Figure 3-17. Postmortem histological evaluation of the repaired chondral defects weeks after stem cell injection. H&E staining (A), IHC for collagen type I assessment (B), IHC for collagen type II assessment (C), Masson’s trichrome for cartilage detection (D), Toluidine blue staining for collagen type II detection (E), Safranin O staining for cartilage matrix production evaluation (F). Arrowheads indicate the border of repaired cartilage.   Serial sectioning and Prussian blue staining were performed to confirm the presence of the labeled cells in the repaired cartilage. Results as shown in Figure 3.18, 3.19 and 3.20 also confirmed the presence of the labeled MSCs in the biopsies from the surgical scars and para-patellar fat tissues respectively.   Figure 3-18. Prussian blue staining of the repaired cartilage defect. 74   . (D), Toluidine blue staining for collagen type II detection (E), Safranin O staining for cartilage matrix production evaluation (F). Arrowheads indicate the border of repaired cartilage. . cartilage. Serial sectioning and Prussian blue staining were performed to confirm the presence of the labeled cells in the repaired cartilage. Results as shown in Figure 3.18, 3.19 and 3.20. repaired chondral defects 6 weeks after stem cell injection. H&E staining (A), IHC for collagen type I assessment (B), IHC for collagen type II assessment (C), Masson’s trichrome for cartilage