The final product was lyophilized

The final product was lyophilized. == Synthesis of RGD-modified PEGylated CS-SA (RGD-PEG-CS-SA) copolymers == Briefly, 10 mg of RGD peptide was dissolved in dried dimethyl sulfoxide (DMSO), and 3.1 L (Boc)2O was added into the solution. of drug-loaded RGD-PEG-CS-SA micelles in cells that overexpress integrins (3and 5) and integrin-deficient cells. == Results == Using DOX as a model drug, the drug encapsulation efficiency could reach 90%, and the in vitro drug-release profiles suggested that the micelles could be used as a controlled-release carrier for the hydrophobic drug. Qualitative and quantitative analysis of cellular uptake indicated that RGD-modified micelles could significantly increase the DOX concentration in integrin-overexpressing human hepatocellular carcinoma cell line (BEL-7402), but not in human epithelial carcinoma SU 3327 cell line (Hela). The competitive cellular-uptake test showed that the cellular uptake of RGD-modified micelles in BEL-7402 cells was significantly inhibited in the presence of excess free RGD peptides. In vitro cytotoxicity tests demonstrated DOX-loaded RGD-modified micelles could specifically enhance the cytotoxicity against BEL-7402 compared with DOX-loaded PEG-CS-SA and doxorubicin hydrochlorate. == Conclusion == This study suggests that RGD-modified PEG-CS-SA micelles are promising drug carriers for integrin-overexpressing tumor active targeting therapy. Keywords:cellular uptake, chitosan polymeric micelles, cytotoxicity, doxorubicin, integrin, RGD peptide == Introduction == It is well-known that cancer cells are inherently more vulnerable SU 3327 to chemotherapy than the majority of normal cells, but most anticancer drugs are nonselective and can cause injury to normal tissues. In recent years, efforts have focused on effective and safe cancer therapy by increasing tumor targeting while sparing normal cells.1It has successfully been demonstrated that SU 3327 polymers can form effective delivery systems for anticancer drugs via an enhanced permeation and retention (EPR) effect, termed as passive targeting.2Polymeric micelles as drug delivery systems (DDSs) were introduced in the early 1990s by Kataokas group through the development of doxorubicin-conjugated block copolymer micelles.3They have Rabbit Polyclonal to PKC zeta (phospho-Thr410) also been used for the delivery of many anticancer agents in preclinical and clinical studies.46 However, since most clinical conditions do not allow passive targeting, active targeting, where the nanoparticles are delivered to the targets by specific ligands, becomes necessary. Active-targeted delivery of anticancer drugs is a promising approach for delivery of nanoparticle systems. Long circulation times will allow effective transport of nanoparticles to the tumor site through the EPR effect, and the targeting molecule can increase endocytosis of the nanoparticles.7Polymeric micelles are the only reported DDS that conquers multiple-drug resistance through absolute targeting using various approaches such as passive targeting, folate-mediated DDSs, and pH-sensitive and thermosensitive DDSs.8 Chitosan (CS), a biodegradable, biocompatible polysaccharide with low toxicity and immunity system induction,9has been widely accepted as a potential material for drug delivery carriers.10,11Poly(ethylene glycol) (PEG) is a nontoxic and nonirritant hydrophilic polymer.12PEGylation is one of the most popular methods to overcome the uptake of polymeric micelles by macrophage, which may reduce the half-life of micelles in blood. As a result, PEGylation may improve the stability of the drug-loaded micelles and prolong circulation in blood.1315 Previously, the authors developed PEGylated stearic acid-grafted CS (PEG-CS-SA), which is an amphiphilic block copolymer that can self-aggregate into spherical micelles in an aqueous medium. Importantly, it was found that PEG-CS-SA micelles can be rapidly internalized into SU 3327 tumor cells and overcome the uptake by macrophage. However, the PEG-CS-SA micelles could also be internalizated into normal cells.16 By coupling specific tumor-homing ligands, such as antibodies, sugar, folate, or peptides, to the nanoparticles, an active targeting of drug to cancer cells with fewer side effects was obtained. Solid tumors need new blood vessels to feed and nourish.