destabilization-medial-meniscus-cartilage-scratch-murine-model

Destabilization of the Medial Meniscus and Cartilage Scratch Murine Model of Accelerated Osteoarthritis

Osteoarthritis is the most prevalent musculoskeletal disease in people over 45, leading to an increasing economic and societal cost. Animal models are ...

University of Glasgow

Phosphatases are essential for the mineralization of the extracellular matrix within the skeleton. Their precise identities and functions however remain unclear. PHOSPHO1 is a phosphoethanolamine/phosphocholine phosphatase involved in the generation of inorganic phosphate for bone mineralization. It is highly expressed at sites of mineralization in bone and cartilage. The bones of Phospho1(-/-) mice are hypomineralized, bowed and present with spontaneous greenstick fractures at birth. In this study we show that PHOSPHO1 is essential for mechanically competent mineralization that is able to withstand habitual load. Long bones from Phospho1(-/-) mice did not fracture during 3-point bending but deformed plastically. With dynamic loading nanoindentation the elastic modulus and hardness of Phospho1(-/-) tibiae were significantly lower than wild-type tibia. Raman microscopy revealed significantly lower mineral:matrix ratios and lower carbonate substitutions in Phospho1(-/-) tibia. The altered dihydroxylysinonorleucine/hydroxylysinonorleucine and pyridinoline/deoxypyridinoline collagen crosslink ratios indicated possible changes in lysyl hydroxylase-1 activity and/or bone mineralization status. The bone formation and resorption markers, N-terminal propeptide and C-terminal telopeptide of Type I collagen, were both increased in Phospho1(-/-) mice and this we associated with increased bone remodeling during fracture repair or an attempt to remodel a mechanically competent bone capable of withstanding physiological load. In summary these data indicate that Phospho1(-/-) bones are hypomineralized and, consequently, are softer and more flexible. An inability to withstand physiological loading may explain the deformations noted. We hypothesize that this phenotype is due to the reduced availability of inorganic phosphate to form hydroxyapatite during mineralization, creating an undermineralized yet active bone.

PHOSPHO1 is essential for mechanically competent mineralization and the avoidance of spontaneous fractures.

The emergence of bone as an endocrine regulator has prompted a re-evaluation of the role of bone mineralization factors in the development of metabolic disease. Ectonucleotide pyrophosphatase/phosphodiesterase-1 (NPP1) controls bone mineralization through the generation of pyrophosphate and is elevated in dermal fibroblast cultures and muscle of patients with insulin resistance. We investigated the metabolic phenotype associated with impaired bone metabolism in mice lacking the NPP1 gene (Enpp1(-/-) mice). Enpp1(-/-) mice exhibited mildly improved glucose homeostasis on a normal diet but showed a pronounced resistance to obesity and insulin resistance in response to chronic high fat feeding. Enpp1(-/-) mice had increased levels of the insulin sensitising bone-derived hormone osteocalcin but unchanged insulin signaling within osteoblasts. A fuller understanding of the pathways of NPP1 may inform the development of novel therapeutic strategies for treating insulin resistance.

Deficiency of the bone mineralization inhibitor NPP1 protects against obesity and diabetes.

Proteinase-activated receptor 2 (PAR2) deficiency protects against cartilage degradation in experimental osteoarthritis (OA). The wider impact of this pathway upon OA-associated pathologies such as osteophyte formation and pain is unknown. Herein, we investigated early temporal bone and cartilage changes in experimental OA in order to further elucidate the role of PAR2 in OA pathogenesis.

Proteinase-activated receptor 2 modulates OA-related pain, cartilage and bone pathology.

Protease-activated receptor-2 (PAR2) is one member of a small family of transmembrane, G-protein-coupled receptors. These receptors are activated  cleavage of their N terminus by serine proteases (e.g., tryptase), unveiling an N terminus tethered ligand which binds to the second extracellular loop of the receptor. Increasing evidence has emerged identifying key pathophysiological roles for PAR2 in both rheumatoid arthritis (RA) and osteoarthritis (OA). Importantly, this includes both pro-inflammatory and destructive roles. For example, in murine models of RA, the associated synovitis, cartilage degradation, and subsequent bone erosion are all significantly reduced in the absence of PAR2. Similarly, in experimental models of OA, PAR2 disruption confers protection against cartilage degradation, subchondral bone osteosclerosis, and osteophyte formation. This review focuses on the role of PAR2 in rheumatic disease and its potential as an important therapeutic target for treating pain and joint degradation.

Rheumatic Disease: Protease-Activated Receptor-2 in Synovial Joint Pathobiology.

This chapter describes the surgical procedure for destabilization of medial meniscus in mice. Details on subsequent microCT and histological analysis are also provided, as well as details on osteoarthritis evaluation.

Osteoarthritis Mouse Model of Destabilization of the Medial Meniscus.

Osteoarthritis (OA) is the most prevalent systemic musculoskeletal disorder, characterized by articular cartilage degeneration and subchondral bone (SCB) sclerosis. Here, we sought to examine the contribution of accelerated growth to OA development using a murine model of excessive longitudinal growth. Suppressor of cytokine signalling 2 (SOCS2) is a negative regulator of growth hormone (GH) signalling, thus mice deficient in SOCS2 ( ) display accelerated bone growth.

The role of accelerated growth plate fusion in the absence of SOCS2 on osteoarthritis vulnerability.

Characterise the spatiotemporal responses of trabecular and cortical bone to complete spinal cord injury (SCI) in the skeletally mature rat in the acute (4-week) period following injury.

Spatiotemporal responses of trabecular and cortical bone to complete spinal cord injury in skeletally mature rats.

Characterise the spatiotemporal trabecular and cortical bone responses to complete spinal cord injury (SCI) in young rats.

Article	Year
PHOSPHO1 is essential for mechanically competent mineralization and the avoidance of spontaneous fractures. Bone\| PubMed ID: 21272676	2011
Deficiency of the bone mineralization inhibitor NPP1 protects against obesity and diabetes. Disease models & mechanisms\| PubMed ID: 25368121	2014
Proteinase-activated receptor 2 modulates OA-related pain, cartilage and bone pathology. Annals of the rheumatic diseases\| PubMed ID: 26698846	2016
Rheumatic Disease: Protease-Activated Receptor-2 in Synovial Joint Pathobiology. Frontiers in endocrinology\| PubMed ID: 29875735	2018
Osteoarthritis Mouse Model of Destabilization of the Medial Meniscus. Methods in molecular biology (Clifton, N.J.)\| PubMed ID: 30729471	2019
The role of accelerated growth plate fusion in the absence of SOCS2 on osteoarthritis vulnerability. Bone & joint research\| PubMed ID: 35272487	2022
Spatiotemporal responses of trabecular and cortical bone to complete spinal cord injury in skeletally mature rats. Bone reports\| PubMed ID: 35637974	2022
Time course changes to structural, mechanical and material properties of bone in rats after complete spinal cord injury. Journal of musculoskeletal & neuronal interactions\| PubMed ID: 35642701	2022

Carmen Huesa

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