[Effects of fibrin gels on cell proliferation and differentiation in MC3T3E1 cell line]

To analyze MC3T3E1 cell morphology, proliferation, and osteogenic differentiation in fibrin gel (FG) so as to lay a fundament for use of FG in tissue engneering.

MC3T3E1 cells were incubated in three concentrations (20, 10 and 5 mg/mL)of FG as the experimental groups (groups A, B and C) and in the common medium culture as the control group (group D). The cell morphology and distribution in FG were observed by inverted phase contrast microscope and confocal laser scanning microscope at different time. The cell proliferation was assessed by fluorospectrophotometer. The alkaline phosphatase (ALP) activity was detected by automatic biochemistry analyses and von Kossa staining was used to analyze calcium salts mineralization. RT-PCR was used to analyze the ALP and bone sialoprotein (BSP) mRNA expression at 14 and 21 days.

In groups A, B and C, the MC3T3E1 cells had long processes which connected each other and formed network; but fusiform or cube cells were observed in group D at 21 days. The fluorescence intensity was increased gradually with time, was the highest at 14 days and the lowest at 28 days in group D; it was highest in groups A, B and C at 28 days, there were statistically significant differences when compared with group D (P < 0.05). The ALP activity was increased gradually with time, and it was the highest at 28 days in group D and at 21 days in groups A and B, there were significant differences (P < 0.05), no statistically significant differences compared with group D at other time points (P > 0.05). The mineralization nodes were seen at 21 and 28 days in group A, but no mineralization nodes was seen in group D at 28 days. The RT-PCR results showed the mRNA expressions of ALP and BSP were enhanced in group A when compared with group D (P < 0.05).

The osteogenic differentiation was most obvious and cell proliferation was most active after 21 days of incubation in FG.