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Joan E. Sanders - One of the best experts on this subject based on the ideXlab platform.
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Tissue response to single-polymer fibers of varying diameters: evaluation of Fibrous Encapsulation and macrophage density.
Journal of Biomedical Materials Research, 2020Co-Authors: Joan E. Sanders, C E Stiles, C L HayesAbstract:An in vivo study was conducted to assess the sensitivity of Fibrous capsule thickness and macrophage density to polymer fiber diameter. Single polypropylene fi- bers of diameters ranging from 2.1 to 26.7 mm were im- planted in the subcutaneous dorsum of Sprague-Dawley rats. Results at 5 weeks demonstrated reduced Fibrous cap- sule thickness for small fibers. Capsule thickness was 0.6 (±1.8) mm, 11.7 (±12.0) mm, 20.3 (±11.6) mm, and 25.5 (±10.0) mm for fibers in the ranges of 2.1 to 5.9, 6.5 to 10.6, 11.1 to 15.8, and 16.7 to 26.7 mm, respectively. Fibers very near to blood vessels had smaller capsules than did those with local vasculature further away. The macrophage density in tissue with fiber diameters 2.1 to 5.9 mm (23.03 ± 8.67%) was com- parable to that of unoperated contralateral control skin (18.72 ± 10.06%). For fibers with diameters in the ranges of 6.5 to 10.6, 11.1 to 15.8, and 16.7 to 26.7 mm, macrophage densities were 33.90 ± 13.08%, 34.40 ± 15.77%, and 41.68 ± 13.98%, respectively, all of which were significantly larger (p < 0.002) than that for the control. The reduced Fibrous capsule thickness and macrophage density for small fibers (
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Fibro-porous meshes made from polyurethane micro-fibers: effects of surface charge on tissue response.
Biomaterials, 2005Co-Authors: Joan E. Sanders, Sarah E. Lamont, Ari Karchin, Steven L. Golledge, Buddy D. RatnerAbstract:The purpose of this research was to evaluate the influence of surface charge on Fibrous Encapsulation, cell nuclei density, and vessel ingrowth into small-fiber, fibro-porous, biomaterial meshes. Meshes electrospun from polyurethane with mean fiber diameters of 5.8 microm and mean fiber spacing of 64.9 microm were plasma coated with films of different relative surface charge: Hexafluoropropylene (HF) (neutral), N,N-dimethylaminoethyl methacrylate (NN) (positive charge), and methacrylic acid (MA) (negative charge). Samples were implanted in rat subcutaneous dorsum for 5 weeks then Fibrous capsule presence around the implants, cell nuclei density, and vessel number were assessed. Results showed that within the resolution of the histological analysis methods used, no implant experienced Fibrous Encapsulation. There was no significant difference between cell nuclei density and coating for the four groups: uncoated, HF-coated, NN-coated, and MA-coated. HF-coated and NN-coated samples had lower vessel numbers than uncoated samples (p = 0.055 and 0.032, respectively). MA-coated samples had vessel numbers not significantly different from uncoated polyurethane (slightly negatively charged) samples (p = 0.879). The results suggest that negatively charged surfaces may facilitate vessel ingrowth into fibro-porous mesh biomaterials.
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Fibrous Encapsulation of single polymer microfibers depends on their vertical dimension in subcutaneous tissue
Journal of Biomedical Materials Research Part A, 2003Co-Authors: Joan E. Sanders, J R RochefortAbstract:The purpose of this research was to investigate possible explanations for why small-diameter microfiber implants do not experience Encapsulation in subcutaneous tissue as do large-diameter fiber implants. Single polypropylene microfibers of approximately rectangular cross-section with rounded edges were twisted about their longitudinal axes and affixed at their ends to polycarbonate frames. The frames were implanted in rat subcutaneous dorsum for a 5-week period, then removed and processed for light microscopy analysis. Fibrous capsule presence/absence and thickness around the implants were assessed, and their relationships to geometric features of the fibers investigated. A logistic regression analysis between presence/absence of a Fibrous capsule and geometric features of interest demonstrated strong predictive ability (92.4% correct predictions) for implant height and a well-defined threshold separating the presence and absence of a Fibrous capsule at 5.9 μm (p < 0.001). Implant height was defined as the vertical distance between the most superficial and deepest level of the implant. This 5.9-μm threshold value of implant height is comparable to the 6.0-μm diameter threshold for capsule presence/absence in fibers of circular cross-section [Sanders et al. J Biomed Mater Res 2000; 52(1):231–237]. Fiber major axis length, minor axis length, aspect ratio, surface area per unit length, implant width, and implant angle did not show similar predictive ability or a well-defined threshold separating the presence and absence of a Fibrous capsule. It is reasoned that for fibers greater than the threshold height of 5.9 μm, separation of collagen fibers in the extracellular matrix creates dead space regions adjacent to the fibers that attract inflammatory cells and stimulate Fibrous capsule formation. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 1181–1187, 2003
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tissue response to single polymer fibers of varying diameters evaluation of Fibrous Encapsulation and macrophage density
Journal of Biomedical Materials Research, 2000Co-Authors: Joan E. Sanders, C E Stiles, C L HayesAbstract:An in vivo study was conducted to assess the sensitivity of Fibrous capsule thickness and macrophage density to polymer fiber diameter. Single polypropylene fi- bers of diameters ranging from 2.1 to 26.7 mm were im- planted in the subcutaneous dorsum of Sprague-Dawley rats. Results at 5 weeks demonstrated reduced Fibrous cap- sule thickness for small fibers. Capsule thickness was 0.6 (±1.8) mm, 11.7 (±12.0) mm, 20.3 (±11.6) mm, and 25.5 (±10.0) mm for fibers in the ranges of 2.1 to 5.9, 6.5 to 10.6, 11.1 to 15.8, and 16.7 to 26.7 mm, respectively. Fibers very near to blood vessels had smaller capsules than did those with local vasculature further away. The macrophage density in tissue with fiber diameters 2.1 to 5.9 mm (23.03 ± 8.67%) was com- parable to that of unoperated contralateral control skin (18.72 ± 10.06%). For fibers with diameters in the ranges of 6.5 to 10.6, 11.1 to 15.8, and 16.7 to 26.7 mm, macrophage densities were 33.90 ± 13.08%, 34.40 ± 15.77%, and 41.68 ± 13.98%, respectively, all of which were significantly larger (p < 0.002) than that for the control. The reduced Fibrous capsule thickness and macrophage density for small fibers (<6 mm) compared with large fibers could be due to the reduced cell-material contact surface area or to a curvature threshold effect that triggers cell signaling. A next step will be to extend the analysis to meshes to evaluate fiber-spacing effects on small-fiber biomaterials. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 231-237, 2000.
C L Hayes - One of the best experts on this subject based on the ideXlab platform.
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Tissue response to single-polymer fibers of varying diameters: evaluation of Fibrous Encapsulation and macrophage density.
Journal of Biomedical Materials Research, 2020Co-Authors: Joan E. Sanders, C E Stiles, C L HayesAbstract:An in vivo study was conducted to assess the sensitivity of Fibrous capsule thickness and macrophage density to polymer fiber diameter. Single polypropylene fi- bers of diameters ranging from 2.1 to 26.7 mm were im- planted in the subcutaneous dorsum of Sprague-Dawley rats. Results at 5 weeks demonstrated reduced Fibrous cap- sule thickness for small fibers. Capsule thickness was 0.6 (±1.8) mm, 11.7 (±12.0) mm, 20.3 (±11.6) mm, and 25.5 (±10.0) mm for fibers in the ranges of 2.1 to 5.9, 6.5 to 10.6, 11.1 to 15.8, and 16.7 to 26.7 mm, respectively. Fibers very near to blood vessels had smaller capsules than did those with local vasculature further away. The macrophage density in tissue with fiber diameters 2.1 to 5.9 mm (23.03 ± 8.67%) was com- parable to that of unoperated contralateral control skin (18.72 ± 10.06%). For fibers with diameters in the ranges of 6.5 to 10.6, 11.1 to 15.8, and 16.7 to 26.7 mm, macrophage densities were 33.90 ± 13.08%, 34.40 ± 15.77%, and 41.68 ± 13.98%, respectively, all of which were significantly larger (p < 0.002) than that for the control. The reduced Fibrous capsule thickness and macrophage density for small fibers (
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tissue response to single polymer fibers of varying diameters evaluation of Fibrous Encapsulation and macrophage density
Journal of Biomedical Materials Research, 2000Co-Authors: Joan E. Sanders, C E Stiles, C L HayesAbstract:An in vivo study was conducted to assess the sensitivity of Fibrous capsule thickness and macrophage density to polymer fiber diameter. Single polypropylene fi- bers of diameters ranging from 2.1 to 26.7 mm were im- planted in the subcutaneous dorsum of Sprague-Dawley rats. Results at 5 weeks demonstrated reduced Fibrous cap- sule thickness for small fibers. Capsule thickness was 0.6 (±1.8) mm, 11.7 (±12.0) mm, 20.3 (±11.6) mm, and 25.5 (±10.0) mm for fibers in the ranges of 2.1 to 5.9, 6.5 to 10.6, 11.1 to 15.8, and 16.7 to 26.7 mm, respectively. Fibers very near to blood vessels had smaller capsules than did those with local vasculature further away. The macrophage density in tissue with fiber diameters 2.1 to 5.9 mm (23.03 ± 8.67%) was com- parable to that of unoperated contralateral control skin (18.72 ± 10.06%). For fibers with diameters in the ranges of 6.5 to 10.6, 11.1 to 15.8, and 16.7 to 26.7 mm, macrophage densities were 33.90 ± 13.08%, 34.40 ± 15.77%, and 41.68 ± 13.98%, respectively, all of which were significantly larger (p < 0.002) than that for the control. The reduced Fibrous capsule thickness and macrophage density for small fibers (<6 mm) compared with large fibers could be due to the reduced cell-material contact surface area or to a curvature threshold effect that triggers cell signaling. A next step will be to extend the analysis to meshes to evaluate fiber-spacing effects on small-fiber biomaterials. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 231-237, 2000.
Wilson Wang - One of the best experts on this subject based on the ideXlab platform.
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surface modification of titanium with curcumin a promising strategy to combat Fibrous Encapsulation
Journal of Materials Chemistry B, 2015Co-Authors: Ronghan He, Kun Wang, Xuefeng Hu, Jason Feng, Chris Steffi, Wilson WangAbstract:Fibrous Encapsulation that prevents the direct contact between an implant and the bone can cause implant failure. However, prevention of Fibrous Encapsulation is difficult because of the lack of effective strategies which can selectively control the growth of fibroblasts and osteoblasts. Because curcumin, an extract from Curcuma longa, was recently found to reduce the formation of Fibrous tissue, it is hypothesized that loading curcumin on implant surfaces would be efficacious in inhibiting Fibrous Encapsulation without adversely affecting the osteoblast functions. To prove this hypothesis, curcumin was loaded on to a titanium surface using poly(dopamine) as an anchor, and the behaviors of fibroblasts and osteoblasts on these curcumin-modified surfaces were investigated. Curcumin was successfully loaded on to titanium and showed a low release after incubation in phosphate-buffered saline for seven days. On the curcumin-modified surfaces, fibroblast proliferation was suppressed, and Fibrous marker expressions as well as collagen synthesis were significantly reduced. These reductions were possibly because of the enhancement of fibroblast apoptosis induced by the surface curcumin. In contrast, no significant reduction in osteoblast functions was observed on the curcumin-modified substrates. These findings may provide a promising solution to reduce Fibrous Encapsulation, and thus may be highly beneficial for orthopaedic applications.
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an in vitro assessment of fibroblast and osteoblast response to alendronate modified titanium and the potential for decreasing Fibrous Encapsulation
Tissue Engineering Part A, 2013Co-Authors: Xuefeng Hu, K G Neoh, E T Kang, Wilson WangAbstract:Fibrous Encapsulation can impair implant osseointegration and cause implant failure but currently there are limited strategies to address this problem. Since bisphosphonates (BPs), a class of drugs widely used to treat bone diseases, was recently found to induce fibroblast apoptosis, we hypothesize that by loading BPs on titanium (Ti) implant surface, Fibrous Encapsulation may be inhibited with simultaneous enhancement of implant osseointegration. This strategy of local administration can also be expected to minimize the adverse side effects of BPs, which are associated with intravenous injections. To verify this hypothesis, alendronate was loaded on Ti surface via a hydroxyapatite (CaP) coating, and the effects of the loaded alendronate on fibroblast proliferation and apoptosis, and osteoblast proliferation, alkaline phosphatase (ALP) activity, and apoptosis were investigated in vitro. With a surface density of loaded alendronate 0.046 mg/cm2 or higher, fibroblast proliferation was suppressed due to incr...
Ronghan He - One of the best experts on this subject based on the ideXlab platform.
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Decreased Fibrous Encapsulation and enhanced osseointegration in vitro by decorin-modified titanium surface
Colloids and Surfaces B: Biointerfaces, 2017Co-Authors: Ronghan He, Jianhua Ren, Yunxiang Lu, Lei Zhu, Junqi Huang, Zhe Wang, Kun WangAbstract:Orthopedic implants, using materials such as titanium, are extensively used in clinical surgeries. Despite its popularity, titanium is still inadequate to reliable osseointegration due to aseptic loosing. Fibrous Encapsulation on the titanium implant interface prevents osseointegration and leads to the loosing of orthopedic implant. In this study, decorin was loaded on titanium surface by polydopamine film to examine Fibrous Encapsulation inhibition and bone growth acceleration. The coating of decorin was evaluated by X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy. Quantitative analysis showed increased decorin coating on titanium surface when decorin in the loading solution increases. To test the effect of decorin modification, fibroblast and osteoblast cultures were utilized in vitro. The results showed that the functions of fibroblasts (proliferation, migration and collagen synthesis) were significantly attenuated on the decorin-modified surfaces and this anti-Fibrous effect could be due to fibrotic gene suppression by decorin. In contrast, osteoblastic activities, such as calcium deposition and alkaline phosphatase (ALP) activity, were enhanced by the modified decorin. These results suggest that decorin coating on titanium surface inhibited proliferation and function of fibroblasts and improved that of osteoblasts. Therefore, this study is potentially useful for enhancing orthopedic implant.
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surface modification of titanium with curcumin a promising strategy to combat Fibrous Encapsulation
Journal of Materials Chemistry B, 2015Co-Authors: Ronghan He, Kun Wang, Xuefeng Hu, Jason Feng, Chris Steffi, Wilson WangAbstract:Fibrous Encapsulation that prevents the direct contact between an implant and the bone can cause implant failure. However, prevention of Fibrous Encapsulation is difficult because of the lack of effective strategies which can selectively control the growth of fibroblasts and osteoblasts. Because curcumin, an extract from Curcuma longa, was recently found to reduce the formation of Fibrous tissue, it is hypothesized that loading curcumin on implant surfaces would be efficacious in inhibiting Fibrous Encapsulation without adversely affecting the osteoblast functions. To prove this hypothesis, curcumin was loaded on to a titanium surface using poly(dopamine) as an anchor, and the behaviors of fibroblasts and osteoblasts on these curcumin-modified surfaces were investigated. Curcumin was successfully loaded on to titanium and showed a low release after incubation in phosphate-buffered saline for seven days. On the curcumin-modified surfaces, fibroblast proliferation was suppressed, and Fibrous marker expressions as well as collagen synthesis were significantly reduced. These reductions were possibly because of the enhancement of fibroblast apoptosis induced by the surface curcumin. In contrast, no significant reduction in osteoblast functions was observed on the curcumin-modified substrates. These findings may provide a promising solution to reduce Fibrous Encapsulation, and thus may be highly beneficial for orthopaedic applications.
David W. Grainger - One of the best experts on this subject based on the ideXlab platform.
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Aging and the Host Response to Implanted Biomaterials
Host Response to Biomaterials, 2020Co-Authors: Mahender Nath Avula, David W. GraingerAbstract:Implant-elicited biochemical and mechanical stimuli create sustained chronic inflammatory signals eliciting the foreign body reactions (FBR), eventually producing Fibrous Encapsulation and predisposing implant sites to infection. Aging produces physiological changes in cellular activities, inflammation, immunity, coagulation, and redox balance. These affect healing, tissue regeneration, and repair mechanisms, resulting in physiological changes, unresolved inflammation, compromised immunity, and dysregulation of critical redox balance. Free radical imbalance is enhanced around implants, further confounding normal healing or device–tissue integration processes. Clinical outcomes for several device categories indicate that patient age affects complication rates and adverse events. Correlations of age-dependent wound healing features with known implant acute inflammatory and chronic responses suggest that aging influences implant host response. Nonetheless, evidence for precise distinctions in physiological or temporal host FBR features in the elderly is scant.
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device based local delivery of sirna against mammalian target of rapamycin mtor in a murine subcutaneous implant model to inhibit Fibrous Encapsulation
Journal of Controlled Release, 2010Co-Authors: Hironobu Takahashi, Yuwei Wang, David W. GraingerAbstract:Abstract Fibrous Encapsulation of surgically implanted devices is associated with elevated proliferation and activation of fibroblasts in tissues surrounding these implants, frequently causing foreign body complications. Here we test the hypothesis that inhibition of the expression of mammalian target of rapamycin (mTOR) in fibroblasts can mitigate the soft tissue implant foreign body response by suppressing fibrotic responses around implants. In this study, mTOR was knocked down using small interfering RNA (siRNA) conjugated with branched polyethylenimine (bPEI) in fibroblastic lineage cells in serum-based cell culture as shown by both gene and protein analysis. This mTOR knock-down led to an inhibition in fibroblast proliferation by 70% and simultaneous down-regulation in the expression of type I collagen in fibroblasts in vitro . These siRNA/bPEI complexes were released from poly(ethylene glycol) (PEG)-based hydrogel coatings surrounding model polymer implants in a subcutaneous rodent model in vivo . No significant reduction in Fibrous capsule thickness and mTOR expression in the foreign body capsules were observed. The siRNA inefficacy in this in vivo implant model was attributed to siRNA dosing limitations in the gel delivery system, and lack of targeting ability of the siRNA complex specifically to fibroblasts. While in vitro data supported mTOR knock-down in fibroblast cultures, in vivo siRNA delivery must be further improved to produce clinically relevant effects on fibrotic Encapsulation around implants.
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Device-based local delivery of siRNA against mammalian target of rapamycin (mTOR) in a murine subcutaneous implant model to inhibit Fibrous Encapsulation
Journal of Controlled Release, 2010Co-Authors: Hironobu Takahashi, Yuwei Wang, David W. GraingerAbstract:Fibrous Encapsulation of surgically implanted devices is associated with elevated proliferation and activation of fibroblasts in tissues surrounding these implants, frequently causing foreign body complications. Here we test the hypothesis that inhibition of the expression of mammalian target of rapamycin (mTOR) in fibroblasts can mitigate the soft tissue implant foreign body response by suppressing fibrotic responses around implants. In this study, mTOR was knocked down using small interfering RNA (siRNA) conjugated with branched polyethylenimine (bPEI) in fibroblastic lineage cells in serum-based cell culture as shown by both gene and protein analysis. This mTOR knock-down led to an inhibition in fibroblast proliferation by 70% and simultaneous down-regulation in the expression of type I collagen in fibroblasts in vitro. These siRNA/bPEI complexes were released from poly(ethylene glycol) (PEG)-based hydrogel coatings surrounding model polymer implants in a subcutaneous rodent model in vivo. No significant reduction in Fibrous capsule thickness and mTOR expression in the foreign body capsules were observed. The siRNA inefficacy in this in vivo implant model was attributed to siRNA dosing limitations in the gel delivery system, and lack of targeting ability of the siRNA complex specifically to fibroblasts. While in vitro data supported mTOR knock-down in fibroblast cultures, in vivo siRNA delivery must be further improved to produce clinically relevant effects on fibrotic Encapsulation around implants. © 2010 Elsevier B.V.