Evaluation of in vitro and in vivo antitumor effects of gambogic acid-loaded layer-by-layer self-assembled micelles

This study aimed to develop a novel type of multilayer micelle using protamine (PRM) and hyaluronic acid (HA) for the delivery of gambogic acid (GA). GA-loaded micelles (GA-M) were simply and   rapidly prepared using lecithin/solutol HS15 using a film-dispersion method. PRM and HA were added in sequence to form layer-by-layer self-assembled micelles (HA-PRM-GA-M), in which particle size, zeta potential , particle morphology, drug loading, encapsulation efficiency, and in vitro release were investigated. Surface charge reversal demonstrated that rapid HA detachment exposed PRM, leading to activation of a “proton sponge” effect in the hyaluronidase (HAase)-rich tumor microenvironment . Compared with coumarin 6-loaded micelles (C6-M), more efficient intracellular trafficking was observed for HA-PRM-C6-M, which is associated with the endosomal/lysosomal escaping ability of the exposed PRM. In vivo imaging showed increased enrichment of near infrared fluorescent dye (DIR)-loaded HA-PRM-DIR-M at the tumor site, suggesting that HA enhanced the active tumor targeting of GA. Furthermore, HA-PRM-GA-M showed the stronger antitumor activity than GA and GA-M against human lung adenocarcinoma (A549) tumor xenografts in nude mice . In summary, our findings show the potential of HA-PRM-GA-M as a novel intravenous drug carrier for the treatment of lung cancer.