Fig. 3

Silencing H19 delays endochondral osteogenesis and remodeling during fracture repair. (A) Histological evaluation of fracture repair was performed with alcian blue/hematoxylin/Orange-g (ABH/OG) staining. External calluses in PO-1 W, AdsimH19 and AdGFP groups showed obvious signs of early recruitment of mesenchymal cells and formation of cartilage (blue). Cartilage callus (blue) in the AdsimH19 group was more than that in the AdGFP group at PO-2 W, and the AdGFP group showed a transition from cartilage (blue) to bone (red) callus formation. The fractures in the PO-4 W and AdGFP group showed cortical unity through the bridge callus, accompanied by bone healing and active new bone remodeling. Partial fractures of periosteal and intramedullary region were not uniform in AdsimH19 group. (B) quantitative analysis of the tissue composition of fracture callus. In the process of fracture repair, the ratio of cartilage area to bone area in AdsimH19 group was significantly increased compared with AdGFP group, *p < 0.05, **p < 0.01. (C) Tartrate-tolerant acid phosphatase (TRAP) staining was used to detect osteoclasts. The total number of trap positive cells (purplish red) in AdsimH19 group was less than that in AdGFP control group. (D) TRAP staining was used for quantitative analysis of osteoclasts, *p < 0.05, compared with AdGFP group.