Zonal variations in the three-dimensional morphology of the chondron measured in situ using confocal microscopy

Youn, Inchan; Choi, Jeong-Sun; Cao, Li; Setton, Lori A.; Guilak, Farshid

doi:10.1016/j.joca.2006.02.017

Cited by 120 publications

(115 citation statements)

References 45 publications

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“…In fact, an electron microscopy study of the articular surface reported associations between ECM surface depressions and superficial cell groups in rabbit cartilage (Clark and Rudd, 1991). In addition, the local zonal collagen architecture appear to influence the chondron shape and orientation (Youn et al, 2006). Thus, specific patterns in the organization of superficial chondrocytes may be associated with the local articular surface structure.…”

Section: Discussionmentioning

confidence: 99%

Distinct horizontal patterns in the spatial organization of superficial zone chondrocytes of human joints

Rolauffs

Williams

Grodzinsky

et al. 2008

Journal of Structural Biology

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A better understanding of the unique cellular and functional properties of the superficial zone of articular cartilage may aid current strategies in tissue engineering which attempts a layered design for the repair of cartilage lesions to avert or postpone the onset of osteoarthritis. However, data pertaining to the cellular organization of non-degenerated superficial zone of articular cartilage is not available for most human joints. The present study analyzed the arrangement of chondrocytes of non-degenerated human joints (shoulder, elbow, knee, and ankle) by using fluorescence microscopy of the superficial zone in a top-down view. The resulting horizontal chondrocyte arrangements were tested for randomness, homogeneity or a significant grouping via point pattern analysis and were correlated with the joint type in which they occurred. The present study demonstrated that human superficial chondrocytes occurred in four distinct patterns of strings, clusters, pairs or single chondrocytes. Those patterns represented a significant grouping (p<0.0001) with horizontal alignment. Each articular joint surface was dominated by only one of these four patterns (p<0.001). Specific patterns correlated with specific diarthrodial joint types (p<0.001). Further studies need to establish whether these organizational patterns are a consequence of their surrounding environment or whether they are linked to a functional purpose.

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Section: Discussionmentioning

confidence: 99%

Distinct horizontal patterns in the spatial organization of superficial zone chondrocytes of human joints

Rolauffs

Williams

Grodzinsky

et al. 2008

Journal of Structural Biology

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“…Unfixed cartilage sections were labelled for type VI collagen, using a modified IF protocol [11]. At room temperature, sections were blocked for 20 min in 10 per cent normal donkey serum (lot no.…”

Section: Immunofluorescence For Type VI Collagenmentioning

confidence: 99%

“…Isolated chondrocytes also demonstrate zonal differences in their mechanical properties, with superficial zone cells exhibiting higher moduli than do middle/deep zone cells [32,33]. While the three-dimensional morphology and thickness of the PCM varies among the cartilage zones [11,14], micropipette aspiration of mechanically isolated chondrons from canine [34] and human [35,36] cartilage revealed zonal uniformity in the mechanical properties of the PCM, despite significant zonal differences in ECM properties. Although recent studies have evaluated the biomechanical properties of the cartilage PCM in situ indirectly using an inverse boundary element analysis coupled with three-dimensional confocal microscopy [37] and directly by atomic force microscopy (AFM) [38], the existence (or lack) of zonal variation in PCM properties in situ has yet to be determined.…”

Section: Introductionmentioning

confidence: 96%

Immunofluorescence-guided atomic force microscopy to measure the micromechanical properties of the pericellular matrix of porcine articular cartilage

Wilusz

DeFrate

Guilak

2012

J. R. Soc. Interface.

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The pericellular matrix (PCM) is a narrow region that is rich in type VI collagen that surrounds each chondrocyte within the extracellular matrix (ECM) of articular cartilage. Previous studies have demonstrated that the chondrocyte micromechanical environment depends on the relative properties of the chondrocyte, its PCM and the ECM. The objective of this study was to measure the influence of type VI collagen on site-specific micromechanical properties of cartilage in situ by combining atomic force microscopy stiffness mapping with immunofluorescence imaging of PCM and ECM regions in cryo-sectioned tissue samples. This method was used to test the hypotheses that PCM biomechanical properties correlate with the presence of type VI collagen and are uniform with depth from the articular surface. Control experiments verified that immunolabelling did not affect the properties of the ECM or PCM. PCM biomechanical properties correlated with the presence of type VI collagen, and matrix regions lacking type VI collagen immediately adjacent to the PCM exhibited higher elastic moduli than regions positive for type VI collagen. PCM elastic moduli were similar in all three zones. Our findings provide further support for type VI collagen in defining the chondrocyte PCM and contributing to its biological and biomechanical properties.

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“…The in situ geometry replicates the cell as an approximate prolate ellipsoid with major and minor diameters of 12 and 8 µm, respectively, where the major diameter is in a direction approximately perpendicular to the direction of loading. When modelled, the PC matrix was represented as 3-µm thick layer surrounding the cell membrane (Youn et al, 2006). The local EC region modelled around the cell extends 50 µm along the axial and radial directions, with the cell centred in this ROI.…”

Section: Study 2: Finite Element Analysis Of Cell Deformationmentioning

confidence: 99%

In-situ measurements of chondrocyte deformation under transient loading

Chahine¹,

Hung²,

Ga³

2007

eCM

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Chondrocytes are responsible for the elaboration and maintenance of the extracellular (EC) matrix in articular cartilage, and previous studies have demonstrated that mechanical loading modulates the biosynthetic response of chondrocytes in cartilage explants. The goal of this study is to investigate the deformation behaviour of the chondrocyte and its microenvironment under transient loading, in order to address the relationship between the applied dynamic deformation and cellular strain. In situ strain measurements were performed on cells in the middle (MZ) zone at early time points during ramp loading and at equilibrium. In this study, we characterized the behaviour of cartilage at the zonal and cellular levels under compressive loading using digital image analysis on miniature samples tested in a custom microscopy-based loading device. The experimental results indicate that significant strain amplification occurs in the microenvironment of the cell, with the minimum (compressive) principal strain found to be nearly 7X higher in the intracellular region (IC), and ~5X higher in the pericellular (PC) matrix than in the EC matrix at peak ramp. A similar strain amplification mechanism was observed in the maximum (tensile) principal strain, and this behaviour persisted even after equilibrium was reached. The experimental results of this study were interpreted in the context of a finite element model of chondrocyte deformation, which modelled the cell as a homogeneous gel, possessing either a spherical or ellipsoidal geometry, surrounded by a semi permeable membrane, and accounted for the presence of a PC matrix. The results of the FEA demonstrate significant strain amplification mechanism in the IC region, greater than had previously been suggested in earlier computational studies of cell-EC matrix interactions. Based on the FEA, this outcome is understood to result from the large disparity between EC matrix and intracellular properties. The results of this study suggest that mechanotransduction of chondrocytes may be significantly mediated by this strain amplification mechanism during loading.

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Zonal variations in the three-dimensional morphology of the chondron measured in situ using confocal microscopy

Cited by 120 publications

References 45 publications

Distinct horizontal patterns in the spatial organization of superficial zone chondrocytes of human joints

Distinct horizontal patterns in the spatial organization of superficial zone chondrocytes of human joints

Immunofluorescence-guided atomic force microscopy to measure the micromechanical properties of the pericellular matrix of porcine articular cartilage

In-situ measurements of chondrocyte deformation under transient loading

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