits in cardiac and respiratory functions compared to control mice, and this is associated with increased inflammation and fibrosis. This study provides new functional outcome measures for preclinical trials of FKRP-related muscular dystrophies.

Anatomical Road Mapping Using CT and MR Enterography for Ultrasound Molecular Imaging of Small Bowel Inflammation in Swine.

To evaluate the feasibility and time saving of fusing CT and MR enterography with ultrasound for ultrasound molecular imaging (USMI) of inflammation in an acute small bowel inflammation of swine. Nine swine with ileitis were scanned with either CT (n = 3) or MR (n = 6) enterography. Imaging times to load CT/MR images onto a clinical ultrasound machine, fuse them to ultrasound with an anatomical landmark-based approach, and identify ileitis were compared to the imaging times without anatomical road mapping. Inflammation was then assessed by USMI using dual selectin-targeted (MBSelectin) and control (MBControl) contrast agents in diseased and healthy control bowel segments, followed by ex vivo histology. Cross-sectional image fusion with ultrasound was feasible with an alignment error of 13.9 ± 9.7 mm. Anatomical road mapping significantly reduced (P < 0.001) scanning times by 40%. Localising ileitis was achieved within 1.0 min. Subsequently performed USMI demonstrated significantly (P < 0.001) higher imaging signal using MBSelectin compared to MBControl and histology confirmed a significantly higher inflammation score (P = 0.006) and P- and E-selectin expression (P ≤ 0.02) in inflamed vs. healthy bowel. Fusion of CT and MR enterography data sets with ultrasound in real time is feasible and allows rapid anatomical localisation of ileitis for subsequent quantification of inflammation using USMI. • Real-time fusion of CT/MRI with ultrasound to localise ileitis is feasible. • Anatomical road mapping using CT/MRI significantly decreases the scanning time for USMI. • USMI allows quantification of inflammation in swine, verified with ex vivo histology.

In vivo imaging of lung inflammation with neutrophil-specific 68Ga nano-radiotracer

In vivo detection and quantification of inflammation is a major goal in molecular imaging. Furthermore, cell-specific detection of inflammation would be a tremendous advantage in the characterization of many diseases. Here, we show how this goal can be achieved through the synergistic combination of nanotechnology and nuclear imaging. One of the most remarkable features of this hybrid approach is the possibility to tailor the pharmacokinetics of the nanomaterial-incorporated biomolecule and radionuclide. A good example of this approach is the covalent binding of a large amount of a neutrophil-specific, hydrophobic peptide on the surface of 68Ga core-doped nanoparticles. This new nano-radiotracer has been used for non-invasive in vivo detection of acute inflammation with very high in vivo labelling efficiency, i.e. a large percentage of labelled neutrophils. Furthermore, we demonstrate that the tracer is neutrophil-specific and yields images of neutrophil recruitment of unprecedented quality. Finally, the nano-radiotracer was successfully detected in chronic inflammation in atherosclerosis-prone ApoE−/− mice after several weeks on a high-fat diet.

Inflammatory and Immune System Markers.

Since preeclampsia was first described by Hippocrates in 400 BC, the theory of its causation has shifted from toxins to a current theory that incorporates both vascular and immunological causation. Poor placentation whether it is genetically predisposed or due to low expression of defective HLA-G on fetal trophoblasts is believed to be the initial insult. Oxidative stress from placental ischemia/hypoxia leads to an overload of trophoblast debris by stimulating apoptosis or necrosis. Partial failure of the maternal immune system to tolerate the paternal alloantigens activates maternal immune cells to secrete cytokines whose pleiotropic functions lead to dysfunction of the maternal vascular and placental endothelium, blood coagulation, and fibrinolytic system. This chapter describes some of the key methodologies (flow cytometry, ELISAs, and multiplex immunoassays) for the identification and quantification of inflammation and immune system markers in the study of preeclampsia pathogenesis, as well as diagnostic and therapeutic development. The methodologies may be utilized for a variety of tissue sources in the study of preeclampsia: maternal peripheral blood, umbilical cord blood, intervillous blood, decidua, chorionic villous, amnion and chorion membranes, and cell culture supernatant.

A 3D Scan Model and Thermal Image Data Fusion Algorithms for 3D Thermography in Medicine.

Objectives At present, medical thermal imaging is still considered a mere qualitative tool enabling us to distinguish between but lacking the ability to quantify the physiological and nonphysiological states of the body. Such a capability would, however, facilitate solving the problem of medical quantification, whose presence currently manifests itself within the entire healthcare system. Methods A generally applicable method to enhance captured 3D spatial data carrying temperature-related information is presented; in this context, all equations required for other data fusions are derived. The method can be utilized for high-density point clouds or detailed meshes at a high resolution but is conveniently usable in large objects with sparse points. Results The benefits of the approach are experimentally demonstrated on 3D thermal scans of injured subjects. We obtained diagnostic information inaccessible via traditional methods. Conclusion Using a 3D model and thermal image data fusion allows the quantification of inflammation, facilitating more precise injury and illness diagnostics or monitoring. The technique offers a wide application potential in medicine and multiple technological domains, including electrical and mechanical engineering.

324 Quantification of Inflammation in Small Bowel Crohn's Disease Patients by Videocapsule Endoscopy and Magnetic Resonance Enterography

324 Quantification of Inflammation in Small Bowel Crohn's Disease Patients by Videocapsule Endoscopy and Magnetic Resonance Enterography

Differentiation and quantification of inflammation, demyelination and axon injury or loss in multiple sclerosis

Axon injury/loss, demyelination and inflammation are the primary pathologies in multiple sclerosis lesions. Despite the prevailing notion that axon/neuron loss is the substrate of clinical progression of multiple sclerosis, the roles that these individual pathological processes play in multiple sclerosis progression remain to be defined. An imaging modality capable to effectively detect, differentiate and individually quantify axon injury/loss, demyelination and inflammation, would not only facilitate the understanding of the pathophysiology underlying multiple sclerosis progression, but also the assessment of treatments at the clinical trial and individual patient levels. In this report, the newly developed diffusion basis spectrum imaging was used to discriminate and quantify the underlying pathological components in multiple sclerosis white matter. Through the multiple-tensor modelling of diffusion weighted magnetic resonance imaging signals, diffusion basis spectrum imaging resolves inflammation-associated cellularity and vasogenic oedema in addition to accounting for partial volume effects resulting from cerebrospinal fluid contamination, and crossing fibres. Quantitative histological analysis of autopsied multiple sclerosis spinal cord specimens supported that diffusion basis spectrum imaging-determined cellularity, axon and myelin injury metrics closely correlated with those pathologies identified and quantified by conventional histological staining. We demonstrated in healthy control subjects that diffusion basis spectrum imaging rectified inaccurate assessments of diffusion properties of white matter tracts by diffusion tensor imaging in the presence of cerebrospinal fluid contamination and/or crossing fibres. In multiple sclerosis patients, we report that diffusion basis spectrum imaging quantitatively characterized the distinct pathologies underlying gadolinium-enhanced lesions, persistent black holes, non-enhanced lesions and non-black hole lesions, a task yet to be demonstrated by other neuroimaging approaches. Diffusion basis spectrum imaging-derived radial diffusivity (myelin integrity marker) and non-restricted isotropic diffusion fraction (oedema marker) correlated with magnetization transfer ratio, supporting previous reports that magnetization transfer ratio is sensitive not only to myelin integrity, but also to inflammation-associated oedema. Our results suggested that diffusion basis spectrum imaging-derived quantitative biomarkers are highly consistent with histology findings and hold promise to accurately characterize the heterogeneous white matter pathology in multiple sclerosis patients. Thus, diffusion basis spectrum imaging can potentially serve as a non-invasive outcome measure to assess treatment effects on the specific components of underlying pathology targeted by new multiple sclerosis therapies.

Imaging of post-infarction myocardial inflammation with hybrid FDG PET/MR: feasibilty and preliminary findings in a canine model

Background An understanding of inflammation following myocardial infarction may be of importance in the development of novel therapeutics to limit the development of heart failure following myocardial injury. However, the quantification of inflammation in this setting continues to be challenging. Hybrid FDG PET/MR may offer a non-invasive in vivo solution through intrinsic registration of these complementary modalities. This study sought to validate its use in a canine model of myocardial infarction (MI).

P142. Quantification of inflammation in small bowel Crohn's disease (SBCD) patients by videocapsule endoscopy (VCE) and magnetic resonance enterography (MRE)

P142. Quantification of inflammation in small bowel Crohn's disease (SBCD) patients by videocapsule endoscopy (VCE) and magnetic resonance enterography (MRE)

Quantification of inflammation in inflammatory eye diseases

Measuring the cells and flare present in the anterior chamber and vitreous humor is a universally accepted method for quantifying inflammation in inflammatory eye diseases. However, one of the major disadvantages of this method is subjective grading. This can be overcome by measuring the cells and flare by laser flaremetry. But it is not widely available. The current review highlights the different methods and various parameters used clinically to assess the inflammation and the role of various imaging techniques in the diagnosis and monitoring of the response to treatment in ocular inflammatory diseases.

Quantification of inflammation: Needs and challenges

Inflammation is a natural response against any external or internal stimuli that disturb the body homeostasis. Although inflammation was initially described in terms of simple clinical symptoms, it has evolved to define a more complex phenomenon. In spite of the advances in immunology, uncertainty prevails on the precise definition of inflammation.

Comparison of Multiple Enzyme Activatable Near-Infrared Fluorescent Molecular Probes for Detection and Quantification of Inflammation in Murine Colitis Models

Activatable near-infrared fluorescent (NIRF) probes have been used for ex vivo and in vivo detection of intestinal tumors in animal models. We hypothesized that NIRF probes activatable by cathepsins or metalloproteinases will detect and quantify dextran sulphate sodium (DSS)-induced acute colonic inflammation in wild type mice or chronic colitis in interleukin-10 (IL-10)-null mice ex vivo or in vivo. Wild type mice given DSS, water controls, and IL-10-null mice with chronic colitis were administered probes by retro-orbital injection. FMT2500 LX system imaged fresh and fixed intestine ex vivo and mice in vivo. Inflammation detected by probes was verified by histology and colitis scoring. NIRF signal intensity was quantified using 2-dimensional region of interest ex vivo or 3-dimensional region of interest analysis in vivo. Ex vivo, 7 probes tested yielded significant higher NIRF signals in colon of DSS-treated mice versus controls. A subset of probes was tested in IL-10-null mice and yielded strong ex vivo signals. Ex vivo fluorescence signal with 680 series probes was preserved after formalin fixation. In DSS and IL-10-null models, ex vivo NIRF signal strongly and significantly correlated with colitis scores. In vivo, ProSense680, CatK680FAST, and MMPsense680 yielded significantly higher NIRF signals in DSS-treated mice than controls, but background was high in controls. Both cathepsin or metalloproteinase-activated NIRF probes can detect and quantify colonic inflammation ex vivo. ProSense680 yielded the strongest signals in DSS colitis ex vivo and in vivo, but background remains a problem for in vivo quantification of colitis.

Histopathology of biodegradable polymers: challenges in interpretation and the use of a novel compact MRI for biocompatibility evaluation

Toxicologic pathology is the art of assessment of potential adverse effects at the tissue level in pre‐clinical studies. In the case of biomaterials and medical devices, the toxicologic pathologists assess the safety (biocompatibility) and efficacy (conditions of the use) of the implantable materials. Proper assessment of biocompatibility of biomaterials is of utmost importance, since it helps to determine their safety after implantation in humans. Biomaterial‐related toxicity can be attributed to several factors, including for example leachable compounds from the material leading to thrombosis or carcinogenesis, or biodegradation of the material causing changes in its physical and compatibility properties. Evaluation of biocompatibility and biofunctionality involves assessment of cytotoxicity, allergic responses, irritation, inflammation and systemic and chronic toxicity. In many of these assessments, the toxicologic pathologist has an important role in determining product safety and potential toxicity. In this article, we review the special needs for proper toxicologic pathology assessment of biomaterials and degradable polymers. We review common adverse effects expected with biomaterials and describe their pathological picture and their clinical relevance. We also introduce a novel compact MR imaging technology as a tool for assessing biocompatibility and efficacy of implanted biodegradable materials, since it allows for the longitudinal imaging and quantification of inflammationin vivocaused by the device implantation, and enabling general inspection of shape, location and integrity of the devicein vivo. Since the MR imaging technique is non‐invasive, the effects of the implantable device can be monitored longitudinally in the same animal without perturbation of the pathology. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Comparison of Multiple Enzyme Activatable Near-Infrared Fluorescent Molecular Probes for Detection and Quantification of Inflammation in Murine Colitis Models:

Comparison of Multiple Enzyme Activatable Near-Infrared Fluorescent Molecular Probes for Detection and Quantification of Inflammation in Murine Colitis Models:

Adsorbed Fibrinogen Enhances Production of Bone- and Angiogenic-Related Factors by Monocytes/Macrophages

Macrophages are phagocytic cells with great importance in guiding multiple stages of inflammation and tissue repair. By producing a large number of biologically active molecules, they can affect the behavior of other cells and events, such as the foreign body response and angiogenesis. Since protein adsorption to biomaterials is crucial for the inflammatory process, we addressed the ability of the pro-inflammatory molecule fibrinogen (Fg) to modulate macrophage behavior toward tissue repair/regeneration. For this purpose, we used chitosan (Ch) as a substrate for Fg adsorption. Freshly isolated human monocytes were seeded on Ch substrates alone or previously adsorbed with Fg, and allowed to differentiate into macrophages for 10 days. Cell adhesion and morphology, formation of foreign body giant cells (FBGC), and secretion of a total of 80 cytokines and growth factors were evaluated. Both substrates showed similar numbers of adherent macrophages along differentiation as compared with RGD-coated surfaces, which were used as positive controls. Fg did not potentiate FBGC formation. In addition, actin cytoskeleton staining revealed the presence of punctuate F-actin with more elongated and interconnecting cells on Ch substrates. Antibody array screening and quantification of inflammation- and wound-healing-related factors indicated an overall reduction in Ch-based substrates versus RGD-coated surfaces. At late times, most inflammatory agents were down-regulated in the presence of Fg, in contrast to growth factor production, which was stimulated by Fg. Importantly, on Ch+Fg substrates, fully differentiated macrophages produced significant amounts of macrophage inflammatory protein-1delta (MIP-1δ), platelet-derived growth factor-BB, bone morphogenetic protein (BMP)-5, and BMP-7 compared with Ch alone. In addition, other important factors involved in bone homeostasis and wound healing, such as growth hormone, transforming growth factor-β3, and insulin-like growth factor-binding proteins, as well as several angiogenic mediators, including endocrine gland-derived vascular endothelial factor, fibroblast growth factor-7, and placental growth factor, were significantly promoted by Fg. This work provides a new perspective on the inflammatory response in the context of bone repair/regeneration mediated by a pro-inflammatory protein (Fg) adsorbed onto a biomaterial (Ch) that does not otherwise exhibit osteogenic properties.