〔Abstract〕 To investigate the role and mechanism of long non-coding RNA (lncRNA) H19 in osteogen- ic differentiation of bone marrow mesenchymal stem cells ( BMSCs) and bone regeneration in mice with foot frac- ture . Methods BMSCs were divided into microrNA-149-5p ( miR-149-5p)-mimic negative control ( miR-mimic - NC) group and miR-149-5p-mimic ( miR-mimic) group and transfected with lncRNA H19-wt and lncRNA H19 , respectively . Mut recombinant plasmid , or bone morphogenetic protein 2 ( BMP2) 3 ′UTR-wt and BMP2 3 ′UTR- mut 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 lncRNA H19 on osteogenic differ- entiation 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-in- hibitor group , osteogenic + si-H19 + pcDNA-NC group , and osteogenic group si-H19 + pcDNA-BMP2 group . Os- teogenic 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 differentia- tion was assessed by ALP activity assay . Real-time fluorescent quantitative PCR (qPCR) was used to detect the ex- pression of lncRNA 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 BMSCs and bone regeneration in mice with foot fracture through miR-149-5p/BMP2 axis .