Heparin modification enhances the delivery and tumor targeting of paclitaxel-loaded N -octyl- N -trimethyl chitosan micelles

Polycations have been widely used as efficient drug and gene carriers. However, the further application of polycation nanocarriers is greatly hampered by the serious cytotoxicity caused by exposed positive charges. Despite recent progress towards the therapeutic delivery of nucleic acids, there remains a compelling need for development of novel delivery systems for various types of drug. Here, we created mixed micelles based on N-octyl-N-trimethyl chitosan (OTMC) and coated them with an anionic polymer for delivery of paclitaxel (PTX). OTMC/PEG-100 stearate (S-100) micelles (PTX-SN) were firstly prepared by a dialysis method with a high drug loading efficiency and positive charge. PTX-SN micelles were then coated with two anionic polymers, heparin sodium (PTX-HSN) and sodium carboxymethyl cellulose (PTX-CSN) to shield positive charges. Both PTX-HSN and PTX-CSN micelles showed decreased cytotoxicity and hemolysis while retaining high uptake efficiency. PTX-HSN micelles were taken up more effectively than PTX-CSN by HeLa cells, which over-express heparanase. PTX-HSN micelles persisted longer in the circulation of rats than free drug in pharmacokinetic studies. DIR-HSN micelles accumulated strongly in tumors, and PTX-HSN micelles significantly inhibited tumor growth in tumor-bearing mice. Overall, the results validate heparin-coated OTMC micelles as safe and effective tumor-targeting carriers that are suitable for anti-tumor drug delivery.