Objective : To investigate the role and mechanism of long non-coding RNA(lncRNA) H19 in osteogenic differentiation of bone marrow mesenchymal stem cells(BMSCs) and bone regeneration in mice with foot fracture. Methods: BMSCs were divided into microrNA-149-5 p(miR-149-5 p)-mimic negative control(miR-mimicNC) group and miR-149-5p-mimic(miR-mimic) group and transfected with IncRNA H19-wt and IncRNA H19,respectively.Mut recombinant plasmid,or bone morphogenetic protein 2(BMP2) 3'UTR-wt and BMP2 3' UTRmut recombinant plasmid were transfected,respectively.Dual-luciferase reporter gene assay was used to detect the luciferase activity of each group.To study the regulatory effect and mechanism of IncRNA H19 on osteogenic differentiation in vitro,BMSCs were divided into control group and osteogenic induction group(osteogenic group).After osteogenic induction,BMSCs were transfected with corresponding plasmids and divided into osteogenic+si-NC group,osteogenic+si-H19 group,osteogenic+si-H19+miR-inhibitor-NC group,osteogenic+si-H19+miR-inhibitor group,osteogenic+si-H19+pcDNA-NC group,and osteogenic group si-H19+pcDNA-BMP2 group.Osteogenic differentiation was evaluated by alkaline phosphatase(ALP) activity assay and alizarin red staining.A mouse foot fracture model was established,and 36 mice were randomly divided into sham operation group,model group,model+pcD-null group,and model+pcD-H19 group,with 9 mice in each group.Osteogenic differentiation was assessed by ALP activity assay.Real-time fluorescent quantitative PCR(qPCR) was used to detect the expression of IncRNA H19,miR-149-5p,and BMP2.Western blot was used to detect the expression of BMP2,OCN,OSX,RUNX2,and OPN. Results : In cells transfected with lncRNA H19-wt , the luciferase activity in miR-mimic group was lower than that in miR-mimic-NC group (P < 0. 05) . The luciferase activity of miR-mimic group was lower than that of miR-mimic-NC group ( P < 0. 05) . Compared with the control group , the alkaline phosphatase activity , the degree of cell mineralization and the expression of lncRNA H19 , BMP2 , OCN , OSX , RUNX2 and OPN increased , and the expression of miR-149-5p decreased in the osteogenic group ( P < 0. 05) . Compared with the osteogenesis + si-NC group , the alkaline phosphatase activity , the degree of cell mineralization and the expression of lncRNA H19 , BMP2 , OCN , OSX , RUNX2 and OPN significantly decreased , and the ex- pression of miR-149-5p increased in the osteogenesis + si-H19 group (P < 0. 05) . Compared with the osteogenesis + si-H19 + miR-inhibitor-NC group , the ALP activity , the degree of cell mineralization and the expression of ln- cRNA H19 , BMP2 , OCN , OSX , RUNX2 and OPN increased in the osteogenesis + si-H19 + miR-inhibitor group . The expression of miR-149-5p significantly decreased (P < 0. 05) . Compared with the osteogenic + si-H19 + pcD- NA-NC group , the alkaline phosphatase activity , the degree of cell mineralization and the expression of BMP2 , OCN , OSX , RUNX2 and OPN significantly increased in the osteogenic + si-H19 + pcDNA-BMP2 group ( P < 0. 05) . Compared with the sham-operation group and the model group , the alkaline phosphatase activity and the expression of lncRNA H19 , BMP2 , OCN , OSX , RUNX2 and OPN decreased , and the expression of miR-149-5p increased (P < 0. 05) . Compared with the model + pcD-null group , the alkaline phosphatase activity and the ex- pression of lncRNA H19 , BMP2 , OCN , OSX , RUNX2 and OPN significantly increased , and the expression of miR-149-5p decreased in the model + pcD-H19 group (P < 0. 05) . Conclusion lncRNA H19 promotes osteogenic differentiation of BMSC s and bone regeneration in mice with foot fracture through miR-149-5p/BMP2 axis .