Maturation of collagen fibril network structure in tibial and femoral cartilage of rabbits.
ABSTRACT The structure and composition of articular cartilage change during development and growth, as well as in response to varying loading conditions. These changes modulate the functional properties of cartilage. We studied maturation-related changes in the collagen network organization of cartilage as a function of tissue depth.
Articular cartilage from the tibial medial plateaus and femoral medial condyles of female New Zealand white rabbits was collected from six age-groups: 4 weeks (n=30), 6 weeks (n=30), 3 months (n=24), 6 months (n=24), 9 months (n=27) and 18 months (n=19). Collagen fibril orientation, parallelism (anisotropy) and optical retardation were analyzed with polarized light microscopy. Differences in the development of depth-wise collagen organization in consecutive age-groups and the two joint locations were compared statistically.
The collagen fibril network of articular cartilage undergoes significant changes during maturation. The most prominent changes in collagen architecture, as assessed by orientation, parallelism and retardation were noticed between the ages of 4 and 6 weeks in tibial cartilage and between 6 weeks and 3 months in femoral cartilage, i.e., orientation became more perpendicular-to-surface, and parallelism and retardation increased with changes being most prominent in the deep zone. At the age of 6 weeks, tibial cartilage had a more perpendicular-to-surface orientation in the middle and deep zones than femoral cartilage (P<0.001) and higher parallelism throughout the tissue depth (P<0.001), while femoral cartilage exhibited more parallel-to-surface orientation (P<0.01) above the deep zone after maturation. Optical retardation of collagen was higher in tibial than in femoral cartilage at the ages of 4 and 6 weeks (P<0.001), while at older ages, retardation below the superficial zone in the femoral cartilage became higher than in the tibial cartilage.
During maturation, there is a significant modulation of collagen organization in articular cartilage which occurs earlier in tibial than in femoral cartilage, and is most pronounced in the deep zone.
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ABSTRACT: Critical-sized osteochondral defects are clinically challenging, with limited treatment options available. By engineering osteochondral grafts using a patient's own cells and osteochondral scaffolds designed to facilitate cartilage and bone regeneration, osteochondral defects may be treated with less complications and better long-term clinical outcomes. Scaffolds can influence the development and structure of the engineered tissue, and there is an increased awareness that osteochondral tissue engineering concepts need to take the in vivo complexities into account in order to increase the likelihood of successful osteochondral tissue repair. The developing trend in osteochondral tissue engineering is the utilization of multiphasic scaffolds to recapitulate the multiphasic nature of the native tissue. Cartilage and bone have different structural, mechanical, and biochemical microenvironments. By designing osteochondral scaffolds with tissue-specific architecture, it may be possible to enhance osteochondral repair within shorter timeframe. While there are promising in vivo outcomes using multiphasic approaches, functional regeneration of osteochondral constructs still remains a challenge. In this review, we provide an overview of in vivo osteochondral repair studies that have taken place in the past three years, and define areas which needs improvement in future studies. Anat Rec, 2013. © 2013 Wiley Periodicals, Inc.The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology 12/2013; · 1.34 Impact Factor
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ABSTRACT: Introduction: The anterior cruciate ligament (ACL) is one of the most important factors in knee stability and motion control so that its injuries result in serious movement problems for patients. The present study clarifies the effect of unilateral ACLT on histological and biomechanical properties of articular cartilage of rabbit knee. Materials and Methods: Ten skeletally mature Dutch white male rabbits were divided into 2 groups. In the surgery group, left anterior cruciate ligament was completely transected through midshaft. Histopathological properties, biomechanical charachteristics and thickness of femoral and tibial articular cartilage in left knee measured at 62nd day post surgery. Normal group underwent no intervention in the same period. Biomechanical characteristics of tibial medial plateau and femoral medial condyle studied by means of the ex vivo biphasic stress–relaxation test. Maximal force, elastic modulus, equilibrium force and aggregate modulus were extracted from these data. Data were statistically analyzed via Mann-Whitney U test. To avoid error in histological sample reading, histological study performed on tibial lateral plateau and femoral lateral condyle. Results: In ACLT group, both femoral and tibial cartilages deteriorated. In comparison to normal group, cartilage thickness in ACLT group decreased significantly only in femoral medial condyle (P = 0.009). All biomechanical parameters of femoral condyle were significantly less than normal group (P < 0.05). The only exception was aggregate modulus that was almost the same in both groups. Biomechanical properties of tibial plateau were not statistically different between the two groups. Conclusion: Although the structural deterioration of articular cartilage in femoral condyle was less severe than tibial plateau within the first 9 weeks following complete ACLT, functional deterioration was significant only in femoral condyle. However, tibial plateau saved its biomechanical charachtristics despite significant degeneration. The biomechanical and histological alteration of the rabbit articular cartilage described in present study provides further evidence that this small animal model exhibits changes identical to secondary osteoarthritis. Keywords: Anterior cruciate ligamnet transaction, Articular cartilage, Biomechanics, Secondary osteoarthritis, RabbitJournal of Research in Rehabilitation Sciences. 06/2012; 8(2):17-26.
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ABSTRACT: Bovine pericardium is used for heart valve leaflet replacement where the strength and thinness are critical properties. Pericardium from neonatal animals (4-7 days old) is advantageously thinner and is considered as an alternative to that from adult animals. Here, the structures of adult and neonatal bovine pericardium tissues fixed with glutaraldehyde are characterized by synchrotron-based small angle X-ray scattering (SAXS) and compared with the mechanical properties of these materials. Significant differences are observed between adult and neonatal tissue. The glutaraldehyde fixed neonatal tissue has a higher modulus of elasticity (83.7 MPa) than adult pericardium (33.5 MPa) and a higher normalised ultimate tensile strength (32.9 MPa) than adult pericardium (19.1 MPa). Measured edge on to the tissue, the collagen in neonatal pericardium is significantly more aligned (orientation index (OI) 0.78) than that in adult pericardium (OI 0.62). There is no difference in the fibril diameter between neonatal and adult pericardium. It is shown that high alignment in the plane of the tissue provides the mechanism for the increased strength of the neonatal material. The superior strength of neonatal compared with adult tissue supports the use of neonatal bovine pericardium in heterografts.BioMed Research International 01/2014; 2014:189197. · 2.71 Impact Factor