Conditioned medium of adipose-derived mesenchymal stem cells combined with bone morphogenetic protein 2 effectively mitigates ovariectomy induced osteoporosis in rats / 中国组织工程研究

ABSTRACT

BACKGROUND: Adipose-derived mesenchymal stem cells (ADSCs) secrete various cytokines and growth factors required for bone remodeling, which are considered to be excellent candidate cells for bone regeneration. Bone morphogenetic protein 2 (BMP2) and ADSCs have a synergistic effect on bone regeneration and can significantly enhance the osteogenic differentiation of ADSCs. OBJECTIVE: To explore the efficacy of conditioned medium of ADSCs combined with BMP2 on postmenopausal osteoporosis in a rat model. METHODS: Healthy and female Sprague-Dawley rats aged 8-10 months (n=75) were obtained from the Animal Center of Shenyang Medical College. Ovariectomy was performed to induce postmenopausal osteoporosis in 60 rats, and the remaining 15 rats underwent surgeries without removal of the ovaries (sham group). Ovariectomized rats were randomized into four groups: Osteoporosis group, conditioned medium group, BMP2 group, and conditioned medium+BMP2 group, followed by injection of DMEM medium, ADSCs conditioned medium, BMP2, and ADSCs conditioned medium+BMP2 via the tail vein, respectively. After 12 weeks of treatment, femurs and serum samples of each group were taken. The number and structure of trabecular bone and trabecular spacing were detected histologically. Serum P1NP, ALP, TRAP, OPG, RANKL levels were detected by ELISA. Western blot and real-time PCR were used to detect RANKL and OPG at protein and mRNA levels. Cytokine chip analysis of cytokines in ADSCs conditioned medium was performed. RESULTS AND CONCLUSION: Compared with the sham group, increased trabecular spacing, fewer trabeculae and marked trabecular disconnection were observed in osteoporosis rats. The trabeculae in conditioned medium+BMP2 group appeared to be more complete and continuous with less widened spacing compared with the osteoporosis, conditioned medium and BMP2 groups. Serum levels of P1NP and ALP were dramatically higher, while TRAP level group was decreased significantly in the conditioned medium+BMP2 group compared with the other groups (both P < 0.05). In the conditioned medium+BMP2 group, RANKL/OPG ratio was reduced significantly compared with the other groups (P < 0.01), further promoting bone formation. ADSCs conditioned medium contained a variety of cytokines that were essential for bone formation and remodeling, including bone morphogenetic proteins 4 and 7, leukemia inhibitory factor, brain-derived neurotrophic factor, osteoprotegerin, and insulin-like growth factor 1. These results demonstrate that ADSCs conditioned medium combined with BMP2 can mitigate osteoporosis induced by ovariectomy and it may be an attractive strategy to treat postmenopausal osteoporosis.