The role of critical micellization concentration in efficacy and toxicity of supramolecular polymers.

The inception and development of supramolecular chemistry have provided a vast library of supramolecular structures and materials for improved practice of medicine. In the context of therapeutic delivery, while supramolecular nanostructures offer a wide variety of morphologies as drug carriers for optimized targeting and controlled release, concerns are often raised as to how their morphological stability and structural integrity impact their in vivo performance. After intravenous (i.v.) administration, the intrinsic reversible and dynamic feature of supramolecular assemblies may lead them to dissociate upon plasma dilution to a concentration below their critical micellization concentration (CMC). As such, CMC represents an important characteristic for supramolecular biomaterials design, but its pharmaceutical role remains elusive. Here, we report the design of a series of self-assembling prodrugs (SAPDs) that spontaneously associate in aqueous solution into supramolecular polymers (SPs) with varying CMCs. Two hydrophobic camptothecin (CPT) molecules were conjugated onto oligoethylene-glycol (OEG)-decorated segments with various OEG repeat numbers (2, 4, 6, 8). Our studies show that the lower the CMC, the lower the maximum tolerated dose (MTD) in rodents. When administrated at the same dosage of 10 mg/kg (CPT equivalent), SAPD 1, the one with the lowest CMC, shows the best efficacy in tumor suppression. These observations can be explained by the circulation and dissociation of SAPD SPs and the difference in molecular and supramolecular distribution between excretion and organ uptake. We believe these findings offer important insight into the role of supramolecular stability in determining their therapeutic index and in vivo efficacy.

Thiolated Nanoparticles Overcome the Mucus Barrier and Epithelial Barrier for Oral Delivery of Insulin.

Oral administration is an ideal alternative for drug delivery due to its convenience and safety. However, oral protein delivery is limited by biological barriers such as the mucus barrier and epithelial barrier, which hamper drugs from entering the blood successfully. Here we presented PC6/CS NPs, a thiolated-polymer-based nanodrug delivery system in the form of poly(acrylic acid)-cysteine-6-mercaptonicotinic acid (PAA-Cys-6MNA, PC6), which is a kind of preactivated thiolated polymer, coated on chitosan (CS) nanoparticles (NPs). Its ability to overcome the mucus barrier and epithelial barrier was investigated. The existence of PC6 made the NPs prone to penetrate the mucus layer as well as strengthened the transcellular transport of insulin on epithelial cells. PC6/CS NPs efficiently enhanced the oral bioavailability of insulin to 16.2%. The improvement resulted from the function of PC6: (1) "diluting" mucus to promote nanoparticle penetration, (2) opening a tight junction to help insulin transport via the paracellular pathway, (3) making the nanoparticle more electrically neutral during the penetration process, and (4) uncoating from PC6/CS NPs so that positive CS NPs were adhered and uptaken by epithelial cells. Our study proves that PC6/CS NPs, which can achieve mucus penetration and epithelial permeation efficiently, are a potential nanocarrier for oral protein delivery.

Effects of crystalline state and self-nanoemulsifying drug delivery system (SNEDDS) on oral bioavailability of the novel anti-HIV compound 6-benzyl-1-benzyloxymethyl-5-iodouracil in rats.

The objective of this study was to investigate the effect of crystalline state and a formulation of self-nanoemulsifying drug delivery system (SNEDDS) on oral bioavailability of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1), a novel non-nucleoside reverse transcriptase inhibitor, in rats. The crystalline states of W-1 were characterized by scanning electron microscope (SEM), differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD). The SNEDDS was formulated by medium-chain lipids, characterized by droplet particle size. The plasma concentrations of W-1 were measured by high performance liquid chromatography (HPLC). The results indicated that W-1 compound were presented as crystalline forms, A and B, the degree of crystallization in form B was higher than that in form A. The SNEDDS of W-1 displayed a significant increase in the dissolution rate than W-1 powder. Furthermore, after oral administration of W-1 (100 mg/kg), the pharmacokinetic parameters of form A, form B, and W-1 SNEDDS were as follows: AUC0-t 526.4 ± 123.5, 305.1 ± 58.5 and 2297 ± 451 ng h/mL (p < .05, when W-1 SNEDDS were compared with either form A or form B), respectively. With SNEDDS formulation, the relative bioavailabilities were enhanced by 4.36-fold and 7.53-fold over the form A and form B of W-1, respectively. In conclusion, the present results suggested that the crystalline states of W-1 might lead to the lower oral bioavailability, and SNEDDS formulation is a promising strategy of improving bioavailability, in spite of that crystalline states usually carry small lot-to-lot variability.

Increased cellular uptake of peptide-modified PEGylated gold nanoparticles.

Gold nanoparticles are promising drug delivery vehicles for nucleic acids, small molecules, and proteins, allowing various modifications on the particle surface. However, the instability and low bioavailability of gold nanoparticles compromise their clinical application. Here, we functionalized gold nanoparticles with CPP fragments (CALNNPFVYLI, CALRRRRRRRR) through sulfhydryl PEG to increase their stability and bioavailability. The resulting gold nanoparticles were characterized with transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-visible spectrometry and X-ray photoelectron spectroscopy (XPS), and the stability in biological solutions was evaluated. Comparing to PEGylated gold nanoparticles, CPP (CALNNPFVYLI, CALRRRRRRRR)-modified gold nanoparticles showed 46 folds increase in cellular uptake in A549 and B16 cell lines, as evidenced by the inductively coupled plasma atomic emission spectroscopy (ICP-AES). The interactions between gold nanoparticles and liposomes indicated CPP-modified gold nanoparticles bind to cell membrane more effectively than PEGylated gold nanoparticles. Surface plasmon resonance (SPR) was used to measure interactions between nanoparticles and the membrane. TEM and uptake inhibitor experiments indicated that the cellular entry of gold nanoparticles was mediated by clathrin and macropinocytosis. Other energy independent endocytosis pathways were also identified. Our work revealed a new strategy to modify gold nanoparticles with CPP and illustrated the cellular uptake pathway of CPP-modified gold nanoparticles.

A tenascin C targeted nanoliposome with navitoclax for specifically eradicating of cancer-associated fibroblasts.

Cancer-associated fibroblasts (CAFs) play a vitally important role during tumor progression. Navitoclax (Nav) can specifically induce apoptosis in CAFs. The present study aims to develop a novel CAF-targeted nanoliposome for cancer therapy. Nav-loaded nanoliposomes modified with peptide FH (FH-SSL-Nav), which specifically binds to tenascin C, a protein mainly expressed by CAFs, were formulated and characterized. Several experiments were performed to evaluate CAFs selective apoptosis, targeting and eradicating. Compared with SSL-Nav, FH-SSL-Nav achieved higher cellular uptake, and exhibited stronger cytotoxicity in vitro. The in vivo tumor stroma targeting effect was further confirmed by near infrared imaging. Accordingly, FH-SSL-Nav displayed improved tumor growth inhibition by eradicating CAFs in Hep G2 tumor-bearing nude mice model. In conclusion, FH-SSL-Nav could achieve targeting delivery of Nav to CAFs in vitro and in vivo, and may offer a potential strategy for cancer therapy based on tumor stroma. From the Clinical Editor: The progression of cancer cells often depends on the underlying tumor microenvironment, in which cancer-associated fibroblasts play an important role. In this article, the authors developed targeted therapy against CAFs using liposomes as carriers. This new modality was shown to be more effective in tumor killing both in vitro and in vivo. The finding may open a new era in cancer therapy.

A nanomedicine based combination therapy based on QLPVM peptide functionalized liposomal tamoxifen and doxorubicin against Luminal A breast cancer.

Though combination chemotherapy or antitumor nanomedicine is extensively investigated, their combining remains in infancy. Additionally, enhanced delivery of estrogen or its analogs to tumor with highly-expressed estrogen-receptor (ER) is seldom considered, despite its necessity for ER-positive breast cancer treatment. Here, nanomedicine based combination therapy using QLPVM conjugated liposomal tamoxifen (TAM) and doxorubicin (DOX) was designed and testified, where the penta-peptide was derived from Ku70 Bax-binding domain. Quantitative, semi-quantitative and qualitative approaches demonstrated the enhanced endocytosis and cytotoxicity of QLPVM conjugated sterically stabilized liposomes (QLPVM-SSLs) in vitro and in vivo. Mechanism studies of QLPVM excluded the possible electrostatic, hydrophobic or receptor-ligand interactions. However, as a weak cell-penetrating peptide, QLPVM significantly induced drug release from QLPVM-SSLs during their interaction with cells, which was favorable for drug internalization. These findings suggested that the nanomedicine based combination therapy using QLPVM-SSL-TAM and QLPVM-SSL-DOX might provide a rational strategy for Luminal A breast cancer. FROM THE CLINICAL EDITOR: Breast cancer remains a leading cause of mortality in women worldwide. Although combined therapy using hormonal antagonist and chemotherapy is the norm nowadays, the use of these agents together in a single delivery system has not been tested. Here, the authors investigated this approach using QLPVM conjugated liposomes in in-vitro and in-vivo models. The positive findings may provide a novel direction for breast cancer treatment in the near future.

[The integrity study on PEG-PCL micelles transcellular transported across MDCK epithelial cell monolayer using FRET technology].

The integrity of poly(ethylene glycol)-co-poly(ε-caprolactone) (PEG-PCL) micelles transcellular transported across madin-darby canine kidney(MDCK) epithelial cells was investigated. Fluorescein isothiocyanate isomer I(FITC) was conjugated to PEG-PCL and the product PEG-PCL-FITC was identified by fluorescence spectra. Two micelles were prepared using the thin-film hydration method: 3,3'-dioctadecyloxacarbocyanine perchlorate (DiO) and 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) co-loaded PEG-PCL micelles (DiO-DiI-M), DiI loaded and PEG-PCL-FITC contained micelles(FITC-DiI-M). The size of the micelles was characterized by dynamic light scattering analysis using a Malvern Zetasizer Nano ZS and it turned out that the particle sizes of both micelles were about 30 nm with identical polydispersity index(PDI). The stability of the micelles in phosphate buffer saline(PBS) was monitored using fluorescence spectra and both micelles were stable within 4 h in PBS. The integrity of PEG-PCL micelles in the transcellular process across MDCK epithelial cell monolayer at 1 and 4 h was investigated using laser confocal scanning microscope and Förster resonance energy transfer(FRET) technology. The Person's coefficient and FRET efficiency of both Transwell layer and Receive layer were recorded. The results show that the FRET efficiency and Person's coefficient of the Receive layer was consistent with that of Transwell layer for both the micelles at 1 h, but decreased at 4 h and FITC-DiI-M decreased more significantly than Di O-DiI-M. The results indicated that the micelles could transport across the MDCK monolayer intactly at 1 h but some of them were disassembled during the 4 h transportation process.

Novel free-paclitaxel-loaded redox-responsive nanoparticles based on a disulfide-linked poly(ethylene glycol)-drug conjugate for intracellular drug delivery: synthesis, characterization, and antitumor activity in vitro and in vivo.

To address the obstacles facing cancer chemotherapeutics, including toxicity, side effects, water insolubility, and lack of tumor selectivity, a novel stimuli-responsive drug-delivery system was developed based on paclitaxel-loaded poly(ethylene glycol)-disulfide-paclitaxel conjugate nanoparticles (PEG-SS-PTX/PTX NPs). The formulation emphasizes several benefits, including polymer-drug conjugates/prodrugs, self-assembled NPs, high drug content, redox responsiveness, and programmed drug release. The PTX-loaded, self-assembled NPs, with a uniform size of 103 nm, characterized by DLS, TEM, XRD, DSC, and (1)H NMR, exhibited excellent drug-loading capacity (15.7%) and entrapment efficiency (93.3%). PEG-SS-PTX/PTX NPs were relatively stable under normal conditions but disassembled quickly under reductive conditions, as indicated by their triggered-aggregation phenomena and drug-release profile in the presence of dithiothreitol (DTT), a reducing agent. Additionally, by taking advantage of the difference in the drug-release rates between physically loaded and chemically conjugated drugs, a programmed drug-release phenomenon was observed, which was attributed to a higher concentration and longer action time of the drugs. The influence of PEG-SS-PTX/PTX NPs on in vitro cytotoxicity, cell cycle progression, and cellular apoptosis was determined in the MCF-7 cell line, and the NPs demonstrated a superior anti-proliferative activity associated with PTX-induced cell cycle arrest in G2/M phase and apoptosis compared to their nonresponsive counterparts. Moreover, the redox-responsive NPs were more efficacious than both free PTX and the non-redox-responsive formulation at equivalent doses of PTX in a breast cancer xenograft mouse model. This redox-responsive PTX drug delivery system is promising and can be explored for use in effective intracellular drug delivery.

Inhibition of metastatic tumor growth and metastasis via targeting metastatic breast cancer by chlorotoxin-modified liposomes.

A liposome system modified with chlorotoxin (ClTx), a scorpion venom peptide previously utilized for targeting brain tumors, was established. Its targeting efficiency and antimetastasis behavior against metastatic breast cancer highly expressed MMP-2, the receptor of ClTx, were investigated. 4T1, a metastatic breast cancer cell line derived from a murine breast tumor, was selected as the cell model. As results, the ClTx-modified liposomes displayed specific binding to 4T1 as determined by flow cytometry and confocal imaging. The cytotoxicity assay revealed that the ClTx modification increased the toxicity compared with nonmodified liposomes. In addition, the modified liposomes also exhibited high in vivo targeting efficiency in the BALB/c mice bearing 4T1 tumors. Importantly, this system inhibited the growth of metastatic tumor and prevented the incidence of lung metastasis in mice bearing 4T1 tumors with only low systemic toxicity. The data obtained from the in vitro and in vivo studies confirmed that the ClTx-modified liposomes increased the drug delivery to metastatic breast cancers. This study proved that the ClTx-modified liposomes had targeting ability to metastatic breast cancer in addition to brain cancer, and displayed an obvious antimetastasis effect. Generally, it may provide a promising strategy for metastatic breast cancer therapy.

[Stabilized thiomer PAA-Cys-6MNA].

The aimed of this study was to prepare stabilized thiomers to overcome the poor stability character of traditional thiomers. Poly(acrylic acid)-cysteine (PAA-Cys) was synthesized by conjugating cysteine with poly(acrylic acid) and poly(acrylic acid)-cysteine-6-mercaptonicotinic acid (PAA-Cys-6MNA, stabilized thiomers) was synthesized by grafting a protecting group 6-mercaptonicotinic acid (6MNA) with PAA-Cys. The free thiol of PAA-Cys was determined by Ellmann's reagent method and the ratio of 6MNA coupled was determined by glutathione reduction method. The study of permeation enhancement and stabilized function was conducted by using Franz diffusion cell method, with fluorescein isothiocyanate dextran (FD4) used as model drug. The influence of polymers on tight junctions of Caco-2 cell monolayer was detected with laser scanning confocal fluorescence microscope. The results indicated that both PAA-Cys and PAA-Cys-6MNA could promote the permeation of FD4 across excised rat intestine, and the permeation function of PAA-Cys-6MNA was not influence by the pH of the storage environment and the oxidation of air after the protecting group 6MNA was grafted. The distribution of tight junction protein of Caco-2 cell monolayer F-actin was influenced after incubation with PAA-Cys and PAA-Cys-6MNA. In conclusion, stabilized thiomers (PAA-Cys-6MNA) maintained the permeation function compared with the traditional thiomers (PAA-Cys) and its stability was improved. The mechanism of the permeation enhancement function of the polymers might be related to their influence on tight junction relating proteins of cells.

Evaluations of therapeutic efficacy of intravitreal injected polylactic-glycolic acid microspheres loaded with triamcinolone acetonide on a rabbit model of uveitis.

Conventional treatments of uveitis are not ideal because of the short period of therapeutic efficacy. In the present study, biodegradable polylactic-glycolic acid microspheres loaded with triamcinolone acetonide (TA) were prepared to achieve sustained drug release and their therapeutic efficacy was investigated on a rabbit model of uveitis. TA-loaded microspheres (TA-MS) were prepared by the solvent evaporation method and characterized for encapsulation efficiency, particle size, morphology and in vitro release. The therapeutic efficacy was studied on the rabbit experimental uveitis model based on scoring of the inflammation, aqueous leukocyte counting, aqueous protein determination and histological examination. The TA-MS exhibited smooth and intact surfaces with an average diameter of 50.87 µm. The drug-loading coefficient and encapsulation efficiency were 15.2 ± 0.6 % and 91.24 ± 3.77 %, respectively. The drug release from TA-MS lasted up to 87 days, but only 46 days for TA suspension. The change in surface morphology also showed sustained drug release from TA-MS. TA-MS exhibited improved therapeutic efficacy in lipopolysaccharide -induced uveitis compared to TA suspension, especially in regard to the inhibition of inflammation. The TA-MS had a longer-term therapeutic effect on intraocular inflammation in LPS-induced uveitis in rabbits compared to TA suspension. The results suggested that TA-MS can be developed as a potential sustained-release system for the treatment of uveitis.

Nanotoxicity comparison of four amphiphilic polymeric micelles with similar hydrophilic or hydrophobic structure.

BACKGROUND: Nanocarriers represent an attractive means of drug delivery, but their biosafety must be established before their use in clinical research. OBJECTIVES: Four kinds of amphiphilic polymeric (PEG-PG-PCL, PEEP-PCL, PEG-PCL and PEG-DSPE) micelles with similar hydrophilic or hydrophobic structure were prepared and their in vitro and in vivo safety were evaluated and compared. METHODS: In vitro nanotoxicity evaluations included assessments of cell morphology, cell volume, inflammatory effects, cytotoxicity, apoptosis and membrane fluidity. An umbilical vein cell line (Eahy.926) and a kind of macrophages (J774.A1) were used as cell models considering that intravenous route is dominant for micelle delivery systems. In vivo analyses included complete blood count, lymphocyte subset analysis, detection of plasma inflammatory factors and histological observations of major organs after intravenous administration to KM mice. RESULTS: All the micelles enhanced inflammatory molecules in J774.A1 cells, likely resulting from the increased ROS levels. PEG-PG-PCL and PEEP-PCL micelles were found to increase the J774.A1 cell volume. This likely correlated with the size of PEG-PG-PCL micelles and the polyphosphoester structure in PEEP-PCL. PEG-DSPE micelles inhibited the growth of Eahy.926 cells via inducing apoptosis. This might relate to the structure of DSPE, which is a type of phospholipid and has good affinity with cell membrane. No evidence was found for cell membrane changes after treatment with these micelles for 24 h. In the in vivo study, during 8 days of 4 time injection, each of the four nanocarriers altered the hematic phase differently without changes in inflammatory factors or pathological changes in target organs. CONCLUSIONS: These results demonstrate that the micelles investigated exhibit diverse nanotoxicity correlated with their structures, their biosafety is different in different cell model, and there is no in vitro and in vivo correlation found. We believe that this study will certainly provide more scientific understandings on the nanotoxicity of amphiphilic polymeric micelles.

[Transcellular process of coumarin 6 loaded PEG-PCL micelles on MDCK epithelial cells].

The transcellular process of coumarin 6 (C6) loaded poly(ethyl ethylene phosphate)-co-poly (epsilon-caprolactone) (PEG-PCL) micelles on Madin-Darby Canine Kidney (MDCK) epithelial cells was investigated. C6 loaded PEG-PCL micelles were prepared using the thin-film hydration method. The size of the micelles was characterized by dynamic light scattering analysis using a Malvern Zetasizer Nano ZS. The critical micelle concentration (CMC) was determined by pyrene fluorescence probe method. And the transcellular process of the micelles on MDCK epithelial cells was investigated by using transmission electron microscope, laser confocal scanning microscope and Förster resonance energy transfer technology. It turned out that the size of PEG-PCL micelles was about 30 nm and CMC was 1.01 microg x mL(-1). PEG-PCL micelles were endocytosed in intact form and they could deliver hydrophobic drugs across the basolateral membrane of the epithelial cells. However, PEG-PCL is hardly being transported in micelle formation itself. The transportation of C6 by PEG-PCL micelles was through the transcellular pathway, yet not the paracellular pathway.

[Cellular toxicity and anti-tumor efficacy of iRGD modified doxorubixin loaded sterically stabilized liposomes].

iRGD-modified sterically stabilized liposomes loaded doxorubicin (iRGD-SSL-DOX) were prepared and their cellular toxicity and anti-tumor efficacy were evaluated, comparing to doxorubixin loaded sterically stabilized liposomes (SSL-DOX) and RGD modified doxorubixin loaded sterically stabilized liposomes (RGD-SSL-DOX). The iRGD peptide, with both tumor targeting and cell penetrating functions, was conjugated to DSPE-PEG-NHS and DSPE-PEG-iRGD was obtained. DSPE-PEG-RGD was gained in the same way. iRGD-SSL-DOX, RGD-SSL-DOX and SSL-DOX were prepared by ammonium sulfate gradient method. The size and zeta potential of the liposomes were characterized by dynamic laser light scattering. The cellular toxicity study was done on B16 melanoma cell line and the anti-tumor efficacy study was carried on B16 cell line bearing C57BL/6 mice. The results showed that the particle sizes of liposomes were all around 90-100 nm. DOX entrapment efficiency was above 95%. The formulations were with good preparation reproducibility. iRGD-SSL-DOX showed no significant difference in B16 cellular toxicity with SSL-DOX and RGD-SSL-DOX, but the anti-tumor efficacy on B16 melanoma bearing C57BL/6 mice was significantly better than that of SSL-DOX, similar as that of RGD-SSL-DOX. Therefore, iRGD modified liposomes loaded DOX would be a promising drug delivery system for tumor therapy.

Spatiotemporally controlled co-delivery of anti-vasculature agent and cytotoxic drug by octreotide-modified stealth liposomes.

PURPOSE: Both combretastatin A-4 (CA-4) and doxorubicin (DOX) was loaded in different form in a targeted nanomedicine in order to achieve the active delivery of these two drugs followed by sequentially suppressing tumor vasculature and tumor cells. METHODS: Octreotide-modified stealth liposomes loaded with CA-4 and DOX (Oct-L[CD]) were prepared and characterized. Then in vitro release, cellular uptake, in vitro antitumor effect, pharmacokinetics, in vivo sequential killing effect, in vivo antitumor efficacy against somatostatin receptor (SSTR) positive cells, as well as the action mechanism of such system, were studied. RESULTS: A rapid release of CA-4 followed by a slow release of DOX was observed in vitro. The active targeted liposomes Oct-L[CD] showed a specific cellular uptake through ligand-receptor interaction and a higher antitumor effect in vitro against SSTR-positive cell line. The in vivo sequential killing effect of such system was found as evidenced by the fast inhibition of blood vessels and slow apoptosis-inducing of tumor cells. Oct-L[CD] also exhibited the strongest antitumor effect in MCF-7 subcutaneous xenograft models. CONCLUSIONS: Oct-modified co-delivery system may have great potential as an effective carrier for cancer therapy.

Peptide PHSCNK as an integrin α5ß1 antagonist targets stealth liposomes to integrin-overexpressing melanoma.

As an integrin α(5)ß(1) antagonist, N-acetyl-proline-histidine-serine-cysteine-asparagine-amide (Ac-PHSCN-NH(2)) is currently in phase II trials for various cancer therapies. In this study Ac-PHSCNK-NH(2) (PHSCNK) was used as a novel homing peptide to prepare ligand-targeted liposomes loaded with doxorubicin (PHSCNK-PL-DOX), with the hypothesis that the therapy target of integrin α(5)ß(1) may also serve as a delivery target. The stealth liposomes loaded with doxorubicin (PL-DOX) were used as the control. PHSCNK-PL-DOX demonstrated an enhanced intracellular uptake and a greater cytotoxicity against melanoma B16F10 cells in comparison with PL-DOX. The novel targeted formulation displayed stronger tumor inhibition and prolonged survival time in comparison with controls in C57BL/6 mice bearing B16F10 tumors, and it exhibited less heart toxicity in hematoxylin-eosin (H&E) staining of tissues. Taking the pharmacokinetics and biodistribution results into account, the authors conclude that α(5)ß(1) integrin-mediated liposomes might be used as a potential delivery system for targeted tumor therapy. FROM THE CLINICAL EDITOR: Lactosyl-norcantharidin TMC nanoparticles were found superior in comparison with Lac-NCTD and Lac-NCTD chitosan nanoparticles from the standpoint of antitumor activity on murine hepatocarcinoma 22 subcutaneous model.

Targeted delivery of a combination therapy consisting of combretastatin A4 and low-dose doxorubicin against tumor neovasculature.

The present study demonstrates the applicability of a novel strategy that employs targeted delivery of combined treatment against tumor neovasculature. Briefly, a ligand of integrins, cyclic arginine-glycine-aspartic acid-tyrosine-lysine pentapeptide (cRGDyK), was conjugated to the PEG end of polyethylene glycol-b-poly lactic acid (PEG-b-PLA), and doxorubicin was chemically linked to the PLA end of PEG-b-PLA. The targeted dual-drug micelle system was prepared by mixing combretastatin A4 (an antivascular agent), PEG-b-PLA, and the above two conjugates using a solution-casting method. The targeted micelles significantly enhanced cellular uptake of the drug by B16-F10 cells and human umbilical vein endothelial cells through a receptor-mediated endocytosis. The cRGDyK-modified dual-drug system achieved an optimal antitumor effect, lifespan increase, antineovasculature, antiproliferation, and apoptosis induction, revealing the advantage of active targeting and the modified combination therapy. In conclusion, the integration of targeted delivery and combination therapy against tumor neovasculature represents a promising approach for cancer treatment. FROM THE CLINICAL EDITOR: A ligand of integrins was conjugated to PEG-b-PLA, and doxorubicin was chemically linked to the PLA. Efficiency was demonstrated in a cancer model. The integration of targeted delivery and combination therapy against tumor neovasculature represents a promising approach for cancer treatment.

A cremophor-free self-microemulsified delivery system for intravenous injection of teniposide: evaluation in vitro and in vivo.

In order to tackle the problems on low water solubility of teniposide, involvement of toxic surfactant in its injection, and the poor stability during infusion, a Cremophor-free teniposide self-microemulsified drug delivery system (TEN-SMEDDS) was prepared for the first time, characterized, and evaluated in comparison with teniposide injection (VUMON) in vitro and in vivo. The optimized formulation contained N, N-dimethylacetamide, medium-chain triglyceride, lecithin, and dehydrated alcohol besides teniposide. The TEN-SMEDDS could form fine droplets with mean diameter of 282 ± 21 nm and zeta potential of -7.5 ± 1.7 mV after dilution with 5% glucose, which were stable within 4 h. The release of teniposide from TEN-SMEDDS and VUMON was similar. However, the pharmacokinetic behavior of TEN-SMEDDS in rats was different from that of VUMON, evidenced by the lower area under the concentration-time curve and larger volume of distribution in emulsion group. Finally, TEN-SMEDDS was found to distribute more teniposide in most tissues, especially in reticuloendothelial system, after intravenous administration to rats. Importantly, brain drug level in TEN-SMEDDS group was higher than or similar to that in control group, although the emulsion system had a lower plasma drug concentration. In conclusion, the novel SMEDDS prepared here, without toxic surfactant and as an oil solution before use, may be potential for clinical use due to its low toxicity and high store stability. It may be favorable for the treatment of some tumors like cerebroma, since it may achieve the relatively higher drug level in brain but lower blood concentration.

Regulating Interactions Between Targeted Nanocarriers and Mononuclear Phagocyte System via an Esomeprazole-Based Preconditioning Strategy.

PURPOSE: The mononuclear phagocyte system (MPS) presents a formidable obstacle that hampers the delivery of various nanopreparations to tumors. Therefore, there is an urgent need to improve the off-MPS targeting ability of nanomedicines. In the present study, we present a novel preconditioning strategy to substantially increase the circulation times and tumor targeting of nanoparticles by regulating nanocarrier-MPS interactions. METHODS: In vitro, the effect of different vacuolar H+-ATPase inhibitors on macrophage uptake of targeted or nontargeted lipid vesicles was evaluated. Specifically, the clinically approved proton-pump inhibitor esomeprazole (ESO) was selected as a preconditioning agent. Then, we further investigated the blocking effect of ESO on the macrophage endocytosis of nanocarriers. In vivo, ESO was first intravenously administered into A549-tumor-bearing nude mice, and 24 h later, the c(RGDm7)-modified vesicles co-loaded with doxorubicin and gefitinib were intravenously injected. RESULTS: In vitro, ESO was found to reduce the interactions between macrophages and c(RGDm7)-modified vesicles by interfering with the latter's lysosomal trafficking. Studies conducted in vivo confirmed that ESO pretreatment greatly decreased the liver and spleen distribution of the targeted vesicles, enhanced their tumor accumulation, and improved the therapeutic outcome of the drug-loaded nanomedicines. CONCLUSION: Our findings indicate that ESO can regulate the nanoparticle-MPS interaction, which provides a feasible option for enhancing the off-MPS targeting of nanomedicines.

Nano-encapsulated tryptanthrin derivative for combined anticancer therapy via inhibiting indoleamine 2,3-dioxygenase and inducing immunogenic cell death.

Aim: We developed a polycaprolactone-based nanoparticle (NP) to encapsulate tryptanthrin derivative CY-1-4 and evaluated its antitumor efficacy. Materials & methods: CY-1-4 NPs were prepared and evaluated for their cytotoxicity and associated mechanisms, indoleamine 2,3-dioxygenase (IDO)-inhibitory ability, immunogenic cell death (ICD)-inducing ability and antitumor efficacy. Results: CY-1-4 NPs were 123 nm in size. In vitro experiments indicated that they could both induce ICD and inhibit IDO. In vivo studies indicated that a medium dose reduced 58% of the tumor burden in a B16-F10-bearing mouse model, decreased IDO expression in tumor tissues and regulated lymphocytes subsets in spleen and tumors. Conclusion: CY-1-4 is a potential antitumor candidate that could act as a single agent with combined functions of IDO inhibition and ICD induction.