Methods: Osteoblast-like MC3T3-E1 cells were cultured onto the electrodeposited calcium phosphate coating and calcium phosphate/chitosan coatings. The cell proliferation rate was calculated according to the increased cell number, which was expressed as cell doubling index. The cell differentiation ability was evaluated in both protein level and gene level. At protein level, we measured the alkaline phosphatase activity and collagen content with biochemical method. At gene level, we measured the bone sialoprotein and osteocalcin mRNA amount with real-time RT-PCR
Results: MC3T3-E1 cells cultured on the electrodeposited calcium phosphate/chitosan coatings had higher cell proliferation rates than those on the electrodeposited calcium phosphate coatings (except day 5, P<0.05). At the same time, both alkaline phosphatase activity (P<0.05) and collagen content were increased when MC3T3-E1 cells were cultured on the electrodeposited calcium phosphate/chitosan coatings at day 7, 10 and 14. Additional, both alkaline phosphatase activity and collagen content were increased with time elapsed for these coatings. Similarly, both bone sialoprotein and osteocalcin genes were up-regulated when MC3T3-E1 cells were cultured on the electrodeposited calcium phosphate/chitosan coatings at day 14. For the BSP gene, the expression of mRNA level was increased to 6.74-fold (0.1 g/L chitosan in solution) and 6.63-fold (0.2 g/L chitosan in solution) (P<0.05). For the OCN gene, the expression of mRNA level was increased to 4.68-fold (0.1 g/L chitosan in solution) and 5.59-fold (0.2 g/L chitosan in solution) (P<0.05). The chitosan concentration in solution did not induce a significant difference between the electrodeposited calcium phosphate coatings (P>0.05)
Conclusion: Our results suggest that the electrodeposited calcium phosphate/chitosan coatings are favorable to the proliferation and differentiation of MC3T3-E1 cells.