Abstract:

BACKGROUND: Simulated weightlessness by tail-suspension can induce bone loss, and the proliferation and differentiation of bone marrow stromal cells directly influence the balance of bone metabolism at the cellular level in the bone marrow cavity, and finally change the bone quality.
OBJECTIVE: To study the osteogenetic and adipocytic differentiation ability of bone marrow stromal cells from tail-suspended rats and the expression of related factors.
METHODS: Sprague-Dawley rats were divided into two groups: control group and tail-suspended group. The bone marrow stromal cells were harvested and cultured in vitro, and induced to osteogenetic or adipocytic differentiation after the first passage. In the osteogenetic differentiation group, the alkaline phosphatase staining was performed on day 16. On day 28, the mineralization of the extracellular matrix was measured, and the mRNA expression of bone morphogenetic protein-2 was detected by real-time PCR. In the adipocytic differentiation group, the lipoprotein lipase activity and mRNA expression were detected on day 21, and on day 30, oil red O staining was performed to detect the lipid droplets.
RESULTS AND CONCLUSION: In the early stage of osteogenetic differentiation of bone marrow stromal cells, the expression of alkaline phosphatase-positive cells in the tail-suspended group was significantly higher than that in the control group. But in the late stage of osteogenetic differentiation of bone marrow stromal cells, the mRNA expression of bone morphogenetic protein-2 and the extracellular matrix mineralization in the tail-suspended group was significantly lower than those in the control group. During the process of adipocytic differentiation of bone marrow stromal cells from tail-suspended rats, the mRNA expression and the activity of lipoprotein lipase as well as the ability of lipid droplets producing in tail-suspended group were significantly higher than those in the control group. Tail suspension could stimulate the osteogenetic differentiation of bone marrow stromal cells at the early stage, but it could significantly suppress other mineralizations and inhibit the osteogenetic differentiation. The mechanism might relate to the mRNA expression of bone morphogenetic protein-2. Tail suspension could promote the adipocytic differentiation of bone marrow stromal cells. The loss of the bone quality occurred in tail-suspended rat partially due to its effects on the differentiation of bone marrow stromal cells.