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BackgroundAgeing is one of the leading risk factors predisposing cartilage to musculoskeletal diseases, including osteoarthritis. Cumulative evidence suggests that small non-coding RNAs play a role in cartilage-related pathological changes. However, little research has been conducted on the effect of ageing on the expression of small non-coding RNAs in cartilage. By using small RNA sequencing, we investigated changes in the expression of small non-coding RNAs between young and old equine chondrocytes.MethodsChondrocytes were extracted from five young (4±1 years) and five old (17.4±1.9 years) macroscopically normal equine metacarpophalangeal joints. Following RNA extraction cDNA libraries were prepared and subjected to small RNA sequencing using the Illumina MiSeq platform. Differential expression analysis was performed in R using package DESeq2. For tRNA fragment analysis, tRNA reads were aligned to horse tRNA sequences using Bowtie2 version 2.2.5. Selected microRNA and small nucleolar RNA findings were validated using qRT-PCR in an extended cohort of equine chondrocytes. tRNA fragments were further investigated in low and high grade OA human cartilage tissue.ResultsIn total, 83 sncRNAs were differentially expressed between young and old equine chondrocytes, including microRNAs, snoRNAs, snRNAs and tRNAs. Of these, 34 were expressed higher and 49 were expressed lower in old chondrocytes compared to young. qRT-PCR analysis confirmed findings in an extended cohort of equine chondrocytes. Ingenuity Pathway Analysis of differentially expressed microRNAs and their predicted target genes linked them to cartilage and OA-related pathways and diseases. tRNA fragment analysis revealed that tiRNA-5035-GluCTC and tiRNA-5031-GluCTC-1 were reduced in both high grade OA human cartilage and old equine chondrocytes.ConclusionFor the first time, we have measured the effect of ageing on the expression of small non-coding RNAs in equine chondrocytes. Changes were detected in a number of different sncRNA species, including microRNAs, small nucleolar RNAs and tRNA fragments. This study supports a role for small non-coding RNAs in ageing cartilage and their potential involvement in age-related cartilage diseases.

OBJECTIVE: Aging is accompanied by a series of changes in mature tissues that influence their properties and functions. Collagen, as one of the main extracellular components of cartilage, becomes highly crosslinked during aging. In this study, the aim was to examine whether a correlation exists between collagen crosslinking induced by artificial aging and mechanical properties of the temporomandibular joint (TMJ) condyle. To evaluate this hypothesis, collagen crosslinks were induced using ribose incubation. METHODS: Porcine TMJ condyles were incubated for 7 days with different concentrations of ribose. The compressive modulus and stiffness ratio (incubated versus control) was determined after loading. Glycosaminoglycan and collagen content, and the number of crosslinks were analyzed. Tissue structure was visualized by microscopy using different staining methods. RESULTS: Concomitant with an increasing concentration of ribose, an increase of collagen crosslinks was found. The number of crosslinks increased almost 50 fold after incubation with the highest concentration of ribose. Simultaneously, the stiffness ratio of the samples showed a significant increase after incubation with the ribose. Pearson correlation analyses showed a significant positive correlation between the overall stiffness ratio and the crosslink level; the higher the number of crosslinks the higher the stiffness. CONCLUSION: The present model, in which ribose was used to mimic certain aspects of age-related changes, can be employed as an in vitro model to study age-related mechanical changes in the TMJ condyle. ispartof: Archives of Oral Biology vol:87 pages:102-109 ispartof: location:England status: published

OBJECTIVE: Aging can cause an increase in the stiffness of hyaline cartilage as a consequence of increased protein crosslinks. By induction of crosslinking, a reduction in the diffusion of solutions into the hyaline cartilage has been observed. However, there is a lack of knowledge about the effects of aging on the biophysical and biochemical properties of the temporomandibular joint (TMJ) cartilage. Hence, the aim of this study was to examine the biophysical properties (thickness, stiffness, and diffusion) of the TMJ condylar cartilage of horses of different ages and their correlation with biochemical parameters. MATERIALS AND METHODS: We measured the compressive stiffness of the condyles, after which the diffusion of two contrast agents into cartilage was measured using Contrast Enhanced Computed Tomography technique. Furthermore, the content of water, collagen, GAG, and pentosidine was analyzed. RESULTS: Contrary to our expectations, the stiffness of the cartilage did not change with age (modulus remained around 0.7 MPa). The diffusion of the negatively charged contrast agent (Hexabrix) also did not alter. However, the diffusion of the uncharged contrast agent (Visipaque) decreased with aging. The flux was negatively correlated with the amount of collagen and crosslink level which increased with aging. Pentosidine, collagen, and GAG were positively correlated with age whereas thickness and water content showed negative correlations. CONCLUSION: Our data demonstrated that aging was not necessarily reflected in the biophysical properties of TMJ condylar cartilage. The combination of the changes happening due to aging resulted in different diffusive properties, depending on the nature of the solution. ispartof: OSTEOARTHRITIS AND CARTILAGE vol:26 issue:12 pages:1744-1752 ispartof: location:England status: published

The extracellular matrix can trigger cellular responses through its composition and structure. Major extracellular matrix components are the proteoglycans, which are composed of a core protein associated with glycosaminoglycans, among which the small leucine-rich proteoglycans (SLRPs) are the largest family. This review highlights how the codon usage pattern can be used to modulate cellular response and discusses the biological impact of post-translational events on SLRPs, including the substitution of glycosaminoglycan moieties, glycosylation, and degradation. These modifications are listed, and their impacts on the biological activities and structural properties of SLRPs are described. We narrowed the topic to skeletal tissues undergoing dynamic remodeling. ispartof: BIOMOLECULES vol:10 issue:1 ispartof: location:Switzerland status: published

Articular cartilage lacks the ability to repair itself and consequently defects in this tissue do not heal. Tissue engineering approaches, employing a scaffold material and cartilage producing cells (chondrocytes), hold promise for the treatment of such defects. In these strategies the limitation of nutrients, such as oxygen, during in vitro culture are of major concern and will have implications for proper bioreactor design. We recently demonstrated that oxygen gradients are indeed present within tissue engineered cartilaginous constructs. Interestingly, oxygen, besides being an essential nutrient, is also a controlling agent of developmental processes including cartilage formation. However, the specific role of oxygen in these processes is still obscure despite the recent advances in the field. In particular, the outcome of published investigations is inconsistent regarding the effect of oxygen tension on chondrocytes. Therefore, this article describes the possible roles of oxygen gradients during embryonic cartilage development and reviews the data reported on the effect of oxygen tension on in vitro chondrocyte proliferation and differentiation from a tissue engineering perspective. Furthermore, possible causes for the variance in the data are discussed. Finally, recommendations are included that may reduce the variation, resulting in more reliable and comparable data.

Many animal models are used to study osteoarthritis (OA). In these models the role of joint loading in the development of CA is not fully understood. We studied the effect of loading on the development of CIA in the canine Groove-model. In ten female beagle dogs OA was induced in one knee according to the Groove-model. The animals were divided in groups with and without forced-loading. Forced-loading was achieved by fixing the contra-lateral limb to the trunk 3 times a week for 4 hours. After 20 weeks joint tissues of all dogs were evaluated. Subjective evaluation revealed less movement with more loading in the forced-loading-group compared to the group without forced-loading. In both groups induction of OA resulted in macroscopical and microscopical CA changes as well as alterations in cartilage metabolism characteristics for OA. Although differences were small, for some parameters they were statistically significant for the forced-loading-group. There were no differences between the contra-lateral healthy joints of both groups. The present study demonstrates that in the Groove-model intensified loading is not a prerequisite for the development of OA, although it adds to some extent to the severity of the OA. (C) 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1332-1338, 2009