Biochemical, histochemical, and immunohistochemical characterization of distal tibial osteochondrosis in horses.

This research explores the difference in biochemical, histochemical, and immunohistochemical characteristics between healthy and osteochondrotic cartilage from the distal section of horse tibias, suggesting an inability for these areas to properly mature and differentiate into bone.

Research Objective

• This research was designed to contrast the various biochemical, histochemical, and immunohistochemical attributes of regular and osteochondrotic (OC) horse cartilage located in the distal section of the tibias. The study involved nine horses suffering from OC and four healthy horses taken as control.

Methods

• OC specimens were collected during arthroscopic removal procedures, while normal control specimens extracted via an aseptic osteotomy. The researchers analysed various contents, including uronic acid, total protein, total glycosaminoglycan (GAG), chondroitin sulfate (CS), and keratan sulfate (KS).
• Following the preservation of collected tissues in a -80 C environment and cryosectioning, histomorphologic, histochemical, and immunohistochemical tests were executed. Two types of monoclonal antibodies (MAB), 3B3, and 5D4, were used for identifying the locations of CS and KS epitopes correspondingly.

Results

• The study found that osteochondrotic lesions had considerably lower quantities of uronic acid, total GAG, and CS, in comparison with normal cartilage.
• OC cartilage displayed less intense staining with toluidine blue, along with irregular cellularity and tidemark characteristics, compared to healthy cartilage.
• While the OC cartilage stained with MAB 3B3 and 5D4 antibodies, the MAB 5D4 did not stain the control cartilage. Additionally, both MAB 3B3 and 5D4 stained the fibrous tissue discovered firmly attached to the OC lesion situated between the parent distal part of the tibia and the OC fragment.

Conclusions

• The OC cartilage lesions of the distal intermediate tibial ridge in horses have distinct biochemical, histochemical, and immunohistochemical properties from normal cartilage from the same location. The findings could be depicting the inability of the chondrocyte (a cell that produces cartilage) of the developing joint to alter matrix components, preventing proper maturation and differentiation into bone.