Effects of exogenous ganglioside GM1 on different stages of cell spreading studied by directly quantifying spreading rate.

We developed novel methods to directly quantify cell spreading rate. By comparing our methods with traditional methods, we found that the enhancement effects of fetal calf serum (FCS) or the inhibitory effects of exogenous ganglioside GM1 occurred at different stages of cell spreading. GM1 mainly influenced the early and late stages of cell spreading of HUVECs. In the presence of 0.5% FCS, GM1 significantly impaired the area-based spreading rates (127.4 ± 35.7 μm(2)/h and 22.2 ± 3.8 μm(2)/h, respectively) on the early (0-0.5 h) and late (12-24 h) stages of cell spreading compared with the controls (238.1 ± 11.7 μm(2)/h and 35.4 ± 19.5 μm(2)/h, respectively), which was confirmed by the data on the GM1-induced changes in average length of actin filaments during cell spreading. The real-time observation and quantification of cold-induced de-spreading of GM1-free or GM1-treated HUVECs further confirmed that GM1 can influence cell de-spreading process having inhibitory (0-10 min) or enhancement (10-20 min or 40-50 min) effects on different stages. The methods can be recruited for investigating effects of other reagents on different stages of cell spreading.