The Experts below are selected from a list of 88080 Experts worldwide ranked by ideXlab platform
Rita A Kandel - One of the best experts on this subject based on the ideXlab platform.
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superficial and Deep Zone articular chondrocytes exhibit differences in actin polymerization status and actin associated molecules in vitro
Osteoarthritis and Cartilage Open, 2020Co-Authors: Elizabeth Delve, Vivian Co, Rita A KandelAbstract:Summary Objective The actin cytoskeleton regulates cell shape and plays a role in regulating chondrocyte phenotype. Most studies investigating regulation of the chondrocyte phenotype by the actin cytoskeleton use chondrocytes isolated from full-thickness (FT) cartilage, which has a heterogeneous cell population. Superficial Zone chondrocytes (SZC) have an elongated morphology and account for 10–20% of chondrocytes, while the remaining chondrocytes in the Deeper Zones appear more rounded. This study characterizes the actin cytoskeleton and expression of actin-associated molecules in SZC and Deep Zone (DZ) chondrocytes (DZC) in vitro in order to identify molecules differentially expressed by SZC and DZC that may contribute to the observed differences in zonal chondrocyte shapes. Design SZ, DZ, and FT chondrocytes isolated from bovine metacarpal-phalangeal joints were cultured in monolayer for 48 h. Macroscopic morphology, actin polymerization status, and expression of select actin-associated molecules (adseverin, cofilin, transgelin, vinculin, MRTF-A, and YAP/TAZ) were determined. Results SZC appeared more elongated and have more filamentous actin compared to DZC, as determined by quantifying cell circularity and G-/F-actin ratio. MRTF-A gene and protein levels were significantly higher in SZC compared to DZC while DZC more highly expressed transgelin and TAZ. Although there was differential gene expression, no significant differences in adseverin, cofilin, vinculin, or YAP protein levels were observed between the two cell populations. Conclusions This study identifies differences in actin polymerization status and expression of actin-associated molecules in primary SZC and DZC in vitro. These findings further our understanding of candidate actin-related pathways that may be regulating zonal chondrocyte phenotype.
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the incorporation of a Zone of calcified cartilage improves the interfacial shear strength between in vitro formed cartilage and the underlying substrate
Acta Biomaterialia, 2012Co-Authors: Jeanphilippe Stpierre, Rita A Kandel, Lu Gan, Jian Wang, R M Pilliar, Marc D GrynpasAbstract:Abstract A major challenge for cartilage tissue engineering remains the proper integration of constructs with surrounding tissues in the joint. Biphasic osteochondral constructs that can be anchored in a joint through bone ingrowth partially address this requirement. In this study, a methodology was devised to generate a cell-mediated Zone of calcified cartilage (ZCC) between the in vitro-formed cartilage and a porous calcium polyphosphate (CPP) bone substitute in an attempt to improve the mechanical integrity of that interface. To do so, a calcium phosphate (CaP) film was deposited on CPP by a sol–gel process to prevent the accumulation of polyphosphates and associated inhibition of mineralization as the substrate degrades. Cartilage formed in vitro on the top surface of CaP-coated CPP by Deep-Zone chondrocytes was histologically and biochemically comparable to that formed on uncoated CPP. Furthermore, the mineral in the ZCC was similar in crystal structure, morphology and length to that formed on uncoated CPP and native articular cartilage. The generation of a ZCC at the cartilage–CPP interface led to a 3.3-fold increase in the interfacial shear strength of biphasic constructs. Improved interfacial strength of these constructs may be critical to their clinical success for the repair of large cartilage defects.
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characterization of the mineral in calcified articular cartilagenous tissue formed in vitro
Tissue Engineering, 1999Co-Authors: Rita A Kandel, Mark Hurtig, Marc D GrynpasAbstract:Cartilagenous tissue with mineralized and nonmineralized layers was generated in vitro using bovine chondrocytes isolated from the Deep Zone of articular cartilage. Mineralization was induced by ad...
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composition of cartilagenous tissue with mineralized and non mineralized Zones formed in vitro
Biomaterials, 1997Co-Authors: Hesheng Yu, Marc D Grynpas, Rita A KandelAbstract:We have previously shown that cartilagenous tissue with both non-mineralized and mineralized Zones can be formed by chondrocytes which have been selectively isolated from the Deep Zone of bovine articular cartilage. In this study, we quantitate proteoglycan and collagen content, calcification, tissue thickness and cellularity over a 10 week culture period in order to study matrix accumulation and tissue formation. The cartilagenous tissue cellularity and proteoglycan and collagen accumulation continued up to 8 weeks and this was paralleled by an increase in tissue thickness. The amount of mineral in the tissue as well as the amount of collagen, in contrast to proteoglycan, was still increasing at 10 weeks. At the end of week 10, the amount of glycosaminoglycan and collagen as a percentage of dry weight of the tissue were 11.0 ± 0.6% and 14.8 ± 0.1%, respectively, compared with 10.5 ± 1.2% and 35.1 ± 5.8% for the in vitro Deep articular cartilage. The amount of calcium as a percentage of dry weight of the cartilagenous tissue was 8.1 ± 0.7% which was similar to the in vivo cartilage (9.1 ± 1.6%). This data suggests that 8 weeks of culture may be necessary before the cartilagenous tissue is suitable for use as a transplant.
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in vitro formation of mineralized cartilagenous tissue by articular chondrocytes
In Vitro Cellular & Developmental Biology – Animal, 1997Co-Authors: Rita A Kandel, Jennifer Boyle, G Gibson, Tony F Cruz, M SpeagleAbstract:Study of the Deep articular cartilage and adjacent calcified cartilage has been limited by the lack of an in vitro culture system which mimics this region of the cartilage. In this paper we describe a method to generate mineralized cartilagenous tissue in culture using chondrocytes obtained from the Deep Zone of bovine articular cartilage. The cells were plated on Millipore CMR filters. The chondrocytes in culture accumulated extracellular matrix and formed cartilagenous tissue which calcified when β-glycerophosphate was added to the culture medium. The cartilagenous tissue generated in vitro contains both type II and type X collagens, large sulfated proteoglycans, and alkaline phosphatase activity. Ultrastructurally, matrix vesicles were seen in the extracellular matrix. Selected area electron diffraction confirmed that the calcification was composed of hydroxyapatite crystals. The chondrocytes, as characterized thus far, appear to maintain their phenotype under these culture conditions which suggests that these cultures could be used as a model to examine the metabolism of cells from the Deep Zone of cartilage and mineralization of cartilagenous tissue in culture.
Peter A Torzilli - One of the best experts on this subject based on the ideXlab platform.
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a biphasic finite element study on the role of the articular cartilage superficial Zone in confined compression
Journal of Biomechanics, 2015Co-Authors: Suzanne A Maher, Peter A TorzilliAbstract:The aim of this study was to investigate the role of the superficial Zone on the mechanical behavior of articular cartilage. Confined compression of articular cartilage was modeled using a biphasic finite element analysis to calculate the one-dimensional deformation of the extracellular matrix (ECM) and movement of the interstitial fluid through the ECM and articular surface. The articular cartilage was modeled as an inhomogeneous, nonlinear hyperelastic biphasic material with depth and strain-dependent material properties. Two loading conditions were simulated, one where the superficial Zone was loaded with a porous platen (normal test) and the other where the Deep Zone was loaded with the porous platen (upside down test). Compressing the intact articular cartilage with 0.2 MPa stress reduced the surface permeability by 88%. Removing the superficial Zone increased the rate of change for all mechanical parameters and decreased the fluid support ratio of the tissue, resulting in increased tissue deformation. Apparent permeability linearly increased after superficial removal in the normal test, yet it did not change in the upside down test. Orientation of the specimen affected the time-dependent biomechanical behavior of the articular cartilage, but not equilibrium behavior. The two tests with different specimen orientations resulted in very different apparent permeabilities, suggesting that in an experimental study which quantifies material properties of an inhomogeneous material, the specimen orientation should be stated along with the permeability result. The current study provides new insights into the role of the superficial Zone on mechanical behavior of the articular cartilage.
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maturational differences in superficial and Deep Zone articular chondrocytes
Cell and Tissue Research, 2006Co-Authors: Chisa Hidaka, Christina Cheng, Deborah Alexandre, Madhu Bhargava, Peter A TorzilliAbstract:To examine whether differences in chondrocytes from skeletally immature versus adult individuals are important in cartilage healing, repair, or tissue engineering, superficial Zone chondrocytes (SZC, from within 100 μm of the articular surface) and Deep Zone chondrocytes (DZC, from 30%–45% of the Deepest un-mineralized part of articular cartilage) were harvested from immature (1–4 months) and young adult (18–36 months) steers and compared. Cell size, matrix gene expression and protein levels, integrin levels, and chemotactic ability were measured in cells maintained in micromass culture for up to 7 days. Regardless of age, SZC were smaller, had a lower type II to type I collagen gene expression ratio, and higher gene expression of SZ proteins than their DZC counterparts. Regardless of Zone, chondrocytes from immature steers had higher levels of Sox 9 and type II collagen gene expression. Over 7 days in culture, the SZC of immature steers had the highest rate of proliferation. Phenotypically, the SZC of immature and adult steers were more stable than their respective DZC. Cell surface α5 and α2 integrin subunit levels were higher in the SZC of immature than of adult steers, whereas β1 integrin subunit levels were similar. Both immature and adult SZC were capable of chemotaxis in response to fetal bovine serum or basic fibroblast growth factor. Our data indicate that articular chondrocytes vary in the different Zones of cartilage and with the age of the donor. These differences may be important for cartilage growth, tissue engineering, and/or repair.
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Influence of stress rate on water loss, matrix deformation and chondrocyte viability in impacted articular cartilage
Journal of Biomechanics, 2005Co-Authors: Dejan Milentijevic, Peter A TorzilliAbstract:Abstract The biomechanical response of articular cartilage to a wide range of impact loading rates was investigated for stress magnitudes that exist during joint trauma. Viable, intact bovine cartilage explants were impacted in confined compression with stress rates of 25, 50, 130 and 1000 MPa/s and stress magnitudes of 10, 20, 30 and 40 MPa. Water loss, cell viability, dynamic impact modulus (DIM) and matrix deformation were measured. Under all loading conditions the water loss was small (∼15%); water loss increased linearly with increasing peak stress and decreased exponentially with increasing stress rate. Cell death was localized within the superficial Zone (⩽ 12% of total tissue thickness); the depth of cell death from the articular surface increased with peak stress and decreased with increasing stress rate. The DIM increased (200–700 MPa) and matrix deformation decreased with increasing stress rate. Initial water and proteoglycan (PG) content had a weak, yet significant influence on water loss, cell death and DIM. However, the significance of the inhomogeneous structure and composition of the cartilage matrix was accentuated when explants impacted on the Deep Zone had less water loss and matrix deformation, higher DIM, and no cell death compared to explants impacted on the articular surface. The mechano-biological response of articular cartilage depended on magnitude and rate of impact loading.
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increased stromelysin 1 mmp 3 proteoglycan degradation 3b3 and 7d4 and collagen damage in cyclically load injured articular cartilage
Osteoarthritis and Cartilage, 2004Co-Authors: Chih Tung Christopher Chen, Peter A TorzilliAbstract:Abstract Objective: To determine whether load-induced injury causes alterations in proteoglycan (PG), stromelysin-1 (MMP-3) and collagen in articular cartilage. Methods: Mature bovine cartilage was cyclically loaded at 0.5Hz with 1 and 5MPa for 1, 6 and 24h. Immediately after loading explants were evaluated for cell viability. Alterations in matrix integrity were determined by measuring PG content, PG degradation using 7D4 and 3B3(-) antibodies, broken collagen using COL2-3/4m antibody, and stromelysin-1 content using a MMP-3 antibody. Results: Mechanical load caused cell death and PG loss starting from the articular surface and increasing in depth with loading time. There was a decrease in the 7D4 epitope (native chondroitin sulfate) in the superficial Zone of cartilage loaded for longer than 1h, but an increase around chondrocytes in the Deep Zone. The 3B3(-) staining for degraded/abnormal chondroitin-4-sulfate neoepitope appeared only in cartilage loaded under the most severe condition (5MPa, 24h). The elevation of stromelysin-1 was co-localized with broken collagen (COL2-3/4m) at the articular surface in explants loaded with 1 and 5MPa for 24h. Conclusions: Cell death and PG loss occurred within 6h of cyclic loading. The elevation of MMP-3 following cell death was consistently found in the superficial Zone of loaded cartilage. Since MMP-3 can degrade PG and super-activate procollagenase, the increase of MMP-3 can therefore induce matrix degradation and PG depletion in mechanically injured articular cartilage, both of which are important to the development of osteoarthritis.
Ronald K June - One of the best experts on this subject based on the ideXlab platform.
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development and analytical validation of a finite element model of fluid transport through osteochondral tissue
Journal of Biomechanics, 2021Co-Authors: Brady D Hislop, Chelsea M Heveran, Ronald K JuneAbstract:Abstract Fluid transport is critical to joint health. In this study we evaluate an unexplored component of joint fluid transport –fluid transport between cartilage and bone. Such transport across the cartilage-bone interface could potentially provide chondrocytes with an additional source of nutrients and signaling molecules. A biphasic viscoelastic model using an ellipsoidal fiber distribution was created with three distinct layers of cartilage (superficial Zone, middle Zone, and Deep Zone) along with a layer of subchondral bone. For stress-relaxation in unconfined compression, our results for compressive stress, radial stress, and effective fluid pressure were compared with established biphasic analytical solutions. Our model also shows the development of fluid pressure gradients at the cartilage-bone interface during loading. Fluid pressure gradients that develop at the cartilage-bone interface show consistently higher pressures in cartilage following the initial loading to 10% stain, followed by convergence of the pressures in cartilage and bone during the 400 s relaxation period. These results provide additional evidence that fluid is transported between cartilage and bone during loading and improves upon estimates of the magnitude of this effect through incorporating a realistic distribution and estimate of the collagen ultrastructure. Understanding fluid transport between cartilage and bone may be key to new insights about the mechanical and biological environment of both tissues in health and disease.
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development and analytical validation of a finite element model of fluid transport through osteochondral tissue
bioRxiv, 2020Co-Authors: Brady D Hislop, Chelsea M Heveran, Ronald K JuneAbstract:Fluid transport between cartilage and bone is critical to joint health. The objective of this study was to develop and analytically validate a finite element model of osteochondral tissue capable of modeling cartilage-bone fluid transport. A biphasic viscoelastic model using an ellipsoidal fiber distribution was created with three distinct layers of cartilage, superficial Zone, middle Zone, and Deep Zone along with a layer of bone. For stress-relaxation in unconfined compression, our results for compressive stress, radial stress, effective fluid pressure, and elastic recoil were compared with established biphasic analytical solutions. Our model also shows the development of fluid pressure gradients at the cartilage-bone interface during loading. This model is the first to capture fluid pressure gradients at the cartilage-bone interface for unconfined compression. These results provide additional evidence that fluid is transported between cartilage and bone during loading. Our study examines fluid transport between cartilage and bone from a new perspective using viscoelastic assumptions, in contrast with previous models that used poroelastic models. Further our model incorporates an ellipsoidal fiber distribution for collagen fibers while a previous model used a volume element model. Understanding the velocity and flux of fluid transport between cartilage and bone is key to elucidating the role of transport between cartilage and bone in joint health.
Nora T. Khanarian - One of the best experts on this subject based on the ideXlab platform.
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ftir i compositional mapping of the cartilage to bone interface as a function of tissue region and age
Journal of Bone and Mineral Research, 2014Co-Authors: Nora T. Khanarian, Margaret K Boushell, Jeffrey P Spalazzi, Nancy Pleshko, Adele L Boskey, Helen H. LuAbstract:Soft tissue-to-bone transitions, such as the osteochondral interface, are complex junctions that connect multiple tissue types and are critical for musculoskeletal function. The osteochondral interface enables pressurization of articular cartilage, facilitates load transfer between cartilage and bone, and serves as a barrier between these two distinct tissues. Presently, there is a lack of quantitative understanding of the matrix and mineral distribution across this multitissue transition. Moreover, age-related changes at the interface with the onset of skeletal maturity are also not well understood. Therefore, the objective of this study is to characterize the cartilage-to-bone transition as a function of age, using Fourier transform infrared spectroscopic imaging (FTIR-I) analysis to map region-dependent changes in collagen, proteoglycan, and mineral distribution, as well as collagen organization. Both tissue-dependent and age-related changes were observed, underscoring the role of postnatal physiological loading in matrix remodeling. It was observed that the relative collagen content increased continuously from cartilage to bone, whereas proteoglycan peaked within the Deep Zone of cartilage. With age, collagen content across the interface increased, accompanied by a higher degree of collagen alignment in both the surface and Deep Zone cartilage. Interestingly, regardless of age, mineral content increased exponentially across the calcified cartilage interface. These observations reveal new insights into both region- and age-dependent changes across the cartilage-to-bone junction and will serve as critical benchmark parameters for current efforts in integrative cartilage repair.
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a functional agarose hydroxyapatite scaffold for osteochondral interface regeneration
Biomaterials, 2012Co-Authors: Nora T. Khanarian, Nora M Haney, Rachel A BurgaAbstract:Regeneration of the osteochondral interface is critical for integrative and functional cartilage repair. This study focuses on the design and optimization of a hydrogel-ceramic composite scaffold of agarose and hydroxyapatite (HA) for calcified cartilage formation. The first study objective was to compare the effects of HA on non-hypertrophic and hypertrophic chondrocytes cultured in the composite scaffold. Specifically, cell growth, biosynthesis, hypertrophy, and scaffold mechanical properties were evaluated. Next, the ceramic phase of the scaffold was optimized in terms of particle size (200 nm vs. 25 μm) and dose (0-6 w/v%). It was observed that while Deep Zone chondrocyte (DZC) biosynthesis and hypertrophy remained unaffected, hypertrophic chondrocytes measured higher matrix deposition and mineralization potential with the addition of HA. Most importantly, higher matrix content translated into significant increases in both compressive and shear mechanical properties. While cell hypertrophy was independent of ceramic size, matrix deposition was higher only with the addition of micron-sized ceramic particles. In addition, the highest matrix content, mechanical properties and mineralization potential were found in scaffolds with 3% micro-HA, which approximates both the mineral aggregate size and content of the native interface. These results demonstrate that the biomimetic hydrogel-ceramic composite is optimal for calcified cartilage formation and is a promising design strategy for osteochondral interface regeneration.
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A Hydrogel-Mineral Composite Scaffold for Osteochondral Interface Tissue Engineering
Tissue Engineering Part A, 2011Co-Authors: Jie Jiang, Nora T. Khanarian, Leo Q. Wan, Helen H. Lu, Van C. MowAbstract:Osteoarthritis is the leading cause of physical disability among Americans, and tissue engineered cartilage grafts have emerged as a promising treatment option for this debilitating condition. Currently, the formation of a stable interface between the cartilage graft and subchondral bone remains a significant challenge. This study evaluates the potential of a hybrid scaffold of hydroxyapatite (HA) and alginate hydrogel for the regeneration of the osteochondral interface. Specifically, the effects of HA on the response of chondrocytes were determined, focusing on changes in matrix production and mineralization, as well as scaffold mechanical properties over time. Additionally, the optimal chondrocyte population for interface tissue engineering was evaluated. It was observed that the HA phase of the composite scaffold promoted the formation of a proteoglycan- and type II collagen-rich matrix when seeded with Deep Zone chondrocytes. More importantly, the elevated biosynthesis translated into significant increases in both compressive and shear moduli relative to the mineral-free control. Presence of HA also promoted chondrocyte hypertrophy and type X collagen deposition. These results demonstrate that the hydrogel-calcium phosphate composite supported the formation of a calcified cartilage-like matrix and is a promising scaffold design for osteochondral interface tissue engineering.
Lars Oesterhelweg - One of the best experts on this subject based on the ideXlab platform.
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life threatening versus non life threatening manual strangulation are there appropriate criteria for mr imaging of the neck
European Radiology, 2009Co-Authors: Andreas Christe, Harriet C Thoeny, Steffen Ross, Danny Spendlove, Dechen W Tshering, Stephan A Bolliger, Silke Grabherr, Michael J Thali, Peter Vock, Lars OesterhelwegAbstract:The aim of the study was to determine objective radiological signs of danger to life in survivors of manual strangulation and to establish a radiological scoring system for the differentiation between life-threatening and non-life-threatening strangulation by dividing the cross section of the neck into three Zones (superficial, middle and Deep Zone). Forensic pathologists classified 56 survivors of strangulation into life-threatening and non-life-threatening cases by history and clinical examination alone, and two blinded radiologists evaluated the MRIs of the neck. In 15 cases, strangulation was life-threatening (27%), compared with 41 cases in which strangulation was non-life-threatening (73%). The best radiological signs on MRI to differentiate between the two groups were intramuscular haemorrhage/oedema, swelling of platysma and intracutaneous bleeding (all p = 0.02) followed by subcutaneous bleeding (p = 0.034) and haemorrhagic lymph nodes (p = 0.04), all indicating life-threatening strangulation. The radiological scoring system showed a sensitivity and specificity of approximately 70% for life-threatening strangulation, when at least two neck Zones were affected. MRI is not only helpful in assessing the severity of strangulation, but is also an excellent documentation tool that is even admissible in court.
