Objective: To determine the effects of nerve growth factor (NGF) on proliferation of hepatic stellate cells (HSCs) and investigate the related molecular mechanism.
Methods: After incubating cultured HSCs for 24 h with different concentrations of NGF (100, 200 or 400 ng/mL), the cell proliferation was observed by XTT colorimetric assay and cell cycle was detected by flow cytometry. Morphological changes in response to a 24 h exposure to 100 ng/mL NGF were observed by transmission electron microscopy.
Results: NGF significantly inhibited HSC proliferation (P less than 0.05) in a dose-independent manner. The optical densities of the XTT colorimetric assay were 0.66+/-0.03 for 100 ng/mL NGF, 0.69+/-0.03 for 200 ng/mL NGF, and 0.66+/-0.03 for 400 ng/mL NGF, all of which were significantly lower than that of the control group (0.73+/-0.01; P less than 0.05). All concentrations of NGF led to significantly higher numbers of HSCs in the G2 phase (100 ng/mL: 14.83+/-5.41%, 200 ng/mL: 14.73+/-2.50%, and 400 ng/mL: 14.87+/-2.06%), compared to that detected in the control group (7.47+/-4.39%; P less than 0.05). Twenty-four hours of exposure to 100 ng/mL NGF caused morphological changes indicative of apoptosis.
Conclusion: NGF inhibits the proliferation of HSCs, possibly by arresting the cells in the G2 phase of the cell cycle. NGF-inhibited cells may also undergo apoptosis.