Local Tissue Response Research Articles

A Nitinol “U-Clip” versus Sutured Arteriovenous Anastomosis: Local Tissue Response and Intimal Hyperplasia Development in a Sheep Model

This study sought to compare the local tissue response and subsequent volume of intimal hyperplasia (IH) that develops throughout the maturation of an arteriovenous fistula created using continuous/interrupted polypropylene with that of a novel, metal-alloy, penetrating anastomotic clip device. Forty-six fistulae were created in 23 sheep under a paired design using the nitinol U-Clip (n = 23) in one hind limb and continuous (n = 20) or interrupted (n = 3) polypropylene suture for the other. Animals were killed at 4 (n = 3), 14 (n = 3), 28 (n = 10), 42 (n = 3), and 180 (n = 4) days. Histological sections were evaluated for quantitative histology and immunohistochemistry. Compared with continuous polypropylene, U-Clip specimens demonstrated less intima–media area per unit length (IMA/L), proliferating cells, and tissue necrosis at all time points (MANOVA, F = 9.8–24.1, all p≤.005; observed power >82%). Specifically, values of IMA/L were reduced by 5% (p = .97), 37% (p = .02), 33% (p < .01), 9% (p = .42), and 14% (p = .22) at the time points of 4, 14, 28, 42, and 180 days respectively. Proliferating cells were reduced by 75% (p < .01), 72% (p = .03), 76% (p = .03), 27% (p = .31), and 60% (p = .01) and tissue necrosis by 67% (p < .01), 58% (p = .02), 40% (p = .33), 21% (p = .43), 77% (p = .11). In a 28-day comparison between U-Clip and interrupted polypropylene the U-Clip group demonstrated a 4% (p = .65) reduction in IMA/L, 74% (p < .01) in proliferating cells and 49% (p < .05) in tissue necrosis. These results provide evidence of reduced local tissue necrosis, proliferating cells, and IH, favouring arteriovenous fistulae created using the U-Clip anastomotic device over conventional polypropylene suture techniques most evident over the first 4 weeks.

Systemic IFNγ predicts local implant macrophage response.

Implantation of biomaterials can cause complications often associated with inflammatory reactions. However, repeated evaluation of the implant site would be burdening for patients. Alternatively, blood examinations with analysis of inflammatory serum markers could potentially be useful to reflect the local cellular response for detection and/or prediction of inflammation-related complications. Therefore, following intramuscular implantation of surface-modified Ti implants in rats, this study aimed at examining possible associations between the post-implantation time course of pro-inflammatory (INFγ, IL-2) and anti-inflammatory (IL-4, IL-10) cytokine serum concentrations and the local peri-implant tissue response after 56 days (pro-inflammatory CD68-positive monocytes/macrophages, anti-inflammatory CD163-positive macrophages, MHC class II-positive cells, activated natural killer cells and mast cells). Multivariate correlation analysis revealed a significant interaction between serum IFNγ and peri-implant tissue CD68-positive monocytes/macrophages (p = 0.001) while no interactions were found for other cytokines and cell types. Additional Pearson correlation analysis of IFNγ serum concentrations on each experimental day vs. the CD68-positive monocytes/macrophages response on day 56 demonstrated a consistently positive correlation that was strongest during the first three weeks. Thus, high early pro-inflammatory IFNγ serum concentration was associated with high late number of pro-inflammatory CD68-positive monocyte/macrophages and low early serum IFNγ with low late CD68-positive monocyte/macrophage numbers. Further studies aimed at examination of patient samples could establish the relevance of this association to predict clinical complications. After implantation of titanium samples, high early IFNγ serum concentrations were associated with a pronounced late pro-inflammatory CD68-positive monocyte/ macrophage (red circle) response, while no correlation was found for other investigated cytokines and inflammatory cells (green circle). In contrast, low early IFNγ serum concentrations were correlated with low late monocyte/ macrophage numbers.

Riparin A, a compound from Aniba riparia, attenuate the inflammatory response by modulation of neutrophil migration

Inflammation is a local tissue response to attacks characterized by vascular and cellular events, including intense oxidative stress. Riparin A, a compound obtained from Aniba riparia, has been shown to have antioxidant activity and cytotoxicity in vitro. This study was aimed at evaluating the anti-inflammatory effect of riparin A against acute inflammation. The results of our evaluations in various experimental models indicated that riparin A reduced paw edema induced by carrageenan, compound 48/80, histamine, and serotonin. Furthermore, it decreased leukocyte and neutrophil counts, myeloperoxidase activity, thiobarbituric acid reactive substance (TBARS) levels, and cytokine (tumor necrosis factor-α and interleukin-1β) levels increased by carrageenan-induced peritonitis, and reversed glutathione levels. Riparin A also reduced carrageenan-induced adhesion and rolling of leukocytes on epithelial cells and did not produce gastric-damage as compared with indomethacin. In conclusion, the data show that riparin A reduces inflammatory response by inhibiting vascular and cellular events, modulating neutrophil migration, inhibiting proinflammatory cytokine production, and reducing oxidative stress.

A Nitinol “U-Clip” versus Sutured Arteriovenous Anastomosis: Local Tissue Response and Intimal Hyperplasia Development in a Sheep Model

This study sought to compare the local tissue response and subsequent volume of intimal hyperplasia (IH) that develops throughout the maturation of an arteriovenous fistula created using continuous/interrupted polypropylene with that of a novel, metal-alloy, penetrating anastomotic clip device. Forty-six fistulae were created in 23 sheep under a paired design using the nitinol U-Clip (n=23) in one hind limb and continuous (n=20) or interrupted (n=3) polypropylene suture for the other. Animals were killed at 4 (n=3), 14 (n=3), 28 (n=10), 42 (n=3), and 180 (n=4) days. Histological sections were evaluated for quantitative histology and immunohistochemistry. Compared with continuous polypropylene, U-Clip specimens demonstrated less intima-media area per unit length (IMA/L), proliferating cells, and tissue necrosis at all time points (MANOVA, F=9.8-24.1, all p≤.005; observed power >82%). Specifically, values of IMA/L were reduced by 5% (p=.97), 37% (p=.02), 33% (p<.01), 9% (p=.42), and 14% (p=.22) at the time points of 4, 14, 28, 42, and 180 days respectively. Proliferating cells were reduced by 75% (p<.01), 72% (p=.03), 76% (p=.03), 27% (p=.31), and 60% (p=.01) and tissue necrosis by 67% (p<.01), 58% (p=.02), 40% (p=.33), 21% (p=.43), 77% (p=.11). In a 28-day comparison between U-Clip and interrupted polypropylene the U-Clip group demonstrated a 4% (p=.65) reduction in IMA/L, 74% (p<.01) in proliferating cells and 49% (p<.05) in tissue necrosis. These results provide evidence of reduced local tissue necrosis, proliferating cells, and IH, favouring arteriovenous fistulae created using the U-Clip anastomotic device over conventional polypropylene suture techniques most evident over the first 4 weeks.

Rat animal model for preclinical testing of microparticle urethral bulking agents.

To develop an economic, practical and readily available animal model for preclinical testing of urethral bulking therapies, as well as to establish feasible experimental methods that allow for complete analysis of hard microparticle bulking agents. Alumina ceramic beads suspended in hyaluronic acid were injected into the proximal urethra of 15 female rats under an operating microscope. We assessed overall lower urinary tract function, bulking material intraurethral integrity and local host tissue response over time. Microphotographs were taken during injection and again 6 months postoperatively, before urethral harvest. Urinary flow rate and voiding frequency were assessed before and after injection. At 6 months, the urethra was removed and embedded in resin. Hard tissue sections were cut using a sawing microtome, and processed for histological analysis using scanning electron microscopy, light microscopy and immunohistochemistry. Microphotographs of the urethra showed complete volume retention of the bulking agent at 6 months. There was no significant difference between average urinary frequency and mean urinary flow rate at 1 and 3 months postinjection as compared with baseline. Scanning electron microscopy proved suitable for evaluation of microparticle size and integrity, as well as local tissue remodeling. Light microscopy and immunohistochemistry allowed for evaluation of an inflammatory host tissue reaction to the bulking agent. The microsurgical injection technique, in vivo physiology and novel hard tissue processing for histology, described in the present study, will allow for future comprehensive preclinical testing of urethral bulking therapy agents containing microparticles made of a hard material.

Transfusion of Stored Red Blood Cells Activates an Inflammatory Program in Mouse Spleen That Is Enhanced By Endotoxemia

BACKGROUND: Transfusion of stored red blood cells (RBCs) induces a variable amount of erythrophagocytosis depending on the extent of RBC damage suffered from the storage lesion. Both murine and canine studies show that transfusion of RBCs after prolonged refrigerated storage leads to inflammation, as evidenced by increased post-transfusion levels of circulating pro-inflammatory cytokines. An analogous cytokine response was not observed in healthy humans volunteers. However, underlying inflammation may synergize with the cytokine response to stored RBCs; thus, results with healthy human volunteers may not reflect those with ill patients. Finally, plasma cytokine profiles may not accurately reflect local tissue responses at sites of erythrophagocytosis, such as the liver and spleen.AIMS: A mouse model was used to identify splenic transcriptional programs underlying the inflammatory response to stored RBC transfusions. Furthermore, mice were pretreated with a sub-lethal dose of lipopolysaccharide (LPS) to test the effect of underlying inflammation on the response to transfusion.METHODS: RBCs from 8-12 week old wild-type C57BL/6 male mice donors were collected, leukoreduced, and stored in citrate-phosphate-dextrose-adenine (CPDA)-1. Cohorts of syngeneic mice (n=3 per group) were infused with saline or transfused with one human equivalent unit of fresh RBCs (<24 hours old) or stored RBCs (11 days old). In parallel, cohorts of mice were pretreated with 1 μg of LPS (E. coli 0111:B4) and similarly transfused. Two hours after transfusion, blood and organs were collected and plasma cytokine levels were measured by a multiplex assay. Total RNA from each spleen was processed for hybridization to Affymetrix WT Gene microarrays. Whole genome expression profiles were analyzed using publicly available NIA Array and Gene Set Enrichment Analysis (GSEA) software.RESULTS: The 2-hour post-transfusion RBC recovery averaged 75% for mice transfused older RBCs. Non-LPS treated mice transfused with stored RBCs showed no statistically significant change in any plasma cytokine post-transfusion, however several cytokines were increased by stored RBC transfusion in LPS pretreated mice. Principle Component Analysis revealed a distinct splenic gene expression program associated with stored RBC transfusion in both LPS treated and non-LPS treated mice. GSEA showed significant enrichment of macrophage activation gene sets in spleens from non-LPS treated mice transfused with stored RBCs (see Figure). LPS pre-treatment increased baseline expression of macrophage activation genes, and these genes were further increased by stored RBC transfusion. Specifically, transfusion of stored RBCs acted in synergy with LPS to induce the cytokine genes (Il6 and Il1a), chemokine genes (Ccl2, Ccl3, Cxcl1, Cxcl2), the immediate early gene Fos, and the gene encoding COX-2 (Ptgs2; see Figure). Finally, a set of genes activated by stored blood transfusion independent of inflammation was identified. These genes included oxidative stress inducible genes (Hmox1 and Osgin) as well as GDF-15, which has previously been associated with states of hemolysis or ineffective erythropoieisis such as sickle cell disease and thalassemia.CONCLUSIONS: Taken together, these results suggest that although transfusion of one unit of stored RBCs in mice does not lead to a significant difference in circulating cytokine levels at two-hours post-transfusion, it does lead to activation of a distinct inflammatory transcriptional program in spleen. Moreover, sublethal endotoxemia synergizes with stored RBC transfusions to enhance expression of a specific subset of these inflammatory genes. Thus, stored RBC transfusions may be well tolerated by healthy human volunteers, but have a more detrimental impact on hospitalized patients, particularly those with sepsis and low-grade endotoxinemia. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Preclinical biosafety evaluation of cell-based therapies: emerging global paradigms.

Cell-based therapies have the potential to treat a diversity of disease conditions, many representing significant and long-standing unmet medical needs. Certain properties of cell-based therapies, such as differentiation potential and proliferative potential, present safety concerns uniquely distinct from those of small molecule drugs and other macromolecule biologics. These cellular products carry risks associated with localized host tissue response, long-term persistence, ectopic tissue formation, differentiation to undesirable cell and tissue types, uncontrollable biodistribution, tumorigenicity, and immunogenicity. Such risks are generally evaluated in preclinical animal model studies as part of a comprehensive safety program prior to administration in humans. However, safety assessment for these products can be challenging because of inconsistent approaches to product characterization, inadequately defined product parameters that anticipate adverse events, and the lack of standardized approaches in evaluating in vivo host responses. In this symposium, we introduced cell-based therapies as an emerging product class to the Society of Toxicologic Pathology (STP) and highlighted key challenges for consideration during product biosafety evaluation.

Novel radiopaque ultrahigh molecular weight polyethylene sublaminar wires in a growth-guidance system for the treatment of early-onset scoliosis: feasibility in a large animal study.

In vivo analysis in an ovine model. To evaluate the feasibility of radiopaque ultrahigh molecular weight polyethylene (UHMWPE) sublaminar wires in a growth-guidance spinal system by assessing stability, biocompatibility, and growth potential. Several growth-guidance systems have been developed for the treatment of early-onset scoliosis. The use of gliding pedicle screws and metal sublaminar wires during these procedures can cause metal-on-metal debris formation and neurological deficits. Novel radiopaque UHMWPE wires are introduced to safely facilitate longitudinal growth and provide stability in a growth-guidance system for early-onset scoliosis. Twelve immature sheep received posterior segmental spinal instrumentation; pedicle screws were inserted at L5 and radiopaque UHMWPE (bismuth trioxide) wires were passed sublaminarly at each level between L3 and T12 and fixed to dual cobalt-chromium rods. Four age-matched animals that were not operated were evaluated to serve as a control group. Radiographs were obtained to measure growth of the instrumented segment. After 24 weeks, the animals were killed and the spines were harvested for histological evaluation and high-resolution peripheral quantitative computed tomographic analysis. No neurological deficits occurred and all instrumentation remained stable. One animal died from an unknown cause. Substantial growth occurred in the instrumented segments (L5-T11) in the intervention group (27 ± 2 mm), which was not significantly different to the control group, (30 ± 4 mm, P = 0.42). High-resolution peripheral quantitative computed tomographic analysis clearly showed safe routing and fixation of the UHMWPE wires and instrumentation. Despite the noted growth, ectopic bone formation with the formation of bony bridges was observed in all animals. Histology revealed no evidence of chronic inflammation or wear debris. This study shows the first results of radiopaque UHMWPE sublaminar wires as part of a growth-guidance spinal system. UHMWPE sublaminar wires facilitated near-normal longitudinal spinal growth. All instrumentation remained stable throughout follow-up; no wire breakage or loosening occurred and no adverse local-tissue response to these wires was observed. N/A.

MSCs conditioned media and umbilical cord blood plasma metabolomics and composition.

Human mesenchymal stem cells (hMSCs) from umbilical cord (UC) blood (UCB) and matrix are tested clinically for a variety of pathologies but in vitro expansion using culture media containing fetal bovine serum (FBS) is essential to achieve appropriate cell numbers for clinical use. Human UCB plasma (hUCBP) can be used as a supplement for hMSCs culture, since UCB is rich in soluble growth factors and due to worldwide increased number of cryopreserved UCB units in public and private banks, without the disadvantages listed for FBS. On the other hand, the culture media enriched in growth factors produced by these hMSCs in expansion (Conditioned medium - CM) can be an alternative to hMSCs application. The CM of the hMSCs from the UC might be a better therapeutic option compared to cell transplantation, as it can benefit from the local tissue response to the secreted molecules without the difficulties and complications associated to the engraftment of the allo- or xeno-transplanted cells. These facts drove us to know the detailed composition of the hUCBP and CM, by 1H-NMR and Multiplexing LASER Bead Technology. hUCBP is an adequate alternative for the FBS and the CM and hUCBP are important sources of growth factors, which can be used in MSCs-based therapies. Some of the major proliferative, chemotactic and immunomodulatory soluble factors (TGF-β, G-CSF, GM-CSF, MCP-1, IL-6, IL-8) were detected in high concentrations in CM and even higher in hUCBP. The results from 1H-NMR spectroscopic analysis of CM endorsed a better understanding of hMSCs metabolism during in vitro culture, and the relative composition of several metabolites present in CM and hUCBP was obtained. The data reinforces the potential use of hUCBP and CM in tissue regeneration and focus the possible use of hUCBP as a substitute for the FBS used in hMSCs in vitro culture.

Primary fabrication of a tissue-engineered mesh for pelvic floor reconstruction and research in vivo

To explore the fabrication of a tissue-engineered mesh fabricated with autologous adipose-derived mesenchymal stem cells (ADSC) and silk fibroin scaffold for female pelvic reconstruction. Sprague-Dawley rat adipose tissue was obtained from inguinal region. Mesenchymal stem cells were isolated and proliferated in vitro. The sericin of silk was removed after knitting in to web. Then a compound scaffold freeze-dried of silk fibroin web and silk fibroin solution was prepared for ADSC seeding. after 1-week culturing, the cellular morphology and extracellular matrix secretion on scaffold were observed by scanning electronic microscopy. The tissue-engineered meshes were implanted subcutaneously into the homologous rats while silk fibroin scaffolds served as control. Then the biomechanics, collagen matrix and local tissue response to tissue-engineered meshes in vivo with that to silk fibroin scaffolds were estimated. ADSC were fibroblast-like and proliferated well in vitro. SEM showed that the scaffold had an interwoven structure with a smooth surface and the silk sponges in scaffold had a uniform and porous structure. ADSC adhered firmly to the scaffold, secreted extracellular matrix and formed cell sheets on scaffold. In vivo studies showed that the tissue matrix of tissue-engineered meshes was better organized than silk fibroin scaffolds. They also had higher failure force (3.081 ± 0.121 vs 2.167 ± 0.148 N) and Young's modulus (3.191 ± 0.146 vs 2.263 ± 0.213 MPa) and more collagen content (18.648 ± 0.867 vs 14.123 ± 0.989 µg/mg) than silk fibroin scaffolds (P < 0.05). As a suitable cell type for tissue engineering, ADSC may be successfully isolated and stably proliferated in vitro. The tissue-engineered meshes have an excellent biocompatibility and appropriate properties for pelvic floor reconstruction.

Counting CD4(+) and CD8(+) T cells in the spleen: a novel in vivo method for assessing biomaterial immunotoxicity.

As immunotoxicity assessments of newly developed biomaterials are often restricted to use in assessment of local tissue response at the implantation site, they do not always show an immune response acceptable to qualify them for clinical use. We tested a new method to assess systemic toxicity: counting the CD4+ and CD8+ cells in the spleen. Three different biomaterials were subcutaneously implanted in three groups of rats for the same time period. After 31 days, their spleens were harvested, and CD4+ and CD8+ cells were counted. The mean CD4+/CD8+ cell counts were 24.5 ± 3.6/19.8 ± 4.0 (porous collagen matrix group), 25.5 ± 7.1/21.6 ± 3.8 [synthetic collagen matrix (Duragen®) group] and 28.1 ± 4.1/19.6 ± 3.7 (porcine dermis group). Differences in cell counts were not significant. The immunotoxic response generated against porous collagen matrix was comparable to that produced by a similar biomaterial already used clinically. This is, to the best of our knowledge, the first study on cytotoxic lymphocytes in the spleen to quantify systemic immune response to a biomaterial; however, such studies have been conducted with bacterial and viral antigens, and with vaccines. We believe that the present study provides a viable method for larger studies to confirm our current findings.

Plasma-Activated Electrospun Polylactide Fiber Meshes as Matrices for Tissue Engineering

Poly (L-lactide-co-D/L-lactide)-based fiber meshes resembling structural features of the native extracellular matrix have been prepared by electrospinning. Subsequent coating of the electrospun fibers with an ultrathin plasma polymerized allylamine (PPAAm) layer changed the hydrophobic nature of the polylactide surface into a hydrophilic polymer network and provided positively charged amino groups on the fiber surface able to interact with negatively charged pericellular matrix components. Cell experiments in vitro using different types of human epithelial cells (gingiva, uroepithel) revealed that the PPAAm-activated surfaces promoted the occupancy of the meshes by cells accompanied by improved initial cell spreading. An in vivo study in a rat intramuscular implantation model demonstrated that the local inflammatory tissue response did not differ between PPAAm-coated and untreated polylactide meshes.

Anti-Adhesive Finishing of Temporary Implant Surfaces by a Plasma-Fluorocarbon-Polymer

Titanium implant surfaces should ideally be designed to support the subsequent clinical application. Therefore temporarily used implants have to fulfill both the mechanical stabilization of the bone stock and furthermore in trauma surgery the disintegration into the bone because the implant should be removed after fracture healing. The anti-adhesive plasma-fluorocarbon-polymer (PFP) films were synthesized using two different low-pressure plasma sources, the 2.45 GHz microwave (mw) and the 13.56 MHz capacitively coupled radio-frequency (rf) discharge in a mixture of the precursor octafluoropropane (C3F8) and hydrogen (H2). The film properties were characterized using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, water contact angle measurements, and abrasive strength tests. Cell adhesion and spreading of human osteoblasts were clearly reduced on these PFP surfaces. Firstin vivodata on the biocompatibility of the PFP films deposited in the rf-discharge demonstrate that the local inflammatory tissue response for PFP coating was comparable to controls, while a PFP coating deposited in mw plasma induced stronger tissue reactions.

Pharmacokinetics and safety of human recombinant hepatocyte growth factor administered to vocal folds

Previous animal studies demonstrated that hepatocyte growth factor (HGF) has the potential to regenerate scarred vocal folds. In addition, HGF is now produced under a good manufacturing practice (GMP) procedure. Therefore, human clinical trials of HGF are warranted in patients with vocal fold scarring. In the current study, we investigated the pharmacokinetics and the local tissue responses of HGF administered to rat vocal folds. Prospective animal experiment. Five μg of recombinant human HGF was administered to the vocal folds of Sprague-Dawley rats (n = 60) using a microsyringe. The concentration of HGF in larynges and blood was investigated by enzyme-linked immunosorbent assay. To evaluate the local tissue responses caused by HGF administration, endoscopic and histological examinations were performed. HGF concentration in the larynges was 50.1 μg/g tissue 5 minutes after administration. The concentration decreased rapidly to 1.71 μg/g tissue at 12 hours after administration and to 0.29 ng/g tissue at 24 hours after administration. Seven days after administration, HGF concentration was minimal in one-half of the cases and was not detected in the other cases. Transmission of HGF to blood was detected in two of six cases at 5 minutes after administration, but was no longer detected 12 hours later. Endoscopic and histological examinations revealed no edema or erythema of the vocal folds in any of the cases. The current results contribute to the safety and pharmacokinetic management of future clinical trials using HGF administered to vocal folds.

Mast cell-derived IL-33 orchestrates antigen-driven tissue inflammation by promoting a unique inflammatory basophil response (HYP3P.352)

Abstract While IL-33 is commonly described as an epithelial derived cytokine, we previously showed that IgE activation of mast cells induces IL-33 expression. In vivo, IgE-primed mast cells serve as peripheral sensors for antigen (Ag) and drive an early edema followed by an antigen-driven tissue inflammation (ADTI). Histamine drives the edematous response but the mechanisms controlling local ADTI are unclear. Here, we sought to examine the roles of IL-33 and its receptor, ST2 in this process. Using a passive cutaneous anaphylaxis model, we show that mast cell-derived IL-33 is both sufficient and necessary for the ADTI response, which is dominated by CD45+Gr-1high neutrophils. ST2-expressing basophils are essential for ADTI and we show that IL-33 serves to activate them, rather than cause migration. Using microarray analysis to examine responses to either IgE/Ag or IL-33 activation, we show that IL-33 promotes an atypical basophil response characterized by neutrophilic chemokines. Interestingly, we find that histamine is necessary for both phases but, while H1R or H2R are required for edema, ADTI is dependent on basophil expression of H4R. In summary, our findings define a mechanism through which mast cells regulate local tissue responses to Ag. We propose a model whereby mast cell histamine release initially attracts basophils via H4R. Basophils are then activated by mast cell-derived IL-33, via ST2, to produce an atypical profile of cytokines and chemokines that recruit neutrophils.

The effects of extracorporeal shockwave therapy on matrix metalloprotease activity in tendinopathy (1046.8)

INTRODUCTION Extracorporeal shockwave therapy (ESWT) is an effective, non‐invasive treatment for degenerative tendinopathies, however, the biological mechanisms underpinning its therapeutic effects are largely unknown.METHODS The local tissue response of matrix metalloproteinase (MMP) ‐2 and ‐9 (gelatinases involved in extracellular matrix remodelling) to ESWT was examined in 18 healthy (18 Achilles) and 10 degenerative (4 Achilles, 6 patellar) tendons using microdialysis. Dialysate samples were collected from the peritendinous space before and after a single ESWT session. Analysis of MMP‐2 and ‐9 activities were completed using gelatin zymography.RESULTS Active MMP‐9 increased ~350% after ESWT, whereas pro‐MMP‐9 was not detected in our samples. There was a ~200% increase in a heavy MMP‐2 complex (~135 kDa; likely an MMP‐2 dimer) after ESWT when compared to baseline, however, levels of pro‐ and active MMP‐2 monomers did not change significantly. There were no response differences between healthy and degenerative tendons.CONCLUSION These findings provide evidence of the biological mechanisms underpinning ESWT in humans in vivo. Our findings are consistent with studies examining MMP activity after exercise and suggest that the mechanical stimulus provided by ESWT might initiate tendon remodeling in tendinopathy by promoting the catabolic processes required to remove damaged matrix constituents.Grant Funding Source: Engineering and Physical Sciences Reserach Council Knowledge Transfer Partnership

Pseudotumors After Non-MoM Hip Replacements.

Adverse local tissue response (ALTR) to metal debris associated with hip arthroplasty is presently a hot topic of discussion in the orthopaedic community. Most of the cases reported have involved metal-on-metal (MoM) bearings; consequently, there has been a drive to design devices with alternative bearing surfaces. However, two case reports in the March 2014 editions of JBJS Case Connector and a third from 2012 suggest that ALTR and resulting pseudotumor formation can occur with non-MoM bearings. In the March 12, 2014 JBJS Case Connector , Koper et al. report on a seventy-one-year-old woman who underwent bilateral total hip arthroplasty, with each side incorporating a cobalt-chromium-lined cup and a ceramic head. She experienced two dislocations of the right hip within two years after surgery. Approximately three years postsurgery, she presented with right groin pain and audible crepitation of the right hip. No mass was palpable on physical examination, but CT revealed a solid 8-cm mass in the adductor magnus muscle, and MRI showed an 8.3-cm inhomogeneous lesion in the iliopsoas muscle. A radiograph revealed an estimated acetabular anteversion angle of 38° and an inclination angle of 57°. Serum cobalt and chromium levels were both markedly elevated, while infection parameters were unremarkable. During revision surgery with an uncemented polyethylene-lined cup and a ceramic head, surgeons removed a pseudotumor and aspirated a large amount of dark gray fluid. Light microscopy of the removed tissue revealed a polypoid …

Long-Acting Atypical Antipsychotics: Characterization of the Local Tissue Response

PurposeLong-acting injectables (LAIs) are increasingly recognized as an effective therapeutic approach for treating chronic conditions. Many LAIs are formulated to create a poorly soluble depot from which the active agent is delivered over time. This long residing depot can cause localized chronic-active inflammation in the tissue, which has not been well defined in the literature. The purpose of this work is to establish an experimental baseline for describing these responses.MethodsNon-human primates and rodents were used to examine the response to LAI formulations of two clinically relevant atypical antipsychotics, aripiprazole monohydrate and olanzapine pamoate monohydrate.ResultsA foreign body response develops with elevations of key cytokines such as IL-1α, IL-1β, TNFα, and IL6 at the site of injection. However, the tissue response for the two atypical antipsychotics compounds diverge as evidenced by quantitative differences observed in cytokine levels at various time points after dosing.ConclusionsOur studies show that, while the drugs are in the same therapeutic class, the response to each of these compounds can be distinguished qualitatively and quantitatively, supporting the idea that the injection site reaction involves a multiplicity of factors including the properties of the compound and cellular dynamics at the site of injection.

Local and systemic tissue response submitted to injection of 2 and 30% polymethylmethacrylate in rats′ tongue

Adverse effects on the oral mucosa after the use of dermal fillers have been reported due to their increased use for facial aesthetics. This study aimed to evaluate, clinically and histologically, the local and systemic effects of two concentrations of polymethylmethacrylate (PMMA) dermal filler in rats. Fifty-four female rats were allocated into three treatment groups (2% PMMA, 30% PMMA and 0.9% NaCl), according to the substance injected in the tongue, and three experimental periods: 7, 60 and 90days. The rats were clinically evaluated and then euthanised, and their tongue and right kidney removed. The histological sections were stained with haematoxylin/eosin and picrosirius. Clinically, significant differences were found between test groups as to the occurrence of nodules (Kruskal-Wallis; p<0.001). Histologically, there was greater inflammatory response in the PMMA compared with control (Kruskal-Wallis; p<0.001). 30% PMMA had greater collagen formation (anova mixed models; p<0.01). No migration of the material towards kidney was found. Polymethylmethacrylate induced intense reaction in the initial period of observation (7days), followed by gradual decrease during the study, favouring the presence of fibroplasia adjacent to the material.

Gadolinium enhancement in newly diagnosed patients with lumbar disc herniations are associated with inflammatory peridiscal tissue reactions – Evidence of fragment degradation?

ObjectiveIt is debatable whether a local inflammatory tissue response caused by herniated disc material contributes to sciatic pain and/or sensorimotor deficits. The impact of inflammatory changes on local tissue remodelling, the healing process and the clinical course of disease remains unclear. MethodsIn this prospective observational study, we included a total of 31 patients with a single-level, unilateral lumbar disc herniation. The diagnosis was confirmed by magnetic resonance imaging (MRI)±gadolinium. The presence of peridiscal contrast enhancement was correlated with the extent of inflammatory reactions in the herniated fragments as confirmed by immunohistochemistry; clinical symptoms, including the duration of radicular pain; and the incidence of sensorimotor deficits. ResultsPeridiscal contrast enhancement was found in 17 patients (55%) and was encasing the adjacent rootlet in 4 cases. There was no significant correlation between gadolinium uptake and the presence of sensorimotor deficits or the duration of radicular symptoms. Degenerative changes were observed in all 31 disc specimens. Overall, 18 cases exhibited increased cellularity in the marginal areas, which were mostly populated by CD68+ macrophages and fibroblasts. Additionally, these areas displayed a limited number of CD3+ T-lymphocytes and different degrees of concomitant neovascularisation, which represented a chronic and unspecific immune response. Peridiscal contrast enhancement on MRI was significantly correlated with the histopathological characteristics of tissue inflammation. However, no correlation was found between the histological evidence and the degree of inflammation and neurological symptoms. ConclusionGadolinium-enhanced MRI is a sensitive method to detect unspecific inflammatory reactions in therapy-naïve disc herniations. However, the neuroradiological and histological evidence of peridiscal inflammation was not correlated with the severity of pain or sensorimotor deficits in our patients. Additional research is needed because the occurrence of local inflammation may indicate an ongoing degradation of herniated fragments and thus be helpful in therapeutic decision-making.