Fig. 3
Immunohistochemical analyses for cartilage matrix proteins in MSC pellets after chondrogenic induction with adenoviral gene transfer of SOX9 compared to TGFB1 or IGF1 alone, or in combination. Monolayer cultures of MSCs were infected with Ad.GFP (Control; a), Ad.SOX9 (b), Ad.TGFB1 + Ad.SOX9 (c), Ad.TGFB1 alone (d), Ad.IGF1 + Ad.SOX9 (e), or Ad.IGF1 alone (f) at 5 × 102 vp/cell, seeded into aggregates 24 h after infection and cultured in serum-free medium for 21 days. Immunohistochemical staining was performed on representative sections after 10 and 21 for collagen type II (COL II; left panels), the predominant collagen hyaline cartilage, and chondroitin-4-sulphate (CS4; right panels) one of the proteoglycan matrix components (a-f). Uninfected, with recombinant TGF-β1 treated pellets after 21 days of culture are shown for comparison (g). Panels (a-g) are reproduced at low (50x; bar = 200 μm) or high (200x; bar = 50 or 100 μm) magnification as indicated, and regions of positive immunostaining appear red