Charge reversible hyaluronic acid-modified dendrimer-based nanoparticles for siMDR-1 and doxorubicin co-delivery

Dendrimer-based nanoparticles have shown promising applications in delivery of small interference RNA (siRNA) to downregulate proteins that contribute to multidrug resistance (MDR). Various types of modification can further enhance the anti-tumor efficacy of dendrimer-based nanoparticles. In this study, generation 4 polyamodoamine (PAMAM) was conjugated with PEG_2k-DOPE. The PAMAM-PEG_2k-DOPE co-polymer, together with mPEG_2k-DOPE, was formulated into mixed dendrimer micelles (MDMs) that can complex siRNA through the cationic PAMAM moieties and encapsulate hydrophobic drug in the micellar lipid cores. DOPE-conjugated hyaluronic acid (HA) was coated on the surface of MDMs to shield the exposed positive charge on PAMAM and to increase the cellular association with CD44⁺ cancer cells. The HA-modified MDMs could form stable complexes with siRNA, prevent RNase-mediated siRNA degradation and maintain its integrity. Cellular association and cytotoxicity of HA-modified MDMs were investigated in A2780 ADR, MDA-MB-231 and HCT 116 cell lines. The HA-modified MDMs alleviated the toxicity from cationic charge, increase the cancer cell specificity and enhance the cancer cell killing effect in CD44⁺ cell line.