Influence of exogenous hyaluronan on synthesis of hyaluronan and collagenase by equine synoviocytes.

The research study explores the impact of externally administered hyaluronan (HA) on the synthesis of HA and collagenase in horse (equine) synoviocytes, studying both healthy and inflamed joints. It found that the presence of HA did not significantly affect either the speed or size of newly created HA, but exposure to higher concentrations of HA showed increased collagenase activity in abnormal synovium.

Methodology

• The experiment was conducted using synoviocytes (the cells that produce synovial fluid in joints) sourced from the middle carpal joint of three horses with normal joint conditions. These served as control. Cells from six other horses with osteochondral (relating to cartilage and bone) fractures were also used. These represented the affected or principal group.
• The cells were grown in monolayer cultures and were then exposed to three different commercial HA products in varying concentrations: 0, 200, 400, and 1,500 micrograms/ml.
• Newly formed HA was radioactively marked using [3H]glucosamine and quantified using cetylpyridinium chloride precipitation and liquid scintillation counting. This process assisted in tracking and studying the newly synthesized HA.
• The size of the radioactive HA was assessed through high-performance liquid chromatography.
• Collagenase activity, meaning the action of breaking down collagen, was evaluated through a quantitative radioactive collagen-film assay.

Results

• The results revealed that the application of exogenous HA didn’t significantly affect the rate of synthesis or the hydrodynamic (relating to fluid motion) size of the newly produced HA for both normal and affected cell cultures.
• Notably, there was a clear increase in collagenase activity in the supernatants (fluid above solid residue after centrifugation or precipitation) derived from the abnormal synovium when exposed to HA concentrations of 400 and 1,500 micrograms/ml. This activity was significantly more pronounced compared to exposure to lower concentrations.

Conclusion

• The findings suggest that while HA is generally considered beneficial in treating equine joint problems, the primary mechanisms through which HA exerts its effects do not seem to include stimulating the synthesis of greater-molecular-weight HA or significantly inhibiting collagenase synthesis.
• Important consequences of these findings may include adjusting therapeutic applications of HA in veterinary medicine, especially in treatments for equine joint disorders.