ObjectiveTo discuss the effect of glucosamine-hydrochloride (Glu/Ch) in protecting and repairing the cartilage in blood-induced joint damage (BJD) in vivo. MethodsThirty-two adult New Zealand rabbits were randomly divided into 4 groups (n=8):high-dose Glu/Ch treated group (group A), low-dose Glu/Ch treated group (group B), positive control group (group C), and negative control group (group D). A joint bleeding model was established by blood injection into articular cavity in groups A, B, and C. Glu/Ch was given by gavage in groups A (250 mg/kg) and B (21.5 mg/kg) once a day for 8 weeks, and the same dosage of saline was given in groups C and D. The serum cartilage oligomeric matrix protein (COMP), serum chondroitin sulfate 846(CS846), and urinary C-terminal telopepide of type II collagen (CTX-II) were measured at 3 days, 7 days, 2 weeks, and 8 weeks after modeling. The expressions of cytokines such as interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) in synovial fluid were analyzed by ELISA at 8 weeks after modeling. The expression of matrix metalloproteinase 13(MMP-13) was detected by immunohistochemistry. Alcian blue staining and Safranin-O staining were performed to calculate the percentage of the positive staining areas. The proteoglycan content was detected by semi-quantitative analysis in the articular cartilage. ResultsThe COMP concentration was significantly higher in groups A, B, and C than group D, and in groups B and C than group A at 3 days after modeling (P<0.05); no significant difference was found among groups A, B, and D at 7 days (P>0.05), and it was significantly lower in groups A, B, and D than group C (P<0.05); there was no significant difference among 4 groups after 2 and 8 weeks (P>0.05). Difference in CS846 concentration had no significance among 4 groups at each time point (P>0.05). The CTX-II concentration of groups A, B, and C was significantly higher than that of group D at each time point (P<0.05); it was significantly lower in group A than groups B and C at 7 days, 2 weeks, and 8 weeks (P<0.05). The TNF-α concentration of groups A and B was significantly higher than group D, and was significantly lower than group C at 8 weeks (P<0.05), but no significant difference was observed between groups A and B (P>0.05). The IL-1β concentration was significantly higher in group C than the other groups (P<0.05), and in group B than groups A and D (P<0.05), but there was no significant difference between groups A and D (P>0.05). The MMP-13 expression was significantly higher in group C than groups A, B, and D (P<0.05), in groups A and B than group D (P<0.05). A significant decrease in the area stained with Alcian blue and Safranin-O was observed in group C. There were significant differences in the percentage of the positive stained areas of Alcian blue and Safranin-O among 4 groups (P<0.05). The relative quantities of proteoglycan from small to large in order was groups C, B, A, and D, respectively, showing significant differences (P<0.05). ConclusionThe metabolism disorder of cartilage matrix and synovium inflammatory reaction can be observed in rat joint bleeding model. Glu/Ch has certain protective effect on the cartilage after BJD by down-regulating IL-1β, TNF-α, and MMP-13, as well as increasing proteoglycan content in the cartilage.