Biological evaluation of redox-sensitive micelles based on hyaluronic acid-deoxycholic acid conjugates for tumor-specific delivery of paclitaxel.

Tumor-targeted drug delivery and microenvironment-responsive drug release are attractive strategies in cancer treatment. Our previous study demonstrated that redox-sensitive micelles based on hyaluronic acid-deoxycholic acid (HA-ss-DOCA) conjugates exhibited excellent drug-loading capacities (34.1%) for paclitaxel (PTX) and rapid drug release in response to reducing agent, glutathione. In the present study, the physicochemical and biological properties of PTX-loaded HA-ss-DOCA (PTX-HA-ss-DOCA) micelles were investigated further. The micelles have an average size of about 120 nm and a zeta potential of about -36 mV. Transmission electron microscopy and wide-angle X-ray diffraction analysis demonstrated redox-sensitive degradation of micelles in the presence of glutathione. Moreover, the encapsulated payload was effectively released from HA-ss-DOCA micelles into cytoplasm and then rapidly transported into nuclei. In vitro cytotoxicity and cell apoptosis assay further revealed that HA significantly improved the tumor-specific drug delivery of HA-ss-DOCA micelles via receptor-mediated endocytosis, while efficient intracellular drug release and transportation lead to marked inhibition of tumor cell growth, as compared to Taxol(®) and insensitive micelles. More importantly, PTX-HA-ss-DOCA micelles demonstrated superior in vivo antitumor activity compared with Taxol(®) and insensitive control, and decreased systemic toxicity. Herein we present data which provide valuable insight into the design and development of tumor-specific drug delivery systems.

Li J ，Yin T ，Wang L ，Yin L ，Zhou J ，Huo M ... -  《-》

Redox-sensitive micelles self-assembled from amphiphilic hyaluronic acid-deoxycholic acid conjugates for targeted intracellular delivery of paclitaxel.

A targeted intracellular delivery system of paclitaxel (PTX) was successfully developed based on redox-sensitive hyaluronic acid-deoxycholic acid (HA-ss-DOCA) conjugates. The conjugates self-assembled into nano-size micelles in aqueous media and exhibited excellent drug-loading capacities (34.1%) and entrapment efficiency (93.2%) for PTX. HA-ss-DOCA micelles were sufficiently stable at simulated normal physiologic condition but fast disassembled in the presence of 20 mm reducing agent, glutathione. In vitro drug release studies showed that the PTX-loaded HA-ss-DOCA micelles accomplished rapid drug release under reducing condition. Intracellular release of fluorescent probe nile red indicated that HA-ss-DOCA micelles provide an effective approach for rapid transport of cargo into the cytoplasm. Enhanced cytotoxicity of PTX-loaded HA-ss-DOCA micelles further confirmed that the sensitive micelles are more potent for intracellular drug delivery as compared to the insensitive control. Based on flow cytometry and confocal microscopic analyses, observations revealed that HA-ss-DOCA micelles were taken up to human breast adenocarcinoma cells (MDA-MB-231) via HA-receptor mediated endocytosis. In vivo investigation of micelles in tumor-bearing mice confirmed that HA-ss-DOCA micelles possessed much higher tumor targeting capacity than the insensitive control. These results suggest that redox-sensitive HA-ss-DOCA micelles hold great potential as targeted intracellular delivery carriers of lipophilic anticancer drugs.

Li J ，Huo M ，Wang J ，Zhou J ，Mohammad JM ，Zhang Y ，Zhu Q ，Waddad AY ，Zhang Q ... -  《-》

Paclitaxel delivered by CD44 receptor-targeting and endosomal pH sensitive dual functionalized hyaluronic acid micelles for multidrug resistance reversion.

The drug efflux mediated by P-glycoprotein (P-gp) transporter is a major factor responsible for multidrug resistance (MDR) of paclitaxel (PTX). The efficient intracellular PTX delivery is a promising strategy for overcoming the MDR of tumor cells. A CD44 receptor targeting and endosome-pH sensitive dual functionalized hyaluronic acid-deoxycholic acid-histidine (HA-DOCA-His) micellar formulation was developed to overcome MDR, and a CD44 receptor targeting hyaluronic acid-deoxycholic acid (HA-DOCA) micelles was used as a comparison. Compared with Taxol solution and HA-DOCA micelles, the cytotoxicity of PTX loaded in HA-DOCA-His micelles against drug-resistant tumor cells was improved significantly and possessed superior MDR-overcoming performance; this phenomenon is due to the increased intracellular PTX delivery by CD44 receptor-mediated endocytosis pathway and endosome-pH sensitivity-mediated PTX triggering release. Upon pharmacokinetic study, PTX/HA-DOCA-His micelles demonstrated longer blood circulation time, larger AUC, decreased Vd and CL than the Taxol solution. More importantly, PTX/HA-DOCA-His micelles were more effective in tumor growth inhibition in MCF-7/Adr tumor-bearing mice compared with PTX/HA-DOCA micelles and Taxol solution. Dual targeting strategy-functionalized HA-DOCA-His micelles demonstrated excellent MDR-reversing ability for therapeutic efficacy and improvement on MDR tumors, thereby providing an effective targeting strategy for PTX delivery of nano-drug delivery system in MDR cancer chemotherapy.

Liu Y ，Zhou C ，Wei S ，Yang T ，Lan Y ，Cao A ，Yang J ，Hou Y ... -  《-》

CD44 Receptor Targeting and Endosomal pH-Sensitive Dual Functional Hyaluronic Acid Micelles for Intracellular Paclitaxel Delivery.

Liu Y ，Zhou C ，Wang W ，Yang J ，Wang H ，Hong W ，Huang Y ... -  《-》

Intracellular delivery and antitumor effects of a redox-responsive polymeric paclitaxel conjugate based on hyaluronic acid.

Polymer-drug conjugates have demonstrated application potentials in optimizing chemotherapeutics. In this study a new bioconjugate, HA-ss-PTX, was designed and synthesized with cooperative dual characteristics of active tumor targeting and selective intracellular drug release. Paclitaxel (PTX) was covalently attached to hyaluronic acid (HA) with various sizes (MW 9.5, 35, 770 kDa); a cross-linker containing disulfide bond was also used to shield drug leakage in blood circulation and to achieve rapid drug release in tumor cells in response to glutathione. Incorporation of HA to the conjugate enhanced the capabilities of drug loading, intracellular endocytosis and tumor targeting of micelles in comparison to mPEG. HA molecular weight showed significant effect on properties and antitumor efficacy of the synthesized conjugates. Intracellular uptake of HA-ss-PTX toward MCF-7 cells was mediated by CD44-caveolae-mediated endocytosis. Compared to Taxol and mPEG-ss-PTX, HA9.5-ss-PTX demonstrated improved tumor growth inhibition in vivo with a TIR of 83.27 ± 5.20%. It was concluded that HA9.5-ss-PTX achieved rapid intracellular release of PTX and enhanced its therapeutic efficacy, thus providing a platform for specific drug targeting and controlled intracellular release in chemotherapeutics. Polymer-drug conjugates, promising nanomedicines, still face some technical challenges including a lack of specific targeting and rapid intracellular drug release at the target site. In this manuscript we designed and constructed a novel bioconjugate HA-ss-PTX, which possessed coordinated dual characteristics of active tumor targeting and selective intracellular drug release. Redox-responsive disulfide bond was introduced to the conjugate to shield drug leakage in blood circulation and to achieve rapid drug release at tumor site in response to reductant like glutathione. Paclitaxel was selected as a model drug to be covalently attached to hyaluronic acid (HA) with various sizes to elucidate the structure-activity relationship and to address whether HA could substitute PEG as a carrier for polymeric conjugates. Based on a series of in vitro and in vivo experiments, HA-ss-PTX performed well in drug loading, cellular internalization, tumor targeting by entering tumor cells via CD44-caveolae-mediated endocytosis and rapidly release drug at target in the presence of GSH. One of the key issues in clinical oncology is to enhance drug delivery efficacy while minimizing side effects. The study indicated that this new polymeric conjugate system would be useful in delivering anticancer agents to improve therapeutic efficacy and to minimize adverse effects, thus providing a platform for specific drug targeting and controlled intracellular release in chemotherapeutics.

Yin S ，Huai J ，Chen X ，Yang Y ，Zhang X ，Gan Y ，Wang G ，Gu X ，Li J ... -  《-》