Fig. 2

Effect of H19 loss on the process of fracture repair. (A) Expression of red fluorescent protein (RFP) derived from adenovirus simH19 in tibial fracture of AdsimH19 mice. Immunohistochemical staining of fracture callus revealed RFP-positive cells (brown) in periosteum, external cartilage callus and internal cartilage callus. (B) Quantitative analysis of H19 in the tissues around the fracture site. Quantitative PCR analysis of the tissues around the fracture site showed that the expression of H19 in the AdsimH19 group was significantly lower than that in the AdGFP group, *p < 0.05. (C) The effect of H19 on the process of fracture repair. X-ray images of fractures showed initial signs of external callus formation in the AdGFP group at the 2nd week post operation (PO-2 W), and cortical space disappeared by bridging internal and external callus at the 4th week post operation (PO-4 W). In the AdsimH19 group, obvious callus was formed and extended outward from the fracture line at week 2 (PO-2 W) and week 3 (PO-3 W), and fracture healing was delayed at week 4 (PO-4 W). (D) Micro-CT (µCT) analysis showed that the callus of fractures in the AdGFP group was almost completely bridged with PO-2 W and completely bridged with PO-4 W. The AdsimH19 group showed a large amount of radiative space between the cortices of the PO-2 W fissure and continued to PO-4 W. (E) Quantitative analysis by micro-CT (µCT).BV, bone tissue volume; BV/TV, bone volume fraction; SMI, structure model index; Tb.N, trabecular number; Tb.Th, trabecular thickness; Conn.Dn, Connectivity Density; *p < 0.05, **p < 0.01, compared with AdGFP group.