Abstract
Background: Osteoporosis is associated with a metabolic imbalance between adipogenesis and osteogenesis. We hypothesized that implanting a carrier for differentiated stem cells and signaling molecules inside adipose tissues could be used to enable transdifferentiation between cells, upregulate osteogenesis, and support bone formation, which may regain the balance between osteogenesis and adipogenesis. Methodology: A CL1 human mesenchymal stem cell line was grown in an osteogenic medium to differentiate into osteoblasts, and the differentiated cells were then exposed to an adipogenic medium to stimulate differentiation into adipocytes. Osteogenic and adipogenic differentiation were confirmed by the following assays: alkaline phosphatase staining, Nile red Staining, and quantitative real-time polymerase chain reaction (qPCR). The ratio of adipocytes to osteocytes for both cases was calculated. To evaluate bone induction in vivo, a calcium sulfate/hydroxyapatite cement was prepared in a syringe and then seeded with 10(6) cells/mL of rat bone marrow stromal cells (rMSCs) and covered with 1 mL of tissue culture media containing 0.1 mg of bone morphogenetic protein 7 (BMP-7). The construct was injected into the abdominal fat tissue of 10 male Sprague-Dawley rats. Results: The conversion of osteocytes to adipocytes was 20-fold greater than the reverse conversion, and the area of bone regeneration was 15.7 +/- 3.7%, the area of adipose tissue was 65.8 +/- 13.1%, and the area of fibrous tissue was 18.3 +/- 7.8%. Conclusion: Adipogenic interconversion and associated bone formation demonstrate the potential of a new therapy for balancing osteogenesis and adipogenesis.