Galactose-installed photo-crosslinked pH-sensitive degradable micelles for active targeting chemotherapy of hepatocellular carcinoma in mice

In this study, we designed and developed galactose-installed photo-crosslinked pH-sensitive degradable micelles (Gal-CLMs) for active targeting chemotherapy of hepatocellular carcinoma in mice. Gal-CLMs were readily obtained from co-self-assembly of poly(ethylene glycol)-b-poly(mono-2,4,6-trimethoxy benzylidene-pentaerythritol carbonate-co-acryloyl carbonate) (PEG-b-P(TMBPEC-co-AC)) and Gal-PEG-b-poly(ε-caprolactone) (Gal-PEG-b-PCL) copolymers followed by photo-crosslinking. Notably, paclitaxel (PTX)-loaded Gal-CLMs (Gal-PTX-CLMs) showed a narrow distribution (PDI=0.08-0.12) with average sizes ranging from 92.1 to 136.3nm depending on the Gal contents. The release of PTX from Gal-CLMs while inhibited at physiological pH was enhanced under endosomal pH conditions. MTT assays in asialoglycoprotein receptor (ASGP-R) over-expressing HepG2 cells demonstrated that half-maximal inhibitory concentration (IC50) values of Gal-PTX-CLMs decreased from 11.7 to 2.9 to 1.1μg/mL with increasing Gal contents from 10% to 20% to 30%, supporting receptor-mediated endocytosis mechanism. The in vivo biodistribution studies in human hepatoma SMMC-7721 tumor-bearing nude mice displayed that Gal20-PTX-CLMs resulted in significantly enhanced drug accumulation in the tumors over non-targeting PTX-CLM counterpart. In accordance, Gal20-PTX-CLMs caused much greater tumor growth inhibition than non-targeting PTX-CLMs as well as non-crosslinking Gal20-PTX-NCLM controls (average tumor volume: ca. 35mm(3)versus 144mm(3) and 130mm(3), respectively). Histological analysis showed that Gal20-PTX-CLMs induced more extensive apoptosis of tumor cells while less damage to normal liver and kidney compared to Taxol. Ligand-installed photo-crosslinked pH-responsive degradable micelles have a great potential for targeted cancer chemotherapy.