ABSTRACT
The redox responsive nanocarriers have made a considerable progress in achieving triggered drug release by responding to the endogenous occurring difference between the extra- and intra- cellular redox environments. Despite the promises, this redox difference exists both in normal and tumor tissue. So a non-selective redox responsive drug delivery system may result in an undesired drug release in normal cells and relevant side-effects. To overcome these limitations, we have developed a chitosan based glycolipid-like nanocarrier (CSO-ss-SA) which selectively responded to the reducing environment in tumor cells. The CSO-ss-SA showed an improved reduction-sensitivity which only fast degraded and released drug in 10mM levels of glutathione (GSH). The CSO-ss-SA could transport the drug fast into the human ovarian cancer SKOV-3 cells and human normal liver L-02 cells by internalization, but only fast release drug in SKOV-3 cells. By regulating the intracellular GSH concentration in SKOV-3 cells, it indicated that the cellular inhibition of the PTX-loaded CSO-ss-SA showed a positive correlation with the GSH concentration. The CSO-ss-SA was mainly located in the liver, spleen and tumor in vivo, which evidenced the passive tumor targeting ability. Despite the high uptake of liver and spleen, drug release was mainly occurred in tumor. PTX-loaded CSO-ss-SA achieved a remarkable tumor growth inhibition effect with rather low dose of PTX. This study demonstrates that a smartly designed glycolipid-like nanocarrier with selective redox sensitivity could serve as an excellent platform to achieve minimal toxicity and rapid intracellular drug release in tumor cells.
Subject(s)
Chitosan/analogs & derivatives , Delayed-Action Preparations/chemistry , Glycolipids/chemistry , Animals , Cell Line , Cell Line, Tumor , Chitosan/metabolism , Delayed-Action Preparations/metabolism , Drug Delivery Systems , Drug Liberation , Female , Glycolipids/metabolism , Humans , Mice, Inbred BALB C , Micelles , Ovarian Neoplasms/drug therapy , Ovarian Neoplasms/metabolism , Oxidation-Reduction , Stearic AcidsABSTRACT
To improve the gene transfection efficiency mediated by chitosan-g-stearic acid (CS) micelles, poly(ethylene glycol)-b-poly(γ-glutamic acid) (PG) was incorporated into a CS-based gene delivery system. CS/PG/pDNA complexes were prepared by ionic interaction. CS and PEGylated CS (PCS) micelles were introduced to prepare binary complexes for use as controls. CS/PG/pDNA complexes possessed similar sizes and presented as irregular spheroids in shape. The incorporation of PG into CS/pDNA complexes did not affect the ability of CS to compact pDNA and also showed a protective effect against DNase I based degradation of pDNA. Importantly, PG could increase gene transfection efficiency, which was also affected by the mixing methods used for the preparation of CS/PG/pDNA ternary complexes. The transfection efficiencies mediated by CS/PG/pDNA complexes against HEK293 and EC-1 cells reached up to 40.8% and 11.6%, respectively, which were much higher than those of CS/pDNA complexes (1.3% and 4.0%) and PCS/pDNA complexes (0.8% and 2.4%). In addition, the incorporation of PG into CS/pDNA complexes significantly enhanced cellular uptake in HEK293 and EC-1 cells and, additionally, improved endosomal escape and intracellular vector unpacking. However, the incorporation of PG reduced the cellular uptake of CS/PG/pDNA complexes in macrophages (RAW264.7 cells). It was further demonstrated that, in addition to a nonspecific charge-mediated binding to cell membranes, a γ-PGA-specific receptor-mediated pathway was involved in the internalization of CS/PG/pDNA complexes. These results indicated that PG played multiple important roles in enhancing the transfection efficiency of CS/PG/pDNA complexes.
