Effect of centrifugal force on osteoblastic differentiation of bone marrow stroma cells in vitro / 中国组织工程研究

ABSTRACT

BACKGROUND: Centrifugal force is a contributing factor inducing osteoblastic differentiation from bone marrow stroma cells.OBJECTIVE: To explore whether centrifugal force promote osteoblastic differentiation from rabbit marrow stroma cell seeded on polylactic-co-glycolic acid (PLGA) scaffolds. METHODS: Rabbit bone marrow stroma cells were isolated and cultured by whole bone marrow method, purified by attachment method, and digested by trypsin-EDTA at 80% confluency. The cell concentration was adjusted to 1×10~9/L. PLGA was cut into pieces, 5 mm×5 mm, soaked in serum-conditioned culture medium for 24 hours. The third passage of bone stroma cell suspension at a density of 300 μL was respectively seeded into the PLGA material. The scaffold/cell compound was placed in centrifuge tube, with cell at the upper layer and cultured in osteoblastic induced medium containing antiscorbic acid, β-sodium glycerophosphate, and dexamethasone respectively under centrifugal force every 12 hours (1 000 r/min for 30 minutes, relative centrifugal force 132 g) and static condition. Alkaline phosphatase activity, osteocalcin content and calcium content as well as observation by light microscopy were used to evaluate osteoblastic differentiation. RESULTS AND CONCLUSION: After 16 days of in vitro culture, the scaffolds of centrifugal force group were coated by multiplayer cells and mineralized matrix, but only a thin layer of cells were observed on the scaffold of control group. The centrifugal force system resulted in a significant decrease in alkaline phosphatase activity at day 2 (P < 0.05) but significant increase at day 4 compared with the static culture condition (P < 0.05). During the whole culture time, osteocalcin secretion remained low in control group. At days 12 and 16, a significant enhancement in osteocalcin secretion was observed for centrifugal force culture compared with static culture conditions (P < 0.05). Moreover, after 16 days of culture a significant increase in calcium deposition was observed in the scaffolds subjected to centrifugal force compared with static culture condition (P < 0.05). Centrifugal force can enhance osteoblastic differentiation and mineralized matrix production of bone marrow stroma cell seeded in PLGA.