gms | German Medical Science

Objective: Arthrofibrosis is a disabling complication after knee trauma and surgery and is characterized clinically by pain and joint stiffness. A chronic inflammatory process due to an immune response as well as genetic factors may play a crucial role in the mechanism of primary arthrofibrosis. Anti-inflammatory drugs are one of the traditional treatments. However, anti-fibrotic therapy for the effective treatment of arthrofibrosis may be a promising tool in the future. In this study, dexamethasone and decorin of different concentrations were employed to treat the fibroblasts from arthrofibrotic tissue, and then cell proliferation and expression of a fibrotic marker-alpha-SMA (alpha-Smooth Muscle Actin) were investigated.

Method: Ten patients' fibroblasts from the arthrofibrotic tissue (A'Fib) of the infrapattelar fat pad were harvested, grown in vitro and combined. After A'Fib were seeded into the 6-well plates at a density of 3×10^4/well, different concentrations of dexamethasone (DEX, 10^-8 M and 10^-6 M) and decorin (DCN, 500 pg/ml and 0.5 ug/ml) were added to individual well, respectively. A'Fib without stimulation and the fibroblasts from healthy infrapattelar fat pad (Fib) served as controls. On days 3, 5 and 7, MTS was performed to determine the effect of DEX and DCN on cell proliferation, and the expression of alpha-SMA was detected by immunofluorescence on days 1 and 7. Comparison among groups were performed by one-way ANOVA with the Student-Newman-Keuls test (SPSS 15.0), and p<0.05 was considered statistically significant (n=6).

Results and conclusion: Based on the results of MTS, A'Fib exhibited a higher proliferation rate than Fib (p<0.05) at each time point. After 7 days, DEX-treated groups had the highest cell number among all the groups (p<0.05), and the minimum cell number was observed in the 0.5 ug/ml DCN-treated group (p<0.05). There was no significant difference between 500 pg/ml DCN-treated group and A'Fib control. According to the immunofluorescent staining, the percentage of alpha-SMA positive cells was significantly higher in A'Fib control than in Fib control on the first day (p<0.05). After 7 days, the expression of alpha-SMA in 0.5 µg/ml DCN group was decreased slightly, which was not significantly different from that in the A'Fib control. Compared to the data obtained on day 1, the expression of alpha-SMA was declined by 32.28 ± 17.64%, 53.61 ± 13.41%, and 40.20 ± 1.32% in 10^-8 M DEX-treated, 10^-6 M DEX-treated and 500 pg/ml DCN-treated groups, respectively, which were significantly lower than that in the A'Fib control (P<0.05).

In conclusion, decorin of high concentration inhibits the proliferation of A'Fib, and dexamethasone increases their proliferation rate. Both dexamethasone and low concentration decorin down-regulated the expression of fibrotic markers, which indicates that they may be effective drugs for anti-fibrotic therapy.