Gremlin-1 and BMP-4 Overexpressed in Osteoarthritis Drive an Osteochondral-Remodeling Program in Osteoblasts and Hypertrophic Chondrocytes.

Osteoarthritis (OA) is a whole joint disease characterized by an important remodeling of the osteochondral junction. It includes cartilage mineralization due to chondrocyte hypertrophic differentiation and bone sclerosis. Here, we investigated whether gremlin-1 (Grem-1) and its BMP partners could be involved in the remodeling events of the osteochondral junction in OA.

Neuromedin B promotes chondrocyte differentiation of mesenchymal stromal cells via calcineurin and calcium signaling.

Background: Articular cartilage is a complex tissue with poor healing capacities. Current approaches for cartilage repair based on mesenchymal stromal cells (MSCs) are often disappointing because of the lack of relevant differentiation factors that could drive MSC differentiation towards a stable mature chondrocyte phenotype.

Results: We used a large-scale transcriptomic approach to identify genes that are modulated at early stages of chondrogenic differentiation using the reference cartilage micropellet model.

Pyrroline-5-Carboxylate Reductase 1 Directs the Cartilage Protective and Regenerative Potential of Murphy Roths Large Mouse Mesenchymal Stem Cells.

Murphy Roths Large (MRL) mice possess outstanding capacity to regenerate several tissues. In the present study, we investigated whether this regenerative potential could be associated with the intrinsic particularities possessed by their mesenchymal stem cells (MSCs). We demonstrated that MSCs derived from MRL mice (MRL MSCs) display a superior chondrogenic potential than do C57BL/6 MSC (BL6 MSCs).

Establishment of a collection of human pluripotent stem cell lines (iPSC) from mesenchymal stem cells (MSC) from three healthy elderly donors.

The study of molecular mechanism driving osteoarticular diseases like osteoarthritis or osteoporosis is impaired by the low accessibility to mesenchymal stem cells (MSC) from healthy donors (HD) for differential multi-omics analysis. Advances in cell reprogramming have, however, provided both a new source of human cells for laboratory research and a strategy to erase epigenetic marks involved in cell identity and the development of diseases. To unravel the pathological signatures on the MSC at the origin of cellular drifts during the formation of bone and cartilage, we previously developed iPSC from MSC of osteoarthritis donors.

Adipocyte-induced transdifferentiation of osteoblasts and its potential role in age-related bone loss.

Our preliminary findings have lead us to propose bone marrow adipocyte secretions as new contributors to bone loss. Indeed, using a coculture model based on human bone marrow stromal cells, we previously showed that soluble factors secreted by adipocytes induced the conversion of osteoblasts towards an adipocyte-like phenotype. In this study, microarray gene expression profiling showed profound transcriptomic changes in osteoblasts following coculture and confirmed the enrichment of the adipocyte gene signature.

Generation of human pluripotent stem cell lines (iPSCs) from mesenchymal stem cells (MSCs) from three elderly patients with osteoarthritis.

Mesenchymal stem cells (MSCs) are a unique population of adult stem cells that can differentiate into many cell types. As such, MSCs represent an interesting source of stem cells for use in the clinical treatment of a variety of disorders involving tissue regeneration. It is therefore crucial to investigate further, whether MSCs from patients with bone or cartilage diseases are able to provide iPSCs lines with efficient differentiation ability into MSC derivatives.

Divergent effects of strontium and calcium-sensing receptor positive allosteric modulators (calcimimetics) on human osteoclast activity.

Background And Purpose: Strontium ranelate, a drug approved and until recently used for the treatment of osteoporosis, mediates its effects on bone at least in part via the calcium-sensing (CaS) receptor. However, it is not known whether bone-targeted CaS receptor positive allosteric modulators (PAMs; calcimimetics) represent an alternative (or adjunctive) therapy to strontium (Sr ).

Experimental Approach: We assessed three structurally distinct calcimimetics [cinacalcet, AC-265347 and a benzothiazole tri-substituted urea (BTU-compound 13)], alone and in combination with extracellular calcium (Ca ) or Sr , in G protein-dependent signalling assays and trafficking experiments in HEK293 cells and their effects on cell differentiation, tartrate-resistant acid phosphatase (TRAP) activity and hydroxyapatite resorption assays in human blood-derived osteoclasts.

G protein-coupled receptors as anabolic drug targets in osteoporosis.

Osteoporosis is a progressive bone disorder characterised by imbalance between bone building (anabolism) and resorption (catabolism). Most therapeutics target inhibition of osteoclast-mediated bone resorption, but more recent attention in early drug discovery has focussed on anabolic targets in osteoblasts or their precursors. Two marketed agents that display anabolic properties, strontium ranelate and teriparatide, mediate their actions via the G protein-coupled calcium-sensing and parathyroid hormone-1 receptors, respectively.

High throughput, quantitative analysis of human osteoclast differentiation and activity.

Osteoclasts are multinuclear cells that degrade bone under both physiological and pathophysiological conditions. Osteoclasts are therefore a major target of osteoporosis therapeutics aimed at preserving bone. Consequently, analytical methods for osteoclast activity are useful for the development of novel biomarkers and/or pharmacological agents for the treatment of osteoporosis.

Bearing arms against osteoarthritis and sarcopenia: when cartilage and skeletal muscle find common interest in talking together.

Osteoarthritis, a disease characterized by cartilage degradation, abnormal subchondral bone remodelling and some grade of inflammation, and sarcopenia, a condition of pathological muscle weakness associated with altered muscle mass, strength, and function, are prevalent disorders in elderly people. There is increasing evidence that decline in lower limb muscle strength is associated with knee or hip osteoarthritis in a context of pain, altered joint stability, maladapted postures and defective neuromuscular communication. At the cellular and molecular levels, chondrocytes and myoblasts share common pathological targets and pathways, and the close anatomical location of both cell types suggest a possibility of paracrine communication.

Recent progress toward biomarker identification in osteoarthritis.

Osteoarthritis (OA), the most common and disabling form of arthritic disease, is characterized by a slow and progressive degeneration of articular cartilage. Its etiology is multifactorial and includes genetic predisposition, obesity and aging. In addition to the cartilage itself, OA also involves the surrounding tissues, including the synovium and the subchondral bone.

Which elements are involved in reversible and irreversible cartilage degradation in osteoarthritis?

Osteoarthritis (OA) is a disease of the entire joint. Different treatment strategies for OA have been proposed and tested clinically without the desired efficacy. One reason for the scarcity of current chondroprotective agents may be the insufficient understanding of the patho-physiology of the joint and whether the joint damage is reversible or irreversible.

Longitudinal profiling of articular cartilage degradation in osteoarthritis by high-resolution magic angle spinning 1H NMR spectroscopy: experimental study in the meniscectomized guinea pig model.

This study assessed the 1H HRMAS NMR spectroscopic profile of articular cartilage in both physiological and osteoarthitic situations. One-dimensional and two-dimensional 1H HRMAS NMR spectra were obtained from the tibial plateau cartilage of healthy and operated (unilateral medial meniscectomy and sham surgery) guinea pigs at different stages of disease, over a 6-month period. The major osteoarthritis-induced 1H HRMAS NMR changes were an increase of the N-acetyl peak of proteoglycans (at day 20 after meniscectomy) and a decrease after day 60 as the pathology evolved.

The disease modifying osteoarthritis drug (DMOAD): Is it in the horizon?

Till date, the pharmaceutical industry has failed to bring effective and safe disease modifying osteoarthritic drugs (DMOADs) to the millions of patients suffering from this serious and deliberating disease. We provide a review of recent data reported on the investigation of DMOADs in clinical trials, including compounds inhibiting matrix-metalloproteinases (MMPs), bisphosphonates, cytokine blockers, calcitonin, inhibitors of inducible nitric oxide synthase (iNOS), doxycycline, glucosamine, and diacereine. We discuss the challenges associated with the drug development process in general and with DMOADs in particular, and we advance the need for a new development paradigm for DMOADs.

Early detection and monitoring of cartilage alteration in the experimental meniscectomised guinea pig model of osteoarthritis by 99mTc-NTP 15-5 scintigraphy.

Purpose: This study in the meniscectomised guinea pig aimed to demonstrate that the radiotracer (99m)Tc-NTP 15-5 would have pathophysiological validity for in vivo osteoarthritis imaging.

Methods: The specificity of (99m)Tc-NTP 15-5 for cartilage was determined in healthy animals (n = 13), by tissue radioactivity counting, joint autoradiography and scintigraphy. (99m)Tc-NTP 15-5 scintigraphy was performed at 20, 50, 80, 115, 130, 150 and 180 days after medial meniscectomy (n = 10 MNX) or sham operation (n = 5), and scintigraphic ratios (operated/contralateral) were calculated for femoral (F) and tibial (T) areas.

Effect of inhibition of matrix metalloproteinases on cartilage loss in vitro and in a guinea pig model of osteoarthritis.

Objective: To study the effects of a matrix metalloproteinase (MMP) inhibitor (S-34219) on osteoarthritis (OA) cartilage cultures and in the meniscectomized guinea pig model of OA.

Methods: The inhibitory activity of S-34219 on MMPs and aggrecanase was studied by fluorimetry and immunoassay, respectively. The effects of S-34219 on proteoglycan and collagen degradation were studied in cultures of rabbit and human cartilage.

Methods for cartilage and subchondral bone histomorphometry.

This chapter presents the histological assessment of cartilage and bone of tibial plateaus, by procedures that have been applied and validated in two animal models of osteoarthritis: meniscectomized rats and guinea pigs. It starts from bone sampling, followed by all the steps of sample preparation from embedding to sectioning (without prior decalcification), staining, and mounting. Depending on the cartilage or bone components to be visualized, two dyes are described: safranin O and Goldner's trichrome.

Culture of chondrocytes in alginate beads.

A classic method for the encapsulation and culture of chondrocytes in alginate beads is described. Chondrocytes are released from cartilage matrix by collagenase/dispase digestion and mixed with a solution of 1.25% alginic acid until a homogenous suspension is obtained.

Urinary collagen type II C-telopeptide fragments are sensitive markers of matrix metalloproteinase-dependent cartilage degradation in rat adjuvant-induced arthritis.

Objective: To assess the relevance of collagen type II C-telopeptide fragments (CTX-II) as markers of cartilage degradation during adjuvant-induced arthritis in rats.

Methods: Rats were injected with Freund's adjuvant on day 0 and treated orally for 21 days twice a day with vehicle or 10 or 20 mg/kg of a newly designed matrix metalloproteinase inhibitor (MMP-Inh). Urine samples were collected for 24 h between days 19 and 20 and the concentration of the cartilage-derived CTX-II was measured with a 2-site, sandwich-type ELISA.

Solid-phase synthesis of alpha-substituted 3-bisarylthio N-hydroxy propionamides as specific MMP inhibitors.

A novel series of potent and specific MMP-2,3,9,13 inhibitors has been obtained by modulation on solid phase by alpha and aryl substitutions on 3-arylthio-N-hydroxy-propionamides starting from itaconic acid.