Abstract:

BACKGROUND: Bone marrow adipocytes and osteoblasts are derived from bone marrow stromal cells. Both of them have homology and have transdifferentiation each other under a certain condition.
OBJECTIVE: To investigate the activity of bone marrow adipocytes differentiation into osteoblasts and to explore the new treatment method for the steroid-induced osteonecrosis of the femoral head.
METHODS: Osteogenic and adipogenic differentiation of confluent preadipocytes 3T3-L1 was performed. Changes in cell morphology were observed at various time points following culture. The levels of peroxisome proliferators activated receptor γ2 (PPARγ2), runt-related transcription factor 2 (Runx2), osteocalcin (OCN) and collagen type I (Col I) mRNA expression were investigated by RT-PCR at days 5 and 21 following culture. Western blotting was used to evaluate cellular PPARγ2, Runx2, OCN and Col I production on day 21 following osteogenic and adipogenic culture. Cultured cells received alkaline phosphatase staining, alizarin red staining and oil red O staining. 3T3-L1 osteogenic transdifferentiation and activity expression of osteoblasts were observed.
RESULTS AND CONCLUSION: On day 5 following osteogenic induction, 3T3-L1 cells became spindle shape. Compared with control group, real-time quantity-PCR results demonstrated that PPARγ2 mRNA expression was reduced, but Runx2, OCN and Col I mRNA expression was slightly increased. On day 21, these changes were more significant. Western blot exhibited that Runx2, OCN and Col I expression was increased, but no PPARγ2 expression was detected. Positive expression of alkaline phosphatase staining was more. Alizarin red staining showed many scattered calcified nodes. Oil red O staining showed slight lipid droplet. Results indicated that mouse bone marrow stromal cells-derived preadipocytes 3T3-L1 can differentiate into osteoblasts with bioactivity to a certain degree following culture. There is the plasticity between adipocytes and osteoblasts.