Internalization and mechanisms of toxicity of lipid nanocapsules in HepG2 and HepaRG hepatoma cells upon acute and chronic exposures.

Lipid nanocapsules (LNCs) used as nanomedicine have been developed to enhance pharmacokinetics and decrease side effects of drugs, particularly for cancer therapies. After intravenous administration, LNCs possess an important hepatic tropism however, few data exist about their toxicity and even less after repeated exposure. This study aimed to assess the in vitro toxicity and internalization of unloaded LNCs, of 50 and 100 nm size, on HepG2 and HepaRG liver cell lines. Internalization of the 50 nm LNCs was slower compared to the 100 nm LNCs and both LNCs exhibited a higher toxicity on cancerous HepG2 cells compared to differentiated HepaRG cells. LNCs were mainly internalized via caveolin-mediated endocytosis in both cell lines. Upon chronic exposure, the toxicity of LNCs on HepaRG cells increased, although the pathways of internalization remained unchanged. Cell death studies have demonstrated an involvement of ferroptosis, but not of apoptosis. After acute and repeated exposures on HepaRG cells, the 100 nm LNCs showed a good safety profile. Finally, LNCs induced a more significant toxicity associated with faster internalization in the HepG2 cancerous model than in the differentiated HepaRG cells. This provides good evidence for LNCs to potentialize the cytotoxic effects of an active drug on liver cancer cells.