Abstract: BACKGROUND: Jaws are most vulnerable to osteoporosis. Adipose-derived mesenchymal stem cells and bone morphogenetic protein 2 have the effect of promoting bone regeneration in osteoporosis. However, the repair effect of bone morphogenetic protein 2 modified adipose-derived mesenchymal stem cells on alveolar bone defects in osteoporosis is rarely reported.  
OBJECTIVE: To explore the repair effect of adipose-derived mesenchymal stem cells overexpressing bone morphogenetic protein 2 on alveolar bone defects in osteoporosis rats.
METHODS: (1) The rat adipose-derived mesenchymal stem cells were infected with lentivirus overexpressing bone morphogenetic protein 2 gene, and identified by detecting the expression of green fluorescent protein and bone morphogenetic protein 2. (2) Osteoporosis rat model was established by ovariectomy. A 3 mm × 3 mm × 3 mm cylindrical defect was prepared at the first molar position on both sides of the upper jaw. (3) Gelatin sponge was implanted in rats of the sham operation group and osteoporosis group. In the adipose-derived stem cell group, the adipose-derived mesenchymal stem cells infected with empty vector lentivirus and gelatin sponge complex were implanted. In the adipose-derived mesenchymal mesenchymal stem cell group overexpressing bone morphogenetic protein 2, a complex of adipose-derived mesenchymal stem cells overexpressing bone morphogenetic protein 2 and gelatin sponge was implanted. Relevant indexes were tested one month later.  
RESULTS AND CONCLUSION: (1) The transfection efficiency of the adipose-derived mesenchymal stem cell group and adipose-derived mesenchymal stem cell group overexpressing bone morphogenetic protein 2 reached more than 70%. Compared with the adipose-derived mesenchymal stem cell group, the level of bone morphogenetic protein-2 protein in the adipose-derived mesenchymal stem cell group overexpressing bone morphogenetic protein-2 was significantly higher (P < 0.05). (2) A large amount of new bone could be seen in the bone defect area of the sham operation group. Compared with the sham operation group, the osteoporotic group had a small amount of new bone formation; the new bone area was significantly reduced, and alkaline phosphatase, osteocalcin, and bone morphogenetic protein 2 mRNA and protein levels were significantly reduced. Compared with the osteoporosis group, the adipose-derived mesenchymal stem cell group and the adipose-derived mesenchymal stem cell group overexpressing bone morphogenetic protein 2 had a large number of new bone formation; the area of new bone was significantly increased, and the levels of alkaline phosphatase, osteocalcin, and bone morphogenetic protein 2 mRNA and protein were significantly increased. Moreover, the adipose-derived mesenchymal stem cell group overexpressing bone morphogenetic protein 2 was superior to the adipose-derived mesenchymal stem cell group (all P < 0.05). (3) The results showed that bone morphogenetic protein 2 was less expressed in the alveolar bone of osteoporosis rats, and adipose-derived mesenchymal stem cells overexpressing bone morphogenetic protein 2 could promote osteogenesis and regeneration of alveolar bone defects in osteoporosis rats.

Key words: bone morphogenetic protein-2, adipose-derived mesenchymal stem cell, osteoporosis, alveolar bone, repair