Confocal microscopy indentation system for studying in situ chondrocyte mechanics

Han, Sang Kuy; Colarusso, Pina; Herzog, Walter

doi:10.1016/j.medengphy.2009.05.013

Cited by 33 publications

(41 citation statements)

References 15 publications

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“…The indenter (i.e. the flat plate) is often made of glass, which enables in situ observation of cell deformation [20,47]. Tables 1 and 2 summarize the effective contact radius, effective contact stress and representative strain for various tip geometries.…”

Section: Extended Atomic Force Microscope Testing Rigsmentioning

confidence: 99%

Nanobiomechanics of living cells: a review

Chen

2014

Interface Focus.

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Nanobiomechanics of living cells is very important to understand cellmaterials interactions. This would potentially help to optimize the surface design of the implanted materials and scaffold materials for tissue engineering. The nanoindentation techniques enable quantifying nanobiomechanics of living cells, with flexibility of using indenters of different geometries. However, the data interpretation for nanoindentation of living cells is often difficult. Despite abundant experimental data reported on nanobiomechanics of living cells, there is a lack of comprehensive discussion on testing with different tip geometries, and the associated mechanical models that enable extracting the mechanical properties of living cells. Therefore, this paper discusses the strategy of selecting the right type of indenter tips and the corresponding mechanical models at given test conditions.

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Section: Extended Atomic Force Microscope Testing Rigsmentioning

confidence: 99%

Nanobiomechanics of living cells: a review

Chen

2014

Interface Focus.

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“…The aim of this study was to develop a method to investigate biological responses of chondrocytes in intact articular cartilage attached to its native bone in response to mechanical perturbations. To this end, a custom built Confocal Laser Scanning Microscopy (CLSM) setup, designed for quantifying chondrocyte mechanobiology in intact cartilage, 33 was used. Calcium signaling in chondrocytes of superficial zone, lapine femoral condyle cartilage was measured during compressive loading at two temperatures.…”

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confidence: 99%

Mechanically induced calcium signaling in chondrocytes in situ

Han

Wouters

Clark

2011

Journal Orthopaedic Research

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Changes in intracellular calcium (Ca 2þ ) concentration, also known as Ca 2þ signaling, have been widely studied in articular cartilage chondrocytes to investigate pathways of mechanotransduction. Various physical stimuli can generate an influx of Ca 2þ into the cell, which in turn is thought to trigger a range of metabolic and signaling processes. In contrast to most studies, the approach used in this study allows for continuous real time recording of calcium signals in chondrocytes in their native environment. Therefore, interactions of cells with the extracellular matrix (ECM) are fully accounted for. Calcium signaling was quantified for dynamic loading conditions and at different temperatures. Peak magnitudes of calcium signals were greater and of shorter duration at 378C than at 218C. Furthermore, Ca 2þ signals were involved in a greater percentage of cells in the dynamic compared to the relaxation phases of loading. In contrast to the time-delayed signaling observed in isolated chondrocytes seeded in agarose gel, Ca 2þ signaling in situ is virtually instantaneous in response to dynamic loading. These differences between in situ and in vitro cell signaling responses might provide crucial insight into the role of the ECM in providing pathways of mechanotransduction in the intact cartilage that are absent in isolated cells seeded in gel constructs.

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“…Width and depth (x-and y-directions) of cells were then defined along the minor and major axes of the cell cross sections taken perpendicular to the height of cells (z-direction). This was done by analysing maximum distances between cell edges in the x and y directions of an orthogonal reference frame in the horizontal plane, and the z direction in the vertical plane using MATLAB R2007b (MathWorks Inc., USA) (Han et al 2009(Han et al , 2010.…”

Section: Confocal Laser Scanning Microscopy (Clsm)mentioning

confidence: 99%

“…However, we believe that cutting of the sample may still alter the 3D structure of cartilage in the proximity of the cut edge, which in turn could affect cell mechanics. Chondrocytes have also been studied previously in intact cartilage samples under osmotic (Korhonen et al 2010a,b) and mechanical (Han et al 2009(Han et al , 2010 loading conditions. Based on these earlier studies, it has been suggested that hypo-osmotically challenged cells in cartilage explants first increase in volume and then recover back to the original volume (Bush and Hall 2001a), while cell volumes in intact tissues do not recover back to the original, unchallenged volume after the initial volume increase (Korhonen et al 2010b).…”

Section: Introductionmentioning

confidence: 99%

“…Mechanical and electrostatic interactions between collagen and PGs may also contribute to the total cartilage swelling and shrinking (Schmidt et al 1990; Mow et al 1992). In the intact cartilage tissue, cell volume and morphology have been suggested to be related to the collagen and PG contents and collagen orientation of the extracellular and pericellular matrix (ECM and PCM) Korhonen et al 2010a,b;Han et al 2009Han et al , 2010, while some studies have suggested that in situ chondrocytes in the cartilage explants may not be affected by the ECM/PCM (Bush and Hall 2001a). Correlations between the PG/collagen content and cell volume change following osmotic challenge in intact cartilage and cartilage explants could give deeper insight into this issue.…”

Section: Introductionmentioning

confidence: 99%

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Hypotonic challenge modulates cell volumes differently in the superficial zone of intact articular cartilage and cartilage explant

Turunen

Saarakkala

Koistinen

et al. 2011

Biomech Model Mechanobiol

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The objective of this study was to evaluate the effect of sample preparation on the biomechanical behaviour of chondrocytes. We compared the volumetric and dimensional changes of chondrocytes in the superficial zone (SZ) of intact articular cartilage and cartilage explant before and after a hypotonic challenge. Calcein-AM labelled SZ chondrocytes were imaged with confocal laser scanning microscopy through intact cartilage surfaces and through cut surfaces of cartilage explants. In order to clarify the effect of tissue composition on cell volume changes, Fourier Transform Infrared microspectroscopy was used for estimating the proteoglycan and collagen contents of the samples. In the isotonic medium (300 mOsm), there was a significant difference (p < 0.05) in the SZ cell volumes and aspect ratios between intact cartilage samples and cartilage explants. Changes in cell volumes at both short-term (2 min) and long-term (2 h) time points after the hypotonic challenge (180 mOsm) were significantly different (p < 0.05) between the groups. Further, proteoglycan content was found to correlate significantly (r(2) = 0.63, p < 0.05) with the cell volume changes in cartilage samples with intact surfaces. Collagen content did not correlate with cell volume changes. The results suggest that the biomechanical behaviour of chondrocytes following osmotic challenge is different in intact cartilage and in cartilage explant. This indicates that the mechanobiological responses of cartilage and cell signalling may be significantly dependent on the integrity of the mechanical environment of chondrocytes.

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Confocal microscopy indentation system for studying in situ chondrocyte mechanics

Cited by 33 publications

References 15 publications

Nanobiomechanics of living cells: a review

Nanobiomechanics of living cells: a review

Mechanically induced calcium signaling in chondrocytes in situ

Hypotonic challenge modulates cell volumes differently in the superficial zone of intact articular cartilage and cartilage explant

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