https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(11)60243-2.pdf

Osteoarthritis: an update with relevance for clinical practice

https://www.cell.com/trends/biotechnology/pdf/S0167-7799(12)00115-1.pdf

Recent advances in bone tissue engineering scaffolds.

https://www.oarsijournal.com/article/S1063-4584(10)00238-4/pdf

The OARSI histopathology initiative – recommendations for histological assessments of osteoarthritis in the mouse

https://www.cell.com/trends/biotechnology/pdf/S0167-7799(09)00015-8.pdf

Classification of platelet concentrates: from pure platelet-rich plasma (P-PRP) to leucocyte- and platelet-rich fibrin (L-PRF).

The extracellular matrix (ECM), and especially the connective tissue with its collagen, links tissues of the body together and plays an important role in the force transmission and tissue structure maintenance especially in tendons, ligaments, bone, and muscle. The ECM turnover is influenced by physical activity, and both collagen synthesis and degrading metalloprotease enzymes increase with mechanical loading. Both transcription and posttranslational modifications, as well as local and systemic release of growth factors, are enhanced following exercise. For tendons, metabolic activity, circulatory responses, and collagen turnover are demonstrated to be more pronounced in humans than hitherto thought. Conversely, inactivity markedly decreases collagen turnover in both tendon and muscle. Chronic loading in the form of physical training leads both to increased collagen turnover as well as, dependent on the type of collagen in question, some degree of net collagen synthesis. These changes will modify the mechanical properties and the viscoelastic characteristics of the tissue, decrease its stress, and likely make it more load resistant. Cross-linking in connective tissue involves an intimate, enzymatical interplay between collagen synthesis and ECM proteoglycan components during growth and maturation and influences the collagen-derived functional properties of the tissue. With aging, glycation contributes to additional cross-linking which modifies tissue stiffness. Physiological signaling pathways from mechanical loading to changes in ECM most likely involve feedback signaling that results in rapid alterations in the mechanical properties of the ECM. In developing skeletal muscle, an important interplay between muscle cells and the ECM is present, and some evidence from adult human muscle suggests common signaling pathways to stimulate contractile and ECM components. Unaccostumed overloading responses suggest an important role of ECM in the adaptation of myofibrillar structures in adult muscle. Development of overuse injury in tendons involve morphological and biochemical changes including altered collagen typing and fibril size, hypervascularization zones, accumulation of nociceptive substances, and impaired collagen degradation activity. Counteracting these phenomena requires adjusted loading rather than absence of loading in the form of immobilization. Full understanding of these physiological processes will provide the physiological basis for understanding of tissue overloading and injury seen in both tendons and muscle with repetitive work and leisure time physical activity.

Role of Extracellular Matrix in Adaptation of Tendon and Skeletal Muscle to Mechanical Loading

The function of CD146 in human annulus fibrosus cells and mechanism of the regulation by TGF-β.

Intradiscal Injection of a Slow Release Formulation of Celecoxib for the Treatment of Dogs with Low Back Pain

Quantitative bioimaging of glycosamoglycans in cartilage tissue-engineering using contrast enhanced computed tomography

Background At the moment, osteoarthritis (OA) is seen as a multifactorial disease, caused by a combination of i.a. genetics, overloading, obesity and trauma in the past. Disturbance of joint homeostasis, due to several risk factors, can also cause OA1. In the present study we investigated the role of biomechanical loading and biochemical joint homeostasis in the development of osteoarthritis, in an experimental caprine model of joint damage.

Objectives Is the development of experimentally induced OA more due to changed biomechanics or is it due to a changed joint homeostasis?

Methods In nine skeletally mature female milk goats, cartilage damage was introduced in the right stifle joint according to the Groove model2. Grooves were made with a K-wire with a bend tip, only on the medial femoral condyle and maximally 0.5mm deep; preventing the subchondral plate from damage. The left stifle joint served as a control. After 20 weeks the goats were sacrificed and the cartilage and synovial tissue was analyzed on macroscopical, histological (both OARSI goat score) and biochemical (proteoglycan (PG) turnover) OA characteristics.

Results Macroscopic analysis showed a significant increase in the OARSI goat cartilage score for both the femoral and tibial experimental medial compartment compared to control (femur and tibia; +225% p<0.001 and +42.9% p<0.04 respectively). No effect on the ungrooved lateral compartment was seen. The histological analysis of the cartilage corroborated these results. A significant increase in the OARSI score for the experimental medial compartment (+225% p<0.001 and +81,7% p<0.006, respectively for femur and tibia) was seen. Biochemical analysis showed a decreased PG content in the medial experimental compartment compared to control (femur -12.1% p=0.038 and tibia -7.3% p=0.031). There was a slight increase in synovial inflammation in the experimental joint (p<0.003). For all previous mentioned analyses, no changes in the experimental lateral compartment or the control joint were found.

Conclusions The present study shows clearly that the development of joint damage is much more dependent on the biomechanical component, since all detectable damage is in the medial compartment. Although joint homeostasis is disturbed, indicated by moderate synovial inflammation, this did not lead to generalised OA in this time period.

1. Abramson et al. Arthritis Res Ther. 2009.

2. Mastbergen et al. Osteoarthritis and Cartilage 2006.

Disclosure of Interest None Declared

FRI0314 Aetiology of experimentally induced osteoarthritis of the knee; biomechanical or biochemical factors?

Repopulating the degenerated intervertebral disc (IVD) with tissue‐specific nucleus pulposus cells (NPCs) has already been shown to promote regeneration in various species. Yet the applicability of NPCs as cell‐based therapy has been hampered by the low cell numbers that can be extracted from donor IVDs and their potentially limited regenerative capacity due to their degenerated phenotype. To optimize the expansion conditions, we investigated the effects of increasing culture medium osmolarity during expansion on the phenotype of dog NPCs and their ability to produce a healthy extracellular matrix (ECM) in a 3D culture model.

/pdf/hyperosmolar-expansion-medium-improves-nucleus-pulposus-cell-2l4l0xvi.pdf

Laura B. Creemers

Papers

The function of CD146 in human annulus fibrosus cells and mechanism of the regulation by TGF-β.

Intradiscal Injection of a Slow Release Formulation of Celecoxib for the Treatment of Dogs with Low Back Pain

Quantitative bioimaging of glycosamoglycans in cartilage tissue-engineering using contrast enhanced computed tomography

FRI0314 Aetiology of experimentally induced osteoarthritis of the knee; biomechanical or biochemical factors?

Hyperosmolar expansion medium improves nucleus pulposus cell phenotype