Increase in molar mass distinguishes chondroitin sulfate from osteoarthritis and normal extracellular cartilage matrix.

PURPOSE: To determine alterations of chondroitin sulfate (CS) that reflect cartilage damage in an experimental osteoarthritis (OA) model as well as in human OA samples.

MATERIALS AND

METHODS

Rats were subjected to anterior cruciate ligament transection (ACLT; OA) or a sham procedure and sacrificed 14, 28, or 70 days after ACLT for histopathology and analysis of extracted CS. Cartilage samples from 14 patients undergoing hip or shoulder arthroplasty secondary to OA or fracture (control) were subjected to the same protocol. The CS content (µg/mg dry cartilage) after proteolysis was determined by densitometry, using agarose-gel electrophoresis. Molar mass (MM) and peak MM of CS were determined using high-performance size-exclusion chromatography (HPSEC).

RESULTS

OA and sham joints at 70 d had 24 [22-24] and 3 [1-6] median histopathology scores, respectively (p < 0.001). Relative CS content (77.7 ± 8.3 µg/mg) was significantly increased in OA samples 70 d after ACLT, as compared to sham (53.5 ± 10.0 µg/mg). Peak MM of CS was higher in OA than in sham samples (P < 0.05). Similarly, CS content and peak MM were higher in cartilage from human OA patients, as compared to fracture samples, reproducing experimental data.

CONCLUSION

Cartilage matrix from experimental and human OA samples has increased in the relative CS content. Increase in the peak MM distinguishes CS of the extracellular matrix of OA from normal cartilage.