Cartilage matrix glycoprotein is present in serum in experimental canine osteoarthritis

Comprehensive Study on Scoring and Grading Systems for Predicting the Severity of Knee Osteoarthritis

Knee Osteoarthritis (KOA) is a degenerative joint ailment characterized by cartilage loss, which can be seen using imaging modalities and converted into imaging features. The older population is the most affected by knee OA, which affects 16% of people worldwide who are 15 years of age and older. Due to cartilage tissue degradation, primary knee OA develops in older people. In contrast, joint overuse or trauma in younger people can cause secondary knee OA. Early identification of knee OA, according to research, may be a successful management tactic for the condition. Scoring scales and grading systems are important tools for the management of knee osteoarthritis as they allow clinicians to measure the progression of the disease's severity and provide suggestions on suitable treatment at identified stages. The comprehensive study reviews various subjective and objective knee evaluation scoring systems that effectively score and grade the KOA based on where defects or changes in articular cartilage occur. Recent studies reveal that AI-based approaches, such as that of DenseNet, integrating the concept of deep learning for scoring and grading the KOA, outperform various state-of-the-art methods in order to predict the KOA at an early stage.

W, Chen H, Yu C, Yang L, Fu Y, Li J, Fu S, Sun Z, Fei L, Guo Q, Wang J, Xiao Y, Wang X, Zhang P, Ma L, Ge D, Xu S, Caballero-Pérez J, Cruz-Ramírez A, Zhou Y, Chen M, Fei JF, Han X, Guo G. Construction of the axolotl cell landscape using combinatorial hybridization sequencing at single-cell resolution

The Mexican axolotl (Ambystoma mexicanum) is a well-established tetrapod model for regeneration and developmental studies. Remarkably, neotenic axolotls may undergo metamorphosis, a process that triggers many dramatic changes in diverse organs, accompanied by gradually decline of their regeneration capacity and lifespan. However, the molecular regulation and cellular changes in neotenic and metamorphosed axolotls are still poorly investigated. Here, we develop a single-cell sequencing method based on combinatorial hybridization to generate a tissue-based transcriptomic landscape of the neotenic and metamorphosed axolotls. We perform gene expression profiling of over 1 million single cells across 19 tissues to construct the first adult axolotl cell landscape. Comparison of single-cell transcriptomes between the tissues of neotenic and metamorphosed axolotls reveal the heterogeneity of non-immune parenchymal cells in different tissues and established their regulatory network. Furthermore, we describe dynamic gene expression patterns during limb development in neotenic axolotls. This system-level single-cell analysis of molecular characteristics in neotenic and metamorphosed axolotls, serves as a resource to explore the molecular identity of the axolotl and facilitates better understanding of metamorphosis.

The Mexican axolotl is a well-established tetrapod model for regeneration and development. Here the authors report a scRNA-seq method to profile neotenic, metamorphic and limb development stages, highlighting unique perturbation patterns of cell type-related gene expression throughout metamorphosis.

COMP (cartilage oligomeric matrix protein) is synthesized in ligament, tendon, meniscus, and articular cartilage

The presence of cartilage oligomeric matrix protein (COMP) in extracts of ligament, tendon, meniscus, and canine articular cartilage was demonstrated by Western blot analysis using anti-dog COMP antibody. When the tissues were cultured in the presence of [35-S]methionine/cysteine, metabolically labeled COMP was purified from the culture media and from tissue extracts by DEAE-cellulose gel chromatography. SDS-Polyacrylamide gel electrophoresis (SDS-PAGE) followed by autoradiography and immunoblotting under reducing and non-reducing conditions revealed that COMP is synthesized by the cells of these connective tissues. Increased levels of COMP in samples of both synovial fluid and serum of patients with various joint diseases may not only be derived from cartilage but also from ligaments and tendons. COMP is not a highly tissue-specific cartilage molecule.

Effects of functional electrical stimulation on the joints of adolescents with spinal cord injury

Nineteen adolescent subjects with complete spinal cord injuries resulting in paraplegia or tetraplegia participated in a functional electrical stimulation (FES) program consisting of computerized, controlled exercise and/or weight bearing. The effects of stimulated exercise and standing/walking on the lower extremity joints were prospectively studied. Plain radiographs and MRIs were obtained prior to and following completion of the exercise and standing and walking stages. In addition, the joints of five subjects were studied with synovial biopsies, arthroscopy, and the analysis of serum and synovial fluid for a 550 000 dalton cartilage matrix glycoprotein (CMGP). Pre-exercise joint abnormalities secondary to the spinal cord injury improved following the stimulation program. None of the subjects developed Charcot joint changes. Upon standing with FES, one subject with poor hip coverage prior to participation developed hip subluxation which required surgical repair. No other detrimental clinical effects occurred in the lower extremity joints of subjects participating in an FES program over a 1-year period.

Isolation and partial characterization of a high molecular weight anionic glycoconjugate from transforming growth factor-beta treated bovine articular chondrocyte cultures

A high molecular weight anionic glycoconjugate was isolated from the media of the transforming growth factor-beta treated chondrocyte cultures by anion-exchange chromatography on DEAE-Sephacel and Mono Q columns and was partially characterized. This high molecular weight anionic glycoconjugate was not detected in the non-treated (control) cultures. Characterization studies showed that the glycoconjugate is a non-reducible, non-collagenous glycoprotein containing O-linked, N-linked, and sialic acid substituted carbohydrate units. The isolated glycoconjugate stained "blue" with Stains All and migrated as a single band on sodium dodecyl sulfate gradient gels (2.5-10% acrylamide - diallyl tartardiamide) at an estimated molecular weight of 540 000. Amino acid and amino sugar analyses showed that it is rich in aspartic acid--asparagine, glutamic acid--glutamine, alanine, proline, and glycine, and contains galactosamine and glucoasmine. This transforming growth factor-beta inducible glycoprotein may be involved in cell differentiation and in the cartilage repair process. It may also be used as a marker to localize the biological activity of transforming growth factor-beta in articular cartilage.

Markers of osteoarthritis: a review of the literature

There may be a great potential in the use of diagnostic "markers" of osteoarthritis in synovial fluid to diagnose the disease in an earlier stage and perhaps assess the severity of the disease and monitor the effect of a treatment. In the present study, potential markers are characterized, discussed, and grouped according to the latest knowledge on the etiology, pathogenesis, and pathology of osteoarthritis. They are grouped according to their origin as either cartilage degradation products, or related to the mechanisms of cartilage degradation, or related to chrondrocytic anabolic activity during disease, or related to genetic disorders. Also potential markers that have not yet been studied clinically or experimentally are discussed. Examples of the progress that has been made in human medicine approaching reliable diagnostic markers that should also be tried in veterinary medicine are described.

Synovial fluid and plasma levels of cartilage matrix glycoprotein in arthritis

As cartilage matrix glycoprotein (CMGP) is a prominent matrix constituent, we analyzed the relationship of levels in plasma (CMGPP) and synovial fluid (CMGPS) to each other, to clinical diagnosis, and to degree of radiographic cartilage degeneration. CMGP was measured in matched synovial fluid and plasma specimens from 67 patients with various forms of arthritis using an ELISA technique. CMGPS consistently exceeded CMGPP, CMGPP levels correlated significantly with CMGPS levels, and CMGP retention in joint fluid, as calculated by the ratio CMGPS: CMGPP, was significantly higher in patients whose synovial fluids contain basic calcium phosphate crystals. No correlation of CMGPP or CMGPS with diagnosis or degree of cartilage degeneration was observed. CMGP measurements are not useful diagnostically in patients with chronic arthritis and do not predict degree of radiographic degeneration. The association of basic calcium phosphate crystals with intraarticular retention of CMGP warrants further study.

Cartilage oligomeric matrix protein and thrombospondin 1. Purification from articular cartilage, electron microscopic structure, and chondrocyte binding

Cartilage oligomeric matrix protein (COMP) and thrombospondin 1 (TSP1) were purified in a native form from normal bovine articular cartilage. The key step in the purification scheme was selective extraction with EDTA-containing buffer. Final separation of these two molecules was achieved by heparin affinity chromatography. Particles viewed by electron microscopy after rotary shadowing and negative staining revealed structures similar to their prototype molecules; from the Swarm rat chondrosarcoma for COMP, or from platelets for TSP1. Attachment of primary bovine chondrocytes to purified matrix proteins was investigated. Cells attached to COMP but not to the structurally related TSP1 indicating separate functions for these proteins in cartilage.

Morphologic and molecular changes during the post-natal development of the rabbit vitreous

Rabbits aged 1, 4, 10, 15, and 20 days, and 4 months were anesthetized and perfused with 4% formaldehyde. One eye of each rabbit was processed for paraffin embedding, while the other eye was embedded intact in methacrylate. Rabbits aged 1 and 15 days and 4 months were perfused with 2.5% glutaraldehyde, and the eyes were processed for Epon embedding. The paraffin sections were immunostained to allow detection of a high molecular weight cartilage matrix glycoprotein (CMGP), which is synthesized by the ciliary body and found in the vitreous in adult animals, using a specific mouse monoclonal antibody. CMGP was identified in the vitreous and in the inner layer of the ciliary epithelium only after the fifteenth day of life in amounts comparable to those detected in adult rabbits. Before this time immunostaining with the monoclonal antibody was seen only in the apical region of the inner ciliary epithelial cells. However, electron microscopic observations revealed that the cytoplasmic organelles responsible for the secretion of glycoproteins, i.e. the rough endoplasmic reticulum, Golgi apparatus, and vesicles, were present in the inner layer of ciliary epithelial cells as early as the first day of life. Anteroposterior sections of whole eyes embedded in methacrylate revealed a relatively dense meshwork of vitreous fibrils on the first day of life. The blood vessels were concentrated at the posterior region of the lens, and isolated cells were visible. The blood vessels were not seen after the age of 15 days, and the fiber meshwork and cells were inconspicuous by then.(ABSTRACT TRUNCATED AT 250 WORDS)

A high-molecular-weight (greater than 8.10(5)) non-collagenous glycoprotein is synthesized by bovine cartilage in vitro

A high-molecular-weight (greater than 8.10(5)) glycoprotein was detected in [3H]glucosamine-labeled bovine cartilage. Extraction with varying amounts of guanidinium chloride showed that the molecule was not tightly bound to other matrix substances. Enzyme digestions identified the molecule as a non-collagenous glycoprotein. This glycoprotein constituted 10-20% of the [3H]glucosamine-labeled macromolecular material that was released into culture medium on the first day after labeling. The 3H-labeled glycoprotein was purified by anion-exchange chromatography, CsCl gradient centrifugation and gel filtration. The purified glycoprotein appeared on an SDS-polyacrylamide gel as one slightly polydisperse band, which could not be reduced by beta-mercaptoethanol.

Autoradiographic, electrophoretic, and immunocytochemical studies of glycoproteins of the rabbit iris

L-[3H]fucose was injected either intravitreally or intra-aqueously into adult rabbits which were killed at several time points after injection. SDS-polyacrylamide gel electrophoresis and fluorography of iris extracts revealed that most of the proteins are glycoproteins containing fucose residues. Autoradiography of semi-thin histologic sections demonstrated that glycoprotein synthesis was most prominent in the epithelium of the iris, while little protein synthesis was evident in the stroma of the iris. The results of these experiments indicated that the glycoproteins of the iris undergo renewal. The protein band pattern of the iris extracts was very similar to that of extracts of the ciliary body. The high-molecular-weight cartilage matrix glycoprotein (CMGP), an intrinsic component of the ciliary body, vitreous, and aqueous humor, was detected by immunohistologic studies only in the stroma of the iris. The results of immunohistochemical analyses of the eyes of young rabbits (1-21 days old), in addition to the autoradiographic findings, strongly suggest that CMGP is not an intrinsic glycoprotein of the iris stroma, at least in this species.

The origin of the intrinsic glycoproteins of the rabbit vitreous body: an immunohistochemical and autoradiographic study

A cartilage matrix glycoprotein (CMGP), previously identified in human and bovine vitreous, now has been found in the vitreous body of rabbits aged 1-22 months by immunohistochemical techniques. Epithelial cells of the inner layer of the ciliary epithelium contain material that has immunologic cross-reactivity with a specific antibody to CMGP. These cells also secrete glycoproteins, as determined by autoradiography after intravitreal injection of [3H]fucose. Approximately 14 bands, representing intrinsic glycoproteins containing fucose residues, can be identified in fluorograms of SDS-polyacrylamide gels of vitreous bodies from 6- and 22-month-old rabbits. Fluorograms of gels of samples of vitreous and ciliary bodies from several time points after intravitreal injection of [3H]fucose reveal at least seven comigrating protein bands and also demonstrate turnover of the labeled ciliary body glycoproteins. These results suggest that the inner layer of the ciliary epithelium is the source of the glycoproteins of the vitreous body and that these glycoproteins undergo turnover, probably throughout the entire life of the animals.