ABSTRACT
Objective To investigate the toxicity of lidocaine solid lipid nanoparticles (SLNs) in human neurons.Methods Lidocaine-loaded SLNs were prepared using high pressure homogenization.SHSY5Y cells were cultured in vitro and inoculated on 96-well plates (100 μl/well) at a density of 5× 105 cells/ml.SH-SY5Y cells were randomized into 10 groups (n =30 each) using a random number table:control group (group C), different concentrations of lidocaine groups (L1-4 groups), different concentrations of lidocaine SLN groups (L-SLN1-4 groups), and blank SLN group (group SLN).The cells were cultured routinely in group C.The cells were incubated with the culture medium containing lidocaine with the final concentrations of 1.000％, 0.500％, 0.250％ and 0.125％ in L1-4 groups, respectively.In LSLN1-4 groups, the cells were incubated with the culture medium containing lidocaine SLNs with the final concentrations of 1.000％, 0.500％, 0.250％ and 0.125％ in L1-4 groups, respectively.Before incubation (at the corresponding time points in group C), and at 1, 12 and 24 h of culture or incubation (T0-3) , 6 wells in each group were selected for measurement of the cell survival rate (using methyl thiazolyl tetrazolium assay).The cell morphology was examined with optical microscope at T3.Results Compared with that at T0, the cell survival rate was significantly decreased at each time point in L1-4 and L-SLN1,2 groups, at T2,3 in L-SLN3 group, and at T3 in L-SLN4 group (P＜0.05) , and no significant change was found in SLN and C groups (P＞0.05).The cell survival rate was significantly lower at T2,3 in L1-4 and L-SLN1-3 groups, and at T3 in group L-SLN4 than that at T1, and at T3 in L1-4 and L-SLN1-4 groups than that at T2 (P＜0.05).Compared with group C, the cell survival rate was significantly decreased at each time point in L1-4 and L-SLN1,2 groups, at T2,3 in group L-SLN3, and at T3 in group L-SLN4 (P＜0.05) , and no significant change was found in group SLN (P＞0.05).Compared with group L-SLN at the corresponding concentration, the cell survival rate was significantly decreased at each time point in group L1-4 (P＜0.05).Conclusion Lidocaine SLNs have toxic effect on human neurons, but the effect is weaker than that caused by Iidocaine solution.