Hyaluronic acid secretion by synoviocytes alters under cyclic compressive load in contracted collagen gels

Mechanobiology of Hyaluronan: Connecting Biomechanics and Bioactivity in Musculoskeletal Tissues

Hyaluronan (HA) plays well-recognized mechanical and biological roles in articular cartilage and synovial fluid, where it contributes to tissue structure and lubrication. An understanding of how HA contributes to the structure of other musculoskeletal tissues, including muscle, bone, tendon, and intervertebral discs, is growing. In addition, the use of HA-based therapies to restore damaged tissue is becoming more prevalent. Nevertheless, the relationship between biomechanical stimuli and HA synthesis, degradation, and signaling in musculoskeletal tissues remains understudied, limiting the utility of HA in regenerative medicine. In this review, we discuss the various roles and significance of endogenous HA in musculoskeletal tissues. We use what is known and unknown to motivate new lines of inquiry into HA biology within musculoskeletal tissues and in the mechanobiology governing HA metabolism by suggesting questions that remain regarding the relationship and interaction between biological and mechanical roles of HA in musculoskeletal health and disease.

Hyaluronic Acid and Large Extracellular Vesicles (EVs) in Synovial Fluid and Plasma of Patients With End-Stage Arthritis: Positive Association of EVs to Joint Pain

OBJECTIVE

Hyaluronic acid (HA) in synovial fluid (SF) contributes to boundary lubrication with altered levels in osteoarthritis (OA) and rheumatoid arthritis (RA). SF extracellular vesicles (EVs) may participate in arthritis by affecting inflammation and cartilage degradation. It remains unknown whether HA and EVs display joint-specific alterations in arthritic SFs.

DESIGN

We investigated the numbers and characteristics of HA-particles and large EVs in SF from knees and shoulders of 8 OA and 8 RA patients and 8 trauma controls, and in plasma from 10 healthy controls and 11 knee OA patients. The plasma and SF HA concentrations were determined with a sandwich-type enzyme-linked sorbent assay, and EVs and HA-particles were characterized from plasma and unprocessed and centrifuged SFs with confocal microscopy. The data were compared according to diagnosis, location, and preanalytical processing.

RESULTS

The main findings were: (1) OA and RA SFs can be distinguished from trauma joints based on the distinctive profiles of HA-particles and large EVs, (2) there are differences in the SF HA and EV characteristics between shoulder and knee joints that could reflect their dissimilar mobility, weight-bearing, and shock absorption properties, (3) EV counts in SF and plasma can positively associate with pain parameters independent of age and body adiposity, and (4) low-speed centrifugation causes alterations in the features of HA-particles and EVs, complicating their examination in the original state.

CONCLUSIONS

Arthritis and anatomical location can affect the characteristics of HA-particles and large EVs that may have potential as biomarkers and effectors in joint degradation and pain.

Endogenous production of hyaluronan, PRG4, and cytokines is sensitive to cyclic loading in synoviocytes

Synovial fluid is composed of hyaluronan and proteoglycan-4 (PRG4 or lubricin), which work synergistically to maintain joint lubrication. In diseases like osteoarthritis, hyaluronan and PRG4 concentrations can be altered, resulting in lowered synovial fluid viscosity, and pro-inflammatory cytokine concentrations within the synovial fluid increase. Synovial fibroblasts within the synovium are responsible for contributing to synovial fluid and can be targeted to improve endogenous production of hyaluronan and PRG4 and to alter the cytokine profile. We cyclically loaded SW982 synoviocytes to 0%, 5%, 10%, or 20% strain for three hours at 1 Hz. To assess the impact of substrate stiffness, we compared the 0% strain group to cells grown on tissue culture plastic. We measured the expression of hyaluronan turnover genes, hyaluronan localization within the cell layer, hyaluronan concentration, PRG4 concentration, and the cytokine profile within the media. Our results show that the addition of cyclic loading increased HAS3 expression, but not in a magnitude-dependent response. Hyaluronidase expression was impacted by strain magnitude, which is exemplified by the decrease in hyaluronan concentration due to cyclic loading. We also show that PRG4 concentration is increased at 5% strain, while higher strain magnitude decreases overall PRG4 concentration. Finally, 10% and 20% strain show a distinct, more pro-inflammatory cytokine profile when compared to the unloaded group. Multivariate analysis showed distinct separation between certain strain groups in being able to predict strain group, hyaluronan concentration, and PRG4 concentration from gene expression or cytokine concentration data, highlighting the complexity of the system. Overall, this study shows that cyclic loading can be used tool to modulate the endogenous production of hyaluronan, PRG4, and cytokines from synovial fibroblasts.

Effect of functional lateral shift of the mandible on hyaluronic acid metabolism related to lubrication of temporomandibular joint in growing rats

BACKGROUND

Hyaluronic acid (HA) is a major molecular component of the articular cartilage of the temporomandibular joint (TMJ) influencing joint lubrication. Functional lateral shift of the mandible (FLSM) can lead to malocclusion. This study investigated the effects of FLSM on HA metabolism and lubrication of the TMJ in growing rats.

METHODS

Thirty 5-week-old male Wistar rats were divided into shift, recovery, and control groups. Rats in the shift and recovery groups were fitted with guiding plates to produce a 2-mm FLSM which were removed from the rats in the recovery group 14 days later. Animals were sacrificed at 14 and 28 days after the appliances were attached. Immunohistochemistry of HA-binding protein (HABP), hyaluronan synthase (HAS), and hyaluronoglucosaminidases (HYALs) was examined.

RESULTS

The thickness of HABP-positively stained areas in the lateral regions in the bilateral condyle was reduced during the experimental period in the shift group compared with that in the control group. The proportion of HAS2-stained areas was bilaterally decreased in different regions of condylar cartilage during the experimental period in the shift group. The reduction of the HYAL2-stained area proportion in the condylar cartilage was more significant than that of HYAL1 at 14 days after appliance attachment in the shift group. HAS2 staining was not recovered in the recovery group.

LIMITATIONS

This research was based on animal experiments with a limited experimental period.

CONCLUSION

FLSM altered lubrication related HA metabolism in the articular cartilage of the TMJ in growing rats.

Discovery of Selenocysteine as a Potential Nanomedicine Promotes Cartilage Regeneration With Enhanced Immune Response by Text Mining and Biomedical Databases

Background

Unlike bone tissue, little progress has been made regarding cartilage regeneration, and many challenges remain. Furthermore, the key roles of cartilage lesion caused by traumas, focal lesion, or articular overstress remain unclear. Traumatic injuries to the meniscus as well as its degeneration are important risk factors for long-term joint dysfunction, degenerative joint lesions, and knee osteoarthritis (OA) a chronic joint disease characterized by degeneration of articular cartilage and hyperosteogeny. Nearly 50% of the individuals with meniscus injuries develop OA over time. Due to the limited inherent self-repair capacity of cartilage lesion, the Biomaterial drug-nanomedicine is considered to be a promising alternative. Therefore, it is important to elucidate the gene potential regeneration mechanisms and discover novel precise medication, which are identified through this study to investigate their function and role in pathogenesis.

Methods

We downloaded the mRNA microarray statistics GSE117999, involving paired cartilage lesion tissue samples from 12 OA patients and 12 patients from a control group. First, we analyzed these statistics to recognize the differentially expressed genes (DEGs). We then exposed the gene ontology (GO) annotation and the Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment analyses for these DEGs. Protein-protein interaction (PPI) networks were then constructed, from which we attained eight significant genes after a functional interaction analysis. Finally, we identified a potential nanomedicine attained from this assay set, using a wide range of inhibitor information archived in the Search Tool for the Retrieval of Interacting Genes (STRING) database.

Results

Sixty-six DEGs were identified with our standards for meaning (adjusted P-value < 0.01, |log2 - FC| ≥1.2). Furthermore, we identified eight hub genes and one potential nanomedicine - Selenocysteine based on these integrative data.

Conclusion

We identified eight hub genes that could work as prospective biomarkers for the diagnostic and biomaterial drug treatment of cartilage lesion, involving the novel genes CAMP, DEFA3, TOLLIP, HLA-DQA2, SLC38A6, SLC3A1, FAM20A, and ANO8. Meanwhile, these genes were mainly associated with immune response, immune mediator induction, and cell chemotaxis. Significant support is provided for obtaining a series of novel gene targets, and we identify potential mechanisms for cartilage regeneration and final nanomedicine immunotherapy in regenerative medicine.

Innovative Visualization and Quantification of Extracellular Vesicles Interaction with and Incorporation in Target Cells in 3D Microenvironments

Extracellular vesicles (EVs) showed therapeutic properties in several applications, many in regenerative medicine. A clear example is in the treatment of osteoarthritis (OA), where adipose-derived mesenchymal stem cells (ASCs)-EVs were able to promote regeneration and reduce inflammation in both synovia and cartilage. A still obscure issue is the effective ability of EVs to be internalized by target cells, rather than simply bound to the extracellular matrix (ECM) or plasma membrane, since the current detection or imaging technologies cannot fully decipher it due to technical limitations. In the present study, human articular chondrocytes (ACHs) and fibroblast-like synoviocytes (FLSs) isolated from the same OA patients were cocultured in 2D as well as in 3D conditions with fluorescently labeled ASC-EVs, and analyzed by flow cytometry or confocal microscopy, respectively. In contrast with conventional 2D, in 3D cultures, confocal microscopy allowed a clear detection of the tridimensional morphology of the cells and thus an accurate discrimination of EV interaction with the external and/or internal cell environment. In both 2D and 3D conditions, FLSs were more efficient in interacting with ASC-EVs and 3D imaging demonstrated a faster uptake process. The removal of the hyaluronic acid component from the ECM of both cell types reduced their interaction with ASC-EVs only in the 2D system, showing that 2D and 3D conditions can yield different outcomes when investigating events where ECM plays a key role. These results indicate that studying EVs binding and uptake both in 2D and 3D guarantees a more precise and complementary characterization of the molecular mechanisms involved in the process. The implementation of this strategy can become a valuable tool not only for basic research, but also for release assays and potency prediction for clinical EV batches.