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. 2018 Jul 27;8(1):11357.
doi: 10.1038/s41598-018-29655-5.

Composition, Structure and Tensile Biomechanical Properties of Equine Articular Cartilage During Growth and Maturation

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Free PMC article

Composition, Structure and Tensile Biomechanical Properties of Equine Articular Cartilage During Growth and Maturation

J Oinas et al. Sci Rep. .
Free PMC article

Abstract

Articular cartilage undergoes structural and biochemical changes during maturation, but the knowledge on how these changes relate to articular cartilage function at different stages of maturation is lacking. Equine articular cartilage samples of four different maturation levels (newborn, 5-month-old, 11-month-old and adult) were collected (N = 25). Biomechanical tensile testing, Fourier transform infrared microspectroscopy (FTIR-MS) and polarized light microscopy were used to study the tensile, biochemical and structural properties of articular cartilage, respectively. The tensile modulus was highest and the breaking energy lowest in the newborn group. The collagen and the proteoglycan contents increased with age. The collagen orientation developed with age into an arcade-like orientation. The collagen content, proteoglycan content, and collagen orientation were important predictors of the tensile modulus (p < 0.05 in multivariable regression) and correlated significantly also with the breaking energy (p < 0.05 in multivariable regression). Partial least squares regression analysis of FTIR-MS data provided accurate predictions for the tensile modulus (r = 0.79) and the breaking energy (r = 0.65). To conclude, the composition and structure of equine articular cartilage undergoes changes with depth that alter functional properties during maturation, with the typical properties of mature tissue reached at the age of 5-11 months.

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Equine articular cartilage development during growth and maturation. Upper row: The distribution of collagen content (amide I absorption). Middle row: The distribution of PG content (carbohydrate region). Bottom row: The mean orientation angle of collagen fibril network obtained by PLM. The collagen fibrils with an orientation angle of 0° run parallel with the articular surface, whereas angle 90° corresponds to collagen fibrils running perpendicular to the articular surface. The tidemark was not clearly visible in the young groups.
Figure 2
Figure 2
Distribution of collagen content (A) and proteoglycan content (B) according to the depth of articular cartilage in different age groups. Collagen content was estimated by the amide I region and proteoglycan content by the carbohydrate region. (C) Orientation of the collagen fibril network as a function of depth of the articular cartilage. In the plots, black stars indicate the difference between the adult and newborn groups, red stars indicate the difference between the 11-month-old and the newborn groups. *p < 0.05, **p < 0.01. A.U. = Absorption unit.
Figure 3
Figure 3
Profiles of the biomechanical parameters of cartilage sections according to the tissue depth (from 155 µm up to 930 µm) for the (A) tangent modulus and (B) breaking energy. Statistical comparisons between the age groups were not conducted because of the low number of samples at some depths. Colored numbers indicate the number of tested sections in each age group.
Figure 4
Figure 4
Correlation analysis between the collagen content and the tangent modulus (A) and between the collagen content and the breaking energy. (B) Data from samples with collagen orientation angles between 0 and 40 degrees from all age groups was pooled. Corresponding correlation analysis between the proteoglycan content and the tangent modulus (C) or proteoglycan content and the breaking energy. (D) A.U. = Absorption unit.
Figure 5
Figure 5
Correlation analysis between the orientation angle of the collagen fibril network (obtained by PLM) and the tangent modulus (A) and between the orientation of the collagen fibril network and the breaking energy. (B) The correlation analysis was conducted between the average orientation angle value of each depth and the corresponding biomechanical parameters from all age groups.
Figure 6
Figure 6
Measured values plotted against PLSR predictions for the tangent modulus (A) and the breaking energy (D). The values predicted by the PLSR are shown for wavenumbers selected by the CARS. The wavenumbers selected by the CARS are marked with black dots on the average spectra of both models (B and E). The weights of each selected wavenumber are shown for both models (C and F).
Figure 7
Figure 7
(A) Schematic figure of the left equine metacarpophalangeal joint. (B) Joint surface of the proximal phalanx shows the sampling site of the osteochondral plug. An orientation mark was made with a pointed instrument on the osteochondral block. (C) This orientation mark was utilized in plug trimming and in section preparation to ensure that from each block the horizontal frozen sections for tensile testing were always cut according to the line determined by the frontal plane, i.e., along a line running in lateral to medial direction. (D) Positioning of a specimen between the clamps. The expected area of breaking is indicated.

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References

    1. Aigner T, Sachse A, Gebhard PM, Roach HI. Osteoarthritis: Pathobiology-targets and ways for therapeutic intervention. Advanced Drug Delivery Reviews. 2006;58:128–149. doi: 10.1016/j.addr.2006.01.020. - DOI - PubMed
    1. Huber M, Trattnig S, Lintner F. Anatomy, Biochemistry, and Physiology of Articular Cartilage. Investigative Radiology. 2000;35:573–580. doi: 10.1097/00004424-200010000-00003. - DOI - PubMed
    1. Sophia Fox AJ, Bedi A, Rodeo SA. The basic science of articular cartilage: structure, composition, and function. Sports health. 2009;1:461–468. doi: 10.1177/1941738109350438. - DOI - PMC - PubMed
    1. Bi X, Yang X, Bostrom MPG, Camacho NP. Fourier transform infrared imaging spectroscopy investigations in the pathogenesis and repair of cartilage. Biochimica et Biophysica Acta - Biomembranes. 2006;1758:934–941. doi: 10.1016/j.bbamem.2006.05.014. - DOI - PubMed
    1. Bayliss MT, Venn M, Maroudas A, Ali SY. Structure of proteoglycans from different layers of human articular cartilage. The Biochemical journal. 1983;209:387–400. doi: 10.1042/bj2090387. - DOI - PMC - PubMed

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