Dox Delivery Research Articles

Novel reduction-sensitive micellar nanoparticles assembled from Rituximab-doxorubicin conjugates as smart and intuitive drug delivery systems for the treatment of non-Hodgkin's lymphoma.

In this study, a novel reduction-sensitive drug delivery system, the rituximab-doxorubicin (RTX-DOX) micellar nanoparticle (RDMN), was specially designed for targeted delivery and release of DOX in non-Hodgkin's lymphoma (NHL) cells. The RDMN was fabricated by self-assembling of amphiphilic RTX-DOX conjugates (RDCs), which were synthesized by conjugating the hydrophilic Fab fragments of RTX (an anti-CD20 monoclonal antibody) and hydrophobic DOXs by a reduction-responsive linker, 3-(2-Pyridyldithio) propionyl hydrazide (PDPH). The RDMNs were characterized via dynamic light scattering and transmission electron microscopy, both showed the sizes of approximately 94.1±14.5nm with a uniform size distribution. Polyplex dissociation, which was indicated by accelerated DOX release rate and increased particle size, was observed in the presence of 2.5mm 1,4-dithiothreitol due to the cleavage of disulfide bonds in PDPH linkers. In vitro transfection assays against human NHL cell line, JeKo-1, showed significantly increased uptake for RDMNs, as compared to RDCs and free RTX/DOX. Both in and ex vivo experiments demonstrated that RDMNs showed the highest therapeutic effect among all the experimental groups. These results suggested that this RDMN could be a potential, safe and efficient drug delivery vector, which deserves further investigation in the clinic.

Thermal combination therapies for local drug delivery by magnetic resonance-guided high-intensity focused ultrasound

Several thermal-therapy strategies such as thermal ablation, hyperthermia-triggered drug delivery from temperature-sensitive liposomes (TSLs), and combinations of the above were investigated in a rhabdomyosarcoma rat tumor model (n = 113). Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) was used as a noninvasive heating device with precise temperature control for image-guided drug delivery. For the latter, TSLs were prepared, coencapsulating doxorubicin (dox) and [Gd(HPDO3A)(H2O)], and injected in tumor-bearing rats before MR-HIFU treatment. Four treatment groups were defined: hyperthermia, ablation, hyperthermia followed by ablation, or no HIFU. The intratumoral TSL and dox distribution were analyzed by single-photon emission computed tomography (SPECT)/computed tomography (CT), autoradiography, and fluorescence microscopy. Dox biodistribution was quantified and compared with that of nonliposomal dox. Finally, the treatment efficacy of all heating strategies plus additional control groups (saline, free dox, and Caelyx) was assessed by tumor growth measurements. All HIFU heating strategies combined with TSLs resulted in cellular uptake of dox deep into the interstitial space and a significant increase of tumor drug concentrations compared with a treatment with free dox. Ablation after TSL injection showed [Gd(HPDO3A)(H2O)] and dox release along the tumor rim, mirroring the TSL distribution pattern. Hyperthermia either as standalone treatment or before ablation ensured homogeneous TSL, [Gd(HPDO3A)(H2O)], and dox delivery across the tumor. The combination of hyperthermia-triggered drug delivery followed by ablation showed the best therapeutic outcome compared with all other treatment groups due to direct induction of thermal necrosis in the tumor core and efficient drug delivery to the tumor rim.

Preparation and evaluation of poly(l-histidine) based pH-sensitive micelles for intracellular delivery of doxorubicin against MCF-7/ADR cells

In this study, a pH-sensitive micelle self-assembled from poly(l-histidine) based triblock copolymers of poly(ethylene glycol)–poly(d,l-lactide)–poly(l-histidine) (mPEG-PLA-PHis) was prepared and used as the intracellular doxorubicin (Dox) delivery for cancer chemotherapy. Dox was loaded into the micelles by thin-film hydration method and a Box–Behnken design for three factors at three levels was used to optimize the preparations. The optimized mPEG-PLA-Phis/Dox micelles exhibited good encapsulation efficiency of 91.12%, a mean diameter of 45 nm and narrow size distribution with polydispersity index of 0.256. In vitro drug release studies demonstrated that Dox was released from the micelles in a pH-dependent manner. Furthermore, the cellular evaluation of Dox loaded micelles displayed that the micelles possessed high antitumor activity in vitro with an IC50 of 35.30 µg/ml against MCF-7/ADR cells. The confocal microscopy and flow cytometry experiments indicated that mPEG-PLA-Phis micelles mediated efficient cytoplasmic delivery of Dox with the aid of poly(l-histidine) mediated endosomal escape. In addition, blank mPEG-PLA-Phis micelles were shown to be nontoxic to MCF-7/ADR cells even at a high concentration of 200 µg/ml. The pH-sensitive mPEG-PLA-PHis micelles have been demonstrated to be a promising nanosystem for the intracellular delivery of Dox for MDR reversal.

Molecular dynamics simulation of functionalized graphene surface for high efficient loading of doxorubicin

Molecular dynamics simulations are performed to study the design and optimization of nanocarriers with high drug loading capacity. Functionalized graphene is considered as the nominated high capacity drug carrier and Dox as the drug model. The graphene surface functionalized with hydroxyl (–OH), carboxyl (–COOH), methyl (–CH3) and amine (–NH2) groups and their associated properties are investigated. The simulation results are illustrated that G−COOH surface absorbs Dox more effectively in comparison to other functionalized graphene surfaces due to the higher binding energy of carboxylic groups and the model drug. The effect of hydrogen bonding, temperature and surface porosity are also evaluated. The results show that binding energy and the solubility parameter are temperature-dependent. The simulation results in this present work reveal the underlying mechanisms of Dox loading on neat and functionalized graphene surfaces may be employed to design better graphene-based nanocarriers for the Dox delivery applications.

Optical imaging and anticancer chemotherapy through carbon dot created hollow mesoporous silica nanoparticles.

Multifunctional nanoparticles that combine chemotherapeutic ability with imaging modality comprise promising platform for cancer theranostics. Here we developed a novel theranostic nanoparticle, i.e., carbon-dot created mesoporous hollow silica nanoparticle, to offer unique merit for this purpose. The in vitro and in vivo findings to support this include: i) carbon dots with 1-2nm size in situ generated discretely and uniformly within silica network, ii) hollow and mesoporous structure effective for loading of DOX at high content, iii) release behavior of DOX in a sustainable and pH-dependent manner, iv) chemotherapeutic efficacy in killing cancer cells and suppressing tumor growth through DOX delivery, and v) carbon dot induced multi-color fluorescence imaging within cells and tumor tissues. These collective multifaceted properties may facilitate the novel carbon dot nanocarriers to be a potential candidate for delivering anticancer drug and non-invasive imaging in cancer treatment.

PH-Sensitive Nanoscale Polymers: Highly Efficient Systems for DOX Delivery in Cancer Treatment

Recently, many stimuli-responsive drug delivery systems based on biodegradable and biocompatible polymers have been introduced for controlled release of anticancer drug Doxorubicin. The main role of polymers in these systems is to provide high loading of Doxorubicin and then control the release of the drug in low pH-media. Polymeric micelles and nanoparticles such as magnetic particles, silica and graphene oxide covered with smart polymers include two main categories of Dox-controlled release systems. Herein, we review aforementioned systems which have been used for Doxorubicin release through different response of the system in terms of pH including: swelling or expansion of the polymeric chains, pH-sensitive bond cleavage and loss of electrostatic interactions between the drug and system. The mechanism of drug loading, drug release, advantages and disadvantages of each system are fully discussed.

Lanthanide-integrated supramolecular polymeric nanoassembly with multiple regulation characteristics for multidrug-resistant cancer therapy.

Cancer treatment can in principle be enhanced by the synergistic effects of chemo- and nucleic acid-based combination therapies but the lack of efficient drug nanocarriers and occurrence of multidrug resistance (MDR) are major obstacles adversely affecting the effectiveness. Herein, a lanthanide-integrated supramolecular polymeric nanoassembly that delivers anticancer drugs and siRNA for more effective cancer therapy is described. This nanotherapeutic system is prepared by loading adamantane-modified doxorubicin (Dox) into polyethylenimine-crosslinked-γ-cyclodextrin (PC) through the supramolecular assembly to form the interior Dox-loaded PC (PCD) followed by electrostatically driven self-assembly of siRNA and PCD to produce the PCD/siRNA nanocomplexes. The PCD/siRNA nanocomplex is further decorated with the exterior neodymium (Nd)-integrated PC (Nd-PC) layer to obtain the PCD/siRNA/Nd-PC nanoassembly in which the interior PC serves as an efficient carrier for simultaneous delivery of Dox and siRNA to the human breast cancer cell line, Dox-resistant MCF-7 (MCF-7/ADR) both invitro and invivo. The exterior Nd-PC layer improves the drug sensitivity to the MCF-7/ADR cells as a result of the improved nanoassembly uptake, reduced drug efflux, and enhanced apoptosis, as evidenced by multiple regulation of a series of intracellular proteins related to MDR. Furthermore, invivo delivery of the PCD/siRNA/Nd-PC nanoassembly is demonstrated to inhibit tumor growth in the mouse model with MCF-7/ADR tumor xenografts as a result of reduced angiogenesis and increased necrosis at the tumor site. This study reveals a simple and universal strategy to transform polymer-based nanoassemblies into advanced organic-inorganic nanotherapeutics suitable for cancer MDR therapy.

Multifunctional Nanographene Oxide for Targeted Gene-Mediated Thermochemotherapy of Drug-resistant Tumour

Drug resistance remains a major challenge for anticancer treatment, and one of the major mechanisms of drug resistance is the overexpression of drug efflux transporters in cancer. A new approach for defeating drug resistance is the use of a co-delivery strategy that utilizes small interfering RNA (siRNA) to silence the expression of efflux transporters together with a suitable anticancer drug for drug-resistant cells. In this work, multifunctional graphene capable of integrating multiple functions in one system was employed as a novel co-delivery system for siRNA and doxorubicin (Dox), as well as for the controlled release of intracellular pH-triggered and heat-triggered Dox. Additionally, it was used as a synergistic therapy based on the photothermal effect of graphene oxide (GO) under near-infrared (NIR) irradiation and the chemotherapeutic effect of Dox. The nanocomplex exhibited high drug and siRNA loading. Furthermore, the dual delivery of siRNA and Dox by folic acid (FA)-conjugated polyethylenimine-modified PEGylated nanographene (PPG-FA/siRNA/Dox) exhibited a satisfactory gene silencing effect as well as efficient intracellular delivery of Dox. Thus, Dox could access the nucleus and induce greater cytotoxicity compared with siRNA-absent delivery systems. Significantly, under irradiation, the combined treatment showed more synergistic effect for overcoming drug resistance compared with chemotherapy effect alone.

Development of a hypoxia-triggered and hypoxic radiosensitized liposome as a doxorubicin carrier to promote synergetic chemo-/radio-therapy for glioma.

The treatment of malignant primary brain tumors is challenging. Concomitant radiochemotherapy has become the standard clinical treatment for malignant glioma, but there are two critical challenges to overcome in order to increase efficacy. First, glioma is known to have increased resistant to radiation due to its intra-tumoral hypoxia. In addition, the blood-brain barrier (BBB) restricts the distribution of the chemotherapeutic agent to the brain. Therefore, we developed a hypoxic radiosensitizer-prodrug liposome (MLP), in order to deliver DOX to the tumor and to overcome the above challenges, achieving a synergistic chemo-/radiotherapy treatment of malignant glioma. In this study, hypoxic radiosensitizer nitroimidazoles were conjugated with lipid molecules with a hydrolysable ester bond to form MDH. MDH was mixed together with DSPE-PEG2000 and cholesterol to make MLP liposomes, which were found to have strong radiosensitivity and to promote cargo release under hypoxic conditions, due to the properties of nitroimidazoles under hypoxic conditions. MLP/DOX was found to have distinct advantages, including precise and stealthy pharmacokinetics and efficient passive uptake by the tumor. Furthermore, the combination of MLP/DOX and radiotherapy (RT) significantly inhibited glioma growth as assessed by invivo bioluminescence imaging. These findings suggest that MLP is a promising candidate as a DOX delivery system to enhance the antitumor treatment effects on glioma, owing to synergistic chemo-/radiotherapy.

Two-component reduction-sensitive lipid-polymer hybrid nanoparticles for triggered drug release and enhanced in vitro and in vivo anti-tumor efficacy.

An amphiphilic polymer DLPE-S-S-MPEG was synthesized and employed with PCL to prepare two-component reduction-sensitive lipid-polymer hybrid nanoparticles (SLPNPs) for in vitro and in vivo delivery of a hydrophobic anticancer drug (Doxorubicin, DOX). Insensitive lipid-polymer hybrid nanoparticles (ILPNPs) were prepared as a control. The mean sizes of the LPNPs ranged from 100 nm to 120 nm. The TEM observations showed that the LPNPs have spherical morphologies with homogeneous distribution. The disulfide bond of DLPE-S-S-MPEG was cleaved by dithiothreitol (DTT), which resulted in the disassembly of SLPNPs and triggered the release of encapsulated DOX. The in vitro cytotoxicities of DOX/LPNPs against HeLa cells, HepG2 cells and COS-7 cells were studied. It was demonstrated that DOX/SLPNPs showed higher cytotoxicity against HeLa cells and HepG2 cells than DOX/ILPNPs, but showed a slight difference in the case of COS-7 cells. CLSM observation and FCM measurement further confirmed that the introduction of S-S bonds caused fast intracellular release of DOX from SLPNPs. Moreover, compared with DOX/ILPNPs and free DOX, DOX/SLPNPs exhibited higher antitumor activity. Both DOX/SLPNPs and DOX/ILPNPs showed lower cardiac toxicity and kidney toxicity than free DOX, which were confirmed by histological and immunohistochemical analyses. The tissue distribution of DOX in mice exhibited that two kinds of DOX/LPNPs accumulated extensively in the liver and spleen, while free DOX accumulated mainly in the heart and kidney 12 h after injection. Two-component SLPNPs may be a promising drug delivery carrier for reduction-triggered delivery of DOX.

Investigation on a smart nanocarrier with a mesoporous magnetic core and thermo-responsive shell for co-delivery of doxorubicin and curcumin: a new approach towards combination therapy of cancer

A novel and smart MIO-P(NIPAM-MAm) nanocomposite has been prepared for combinational delivery of Dox and Cur for cancer treatment.

A redox-responsive strategy using mesoporous silica nanoparticles for co-delivery of siRNA and doxorubicin.

Co-delivery of gene and drug therapies for cancer treatment remains a major goal of nanocarrier research. In this study, mesoporous silica nanoparticles (MSNs) were used to co-deliver siRNA and doxorubicin (Dox) for redox-controlled release. The present nanocarrier (MSNs-SS-siRNA@Dox) has mesoporous silica cores that can be loaded with Dox, while siRNA connects to the core surface by disulfide linkage and plays a gatekeeper role. Disulfide linkages were also utilized to target intracellular GSH, and their cleavage led to the release of Dox and siRNA. Release of siRNA and Dox was correlated with GSH concentrations, and rapid release at 10 mM GSH reflected reductive cleavage of intermediate disulfide linkages. Subsequent experiments using an in vitro Dox delivery and release assay indicated that MSNs-SS-siRNA@Dox significantly enhanced the accumulation of Dox in cells compared with that after treatment with free Dox. Moreover, MSNs-SS-siRNA@Dox has sufficient efficiency to knock down target protein expression. More importantly, MSNs-SS-siRNA@Dox displayed great potential for tumor targeting and achieved satisfactory therapeutic effects on tumor growth inhibition in vivo. In summary, the present nanoparticles may provide an effective strategy for the design and development of controlled release and co-delivery of siRNA and drugs for cancer therapy.

Photothermal gold nanocages filled with temperature sensitive tetradecanol and encapsulated with glutathione responsive polycurcumin for controlled DOX delivery to maximize anti-MDR tumor effects.

The design of an ideal drug delivery system with targeted recognition and minimized premature release, especially controlled and specific release that is triggered by endogenous and exogenous dual-stimuli, is a great challenge. A biotin receptor-targeted, near-infrared (NIR) irradiation and redox responsive nano-system has now been developed. The nano-system was constructed by filling the interior of Au nanocages with doxorubicin as a chemotherapy agent trapped in tetradecanol, followed by surface conjugation of biotinylated poly(ethylene glycol)-poly(curcumin-dithiodipropionic acid) (Biotin-PEG-PCDA) as a macromolecular chemosensitizer. Once the nano-system had been delivered into MCF-7/ADR cells by biotin receptor mediated recognition and endocytosis, drug release was triggered by degradation of PCDA via a glutathione induced redox reaction in combination with a solid-liquid change of tetradecanol by photothermal effects under NIR irradiation, which could minimize premature drug release and then maximize the therapeutic efficacy.

Sequential HIFU heating and nanobubble encapsulation provide efficient drug penetration from stealth and temperature sensitive liposomes in colon cancer

Mild hyperthermia generated using high intensity focused ultrasound (HIFU) and microbubbles (MBs) can improve tumor drug delivery from non-thermosensitive liposomes (NTSLs) and low temperature sensitive liposomes (LTSLs). However, MB and HIFU are limited by the half-life of the contrast agent and challenges in accurate control of large volume tumor hyperthermia for longer duration (>30min.). The objectives of this study were to: 1) synthesize and characterized long-circulating echogenic nanobubble encapsulated LTSLs (ELTSLs) and NTSLs (ENTSLs), 2) evaluate in vivo drug release following short duration (~20min each) HIFU treatments administered sequentially over an hour in a large volume of mouse xenograft colon tumor, and 3) determine the impact of the HIFU/nanobubble combination on intratumoral drug distribution. LTSLs and NTSLs containing doxorubicin (Dox) were co-loaded with a nanobubble contrast agent (perfluoropentane, PFP) using a one-step sonoporation method to create ELTSLs and ENTSLs, which then were characterized for size, release in a physiological buffer, and ability to encapsulate PFP. For the HIFU group, mild hyperthermia (40–42°C) was completed within 90min after liposome infusion administered sequentially in three regions of the tumor. Fluorescence microscopy and high performance liquid chromatography analysis were performed to determine the spatial distribution and concentration of Dox in the treated regions. PFP encapsulation within ELTSLs and ENTSLs did not impact size or caused premature drug release in physiological buffer. As time progressed, the delivery of Dox decreased in HIFU-treated tumors with ELTSLs, but this phenomenon was absent in the LTSL, NTSL, and ENTSL groups. Most importantly, PFP encapsulation improved Dox penetration in the tumor periphery and core and did not impact the distribution of Dox in non-tumor organs/tissues. Data from this study suggest that short duration and sequential HIFU treatment could have significant benefits and that its action can be potentiated by nanobubble agents to result in improved drug penetration.

Construction and evaluation of pH-sensitive immunoliposomes for enhanced delivery of anticancer drug to ErbB2 over-expressing breast cancer cells

1,5-Dihexadecyl N,N-diglutamyl-lysyl-L-glutamate (GGLG) liposomes were previously developed to enhance drug delivery efficiency in tumor cells owing to its pH-responsive properties. Herein, we report the modification of GGLG liposomes by conjugating a Fab′ fragment of an ErbB2 antibody to the terminus of PEG (polyethylene glycol)-lipid (Fab′-GGLG liposomes). The conjugation of Fab′ fragments did not affect the antibody activity, drug (doxorubicin, DOX) encapsulation efficiency, stability during storage or pH-sensitivity. However, the binding affinity of Fab′-GGLG liposomes was enhanced to ErbB2-overexpressing HCC1954 cells specifically, and the cell association increased 10-fold in comparison to GGLG liposomes. Consequently, intracellular DOX delivery was enhanced, with an increased cytotoxicity in HCC1954 cells (i.e., IC50 of 1.17 and 3.08 μg/mL for Fab′-GGLG-DOX and GGLG-DOX liposomes, respectively). Further, a significantly enhanced tumor growth inhibition was obtained in an ErbB2-overexpressing breast cancer-bearing mouse model. Therefore, a potent anticancer drug delivery system was constructed by the immunological modification of pH-sensitive liposomes.

Tumor-targeted micelle-forming block copolymers for overcoming of multidrug resistance

New amphiphilic diblock polymer nanotherapeutics serving simultaneously as a drug delivery system and an inhibitor of multidrug resistance were designed, synthesized, and evaluated for their physico-chemical and biological characteristics. The amphiphilic character of the diblock polymer, containing a hydrophilic block based on the N-(2-hydroxypropyl)methacrylamide copolymer and a hydrophobic poly(propylene oxide) block (PPO), caused self-assembly into polymer micelles with an increased hydrodynamic radius (Rh of approximately 15nm) in aqueous solutions. Doxorubicin (Dox), as a cytostatic drug, was bound to the diblock polymer through a pH-sensitive hydrazone bond, enabling prolonged circulation in blood, the delivery of Dox into a solid tumor and the subsequent stimuli-sensitive controlled release within the tumor mass and tumor cells at a decreased pH. The applicability of micellar nanotherapeutics as drug carriers was confirmed by an in vivo evaluation using EL4 lymphoma-bearing C57BL/6 mice. We observed significantly higher accumulation of micellar conjugates in a solid tumor because of the EPR effect compared with similar polymer-drug conjugates that do not form micellar structures or with the parent free drug. In addition, highly increased anti-tumor efficacy of the micellar polymer nanotherapeutics, even at a sub-optimal dose, was observed. The presence of PPO in the structure of the diblock polymer ensured, during in vitro tests on human and mouse drug-sensitive and resistant cancer cell lines, the inhibition of P-glycoprotein, one of the most frequently expressed ATP-dependent efflux pump that causes multidrug resistance. In addition, we observed highly increased rate of the uptake of the diblock polymer nanotherapeutics within the cells. We suppose that combination of unique properties based on MDR inhibition, stimuli sensitiveness (pH sensitive activation of drug), improved pharmacokinetics and increased uptake into the cells made the described polymer micelle a good candidate for investigation as potential drug delivery system.

DOX delivery based on chitosan-capped graphene oxide-mesoporous silica nanohybride as pH-responsive nanocarriers

pH-responsive chitosan-coated graphene oxide-mesoporous silica nanoparticles (GMSN-Cs) was synthesized as a core–shell nanosheets to be used as DOX delivery system. First of all, an inorganic nanohybrid (GMSN) was prepared and subsequently, chitosan was attached to the mesoporous silica part through firm covalent bonds to form a reliable vector for DOX delivery. The chemico-physical properties of the nanosheets were specified, and DOX-loading efficiency and drug releasing was characterized in different pHs. At lower pH, the cumulative release of DOX-loaded GMSN-Cs was more than physiological pH. The in vitro hemolysis and in vivo biochemical analysis results demonstrate negligible toxicity of GMSN-Cs in mice at a high dosage of nanosheets and a disposal time (up to 10 days). DOX can be loaded efficiently on GMSN-Cs, and the resulting DOX–GMSN-Cs represents meaningful cytotoxicity in different pHs and concentrations for MCF-7 cells. The results and observations confirmed that the drug release of DOX-loaded GMSN-Cs can be controlled by physiological stimulant to reduce the side effects.

“Gold nanoparticles composite-folic acid conjugated graphene oxide nanohybrids” for targeted chemo-thermal cancer ablation: In vitro screening and in vivo studies

Nano-graphene oxide (GO) nanometal composite (specifically nanogold and nanosilver) have shown to be a promising material for anticancer therapeutics. Owing to their high drug loading capacity, photothermal and synergizing effects, it is very important to exploit them for targeted chemo-thermal cancer therapeutics. In this work, gold nanoparticles (AuNPs) were selected as the composite metal, folic acid (FA) was taken as GO surface functionalization moiety for active tumor targeting of model anticancer drug Doxorubicin (Dox). AuNPs composite-folate conjugated graphene oxide (FA-GO@Au) nano-platforms were synthesized and characterized in detail. Near-infrared (NIR) sensitivity resulted in an aggravated release of both Dox and ionic gold from the nanohybrid surface. Simultaneous delivery of Dox and AuNPs in the cellular vicinity was further enhanced after localized NIR exposure which resulted in significantly improved cancer cell toxicity. Mechanistic evaluation revealed G0/G1 phase arrest due to increased DNA intercalation and provoked early apoptosis under NIR influence. Pharmacokinetics and organ distribution studies were carried out in healthy mice and rabbits to estimate the actual bio fate of these nanohybrids. In vivo studies showed substantial tumor regression in solid tumor model in Balb/c mice and NIR exposure induced photo-thermal effects further resulted in better tumor management. Study provides substantial evidences both at in vitro and in vivo level to support the fact that NIR induced local photo-thermal effects can solely be used as a tumor targeting tool. This NIR dependent nanohybrid approach presents a precise and flexible strategy for targeted chemotherapy and photo-thermal tumor ablation.

Raspberry-like poly(γ-glutamic acid) hydrogel particles for pH-dependent cell membrane passage and controlled cytosolic delivery of antitumor drugs.

In this research, we synthesized bioderived poly(amino acid) hydrogel particles that showed pH-dependent membrane-disrupting properties and controlled cytosolic delivery of antitumor drugs. Poly(γ-glutamic acid) (γ-PGA) that has been produced extensively using bacteria, especially those of Bacillus subtilis species, was modified with cholesterol (γ-PGA/Chol), and the γ-PGA/Chol conjugates were used to form polymeric nanoparticles the size of 21.0±1.1 nm in aqueous solution. When the polymeric nanoparticles were mixed with doxorubicin (Dox), raspberry-like hydrogel particles (RBHPs) were formed by the electrostatic interaction between the cationically charged Dox and the anionically charged nanoparticles. The average size and surface charge of the RBHPs in aqueous solution were 444.9±122.5 nm and −56.44 mV, respectively. The loaded amount of Dox was approximately 63.9 μg/mg of RBHPs. The RBHPs showed controlled drug release behavior in both in vitro and ex vivo cell-based experiments. Through fluorescence microscopy and fluorescence-activated cell sorting, the cellular uptake of RBHPs into human cervical cancer cells (HeLa) was analyzed. The cytotoxic effect, evaluated by the methyl tetrazolium salt assay, was dependent on both the concentration of RBHPs and the treatment time. The pH-dependent membrane-disrupting properties of the RBHPs and the subsequent cytosolic delivery of Dox were evaluated using a standard hemolysis assay. Upon an increase in hydrophobicity at the lysosomal acidic pH, RBHPs could easily interact, penetrate cell membranes, and destabilize them. Taken together, the data suggested that RBHPs could be used as drug delivery carriers after loading with other therapeutic drugs, such as proteins or small interfering RNA for cancer therapy.

Robust, tumor-homing and redox-sensitive polymersomal doxorubicin: A superior alternative to Doxil and Caelyx?

Pegylated liposomal doxorubicin (Lipo-Dox) is one of the few clinically used cancer nanomedicines. Here we show that tumor-homing, redox-responsive and reversibly crosslinked multifunctional biodegradable polymersomes are a better alternative to liposomes for Dox delivery. Cyclic peptide cNGQGEQc-decorated polymersomes (cNGQ-PS) are easily prepared with a small size and high Dox loading. Dox-loaded cNGQ-PS (cNGQ-PS-Dox) shows superb stability with minimal drug leakage under physiological conditions while spontaneous disassembly and quick drug release in response to 10mM glutathione. MTT assays, flow cytometry and confocal microscopy clearly display efficient receptor-mediated internalization of cNGQ-PS-Dox, fast intracellular drug release, and high antitumor activity in α3β1 integrin-overexpressing A549 lung cancer cells. Intriguingly, cNGQ-PS-Dox presents a remarkably high maximum-tolerated dose of over 100mg/kg, over 6-fold higher than Lipo-Dox. The in vivo pharmacokinetics and biodistribution studies reveal that cNGQ-PS-Dox has a long circulation time and significantly enhanced tumor accumulation (8.60%ID/g) as compared to Lipo-Dox and non-targeting PS-Dox controls. Notably, cNGQ-PS-Dox shows superior treatment of both subcutaneous and orthotopic A549 human lung cancer bearing nude mice to Lipo-Dox, resulting in effective tumor suppression, significantly improved survival time, and markedly reduced adverse effects. cNGQ-PS appears to be a clinically viable system for targeted lung cancer chemotherapy.