Abstract:

BACKGROUND: Mechanical stimulation can promote the osteogenic differentiation of bone marrow stromal cells, but the effect of different magnitude of tensile stress on the bone marrow stromal cells is not clear.
OBJECTIVE: To study the effect of different magnitudes of continuous tensile stress on the osteogenic differentiation of rat bone marrow stromal cells.
METHODS: Rat bone marrow stromal cells were obtained and purified by full-blood attachment culture. The 5%, 10% and 15% continuous tensile stress (1 Hz) were strained on bone marrow stromal cells with Flexercell-4000 mechanical loading system and lasted for 48 hours, and the cells in the control group were cultured without stress. The mRNA and protein expression of osteoblast-related genes alkaline phosphatase, collagen type Ⅰ, osteocalcin and osteoblast-specific transcription factor Runx2 were analyzed at 1, 6, 12, 24 and 48 hours after strain.
RESULTS AND CONCLUSION: The mRNA expression of alkaline phosphatase, collagen type Ⅰ and osteocalcin was increased in rat bone marrow stromal cells subjected to 5% and 10% continuous tensile stress when compared with the control group (P < 0.05), but the 10% tensile stress group increased earlier than the 5% tensile stress group, and the amplitude was higher. The mRNA expression of alkaline phosphatase and collagen type Ⅰ was increased at 6 hours after 15% elongation (P < 0.05), and then decreased gradually. At 48 hours after continuous tensile stress, the indicators above were lower than those in the control group (P < 0.05). The expression of Runx2 protein in bone marrow stromal cells at 6 hours in 15% elongation was higher than that in the control group (P < 0.05), so did the 5% and 10% elongation groups (P < 0.05). It indicates that 5%, 10% and 15% tensile stress can promote the osteogenic differentiation of bone marrow stromal cells, and 10% tonsile stress has the most significant effect.