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Joan E Sanders - One of the best experts on this subject based on the ideXlab platform.
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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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Polymer microfiber mechanical properties: A system for assessment and investigation of the link with Fibrous Capsule formation
Journal of biomedical materials research. Part A, 2003Co-Authors: Joan E Sanders, Brian S. Nicholson, Stuart B. Mitchell, Robert E. LedgerAbstract:A novel microtensile testing instrument was developed to assess the mechanical properties of small-diameter polyethylene, polyurethane, and polyester microfibers. The instrument had a root-mean-square error of 2.96 μN for force measurement and 1.91 μm for displacement measurement. Microfibers ranging in diameter from 1.0 to 10.9 μm were strained at 2 mm/s in the device, and the slopes of their stress–strain curves (material moduli) were determined. Correlations between material modulus and previously published data on Fibrous Capsule presence and thickness for implanted polyethylene, polyurethane, and polyester microfibers were investigated. Results for the 1.0–5.9-μm microfiber diameter range showed that neither the percentage of unencapsulated fibers nor the Capsule thickness correlated well with modulus. Correlation coefficients were 0.04 and 0.09, respectively. However, for the 6.0–10.9 μm diameter range the correlations were strong, 1.00 for both percentage of unencapsulated fibers and Capsule thickness. It is suggested that the results reflect the greater attachment and mechanical interaction of cells with microfibers for the 6.0–10.9 μm-diameter range than for the 1.0–5.9 μm-diameter range. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 1412–1416, 2003
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relative influence of polymer fiber diameter and surface charge on Fibrous Capsule thickness and vessel density for single fiber implants
Journal of Biomedical Materials Research Part A, 2003Co-Authors: Joan E Sanders, Damon V Cassisi, Thomas Neumann, Stephen L Golledge, S G Zachariah, Buddy D Ratner, S D BaleAbstract:Single polypropylene microfibers plasma-coated with polymers of different surface charge [N,N-dimethylaminoethyl methacrylate (NN) (positive charge), methacrylic acid (MA) (negative charge), and hexafluoropropylene (HF) (neutral)] were implanted in the subcutaneous dorsum of Sprague-Dawley rats for 5-week intervals. Thee groups of fiber diameters were used: (I) 1.0 to 5.9 μm; (II) 6.0 to 10.9 μm; and (III) 11.0 to 15.9 μm. Fibrous Capsule thickness and blood-vessel density (number of vessels within 100 μm of the fiber) were assessed in tissue sections in the planes of microfiber cross-sections. Results from a multifactorial analysis of variance demonstrated statistically significant main effects (p < 0.05) for microfiber diameter but not for surface-charge coating. The mean differences in Capsule thickness among the microfiber diameter groups were: between groups II and I: 5.4 μm; between groups III and I: 10.2 μm; and between groups III and II: 4.7 μm. The mean differences in Capsule thickness among surface-charge coatings were: between MA and NN: 0.7 μm; between MA and HF: 1.4 μm; and between NN and HF: 0.7 μm. Many of the 1.0 to 5.9 μm-in-diameter fibers had no Capsule and no sign of a foreign-body reaction. For the vessel density analysis, neither microfiber diameter nor surface-charge coating had a statistically significant effect. Thus the geometric feature of microfiber diameter was more important than was surface charge relative to Fibrous Capsule formation but not relative to local vessel density. This ranking of the relative influence of design features in relation to tissue response provides useful information for prioritization in biomaterial design. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 462–467, 2003
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Relative influence of polymer fiber diameter and surface charge on Fibrous Capsule thickness and vessel density for single-fiber implants
Journal of biomedical materials research. Part A, 2003Co-Authors: Joan E Sanders, Damon V Cassisi, Thomas Neumann, Stephen L Golledge, S G Zachariah, Buddy D Ratner, S D BaleAbstract:Single polypropylene microfibers plasma-coated with polymers of different surface charge [N,N-dimethylaminoethyl methacrylate (NN) (positive charge), methacrylic acid (MA) (negative charge), and hexafluoropropylene (HF) (neutral)] were implanted in the subcutaneous dorsum of Sprague-Dawley rats for 5-week intervals. Thee groups of fiber diameters were used: (I) 1.0 to 5.9 microm; (II) 6.0 to 10.9 microm; and (III) 11.0 to 15.9 microm. Fibrous Capsule thickness and blood-vessel density (number of vessels within 100 microm of the fiber) were assessed in tissue sections in the planes of microfiber cross-sections. Results from a multifactorial analysis of variance demonstrated statistically significant main effects (p < 0.05) for microfiber diameter but not for surface-charge coating. The mean differences in Capsule thickness among the microfiber diameter groups were: between groups II and I: 5.4 microm; between groups III and I: 10.2 microm; and between groups III and II: 4.7 microm. The mean differences in Capsule thickness among surface-charge coatings were: between MA and NN: 0.7 microm; between MA and HF: 1.4 microm; and between NN and HF: 0.7 microm. Many of the 1.0 to 5.9 microm-in-diameter fibers had no Capsule and no sign of a foreign-body reaction. For the vessel density analysis, neither microfiber diameter nor surface-charge coating had a statistically significant effect. Thus the geometric feature of microfiber diameter was more important than was surface charge relative to Fibrous Capsule formation but not relative to local vessel density. This ranking of the relative influence of design features in relation to tissue response provides useful information for prioritization in biomaterial design.
S D Bale - One of the best experts on this subject based on the ideXlab platform.
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relative influence of polymer fiber diameter and surface charge on Fibrous Capsule thickness and vessel density for single fiber implants
Journal of Biomedical Materials Research Part A, 2003Co-Authors: Joan E Sanders, Damon V Cassisi, Thomas Neumann, Stephen L Golledge, S G Zachariah, Buddy D Ratner, S D BaleAbstract:Single polypropylene microfibers plasma-coated with polymers of different surface charge [N,N-dimethylaminoethyl methacrylate (NN) (positive charge), methacrylic acid (MA) (negative charge), and hexafluoropropylene (HF) (neutral)] were implanted in the subcutaneous dorsum of Sprague-Dawley rats for 5-week intervals. Thee groups of fiber diameters were used: (I) 1.0 to 5.9 μm; (II) 6.0 to 10.9 μm; and (III) 11.0 to 15.9 μm. Fibrous Capsule thickness and blood-vessel density (number of vessels within 100 μm of the fiber) were assessed in tissue sections in the planes of microfiber cross-sections. Results from a multifactorial analysis of variance demonstrated statistically significant main effects (p < 0.05) for microfiber diameter but not for surface-charge coating. The mean differences in Capsule thickness among the microfiber diameter groups were: between groups II and I: 5.4 μm; between groups III and I: 10.2 μm; and between groups III and II: 4.7 μm. The mean differences in Capsule thickness among surface-charge coatings were: between MA and NN: 0.7 μm; between MA and HF: 1.4 μm; and between NN and HF: 0.7 μm. Many of the 1.0 to 5.9 μm-in-diameter fibers had no Capsule and no sign of a foreign-body reaction. For the vessel density analysis, neither microfiber diameter nor surface-charge coating had a statistically significant effect. Thus the geometric feature of microfiber diameter was more important than was surface charge relative to Fibrous Capsule formation but not relative to local vessel density. This ranking of the relative influence of design features in relation to tissue response provides useful information for prioritization in biomaterial design. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 462–467, 2003
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Relative influence of polymer fiber diameter and surface charge on Fibrous Capsule thickness and vessel density for single-fiber implants
Journal of biomedical materials research. Part A, 2003Co-Authors: Joan E Sanders, Damon V Cassisi, Thomas Neumann, Stephen L Golledge, S G Zachariah, Buddy D Ratner, S D BaleAbstract:Single polypropylene microfibers plasma-coated with polymers of different surface charge [N,N-dimethylaminoethyl methacrylate (NN) (positive charge), methacrylic acid (MA) (negative charge), and hexafluoropropylene (HF) (neutral)] were implanted in the subcutaneous dorsum of Sprague-Dawley rats for 5-week intervals. Thee groups of fiber diameters were used: (I) 1.0 to 5.9 microm; (II) 6.0 to 10.9 microm; and (III) 11.0 to 15.9 microm. Fibrous Capsule thickness and blood-vessel density (number of vessels within 100 microm of the fiber) were assessed in tissue sections in the planes of microfiber cross-sections. Results from a multifactorial analysis of variance demonstrated statistically significant main effects (p < 0.05) for microfiber diameter but not for surface-charge coating. The mean differences in Capsule thickness among the microfiber diameter groups were: between groups II and I: 5.4 microm; between groups III and I: 10.2 microm; and between groups III and II: 4.7 microm. The mean differences in Capsule thickness among surface-charge coatings were: between MA and NN: 0.7 microm; between MA and HF: 1.4 microm; and between NN and HF: 0.7 microm. Many of the 1.0 to 5.9 microm-in-diameter fibers had no Capsule and no sign of a foreign-body reaction. For the vessel density analysis, neither microfiber diameter nor surface-charge coating had a statistically significant effect. Thus the geometric feature of microfiber diameter was more important than was surface charge relative to Fibrous Capsule formation but not relative to local vessel density. This ranking of the relative influence of design features in relation to tissue response provides useful information for prioritization in biomaterial design.
John A. Jansen - One of the best experts on this subject based on the ideXlab platform.
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Subcutaneous tissue response to titanium, poly(ϵ-caprolactone), and carbonate-substituted hydroxyapatite-coated poly(ϵ-caprolactone) plates: A rabbit study
Journal of Biomedical Materials Research Part A, 2013Co-Authors: Nattharee Chanchareonsook, Henk Tideman, Stephen E. Feinberg, Scott J. Hollister, Leenaporn Jongpaiboonkit, Liao Kin, John A. JansenAbstract:The aim of this study was to evaluate the soft tissue response to poly(ϵ‐caprolactone) (PCL) implants with and without carbonate‐substituted hydroxyapatite (CHA) coating compared to the commonly used titanium alloy (Ti‐6Al‐4V)‐machined surface. Experimental materials were implanted subcutaneously in New Zealand white rabbits for 5 weeks. The tissue attachment strength, as evaluated by a tissue peel test, histological and histomorphology analysis, as well as scanning electron microscopy were compared between groups. The peel test result revealed no statistically significant difference between groups. Histological analysis found Fibrous Capsule formation around all implant materials. The Fibrous Capsule around PCL implants with and without CHA coating was significantly thinner compared with the Capsule thickness around the titanium implants. However, the inflammatory cells, as present at the Fibrous Capsule‐implant interface, were found to be significantly lower in the Ti‐group. In conclusion, the current data do not prove that PCL or PCL with a CHA coating results in a superior soft tissue response compared with a machined titanium implant. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013
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Subcutaneous tissue response to titanium, poly(ϵ-caprolactone), and carbonate-substituted hydroxyapatite-coated poly(ϵ-caprolactone) plates : a rabbit study
Journal of biomedical materials research. Part A, 2013Co-Authors: Nattharee Chanchareonsook, Henk Tideman, Stephen E. Feinberg, Scott J. Hollister, Leenaporn Jongpaiboonkit, Liao Kin, John A. JansenAbstract:The aim of this study was to evaluate the soft tissue response to poly(epsilon-caprolactone) (PCL) implants with and without carbonate-substituted hydroxyapatite (CHA) coating compared to the commonly used titanium alloy (Ti-6Al-4V)-machined surface. Experimental materials were implanted subcutaneously in New Zealand white rabbits for 5 weeks. The tissue attachment strength, as evaluated by a tissue peel test, histological and histomorphology analysis, as well as scanning electron microscopy were compared between groups. The peel test result revealed no statistically significant difference between groups. Histological analysis found Fibrous Capsule formation around all implant materials. The Fibrous Capsule around PCL implants with and without CHA coating was significantly thinner compared with the Capsule thickness around the titanium implants. However, the inflammatory cells, as present at the Fibrous Capsule-implant interface, were found to be significantly lower in the Ti-group. In conclusion, the current data do not prove that PCL or PCL with a CHA coating results in a superior soft tissue response compared with a machined titanium implant.
Taesik Jang - One of the best experts on this subject based on the ideXlab platform.
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reduced Fibrous Capsule formation at nano engineered silicone surfaces via tantalum ion implantation
Biomaterials Science, 2019Co-Authors: Cheonil Park, Si Woo Lee, Jin Young Kim, Eunho Song, Hyundo Jung, Ji Ung Park, Hyounee Kim, Sukwha Kim, Taesik JangAbstract:Although the design of more biocompatible polymeric implants has been studied for decades, their intended functionality continues to be impaired by the response of the host tissue to foreign bodies at the tissue-implant interface. In particular, the formation and contracture of Fibrous Capsules prevent the intimate integration of an implant with surrounding tissues, which leads to structural deformation of the implants and persistent discomfort and pain. We report a new surface nano-engineered silicone implant that reduces Fibrous Capsule formation and improves the biocompatibility of it via sputtering-based plasma immersion ion implantation (S-PIII). This technique can introduce biologically compatible tantalum (Ta) on the silicone surface to produce a Ta-implanted skin layer (<60 nm thick) as well as generate either smooth (Smooth/Ta silicone) or nano-textured (Nano/Ta silicone) surface morphologies. The biologically inert chemical structure and strong hydrophobic surface characteristics of bare silicone are substantially ameliorated after Ta ion implantation. In particular, the Nano/Ta silicone implant's combination of surface nano-texturing as a physical cue and the Ta-implanted layer as a chemical cue was found to be very effective at achieving outstanding hydrophilicity and fibroblast affinity compared to the bare and Smooth/Ta silicone implants. In a mouse in vivo study conducted for 8 weeks, the Nano/Ta silicone implant inhibited Fibrous Capsule formation and contracture on its surface better than the bare silicone based on an analysis of the number of macrophages, myofibroblast differentiation and activation, collagen density, and thickness of Fibrous Capsules.
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Reduced Fibrous Capsule formation at nano-engineered silicone surfaces via tantalum ion implantation
Biomaterials Science, 2019Co-Authors: Cheonil Park, Si Woo Lee, Jin Young Kim, Eunho Song, Hyundo Jung, Ji Ung Park, Hyounee Kim, Sukwha Kim, Taesik JangAbstract:Although the design of more biocompatible polymeric implants has been studied for decades, their intended functionality continues to be impaired by the response of the host tissue to foreign bodies at the tissue-implant interface. In particular, the formation and contracture of Fibrous Capsules prevent the intimate integration of an implant with surrounding tissues, which leads to structural deformation of the implants and persistent discomfort and pain. We report a new surface nano-engineered silicone implant that reduces Fibrous Capsule formation and improves the biocompatibility of it via sputtering-based plasma immersion ion implantation (S-PIII). This technique can introduce biologically compatible tantalum (Ta) on the silicone surface to produce a Ta-implanted skin layer (
B. Ziaie - One of the best experts on this subject based on the ideXlab platform.
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Modeling and characterization of a valved glaucoma drainage device with implications for enhanced therapeutic efficacy
IEEE Transactions on Biomedical Engineering, 2005Co-Authors: V.h. Barocas, J.d. Brown, B. ZiaieAbstract:We report on modeling and bench test results targeted at better understanding of valved glaucoma drainage devices (GDDs), a common current surgical treatment for glaucoma. A simple equivalent circuit is described to model fluid mechanical behavior of the aqueous humor in an eye with glaucoma, both before and after implantation of a valved GDD. Finite element method simulations (FEM), based on the lubrication-von Ka/spl acute/rma/spl acute/n model, are then performed to analyze the valve's mechanical and fluidic performance. Using nanoporous membranes to mimic the in vivo Fibrous Capsule, we have developed a microfluidic bench test to simulate the aqueous humor flow and the post-implantation Fibrous tissue encapsulation around the GDD back plate. Our numerical and bench test results show that, contrary to the prevailing belief, the valve significantly contributes to the total pressure drop even after Fibrous Capsule formation. Furthermore, we show that bypassing the valve through a simple polyimide tube insertion will dramatically lower the intraocular pressure (IOP) after Fibrous Capsule formation. This may offer a new treatment option in some patients with advanced glaucoma.
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Microfluidic characterization of a valved glaucoma drainage device with implications for enhanced therapeutic efficacy
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439), 2003Co-Authors: Z. Li, J.d. Brown, B. ZiaieAbstract:In this paper, we report on the microfluidic characterization of a valved glaucoma drainage device (the Ahmed/spl trade/ glaucoma valve). Using a microfluidic test set-up, we have simulated the aqueous humor flow and post implantation Fibrous tissue encapsulation of the external plate. We have shown that, contrary to the prevailing belief, the valve significantly contributes to the total pressure even after the Fibrous Capsule formation. This was demonstrated both by disabling the valve using sharp dissection, and by bypassing it using a polyimide microtube. ANSYS/spl trade/ and Fluent/spl trade/ simulations verified the pressure measurements following the microtube insertion. Further reduction of intraocular pressure after Fibrous Capsule formation could significantly reduce the potential for glaucoma progression.