Topic:Articular Cartilage
Articular cartilage in horses is a specialized connective tissue found at the ends of bones within joints. It provides a smooth, lubricated surface for articulation and facilitates the transmission of loads with a low frictional coefficient. Articular cartilage is primarily composed of chondrocytes, collagen fibers, and proteoglycans, and it lacks blood vessels, nerves, and lymphatics. This avascular nature contributes to its limited capacity for self-repair following injury. The health and integrity of articular cartilage are essential for maintaining joint function and mobility in horses. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and pathological changes of articular cartilage in equine species, as well as advancements in diagnostic and therapeutic approaches for cartilage-related disorders.
Comparison of the accuracy of radiography and ultrasonography for detection of articular lesions in horses. To compare the accuracy of ultrasonographic and radiographic examination for evaluation of articular lesions in horses. Methods: Cross-sectional study. Methods: Horses (n = 137) with articular lesions. Methods: Radiographic and ultrasonographic examinations of the affected joint(s) were performed before diagnostic or therapeutic arthroscopic surgery. Findings were recorded and compared to lesions identified during arthroscopy. Results: In 254 joints, 432 lesions were identified by arthroscopy. The overall accuracy was 82.9% for ultrasonography and 62.2% for radiography (P < .0001) with a se...
Cell-based therapies for equine joint disease. Joint disease is a major cause of wastage in performance horses. Arthritis can be challenging to treat because articular cartilage has little or no capacity for repair, therapeutic options are limited and are largely targeted at ameliorating clinical signs of joint disease. Cell-based therapies have potential to overcome the intrinsic constraints to articular cartilage repair. This article focuses on cell-based therapies for treatment of equine joint disease. Results from experimental model and human clinical studies are presented along with available data from equine studies.
Chondrocyte apoptosis determined by caspase-3 expression varies with fibronectin distribution in equine articular cartilage. The purpose of this study was to investigate associations between the extent of chondrocyte apoptosis and expression of the articular cartilage (AC) extracellular matrix (ECM) molecules, cartilage oligomeric matrix protein (COMP) and fibronectin. Methods: Cartilage from four sites (when available) on equine left middle carpal joints (n = 12) were used. Expression of COMP and fibronectin was determined using specific polyclonal antibodies and a biotin-streptavidin/peroxidase method. The intensity of staining for matrix molecules was graded (none, mild, moderate, strong) in each cartilage zone. ...
Chondrogenic effects of exogenous retinoic acid or a retinoic acid receptor antagonist (LE135) on equine chondrocytes and bone marrow-derived mesenchymal stem cells in monolayer culture. To determine effects of various concentrations of retinoic acid (RA) or a synthetic RA receptor antagonist (LE135) on equine chondrocytes or bone marrow-derived equine mesenchymal stem cells (BMDMSCs) in monolayer cultures. Methods: Articular cartilage and BMDMSCs from 5 clinically normal horses. Methods: Monolayers of chondrocytes cultured in standard media and of BMDMSCs cultured in chondrogenic media were treated with RA at concentrations of 0, 0.1, 1, or 10 μM or LE135 at concentrations of 0, 0.1, 1, or 10 μM on day 0. On days 7 and 14, samples were analyzed for DNA concentration, chondr...
Cartilage damage involving extrusion of mineralisable matrix from the articular calcified cartilage and subchondral bone. Arthropathy of the distal articular surfaces of the third metacarpal (Mc3) and metatarsal (Mt3) bones in the Thoroughbred racehorse (Tb) is a natural model of repetitive overload arthrosis. We describe a novel pathology that affects the articular calcified cartilage (ACC) and subchondral bone (SCB) and which is associated with hyaline articular cartilage degeneration. Parasagittal slices cut from the palmar quadrant of the distal condyles of the left Mc3/Mt3 of 39 trained Tbs euthanized for welfare reasons were imaged by point projection microradiography, and backscattered electron (BSE) scann...
Reattachment of the articular cartilage component of type 1 subchondral cystic lesions of the medial femoral condyle with polydioxanone pins in 3 horses. 3 horses were referred for treatment of subchondral cystic lesions of 1 or both medial femoral condyles. Results: All horses had clinically apparent lameness confirmed to be due to a radiographically evident subchondral cystic lesion of the medial femoral condyle with a large articular component (> 15 mm) and shallow subchondral depth (< 10 mm). Arthroscopic assessment of affected cartilage revealed undulating cartilage with a relatively smooth surface and extensive residual perimeter attachment. Results: Resorbable polydioxanone pins were used arthroscopically to reattach the cartilage ...
Osteochondrosis lesions of the lateral trochlear ridge of the distal femur in four ponies. Lesions of the lateral trochlear ridge (LTR) of the distal femur were investigated in four pony or pony cross horses. The animals were all geldings and were six to 15 months of age. Lesions were bilateral in three ponies and unilateral in one. Femoropatellar joint effusion and lameness were present in two ponies; clinical signs were absent in the others. The proximal LTR was affected in all four animals. The radiographic appearance of the lesions was a subchondral defect containing mineralised bodies. Arthroscopic and postmortem examination findings included an osteochondral flap, a fissured o...
High throughput proteomic analysis of the secretome in an explant model of articular cartilage inflammation. This study employed a targeted high-throughput proteomic approach to identify the major proteins present in the secretome of articular cartilage. Explants from equine metacarpophalangeal joints were incubated alone or with interleukin-1beta (IL-1β, 10ng/ml), with or without carprofen, a non-steroidal anti-inflammatory drug, for six days. After tryptic digestion of culture medium supernatants, resulting peptides were separated by HPLC and detected in a Bruker amaZon ion trap instrument. The five most abundant peptides in each MS scan were fragmented and the fragmentation patterns compared to m...
Early lesions of articular osteochondrosis in the distal femur of foals. Failure of the cartilage canal blood supply to epiphyseal growth cartilage has been implicated in the pathogenesis of articular osteochondrosis in horses and other animal species. In a previous study of the developmental pattern of the blood supply in the tarsus of foals, early lesions of osteochondrosis were consistently found in regions where the cartilage canal vessels traversed the chondro-osseous junction. The developmental pattern of blood vessels has also been described in the distal femoral epiphysis; however, the group of foals examined in that study did not have lesions of osteochond...
Comparison of the cytotoxic effects of bupivacaine, lidocaine, and mepivacaine in equine articular chondrocytes. To compare the chondrotoxicity of bupivacaine, lidocaine, and mepivacaine in equine articular chondrocytes in vitro. Methods: Prospective, experimental study. Methods: Equine articular chondrocytes. Methods: Primary cultured equine chondrocytes were exposed to 0.5% bupivacaine, 2% lidocaine, or 2% mepivacaine for 30 or 60 minutes. After treatment, cell viability was evaluated by trypan blue exclusion and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay in a dose dependent manner. Apoptosis and necrosis of chondrocytes were analyzed with the double stain...
Brother of CDO (BOC) expression in equine articular cartilage. Brother of CDO (BOC) is a cell surface receptor that derives its name from the structurally related protein, cell adhesion molecule-related/down-regulated by oncogenes (CDO, sometimes CDON). High levels of BOC mRNA and protein expression have been described in embryonic tissues with active cell proliferation and ongoing cellular differentiation(1,2). A microarray-based screen of RNA isolated from 11 different adult equine tissues unexpectedly identified BOC as having an expression pattern restricted to articular cartilage. The objective of this study was to further investigate BOC expression i...
Histopathologic features of distal tarsal joint cartilage and subchondral bone in ridden and pasture-exercised horses. To determine whether histopathologic characteristics of the osteochondral units of equine distal tarsal joints were associated with exercise history in horses without lameness. Methods: 30 cadaver tarsi from horses without lameness and with known exercise history were separated into 3 groups: nonridden, pasture exercise (group P); low-intensity, ridden exercise (group L); and high-intensity, elite competition exercise (group E). Methods: Standardized sites from the centrodistal and tarsometatarsal joints under went histologic preparation. A grading system was adapted to describe location, dept...
The effect of sequence selection and field strength on detection of osteochondral defects in the metacarpophalangeal joint. Six cadaver forelimbs were imaged in two high-field magnetic resonance (MR) systems and one low-field MR system following the creation of osteochondral defects on the palmar distal aspect of the third metacarpal bone. The following sequences were performed using all three systems: proton density (PD) turbo spin echo, T2* gradient echo (GRE), T2-weighted fast spin echo, and short tau inversion recovery. In addition, 3D T1 GRE sagittal standard and motion insensitive sequences were obtained using the low-field system. PD fat saturated and 3D T1-weighted spoiled GRE images with and without fat su...
Effects of high mobility group box protein-1, interleukin-1β, and interleukin-6 on cartilage matrix metabolism in three-dimensional equine chondrocyte cultures. The effects of high mobility group box protein (HMGB)-1, interleukin (IL)-1β, and IL-6 on equine articular chondrocytes were investigated, with emphasis on detecting differences between anatomical sites exposed to different loading in vivo, using three-dimensional (3D) cell cultures established with chondrocytes from dorsal radial facet (DRF, highly loaded) and palmar condyle (PC, less loaded) of the third carpal bone (C3). Expression of important genes involved in cartilage metabolism, presence of glycosaminoglycans and cartilage oligomeric matrix protein (COMP) in pellets, and concentration...
Effect of a collateral ligament sparing surgical approach on mechanical properties of equine proximal interphalangeal joint arthrodesis constructs. To (1) compare the effect of a collateral ligament sparing surgical approach with an open surgical approach on mechanical properties of proximal interphalangeal joint (PIPJ) arthrodesis, and (2) to determine the percentage of articular cartilage surface removed by transarticular (TA) drilling with different diameter drill bits. Methods: Randomized paired limb design. Methods: Cadaveric equine limbs (n=76). Methods: Cadaveric PIPJ were drilled using a 3.5, 4.5, or 5.5 mm drill bit at 80-84° to the dorsal plane to remove articular cartilage and subchondral bone from the distal articular surface...
Hydrolyzed fish collagen induced chondrogenic differentiation of equine adipose tissue-derived stromal cells. Adipose-derived stromal cells (ADSCs) are multipotent cells which, in the presence of appropriate stimuli, can differentiate into various lineages such as the osteogenic, adipogenic and chondrogenic. In this study, we investigated the effect of transforming growth factor beta 1 (TGF-β1) in comparison to hydrolyzed fish collagen in terms of the chondrogenic differentiation potential of ADSCs. ADSCs were isolated from subcutaneous fat of horses by liposuction. Chondrogenesis was investigated using a pellet culture system. The differentiation medium was either supplemented with TGF-β1 (5 ng/ml)...
Pain in osteoarthritis. This article focuses on pain associated with osteoarthritis (OA). It first describes the basic biology of articular cartilage and other joint structures and the defining features of the osteoarthritic disease process. Subsequently, the possible origins of pain in OA are discussed before embarking on how to manage this clinical entity. The emphasis is on the pharmacologic management of joint pain, and attention is paid to systemic therapeutic strategies as well as to local (intra-articular) treatment modalities. Nonmedical ways of modulating joint pain are briefly mentioned, but not extensively...
A polarized light microscopy method for accurate and reliable grading of collagen organization in cartilage repair. Collagen organization, a feature that is critical for cartilage load bearing and durability, is not adequately assessed in cartilage repair tissue by present histological scoring systems. Our objectives were to develop a new polarized light microscopy (PLM) score for collagen organization and to test its reliability. Methods: This PLM score uses an ordinal scale of 0-5 to rate the extent that collagen network organization resembles that of young adult hyaline articular cartilage (score of 5) vs a totally disorganized tissue (score of 0). Inter-reader reliability was assessed using Intraclass C...
The OARSI histopathology initiative – recommendations for histological assessments of osteoarthritis in the horse. Equine models of osteoarthritis (OA) have been used to investigate pathogenic pathways of OA and evaluate therapeutic candidates for naturally occurring equine OA which is a significant clinical disease in the horse. This review focuses on the macroscopic and microscopic criteria for assessing naturally occurring OA in the equine metacarpophalangeal joint as well as the osteochondral fragment-exercise model of OA in the equine middle carpal joint. Methods: A review was conducted of all published OA studies using horses and the most common macroscopic and microscopic scoring systems were summar...
Cytokine and catabolic enzyme expression in synovium, synovial fluid and articular cartilage of naturally osteoarthritic equine carpi. Understanding the expression of catabolic and anabolic genes during osteoarthritis progression should help to identify the major mediators of the disease. Objective: To compare the cytokine and anabolic marker concentrations in synovium, synovial fluid and cartilage between normal and osteoarthritic joints. Methods: Carpi from horses age 2-11 years were used. Tissues were harvested at the time of surgery or euthanasia, and RNA was isolated for RT-PCR analysis. Tumour necrosis factor alpha (TNFα), interleukin-1beta (IL-1β), aggrecanase 1 (ADAMTS-4), aggrecanase 2 (ADAMTS-5), matrix metallopro...
MRI features of metacarpo(tarso)phalangeal region lameness in 40 horses. Lameness originating from the metacarpo(tarso)phalangeal (MP) joint has a significant effect on the use and athletic competitiveness of a horse. The identification of the cause of lameness originating from the MP joint can be challenging, given the limitations of radiography, ultrasonography, and nuclear scintigraphy. Our purpose was to describe the injury types and incidence in magnetic resonance imaging (MRI) studies from 40 horses with lameness attributable to the MP joint region where it was not possible to reach a clinically plausible diagnosis using other imaging modalities. Horses were ...
Regulation of SOX9 in normal and osteoarthritic equine articular chondrocytes by hyperosmotic loading. SOX9 is a transcription factor that is essential for cartilage extracellular matrix (ECM) formation. Osteoarthritis (OA) is characterised by a loss of cartilage ECM. In chondrocytes SOX9 gene expression is regulated by osmotic loading. Here we characterise SOX9 mRNA regulation through static and cyclical application of hyperosmotic conditions in normal and OA monolayer equine chondrocytes. Furthermore, we investigate whether extracellular signal-regulated protein kinase (ERK)1/2 mitogen-activated protein kinases (MAPK) pathways have a role in this regulation of SOX9. Methods: Equine chondrocyt...
The use of intra-articular corticosteroids in the horse: what is known on a scientific basis? Intra-articular use of corticosteroids has become a recent focus (or re-focus) of attention in the Thoroughbred racing industry. This manuscript reviews the clinical use and scientific basis of intra-articular corticosteroid administration including catastrophic injury, articular cartilage degradation and the development of osteoarthritis (OA), as well as the timing of injection relative to racing.
Adult bone marrow stromal cell-based tissue-engineered aggrecan exhibits ultrastructure and nanomechanical properties superior to native cartilage. To quantify the structural characteristics and nanomechanical properties of aggrecan produced by adult bone marrow stromal cells (BMSCs) in peptide hydrogel scaffolds and compare to aggrecan from adult articular cartilage. Methods: Adult equine BMSCs were encapsulated in 3D-peptide hydrogels and cultured for 21 days with TGF-β1 to induce chondrogenic differentiation. BMSC-aggrecan was extracted and compared with aggrecan from age-matched adult equine articular cartilage. Single molecules of aggrecan were visualized by atomic force microscopy-based imaging and aggrecan nanomechanical stiffness...
Coculture of equine mesenchymal stem cells and mature equine articular chondrocytes results in improved chondrogenic differentiation of the stem cells. Bone marrow derived mesenchymal stem cells (MSCs) can be used to repair articular cartilage defects, these cells should be properly stimulated so that they could differentiate morphologically and hold cellular synthetic features closer to maturely differentiated chondrocytes. It is well known that tissue specific environment plays an important role in cell fate determination. Once improved isolation, proliferation and differentiation protocols have been developed, the likelihood of spontaneous differentiation of MSCs into divergent lineages will be reduced, thus increasing their value for cart...
Combined nanoindentation testing and scanning electron microscopy of bone and articular calcified cartilage in an equine fracture predilection site. Condylar fracture of the third metacarpal bone (Mc3) is the commonest cause of racetrack fatality in Thoroughbred horses. Linear defects involving hyaline articular cartilage, articular calcified cartilage (ACC) and subchondral bone (SCB) have been associated with the fracture initiation site, which lies in the sagittal grooves of the Mc3 condyle. We discovered areas of thickened and abnormally-mineralised ACC in the sagittal grooves of several normal 18-month-old horses, at the same site that linear defects and condylar fracture occur in older Thoroughbreds and questioned whether this tissue ...
In vitro expression of receptor activator of nuclear factor-kappaB ligand and osteoprotegerin in cultured equine articular cells. To determine concentrations of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in equine chondrocytes and synoviocytes and to quantify changes in the OPG:RANKL ratio in response to exogenous factors. Methods: Samples of articular cartilage and synovium with grossly normal appearance obtained from metacarpophalangeal and metatarsophalangeal joints of 5 adult (1- to 8-year-old) horses. Methods: Cell cultures of chondrocytes and synoviocytes were incubated with human recombinant interleukin-1beta (hrIL-1beta; 10 ng/mL), lipopolysaccharide (LPS; 10 microg/mL), ...
Distal interphalangeal articular cartilage assessment using low-field magnetic resonance imaging. The suitability of low-field magnetic resonance (MR) imaging for assessment of articular cartilage has been questioned, based on insufficient image quality. The purposes of this study were to describe the MR anatomy of the normal distal interphalangeal (DIP) cartilage, and to evaluate the sensitivity and accuracy of low-field MR imaging for identification of cartilage erosions that were created ex vivo. Imaging sequences included sagittal and dorsal multiple-oblique T1-weighted gradient-recalled echo (GRE) and sagittal dual echo sequences. In the thickest regions, normal cartilage appeared as ...
Fat-suppressed spoiled gradient-recalled imaging of equine metacarpophalangeal articular cartilage. The purpose was to evaluate the capacity of 1.5 T magnetic resonance (MR) imaging to assess articular cartilage in racehorses with naturally occurring metacarpophalangeal joint osteoarthritis. A sagittal, three-dimensional spoiled gradient-recalled echo (SPGR) with fat saturation (FS) sequence was acquired ex vivo on 20 joints. Following joint dissection, specific areas on the third metacarpal condyle were designated for subsequent sampling for histologic cartilage thickness measurement and modified Mankin scoring. Cartilage thickness was measured and cartilage signal intensity was also graded...
Variations in chondrocyte apoptosis may explain the increased prevalence of osteoarthritis in some joints. To investigate whether there are any variations in chondrocyte susceptibility to an apoptotic stimulus between cells of articular cartilage (AC) from equine joints that differ in prevalence of osteoarthritis (OA). Methods: Cartilage from macroscopically normal equine metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints was used. Prior to culture, chondrocyte viability was assessed using the fluorescein diacetate (FDA) and propidium iodide paravital staining method. AC explants were subsequently treated with tumour necrosis factor-α (TNF-α) in comb...