Nanopolymers Delivery of the Bone Morphogenetic Protein-4 Plasmid to Mesenchymal Stem Cells Promotes Articular Cartilage Repair In Vitro and In Vivo

Figure 4

Macroscopic (a–d) and microscopic (e–p) observations of regenerated cartilage at week 6 and week 12. At week 6, in the experimental group, smooth semitransparent tissue newly tissues filled the defect, but there were still concavity toward the center. The new cartilages were stained positive with toluidine blue and collagen type II (a, e, i, m). In the control group, the thickness of the newly rough cartilage was thinner than normal cartilage. The junctions were obvious. Cells aligned areatus. Toluidine blue and collagen type II staining were positive (b, f, j, n). At week 12, the thickness of the regenerative tissue in the experimental group was similar to the adjacent normal cartilage. The surfaces were regular and mostly integrated with the hosts. Aggrecan and collagen type II deposited (c, g, k, o). In the control group, the thickness of the newly cartilage layer was thinner than that of the host. The surfaces were uneven and the margins could be distinguished easily. Cells aligned irregularly. The excellular matrices were also formed because of the positive staining of toluidine blue and collagen type II (d, h, l, p). The bar was 200 μm. N refers to normal cartilage, R refers to regenerative cartilage.