Effects of dexamethasone on proliferation, differentiation and apoptosis of adult human osteoblasts in vitro

OBJECTIVE: To observe the effects of dexamethasone on proliferation, differentiation and apoptosis of adult human osteoblasts in vitro. METHODS: Iliac trabecular bone specimens were obtained from adult patients undergoing necessary surgery. After the bone pieces were digested with collagenase-trypsin, osteoblasts were released and incubated at 37 degrees C in a relative humidity of 95% and 5% CO2. Then, the cells were purified, and their passages were given DMEM-F12 and fetal bovine serum medium. Subsequently, 10(-8) mol/L dexamethasone was added into the culture medium to incubate the osteoblasts for three days, and the cells from control groups were incubated without any drugs. All cells were observed continually with phase contrast microscope and transmission electron microscope. Finally, apoptosis was detected by the use of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) and biochemical indices, alkaline phosphatase (ALP) and osteocalcin (OCN) were used to determine the effects of dexamethasone on proliferation, differentiation and apoptosis of adult osteoblasts in vitro. RESULTS: In the adult osteoblasts obtained by collagenase-trypsin digestion, it achieved high survival, stable biochemical indices and excellent purification. Under the condition of dexamethasone 10(-8) mol/L and osteoblasts 10,000/ml, there was significant promotion of ALP and OCN secretion without cell apoptosis. CONCLUSIONS: Dexamethasone has a significant effect on the proliferation and differentiation of adult osteoblasts in vitro without apoptosis, and dexamethasone at the suggested concentration can be used as positive control in drug studies for osteoporosis treatment.