Figure 7.

Matn1-4^−/− mice develop age-associated osteoarthritis. (A) Immunohistochemistry of knee joints demonstrates the moderate expression of matrilins in the articular cartilage of wild-type mice at 12 months of age. All matrilins have strong expression in the growth plate cartilage. Original magnifications: × 5 for overview pictures and x 20 for inserts. (B) HE staining of the knee joint at 12 and 18 months old control and Matn1-4^−/− mice. Original magnification × 10. (C) Histological grading for cartilage degradation indicates higher incidence and severity of osteoarthritic-like erosion in Matn1-4^−/− mice compared to age-matched controls (* p < 0.05). (D) Analyzing the expression of matrilins in healthy (control) and osteoarthritic human knee articular cartilage derived from the tibia by immunohistochemistry demonstrates upregulation of all matrilins in the OA tissue. The depicted zones: S-superficial; M-middle and D-deep. Original magnifications: ×5 for overview pictures and ×20 for inserts.