Growth Responses of Cartilage to Static and Dynamic Compression

Li, Kelvin W.; Williamson, Amanda K.; Wang, Aaron S.; Sah, Robert L.

doi:10.1097/00003086-200110001-00005

Cited by 56 publications

(34 citation statements)

References 48 publications

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“…Based on these studies, in vivo joint contact pressures are estimated to generally range from 1.0 to 2.5 MPa (and up to 10 MPa for peak loading). The findings in the current and previous studies that both fibrous joints (e.g., the disc) and articular joints generally exist in a 0.5 to 2.5 MPa dynamic stress environment may not be coincidental because chondrocytes are metabolically most active in this load range [81][82][83][84][85][86]. A stress environment that is static, too low, or too high results in decreased chondrocyte proteoglycan production, increased protein degradation, and chondrocyte cell death [85;87-91].…”

Section: Discussionmentioning

confidence: 52%

Mature runt cow lumbar intradiscal pressures and motion segment biomechanics

2009

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Background Context-The optimal animal model for in vivo testing of spinal implants, particularly total or partial disc replacement devices, has not yet been determined. Mechanical and morphological similarities of calf and human spines have been reported; however, limitations of the calf model include open growth plates and oversized vertebrae with growth. Mature runt cows (Corrientes breed) may avoid these limitations.

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Section: Discussionmentioning

confidence: 52%

Mature runt cow lumbar intradiscal pressures and motion segment biomechanics

2009

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“…It should also be noted that the suppressive effect of static compression on the expression [42,43] and synthesis [44][45][46][47][48][49] of structural proteins by chondrocytes has been well-documented, and may well provide a partial explanation for the regional variations in response to equivalent mechanical loading. That is, the greater upregulation of both CII and aggrecan in central region compared with peripheral region cartilage explants may simply reflect the lesser creep consolidation experienced by those samples under dynamic unconfined compression, suggesting that the regional differences in gene expression might reflect the regional differences in mechanical properties as well as thickness.…”

Section: Discussionmentioning

confidence: 99%

The Regional Sensitivity of Chondrocyte Gene Expression to Coactive Mechanical Load and Exogenous TNF-α Stimuli

Bevill

Boyer

Andriacchi

2014

Journal of Biomechanical Engineering

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Both mechanical load and elevated levels of proinflammatory cytokines have been associated with the risk for developing osteoarthritis (OA), yet the potential interaction of these mechanical and biological factors is not well understood. The purpose of this study was to evaluate the response of chondrocytes to the effects of dynamic unconfined compression, TNF-a, and the simultaneous effects of dynamic unconfined compression and TNF-a. The response to these three treatments was markedly different and, taken together, the response in the gene expression of chondrocytes to the different treatment conditions suggest a complex interaction between structure, biology, and mechanical loading.

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“…Mechanical loading has been identified as an important regulator of cartilage cells (i.e., chondrocytes) and overall tissue quality ; Guilak et al 2001; Li et al 2001). The role of mechanical loading on chondrocyte function has been examined in cartilage explants (Kim et al 1995;Davisson et al 2002), high density cell pellets (Graff et al 2003), and 3-D scaffolds (Mauck et For example, when a 1 Hz unconfined dynamic strain of 15% was applied to chondrocytes encapsulated in two different hydrogels for 48 hours, proteoglycan synthesis increased by 40% in agarose (Lee and Bader 1997), but decreased by 10% in PEG gels (Bryant et al 2004b).…”

Section: Introductionmentioning

confidence: 99%

The role of hydrogel structure and dynamic loading on chondrocyte gene expression and matrix formation

Nicodemus

Bryant

2008

Journal of Biomechanics

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Crosslinked poly(ethylene glycol) (PEG) hydrogels are attractive scaffolds for cartilage tissue engineering because of their ability to mimic the aqueous environment and mechanical properties of native cartilage. In this study, hydrogel crosslinking density was varied to study the influence of gel structure and the application of dynamic loading (continuous, 1 Hz, 15% amplitude strain) on chondrocyte gene expression over ∼1 week culture. Gene expression was quantified using real time RT-PCR for collagen II and aggrecan, the major cartilage extracellular matrix (ECM) components, and collagen I, an indicator of chondrocyte de-differentiation. When chondrocytes were encapsulated in PEG gels with low or high crosslinking, a high collagen II expression compared to collagen I expression (1,000 or 100,000:1, respectively) indicated the native chondrocyte phenotype was retained. In the absence of loading, relative gene expression for collagen II and aggrecan was significantly higher (e.g., 2-fold and 4-fold, respectively, day 7) in the low crosslinked gels compared to gels with higher crosslinking. Dynamic loading, however, showed little effect on ECM gene expression in both crosslinked systems. To better understand the cellular environment, ECM production was qualitatively assessed using an in situ immunofluorescent technique and standard histology. A pericellular matrix (PCM) was observed as early as day 3 post-encapsulation and the degree of formation was dependent on gel crosslinking. These results suggest the PCM may protect the cells from sensing the applied loads. This study demonstrates that gel structure has a profound effect on chondrocyte gene expression, while dynamic loading has much less of an effect at early culture times.

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Growth Responses of Cartilage to Static and Dynamic Compression

Cited by 56 publications

References 48 publications

Mature runt cow lumbar intradiscal pressures and motion segment biomechanics

Mature runt cow lumbar intradiscal pressures and motion segment biomechanics

The Regional Sensitivity of Chondrocyte Gene Expression to Coactive Mechanical Load and Exogenous TNF-α Stimuli

The role of hydrogel structure and dynamic loading on chondrocyte gene expression and matrix formation

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