In situ constitutive properties of articular cartilage via osmotic loading and ultrasonic measurement

1985 ◽  
Vol 18 (7) ◽  
pp. 525
Author(s):  
S. Tepic ◽  
T. Macirowski ◽  
R.W. Mann
Keyword(s):  
Articular Cartilage ◽  
Ultrasonic Measurement ◽  
Osmotic Loading ◽  
Constitutive Properties

scholarly journals Versican gene expression in human articular cartilage and comparison of mRNA splicing variation with aggrecan

1993 ◽  
Vol 291 (2) ◽  
pp. 361-367 ◽  
Author(s):  
J Grover ◽  
P J Roughley
Keyword(s):  
Alternative Splicing ◽  
Articular Cartilage ◽  
Regulatory Protein ◽  
Mrna Splicing ◽  
Human Articular Cartilage ◽  
Complement Regulatory Protein ◽  
Mature Adult ◽  
Epidermal Growth ◽  
Egf Domain

The chondrocytes in human articular cartilage from subjects of all ages express mRNAs for both of the aggregating proteoglycans aggrecan and versican, although the level of expression of versican mRNA is much lower than that of aggrecan mRNA. Aggrecan shows alternative splicing of the epidermal growth factor (EGF)-like domain within its C-terminal globular region, but there is no evidence for a major difference in situ in the relative expression of this domain with age. At all ages studied from birth to the mature adult, a greater proportion of transcripts lacked the EGF domain. The relative proportions of the two transcripts did not change upon culture and passage of isolated chondrocytes. In contrast, the neighbouring complement regulatory protein (CRP)-like domain was predominantly expressed irrespective of age, but cell culture did result in variation of the splicing of this domain. Versican possesses two EGF-like domains and one CRP-like domain, but at all ages the three domains were predominantly present in all transcripts. This situation persisted upon culture and passage of the chondrocytes. Thus, unlike aggrecan, the versican expressed by human articular cartilage does not appear to undergo alternative splicing of its C-terminal globular region, either in cartilage in situ or in chondrocytes in culture.

scholarly journals The ciliary protein IFT88 controls post-natal cartilage thickness and influences development of osteoarthritis

2020 ◽  
Author(s):  
CR Coveney ◽  
L Zhu ◽  
J Miotla-Zarebska ◽  
B Stott ◽  
I Parisi ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Cell Biology ◽  
Articular Chondrocytes ◽  
Skeletal Development ◽  
Cartilage Degradation ◽  
Cartilage Thickness ◽  
Tissue Growth ◽  
Calcified Cartilage ◽  
Health And Disease

AbstractMechanical forces are known to drive cellular signalling programmes in cartilage development, health, and disease. Proteins of the primary cilium, implicated in mechanoregulation, control cartilage formation during skeletal development, but their role in post-natal cartilage is unknown. Ift88fl/fl and AggrecanCreERT2 mice were crossed to create a cartilage specific inducible knockout mouse AggrecanCreERT2;Ift88fl/fl. Tibial articular cartilage thickness was assessed, through adolescence and adulthood, by histomorphometry and integrity by OARSI score. In situ cell biology was investigated by immunohistochemistry (IHC) and qPCR of micro-dissected cartilage. OA was induced by destabilisation of the medial meniscus (DMM). Some mice were provided with exercise wheels in their cage. Deletion of IFT88 resulted in a reduction in medial articular cartilage thickness (atrophy) during adolescence from 102.57μm, 95% CI [94.30, 119.80] in control (Ift88fl/fl) to 87.36μm 95% CI [81.35, 90.97] in AggrecanCreERT2;Ift88fl/fl by 8-weeks p<0.01, and adulthood (104.00μm, 95% CI [100.30, 110.50] in Ift88fl/fl to 89.42μm 95% CI [84.00, 93.49] in AggrecanCreERT2;Ift88fl/fl, 34-weeks, p<0.0001) through a reduction in calcified cartilage. Thinning in adulthood was associated with spontaneous cartilage degradation. Following DMM, AggrecanCreERT2;Ift88fl/fl mice had increased OA (OARSI scores at 12 weeks Ift88fl/fl = 22.08 +/− 9.30, and AggrecanCreERT2;Ift88fl/fl = 29.83 +/− 7.69). Atrophy was not associated with aggrecanase-mediated destruction or chondrocyte hypertrophy. Ift88 expression positively correlated with Tcf7l2 and connective tissue growth factor. Cartilage thickness was restored in AggrecanCreERT2;Ift88fl/fl by voluntary wheel exercise. Our results demonstrate that ciliary IFT88 regulates cartilage thickness and is chondroprotective, potentially through modulating mechanotransduction pathways in articular chondrocytes.

Swelling and Curling Behaviors of Articular Cartilage

1998 ◽  
Vol 120 (3) ◽  
pp. 355-361 ◽  
Author(s):  
L. A. Setton ◽  
H. Tohyama ◽  
V. C. Mow
Keyword(s):  
Articular Cartilage ◽  
Residual Strain ◽  
Shape Change ◽  
Articular Surface ◽  
Ion Concentration ◽  
Ex Situ ◽  
Surface Zone ◽  
Sample Orientation ◽  
Residual Strains

A new experimental method was developed to quantify parameters of swelling-induced shape change in articular cartilage. Full-thickness strips of cartilage were studied in free-swelling tests and the swelling-induced stretch, curvature, and areal change were measured. In general, swelling-induced stretch and curvature were found to increase in cartilage with decreasing ion concentration, reflecting an increasing tendency to swell and “curl” at higher swelling pressures. An exception was observed at the articular surface, which was inextensible for all ionic conditions. The swelling-induced residual strain at physiological ionic conditions was estimated from the swelling-induced stretch and found to be tensile and from 3–15 percent. Parameters of swelling were found to vary with sample orientation, reflecting a role for matrix anisotropy in controlling the swelling-induced residual strains. In addition, the surface zone was found to be a structurally important element, which greatly limits swelling of the entire cartilage layer. The findings of this study provide the first quantitative measures of swelling-induced residual strain in cartilage ex situ, and may be readily adapted to studies of cartilage swelling in situ.

Direct Osmotic Pressure Measurements in Articular Cartilage Demonstrate Nonideal and Concentration-Dependent Phenomena

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Brandon K. Zimmerman ◽  
Robert J. Nims ◽  
Alex Chen ◽  
Clark T. Hung ◽  
Gerard A. Ateshian
Keyword(s):  
Articular Cartilage ◽  
Stress Relaxation ◽  
Osmotic Pressure ◽  
Electrostatic Interactions ◽  
Swelling Pressure ◽  
Confined Compression ◽  
Human Cartilage ◽  
Poisson Boltzmann ◽  
Triphasic Theory

Abstract The osmotic pressure in articular cartilage serves an important mechanical function in healthy tissue. Its magnitude is thought to play a role in advancing osteoarthritis. The aims of this study were to: (1) isolate and quantify the magnitude of cartilage swelling pressure in situ; and (2) identify the effect of salt concentration on material parameters. Confined compression stress-relaxation testing was performed on 18 immature bovine and six mature human cartilage samples in solutions of varying osmolarities. Direct measurements of osmotic pressure revealed nonideal and concentration-dependent osmotic behavior, with magnitudes approximately 1/3 those predicted by ideal Donnan law. A modified Donnan constitutive behavior was able to capture the aggregate behavior of all samples with a single adjustable parameter. Results of curve-fitting transient stress-relaxation data with triphasic theory in febio demonstrated concentration-dependent material properties. The aggregate modulus HA increased threefold as the external concentration decreased from hypertonic 2 M to hypotonic 0.001 M NaCl (bovine: HA=0.420±0.109 MPa to 1.266±0.438 MPa; human: HA=0.499±0.208 MPa to 1.597±0.455 MPa), within a triphasic theory inclusive of osmotic effects. This study provides a novel and simple analytical model for cartilage osmotic pressure which may be used in computational simulations, validated with direct in situ measurements. A key finding is the simultaneous existence of Donnan osmotic and Poisson–Boltzmann electrostatic interactions within cartilage.

In Situ Hierarchical Strain Transfer From the Articular Cartilage Surface to the Chondrocyte Nucleus

2012 ◽  
Author(s):  
Jonathan T. Henderson ◽  
Corey P. Neu
Keyword(s):  
Extracellular Matrix ◽  
Articular Cartilage ◽  
Cartilage Surface ◽  
Strain Transfer ◽  
Nuclear Mechanics ◽  
Articular Cartilage Surface ◽  
Matrix Interactions ◽  
Wear And Tear ◽  
Extracellular Matrix Interactions

Osteoarthritis (OA) is a disabling disease, commonly thought of as the “wear and tear” of articular cartilage, afflicting 27 million Americans [1]. Multiple (e.g. biomechanical and biochemical) factors [2] contribute to maintenance of healthy joints through chondrocyte and extracellular matrix interactions. Interestingly, volumetric contractions of nuclei exhibit a zonal dependence [3], suggesting that nuclear mechanics may play a key role in the maintenance of healthy tissue by mechanically-mediated pathways.

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