Mechanical, biochemical, and morphological topography of ovine knee cartilage

Biomechanical properties of articular cartilage in different regions and sites of the knee joint: acquisition of osteochondral allografts

Osteochondral allograft (OCA) transplantation involves grafting of natural hyaline cartilage and supporting subchondral bone into the cartilage defect area to restore its biomechanical and tissue structure. However, differences in biomechanical properties and donor-host matching may impair the integration of articular cartilage (AC). This study analyzed the biomechanical properties of the AC in different regions of different sites of the knee joint and provided a novel approach to OCA transplantation. Intact stifle joints from skeletally mature pigs were collected from a local abattoir less than 8 h after slaughter. OCAs were collected from different regions of the joints. The patella and the tibial plateau were divided into medial and lateral regions, while the trochlea and femoral condyle were divided into six regions. The OCAs were analyzed and compared for Young's modulus, the compressive modulus, and cartilage thickness. Young's modulus, cartilage thickness, and compressive modulus of OCA were significantly different in different regions of the joints. A negative correlation was observed between Young's modulus and the proportion of the subchondral bone (r =  - 0.4241, P < 0.0001). Cartilage thickness was positively correlated with Young's modulus (r = 0.4473, P < 0.0001) and the compressive modulus (r = 0.3678, P < 0.0001). During OCA transplantation, OCAs should be transplanted in the same regions, or at the closest possible regions to maintain consistency of the biomechanical properties and cartilage thickness of the donor and recipient, to ensure smooth integration with the surrounding tissue. A 7 mm depth achieved a higher Young's modulus, and may represent the ideal length.

Preliminary evaluation of fish cartilage as a promising biomaterial in cartilage tissue engineering

Fish cartilage is known as a valuable source of natural biomaterials due to its unique composition and properties. It contains a variety of bioactive components that contribute to its potential applications in different domains such as tissue engineering. The present work aimed to consider the properties of backbone cartilage from fish with a cartilaginous skeleton, including elasmobranch (reticulate whipray: Himantura uarnak and milk shark: Rhizoprionodon acutus) and sturgeon (beluga: Huso huso). The histomorphometric findings showed that the number of chondrocytes was significantly higher in reticulate whipray and milk shark compared to beluga (p < 0.05). The highest GAGs content was recorded in reticulate whipray cartilage compared to the other two species (p < 0.05). The cartilage from reticulate whipray and beluga showed higher collagen content than milk shark cartilage (p < 0.05), and the immunohistochemical assay for type II collagen (Col II) showed higher amounts of this component in reticulate whipray compared to the other two species. Young's modulus of the cartilage from reticulate whipray was significantly higher than that of milk shark and beluga (p < 0.05), while no significant difference was recorded between Young's modulus of the cartilage from milk shark and beluga. The gene expression of ACAN, Col II, and Sox9 showed that the cartilage-ECM from three species was able to induce chondrocyte differentiation from human adipose tissue-derived stem cells (hASCs). From these results, it can be concluded that the cartilage from three species, especially reticulate whipray, enjoys the appropriate biological properties and provides a basis for promoting its applications in the field of cartilage tissue engineering.

High spatial resolution analysis using automated indentation mapping differentiates biomechanical properties of normal vs. degenerated articular cartilage in mice

Characterizing the biomechanical properties of articular cartilage is crucial to understanding processes of tissue homeostasis vs. degeneration. In mouse models, however, limitations are imposed by their small joint size and thin cartilage surfaces. Here we present a three-dimensional (3D) automated surface mapping system and methodology that allows for mechanical characterization of mouse cartilage with high spatial resolution. We performed repeated indentation mappings, followed by cartilage thickness measurement via needle probing, at 31 predefined positions distributed over the medial and lateral femoral condyles of healthy mice. High-resolution 3D x-ray microscopy (XRM) imaging was used to validate tissue thickness measurements. The automated indentation mapping was reproducible, and needle probing yielded cartilage thicknesses comparable to XRM imaging. When comparing healthy vs. degenerated cartilage, topographical variations in biomechanics were identified, with altered thickness and stiffness (instantaneous modulus) across condyles and within anteroposterior sub-regions. This quantitative technique comprehensively characterized cartilage function in mice femoral condyle cartilage. Hence, it has the potential to improve our understanding of tissue structure-function interplay in mouse models of repair and disease.

Raman needle arthroscopy for in vivo molecular assessment of cartilage

The development of treatments for osteoarthritis (OA) is burdened by the lack of standardized biomarkers of cartilage health that can be applied in clinical trials. We present a novel arthroscopic Raman probe that can "optically biopsy" cartilage and quantify key extracellular matrix (ECM) biomarkers for determining cartilage composition, structure, and material properties in health and disease. Technological and analytical innovations to optimize Raman analysis include (1) multivariate decomposition of cartilage Raman spectra into ECM-constituent-specific biomarkers (glycosaminoglycan [GAG], collagen [COL], water [H₂ O] scores), and (2) multiplexed polarized Raman spectroscopy to quantify superficial zone (SZ) COL anisotropy via a partial least squares-discriminant analysis-derived Raman collagen alignment factor (RCAF). Raman measurements were performed on a series of ex vivo cartilage models: (1) chemically GAG-depleted bovine cartilage explants (n = 40), (2) mechanically abraded bovine cartilage explants (n = 30), (3) aging human cartilage explants (n = 14), and (4) anatomical-site-varied ovine osteochondral explants (n = 6). Derived Raman GAG score biomarkers predicted 95%, 66%, and 96% of the variation in GAG content of GAG-depleted bovine explants, human explants, and ovine explants, respectively (p < 0.001). RCAF values were significantly different for explants with abrasion-induced SZ COL loss (p < 0.001). The multivariate linear regression of Raman-derived ECM biomarkers (GAG and H₂ O scores) predicted 94% of the variation in elastic modulus of ovine explants (p < 0.001). Finally, we demonstrated the first in vivo Raman arthroscopy assessment of an ovine femoral condyle through intraarticular entry into the synovial capsule. This study advances Raman arthroscopy toward a transformative low-cost, minimally invasive diagnostic platform for objective monitoring of treatment outcomes from emerging OA therapies.

Ultrasound assessment of sheep stifle joint undergone lipopolysaccharide-induced synovitis

Abstract Synovitis can be induced in animals through the application of bacterial wall lipopolysaccharide and has similar signs to naturally-occurring synovitis. Several studies have been using the sheep species as an experimental model to understand osteoarticular diseases of the femorotibiopatellar (FTP) joint in humans. There are echographic studies on the standardization of normality of the femorotibiopatellar joint in sheep. However, there is a gap in the literature for changes such as acute synovitis. The objective was to serially describe the sonographic aspects of the synovitis process induced by intra-articular infiltration of Escherichia coli (E. coli) lipopolysaccharide in the femorotibiopatellar joint of sheep. Twelve healthy crossbred sheep (Santa Inês x Dorper) were used. Induction of synovitis was performed only in the right FTP joints, which were serially evaluated using ultrasound examination at baseline moment (M0) and 12 (M12), 24 (M24), 48 (M48), 72 (M72), and 120 (M120) hours after lipopolysaccharide infiltration for synovitis induction. Intra-articular application of E. coli lipopolysaccharide resulted in one or more echographic signs of synovitis (increased synovial fluid volume, folding of the synovial membrane, and cellularity in the joint cavity), which were identified early, 12 hours after inoculation, and regressed over the evaluated times (p=0.0001) until disappearing after 120 hours of inoculation.

Biomechanical, Morphological, and Biochemical Characteristics of Articular Cartilage of the Ovine Humeral Head

OBJECTIVE

Shoulder pain is commonly attributed to rotator cuff injury or osteoarthritis. Ovine translational models are used to investigate novel treatments aimed at remedying these conditions to prevent articular cartilage degeneration and subsequent joint degradation. However, topographical properties of articular cartilage in the ovine shoulder are undefined. This study investigates the biomechanical, morphological, and biochemical attributes of healthy ovine humeral head articular cartilage and characterizes topographical variations between surface locations.

DESIGN

Ten humeral heads were collected from healthy skeletally mature sheep and each was segregated into 4 quadrants using 16 regions of interest (ROIs) across the articular surface. Articular cartilage of each ROI was analyzed for creep indentation, thickness, and sulfated glycosaminoglycan (sGAG) and collagen quantity. Comparisons of each variable were made between quadrants and between ROIs within each quadrant.

RESULTS

Percent creep, thickness, and sGAG content, but not collagen content, were significantly different between humeral head quadrants. Subregion analysis of the ROIs within each surface quadrant revealed differences in all measured variables within at least one quadrant. Percent creep was correlated with sGAG (r = -0.32, P = 0.0001). Collagen content was correlated with percent creep (r = 0.32, P = 0.0009), sGAG (r = -0.19, P = 0.049), and thickness (r = -0.19, P = 0.04).

CONCLUSIONS

Topographical variations exist in mechanical, morphologic, and biochemical properties across the articular surface of the ovine humeral head. Recognizing this variability in ovine humeral head cartilage will provide researchers and clinicians with accurate information that could impact study outcomes.

Ultrassonografia da articulação femorotibiopatelar em ovinos submetidos à indução de sinovite por lipopolissacarídeos

Resumo A sinovite pode ser induzida em animais por meio da aplicação de lipopolissacarídeo de parede bacteriana, e apresenta sinais semelhantes à sinovite causada de forma natural. Diversos estudos têm sido realizados utilizando a espécie ovina como modelo experimental na compreensão das enfermidades osteoarticulares da articulação femorotibiopatelar (FTP) em humanos. Existem estudos ecográficos quanto a padronização da normalidade da articulação femorotibiopatelar em ovinos. Porém, para as alterações, como a sinovite aguda há lacuna na literatura. Objetivou-se descrever, de forma seriada, os aspectos ultrassonográficos do processo de sinovite induzida por infiltração intra-articular de lipopolissacarídeo de Escherichia coli (E. coli) na articulação femorotibiopatelar de ovinos. Foram utilizados 12 ovinos mestiços (Santa Inês x Dorper), hígidos. A indução da sinovite foi realizada apenas nas articulações FTP direitas, as quais foram avaliadas, por meio do exame ultrassonográfico de forma seriada, nos momentos basal (M0) e às 12 (M12), 24 (M24), 48 (M48), 72 (M72) e 120 (M120) horas após a infiltração com lipopolissacarídeo para a indução de sinovite. A aplicação intra-articular de lipopolissacarídeo de E. coli resultou em um ou mais sinais ecográficos de sinovite (aumento de volume do fluido sinovial, pregueamento da membrana sinovial e celularidade na cavidade articular), os quais foram identificados precocemente, 12 horas após a inoculação, e regrediram ao longo dos tempos avaliados (p=0,0001), até desaparecerem após 120 horas da inoculação.