Figure 2

After the addition of an intra-articular injection, u-PA^-/- mice with K/BxN serum transfer arthritis show proteoglycan loss and fibrin(ogen) staining in the injected knee joints only. C57BL/6 and u-PA^-/- mice with K/BxN serum transfer arthritis were either left untreated or given an intra-articular injection of saline. Mice were sacrificed 10 days later. (a) Representative histological staining of knee joints for proteoglycan (safranin O) and (b) quantification of proteoglycan loss. (c) Representative histological staining of knee joints for fibrin(ogen) staining and (d) quantification of fibrin(ogen) staining. Results are expressed as the mean ± standard error of the mean (five mice per group). *P = 0.002, untreated u-PA^-/- versus C57BL/6 mice; **P < 0.01, ***P < 0.05, saline-treated versus untreated mice. u-PA^-/-, urokinase-type plasminogen activator gene-deficient.