Kidney-specific drug delivery system for renal fibrosis based on coordination-driven assembly of catechol-derived chitosan

Renal fibrosis is a common progressive kidney disease, and there is a lack of efficient treatment for the condition. In this study, we designed a kidney-specific nanocomplex by forming coordination-driven assembly from catechol-derived low molecular weight chitosan (HCA-Chi), metal ions and active drug molecules. The coordination activities of various metals and ligands, cytotoxicity, immunogenicity and biodistribution of HCA-Chi were investigated. Autofluorescent doxorubicin (DOX) was selected to fabricate HCA-Chi-Cu-DOX ternary nanocomplex for investigating cellular uptake behavior, transmembrane and targeting properties. The nanodevice demonstrated satisfactory stability under normal physiological conditions and pH-responsive drug release in acidic environments. Uptake of HCA-Chi-Cu-DOX by HK-2 cells was dependent on exposure time, concentration, and temperature, and was inhibited by blockers of megalin receptor. Tissue distribution showed that HCA-Chi-Cu-DOX nanocomplex was specifically accumulated in kidney with a renal relative uptake rate (re) of 25.6. When active anti-fibrosis compound emodin was installed in HCA-Chi-Zn-emodin and intravenously injected to the ureter obstructed mice, obvious attenuation of fibrotic progression was exhibited. It was concluded that HCA-Chi coordination-driven nanocomplex showed special renal targeting capacity and could be utilized to develop drug delivery systems for treating renal fibrosis.