Wantong Song

Co-delivery of doxorubicin and paclitaxel by PEG-polypeptide nanovehicle for the treatment of non-small cell lung cancer

Despite progress, combination therapy of different functional drugs to increase the efficiency of anticancer treatment still remains challenges. An amphiphilic methoxy poly(ethylene glycol)-b-poly(l-glutamic acid)-b-poly(l-lysine) triblock copolymer decorated with deoxycholate (mPEsG-b-PLG-b-PLL/DOCA) was synthesized and developed as a nanovehicle for the co-delivery of anticancer drugs: doxorubicin (DOX) and paclitaxel (PTX). The amphiphilic copolymer spontaneously self-assembled into micellar-type nanoparticles in aqueous solutions and the blank nanoparticles possessed excellent stability. Three different domains of the copolymer performed distinct functions: PEG outer corona provided prolonged circulation, middle biodegradable and hydrophilic PLG shell was designed for DOX loading through electrostatic interactions, and hydrophobic deoxycholate modified PLL served as the container for PTX. In vitro cytotoxicity assays against A549 human lung adenocarcinoma cell line demonstrated that the DOX + PTX co-delivered nanoparticles (Co-NPs) exhibited synergistic effect in inducing cancer cell apoptosis. Ex vivo DOX fluorescence imaging revealed that Co-NPs had highly efficient targeting and accumulation at the implanted site of A549 xenograft tumor in vivo. Co-NPs exhibited significantly higher antitumor efficiency in reducing tumor size compared to free drug combination or single drug-loaded nanoparticles, while no obvious side effects were observed during the treatment, indicating this co-delivery system with different functional antitumor drugs provides the clinical potential in cancer therapy.

Doxorubicin-loaded amphiphilic polypeptide-based nanoparticles as an efficient drug delivery system for cancer therapy.

An amphiphilic anionic copolymer, methoxy poly(ethylene glycol)-b-poly(l-glutamic acid-co-l-phenylalanine) (mPEG-b-P(Glu-co-Phe)), with three functionalized domains, was synthesized and used as a nanovehicle for cationic anticancer drug doxorubicin hydrochloride (DOX·HCl) delivery via electrostatic interactions for cancer treatment. The three domains displayed distinct functions: PEG block chain for prolonged circulation; poly(phenylalanine) domain for stabilizing the nanoparticle construct through hydrophobic/aromatic interactions; and the poly(glutamic acid) domain for providing electrostatic interactions with the cationic drug to be loaded. The copolymer could self-assemble into micellar-type nanoparticles, and DOX was successfully loaded into the interior of nanoparticles by simple mixing of DOX·HCl and the copolymer in the aqueous phase. DOX-loaded mPEG-b-P(Glu-co-Phe) nanoparticles (DOX-NP) had a superior drug-loading content (DLC) (21.7%), a high loading efficiency (almost 98%) and a pH-triggered release of DOX. The size of DOX-NP was ∼140 nm, as determined by dynamic light scattering measurements and transmission electron microscopy. In vitro assays showed that DOX-NP exhibited higher cell proliferation inhibition and higher cell uptake in A549 cell lines compared with free DOX·HCl. Maximum tolerated dose (MTD) studies showed that DOX-NP demonstrated an excellent safety profile with a significantly higher MTD (15 mg DOX kg(-1)) than that of free DOX·HCl (5 mg DOX kg(-1)). The in vivo studies on the subcutaneous non-small cell lung cancer (A549) xenograft nude mice model confirmed that DOX-NP showed significant antitumor activity and reduced side effects, and then enhanced tumor accumulation as a result of the prolonged circulation in blood and the enhanced permeation and retention effect, compared with free DOX, indicating its great potential for cancer therapy.

Nanoscaled Poly(l-glutamic acid)/Doxorubicin-Amphiphile Complex as pH-responsive Drug Delivery System for Effective Treatment of Nonsmall Cell Lung Cancer

Nonsmall cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide. Herein, we develop a polypeptide-based block ionomer complex formed by anionic methoxy poly(ethylene glycol)-b-poly(L-glutamic acid) (mPEG-b-PLG) and cationic anticancer drug doxorubicin hydrochloride (DOX·HCl) for NSCLC treatment. This complex spontaneously self-assembled into spherical nanoparticles (NPs) in aqueous solutions via electrostatic interaction and hydrophobic stack, with a high loading efficiency (almost 100%) and negative surface charge. DOX·HCl release from the drug-loaded micellar nanoparticles (mPEG-b-PLG-DOX·HCl) was slow at physiological pH, but obviously increased at the acidic pH mimicking the endosomal/lysosomal environment. In vitro cytotoxicity and hemolysis assays demonstrated that the block copolypeptide was cytocompatible and hemocompatible, and the presence of copolypeptide carrier could reduce the hemolysis ratio of DOX·HCl significantly. Cellular uptake and cytotoxicity studies suggested that mPEG-b-PLG-DOX·HCl was taken up by A549 cells via endocytosis, with a slightly slower cellular internalization and lower cytotoxicity compared with free DOX·HCl. The pharmacokinetics study in rats showed that DOX·HCl-loaded micellar NPs significantly prolonged the blood circulation time. Moreover, mPEG-b-PLG-DOX·HCl exhibited enhanced therapeutic efficacy, increased apoptosis in tumor tissues, and reduced systemic toxicity in nude mice bearing A549 lung cancer xenograft compared with free DOX·HCl, which were further confirmed by histological and immunohistochemical analyses. The results demonstrated that mPEG-b-PLG was a promising vector to deliver DOX·HCl into tumors and achieve improved pharmacokinetics, biodistribution and efficacy of DOX·HCl with reduced toxicity. These features strongly supported the interest of developing mPEG-b-PLG-DOX·HCl as a valid therapeutic modality in the therapy of human NSCLC and other solid tumors.

pH and reduction dual-responsive nanogel cross-linked by quaternization reaction for enhanced cellular internalization and intracellular drug delivery

A novel pH and reduction dual-responsive nanogel with improved cellular internalization was prepared through atom transfer radical polymerization and subsequent quaternization reaction. Doxorubicin (DOX), a model anticancer drug, was loaded into the nanogel via dispersion. The DOX-loaded nanogel presented a stable core-cross-linked structure under physiological conditions, but quickly released its payload in an acidic (pH 6.8) and reductive (10.0 mM glutathione) environment. Confocal fluorescence microscopy and fluorescence flow cytometry revealed that the DOX-loaded nanogel could deliver DOX into the cytoplasm and nucleus of cells, more efficiently than that of free DOX. The improved cellular internalization was more significant under acidic and reductive conditions, which was analogous to the pH and reductive conditions in endosomes and cytoplasm. In vitro cytotoxicity studies demonstrated that the pH and reduction responsive DOX-loaded nanogel could inhibit cellular proliferation more efficiently than free DOX. This dual-bioresponsive nanogel with quaternary ammonium salt group has appeared to be highly promising in the further development of intracellular drug transporters.

Anti-tumor efficacy of c(RGDfK)-decorated polypeptide-based micelles co-loaded with docetaxel and cisplatin

There are two important obstacles for the currently applied anti-cancer drug delivery systems. One is the conflict between long-circulation and cellular uptake while the other one is the achievement of ideal anti-cancer efficacy. To solve these problems, we designed a polypeptide-based micelle system that combined the advantages of receptor mediated endocytosis and multi-drug delivery. Firstly, an amphiphilic PLG-g-Ve/PEG graft copolymer was prepared by grafting α-tocopherol (Ve) and polyethylene glycol (PEG) to poly(l-glutamic acid) (PLG). Then docetaxel (DTX) and cisplatin (CDDP) were co-loaded into the PLG-g-Ve/PEG micelles via hydrophobic and chelation effect. After that, the surface of the dual-drug-loaded micelles was decorated with an αvβ3 integrin targeting peptide c(RGDfK). The targeted dual-drug-loaded micelles showed synergistic cytotoxicity and enhanced internalization rate in mouse melanoma (B16F1) cells. In vivo tests demonstrated that remarkable long circulation, anti-tumor and anti-metastasis efficacy could be achieved using this drug delivery system. This work revealed a strategy for the design and preparation of anti-cancer drug delivery systems with reduced side effect, enhanced anti-tumor and anti-metastasis efficacy.

pH and reduction dual responsive polyurethane triblock copolymers for efficient intracellular drug delivery

A series of pH/reduction dual responsive poly(ethylene glycol)/polyurethane triblock copolymers containing tertiary amines and disulfide bonds are reported. The polyurethane block copolymers self-assembled into stable micelles in aqueous medium at pH 7.4, which responded rapidly to both a narrow pH change within the physiologically relevant pH range and a reduction environment mimicking the intracellular space. The in vitro drug release from doxorubicin (DOX)-loaded polyurethane micelles was significantly accelerated by reducing the pH or by addition of an intracellular reducing agent, glutathione (GSH). Confocal laser scanning microscopy (CLSM) and flow cytometry measurements revealed that the intracellular drug release from the DOX-loaded nanoparticles was increased in the HeLa cells with enhanced intracellular GSH level. In addition, even though the polyurethane block copolymers exhibited good cytocompatibility, the DOX-loaded polyurethane micelles displayed efficient growth inhibition of HeLa and HepG2 cells, which showed a dependence on the intracellular GSH concentration. Owing to their unique responsiveness to dual biological stimuli, the biocompatible and bioreducible polyurethane block copolymers have the potential to serve as a versatile platform for intracellular drug delivery.

Methoxypoly(ethylene glycol)-block-Poly(L-glutamic acid)-Loaded Cisplatin and a Combination With iRGD for the Treatment of Non-Small-Cell Lung Cancers

CDDP is loaded into methoxypoly(ethylene glycol)-block-poly(L-glutamic acid) (mPEG-b-PLG), and a combination with iRGD is applied for NSCLC chemotherapy. The CDDP-loaded micelles show sustained cisplatin release in PBS, dose- and time-dependent inhibition to HeLa and A549 cell proliferation, and no apparent hemolysis activities. In in vivo studies using subcutaneous NSCLC xenograft models (A549), both free CDDP and CDDP-loaded micelles show an evident anti-tumor effect. However, the toxicity of CDDP is significantly reduced in the cases of CDDP-loaded micelles and co-administration with iRGD, and the survival time is prolonged by over 30%. Therefore, mPEG-b-PLG-loaded cisplatin and the combination with iRGD provides a promising new therapy for NSCLC.

Polypeptide-based combination of paclitaxel and cisplatin for enhanced chemotherapy efficacy and reduced side-effects.

A novel methoxy poly(ethylene glycol)-b-poly(l-glutamic acid)-b-poly(l-phenylalanine) (mPEG-b-P(Glu)-b-P(Phe)) triblock copolymer was prepared and explored as a micelle carrier for the co-delivery of paclitaxel (PTX) and cisplatin (cis-diamminedichlo-platinum, CDDP). PTX and CDDP were loaded inside the hydrophobic P(Phe) inner core and chelated to the middle P(Glu) shell, respectively, while mPEG provided the outer corona for prolonged circulation. An in vitro release profile of the PTX+CDDP-loaded micelles showed that the CDDP chelation cross-link prevented an initial burst release of PTX. The PTX+CDDP-loaded micelles exhibited a high synergism effect in the inhibition of A549 human lung cancer cell line proliferation over 72 h incubation. For the in vivo treatment of xenograft human lung tumor, the PTX+CDDP-loaded micelles displayed an obvious tumor inhibiting effect with a 83.1% tumor suppression rate (TSR%), which was significantly higher than that of a free drug combination or micelles with a single drug. In addition, more importantly, the enhanced anti-tumor efficacy of the PTX+CDDP-loaded micelles came with reduced side-effects. No obvious body weight loss occurred during the treatment of A549 tumor-bearing mice with the PTX+CDDP-loaded micelles. Thus, the polypeptide-based combination of PTX and CDDP may provide useful guidance for effective and safe cancer chemotherapy.

Pharmacokinetics, biodistribution and in vivo efficacy of cisplatin loaded poly(l-glutamic acid)-g-methoxy poly(ethylene glycol) complex nanoparticles for tumor therapy

Platinum-based polymeric nano-drugs, especially cisplatin-loaded polymeric nanoparticles (CDDP-NPs), have been extensively exploited for the treatment of solid tumors. However, it is still unclear what role the processing procedure and the properties of the polymeric carrier materials may play in influencing the plasma pharmacokinetics, biodistribution and in vivo efficacy of CDDP-NPs. In this study, a series of poly(l-glutamic acid)-g-methoxy poly(ethylene glycol) (PLG-g-mPEG) copolymers were synthesized for the preparation of CDDP-loaded PLG-g-mPEG (CDDP/PLG-g-mPEG) nanoparticles. All of the parameters, including PLG molecular weight, mPEG/PLG weight ratio, mPEG chain length, ultrafiltration purification and cisplatin loading content, were found to have a significant influence on the plasma pharmacokinetics of the CDDP/PLG-g-mPEG nanoparticles. The blood circulation time of the nanoparticles was prolonged with increases in PLG molecular weight, mPEG/PLG weight ratio, mPEG chain length and CDDP loading content. The use of ultrafiltration purification could prolong the blood circulation time of the nanoparticles as well. Experiments to measure the pharmacokinetics and biodistribution demonstrated that the selected CDDP/PLG-g-mPEG nanoparticles, NP10, had a long blood circulation time and could achieve selective and significant accumulation in Lewis lung carcinoma (LLC) tumors. The platinum plasma concentrations in the LLC tumor-bearing mice receiving NP10 remained up to 46-fold higher than that of mice receiving equivalent doses of free CDDP. In addition, the plasma area under the concentration time curve (AUC) of NP10 was 31-fold higher than that of free CDDP in 48h. The platinum concentration ratio of NP10 to free CDDP in tumors reached as high as 9.4. The tumor AUC ratio of NP10 to CDDP was 6. Using a mouse C26 tumor model, here we demonstrate that NP10 improves the safety and tolerance in vivo when compared to CDDP and effectively inhibits the growth of C26 tumors. Furthermore, increasing the dosage of NP10 by 2 or 3-fold of free CCDP improved its anticancer efficacy to comparable or higher levels. These results indicate that CDDP/PLG-g-mPEG nanoparticles have greater potential for the treatment of solid tumors in clinical application.

Tunable pH-Sensitive Poly(β-amino ester)s Synthesized from Primary Amines and Diacrylates for Intracellular Drug Delivery

The pH sensitivity of a series of PbAEs synthesized from primary amines and diacrylates is studied. By changing alkyl groups of the amine monomers, the pKb can be tuned across a broad range (from 3.5 to 7.2). Micelles formed from a PEG-PbAE block copolymer retain the pH sensitivity of PbAE and can stably load hydrophobic molecules under neutral pH, while quickly dissociate and release their cargoes at pH ≈ 6.0. When the chemotherapy drug DOX is loaded, the micelles show efficient cell proliferation inhibition to HeLa cells and fast intracellular release. Thus, the primary-amine-based PbAEs are shown to be promising in the construction of intracellular targeting drug delivery systems.