Local delivery of artesunate dimer liposomes incorporated injectable hydrogel for H2O2 and pH-independent chemodynamic therapy

Abstract

Chemodynamic therapy (CDT) has emerged as a powerful tumor treatment option by inducing the imbalance of redox homeostasis in cancer cells. Nevertheless, the therapeutic outcomes were greatly limited because of insufficient endogenous H2O2 and upregulated cellular antioxidant defense in the tumor microenvironment (TME). Herein, a liposome-incorporated in-situ alginate hydrogel locoregional treatment strategy was developed, which involves using hemin-loaded artesunate dimer liposomes (HAD-LP) as redox-triggered self-amplified C-center free radical nanogenerator to enhance CDT. First, HAD-LP based on artesunate dimer glycerophosphocholine (ART-GPC) was prepared by a thin film method. Their spherical structure was manifested by dynamic light scattering (DLS) and transmission electron microscope (TEM). The generation of C-center free radicals from HAD-LP was carefully evaluated by using methylene blue (MB) degradation method. The results suggested that the hemin was reduced to heme under the action of glutathione (GSH), which could catalyze the breakage of endoperoxide of ART-GPC derived dihydroartemisinin (DHA) to generate toxic C-centered free radicals in a H2O2 and pH-independent manner. Moreover, the change of intracellular GSH and free radical level was monitored through ultraviolet spectroscopy and confocal laser scanning microscope (CLSM). It was revealed that the hemin reduction induced GSH depletion and elevated free radical level, disrupting cellular redox homeostasis. After co-incubation with MDA-MB-231 or 4 T1 cells, HAD-LP was found to be highly cytotoxic. In order to prolong retention and improve antitumor efficacy, HAD-LP was mixed with alginate and injected intratumorally into 4 T1 tumor bearing mice. The injected HAD-LP and alginate mixture formed in-situ hydrogel and achieved best antitumor effect with the growth inhibition rate of 72.6%. Together, the hemin-loaded artesunate dimer liposome-incorporated alginate hydrogel possessed effective antitumor activity through redox-triggered C-center free radical generation induced apoptosis in a H2O2 and pH-independent manner, which might be a promising candidate in the application of chemodynamic anti-tumor therapy.