Chemosensitizing indomethacin-conjugated chitosan oligosaccharide nanoparticles for tumor-targeted drug delivery.

A chitosan oligosaccharide (CSO)-indomethacin (IDM) conjugate (CI) was synthesized to fabricate chemosensitizing nanoparticles (NPs) for tumor-targeted drug delivery. IDM was conjugated to a CSO backbone via amide bond formation, of which successful synthesis was confirmed by proton-nuclear magnetic resonance analyses. Doxorubicin (DOX)-loaded CI (CI10/DOX; CI:DOX=10:1 [w/w]) NPs with <75nm of mean diameter, polydispersity index of ∼0.2, and positive zeta potential were prepared. The release of DOX from the NPs was enhanced at acidic pH (pH 5.5 and 6.8) compared to physiological pH (pH 7.4). The release of IDM increased in the presence of A549 cell lysates. In A549 cells (human lung carcinoma cells), more efficient cellular uptake of CI10/DOX NPs than that of free DOX was observed by using confocal laser scanning microscopy and flow cytometry. The in vitro cytotoxicity of CI10/DOX NPs in A549 cells was higher than those of free DOX and CI NPs with free DOX groups. In vivo pharmacokinetic studies after intravenous administration in rats showed significantly lower clearance of DOX from NPs compared with the free DOX group. Tumor targetability of the developed CI NPs was also verified by a real-time optical imaging study. In summary, the chemosensitizing CI/DOX NP with enhanced anticancer activity, prolonged blood circulation, and passive tumor targeting can be a promising anticancer drug delivery system for tumor-targeted therapy. STATEMENT OF SIGNIFICANCE: Chemosensitizing nanoparticles (NPs) based on amphiphilic chitosan oligosaccharide-indomethacin (CSO-IDM; CI) conjugate were developed for tumor-targeted delivery of doxorubicin (DOX). IDM was introduced to the CSO backbone as a hydrophobic residue to synthesize an amphiphilic conjugate and a chemosenstizer of DOX for improving antitumor efficacies. IDM, conjugated to CSO, may inhibit the efflux of cellular uptaken DOX via multidrug resistance-associated protein (MRP) and subsequently augment the anti-proliferation potentials of DOX in A549 cells (MRP-expressed human lung cancer cells). Chemosensitizing properties of developed CI NPs were assessed in cell culture models and the tumor targetability of CI/DOX NPs was demonstrated in A549 tumor-xenografted mouse model by a real-time optical imaging. Developed CI NPs can be used as a multifunctional nanosystem for the therapy of MRP-expressed cancers.