OBJECTIVETo study the effect of podophyllotoxin nanostructured lipid carriers (POD-NLC) on immortalized human cervical epithelial cells (H8) infected with HPV in vitro.

METHODSPOD-NLC was prepared by emulsion evaporation method and characterized using transmission electron microscopy, Zetasizer analyzer and high-performance liquid chromatography (HPLC). H8 cells were treated with different concentrations (0.0001-1 µg/ml) of POD-NLC, free POD, or blank nanostructured lipid carriers (NLC), and the cell proliferation was assessed using MTT assay to evaluate the cytotoxic effects. The changes of cell morphology were observed using fluorescence microscopy, and the cell cycle changes and cell apoptosis were analyzed using flow cytometry.

RESULTSPOD-NLC showed a spherical or elliptical shape with good stability in vitro. The average particle size of POD-NLC was 85.6∓10.25 nm, with a Zeta potential of 26.2∓4.1 mV and entrapment efficiency of POD of (88.56∓3.1)%. POD-NLC caused a significant inhibition of H8 cell proliferation in a concentration- and time-dependent manner. At an equivalent concentration, POD-NLC produced a stronger inhibitory effect on cell proliferation than POD. The inhibition rate of H8 cells after a 48-h exposure to POD-NLC and POD reached 95.8% and 65.6%, respectively, and at the highest concentration of 1 µg/ml, the IC(50) of POD-NLC and POD was 0.015 µg/ml and 0.13 µg/ml, respectively. Blank NLC did not obviously affect the proliferation of H8 cells. POD-NLC and POD both caused obvious increases in G(2)/M phase cell percentages and induced typical apoptotic changes of the cells, and their effects were comparable (P>0.05).

CONCLUSIONCompared with POD, POD-NLC has more potent effect in inhibiting H8 cell proliferation and inducing cell apoptosis, suggesting its potential in the treatment of cervical HPV infection.