Reversion of multidrug resistance with polyalkylcyanoacrylate nanoparticles: towards a mechanism of action

Fabrication and characterization of chitosan nanoparticles using the coffee-ring effect for photodynamic therapy

BACKGROUND AND OBJECTIVES

Biocompatible nanoparticles have been increasingly used in a variety of medical applications, including photodynamic therapy. Although the impact of synthesis parameters and purification methods is reported in previous studies, it is still challenging to produce a reliable protocol for the fabrication, purification, and characterization of nanoparticles in the 200-300 nm range that are highly monodisperse for biomedical applications.

STUDY DESIGN/MATERIALS AND METHODS

We investigated the synthesis of chitosan nanoparticles in the 200-300 nm range by evaluating the chitosan to sodium tripolyphosphate (TPP) mass ratio and acetic acid concentration of the chitosan solution. Chitosan nanoparticles were also crosslinked to rose bengal and incubated with human breast cancer cells (MCF-7) to test photodynamic activity using a green laser (λ = 532 nm, power = 90 mW).

RESULTS

We established a simple protocol to fabricate and purify biocompatible nanoparticles with the most frequent size occurring between 200 and 300 nm. This was achieved using a chitosan to TPP mass ratio of 5:1 in 1% v/v acetic acid at a pH of 5.5. The protocol involved the formation of nanoparticle coffee rings that showed the particle shape to be spherical in the first approximation. Photodynamic treatment with rose bengal-nanoparticles killed ~98% of cancer cells.

CONCLUSION

A simple protocol was established to prepare and purify spherical and biocompatible chitosan nanoparticles with a peak size of ~200 nm. These have remarkable antitumor activity when coupled with photodynamic treatment.

Targeted Delivery of Drugs and Genes Using Polymer Nanocarriers for Cancer Therapy

Cancer is one of the primary causes of worldwide human deaths. Most cancer patients receive chemotherapy and radiotherapy, but these treatments are usually only partially efficacious and lead to a variety of serious side effects. Therefore, it is necessary to develop new therapeutic strategies. The emergence of nanotechnology has had a profound impact on general clinical treatment. The application of nanotechnology has facilitated the development of nano-drug delivery systems (NDDSs) that are highly tumor selective and allow for the slow release of active anticancer drugs. In recent years, vehicles such as liposomes, dendrimers and polymer nanomaterials have been considered promising carriers for tumor-specific drug delivery, reducing toxicity and improving biocompatibility. Among them, polymer nanoparticles (NPs) are one of the most innovative methods of non-invasive drug delivery. Here, we review the application of polymer NPs in drug delivery, gene therapy, and early diagnostics for cancer therapy.

The challenges and applications of nanotechnology against bacterial resistance

Bacterial resistance to the antibiotics develops rapidly and is increasingly serious health concern in the world. It is an insoluble topic due to the multiple resistant mechanisms. The overexpression of relative activities of the efflux pump has proven to be a frequent and important source of bacterial resistance. Efflux transporters in the membrane from the resistant bacteria could play a key role to inhibit the intracellular drug intake and impede the drug activities. However, nanoparticles (NPs), one of the most frequently used encapsulation materials, could increase the intracellular accumulation of the drug and inhibit the transporter activity effectively. The rational and successful application of nanotechnology is a key factor in overcoming bacterial resistance. Furthermore, nanoparticles such as metallic, carbon nanotubes and so on, may prevent the development of drug resistance and be associated with antibiotic agents, inhibiting biofilm formation or increasing the access into the target cell and exterminating the bacteria eventually. In the current study, the mechanisms of bacterial resistance are discussed and summarized. Additionally, the opportunities and challenges in the use of nanoparticles against bacterial resistance are also illuminated. At the same time, the use of nanoparticles to combat multidrug-resistant bacteria is also investigated by coupling natural antimicrobials or other alternatives. In short, we have provided a new perspective for the application of nanoparticles against multidrug-resistant bacteria.

Nanomedicines in Diagnosis and Treatment of Cancer: An Update

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Nanomedicine has revolutionized the field of cancer detection and treatment by enabling the delivery of imaging agents and therapeutics into cancer cells. Cancer diagnostic and therapeutic agents can be either encapsulated or conjugated to nanosystems and accessed to the tumor environment through the passive targeting approach (EPR effect) of the designed nanomedicine. It may also actively target the tumor exploiting conjugation of targeting moiety (like antibody, peptides, vitamins, and hormones) to the surface of the nanoparticulate system. Different diagnostic agents (like contrast agents, radionuclide probes and fluorescent dyes) are conjugated with the multifunctional nanoparticulate system to achieve simultaneous cancer detection along with targeted therapy. Nowadays targeted drug delivery, as well as the early cancer diagnosis is a key research area where nanomedicine is playing a crucial role. This review encompasses the significant recent advancements in drug delivery as well as molecular imaging and diagnosis of cancer exploiting polymer-based, lipid-based and inorganic nanoparticulate systems.

Doxorubicin-loaded nanoparticles for patients with advanced hepatocellular carcinoma after sorafenib treatment failure (RELIVE): a phase 3 randomised controlled trial

BACKGROUND

Cytotoxic chemotherapy is generally ineffective in patients with hepatocellular carcinoma. We assessed the intravenous perfusion of doxorubicin-loaded nanoparticles in patients with hepatocellular carcinoma in whom previous sorafenib therapy had failed.

METHODS

We did a multicentre, open-label, randomised, controlled phase 3 trial at 70 sites in 11 countries. Patients with hepatocellular carcinoma with one or more previous systemic therapies, including sorafenib, were randomly assigned to receive 30 mg/m² doxorubicin-loaded nanoparticles (30 mg/m² group), 20 mg/m² doxorubicin-loaded nanoparticles (20 mg/m² group), or standard care using a computer-generated randomisation list prepared by the funder and stratified by geographic region. Patients in the experimental groups received perfusion of the drug every 4 weeks and those in the control group received any systemic anticancer therapy (except sorafenib) as per investigator decision. The primary endpoint was overall survival in the intention-to-treat population. Safety was assessed in the population of patients who received at least one dose of their assigned treatment. This trial is registered with ClinicalTrials.gov, number NCT01655693.

FINDINGS

Between June 15, 2012, and Jan 27, 2017, 541 patients were screened, of whom 144 were excluded and 397 were randomly assigned to one of the groups (133 to the 30 mg/m² group; 130 to the 20 mg/m² group; and 134 to the control group). Median follow-up was 22·7 months (IQR 11·2-34·9). After pooling the doxorubicin groups for the efficacy analysis, median overall survival was 9·1 months (95% CI 8·1-10·4) in the pooled doxorubicin-loaded nanoparticles group and 9·0 months (7·1-11·8) in the control group (HR 1·00 [95% CI 0·78-1·28], two-sided p=0·99). 227 (94%) of 242 patients who received doxorubicin-loaded nanoparticles and 100 (75%) of 134 patients in the control group had at least one treatment-emergent adverse event. The most common drug-related grade 3 or 4 treatment-emergent adverse events were neutropenia (25 [10%] of 242 treated with doxorubicin-loaded nanoparticles and eight [6%] of 134 in the control group), asthenia (six [2%] and four [3%]), and thrombocytopenia (three [1%] and ten [7%]). Six (2%) patients treated with doxorubicin-loaded nanoparticles and one (1%) of those in the control group were deemed by investigators to have had a drug-related death. Serious adverse events occurred in 74 (31%) patients who received doxorubicin-loaded nanoparticles and 48 (36%) in the control group.

INTERPRETATION

Doxorubicin-loaded nanoparticles did not improve overall survival for patients with hepatocellular carcinoma in whom previous sorafenib treatment had failed.

FUNDING

Onxeo.

A journey through the emergence of nanomedicines with poly(alkylcyanoacrylate) based nanoparticles

Starting in the late 1970s, the pioneering work of Patrick Couvreur gave birth to the first biodegradable nanoparticles composed of a biodegradable synthetic polymer. These nanoparticles, made of poly(alkylcyanoacrylate) (PACA), were the first synthetic polymer-based nanoparticulate drug carriers undergoing a phase III clinical trial so far. Analyzing the journey from the birth of PACA nanoparticles to their clinical evaluation, this paper highlights their remarkable adaptability to bypass various drug delivery challenges found on the way. At present, PACA nanoparticles include a wide range of nanoparticles that can associate drugs of different chemical nature and can be administered in vivo by different routes. The most recent technologies giving the nanoparticles customised functions could also be implemented on this family of nanoparticles. Through different examples, this paper discusses the seminal role of the PACA nanoparticles' family in the development of nanomedicines.

Nano-carriers for drug routeing - towards a new era

The objective of this article is to propose a re-visiting of the paradigms of nano-carriers based drug routeing from an industrial viewpoint. The accumulation of drugs in specific body compartments after intravenous administration and the improvement of the oral bioavailability of peptides were taken as examples to propose an update of the translational framework preceding industrialisation. In addition to the recent advances on the biopharmacy of nano-carriers, the evolution of adjacent disciplines such as the biology of diseases, the chemistry of polymers, lipids and conjugates, the physico-chemistry of colloids and the assembling of materials at the nanoscale (referred to as microfluidics) are taken into account to consider new avenues in the applications of drug nano-carriers. The deeper integration of the properties of the drug and of the nano-carrier, in the specific context of the disease, advocates for product oriented programmes. At the same time, the advent of powerful collaborative digital tools makes possible the extension of the expertise spectrum. In this open-innovation framework, the Technology Readiness Levels (TRLs) of nano-carriers are proposed as a roadmap for the translational process from the Research stage to the Proof-of-Concept in human.

Antibody-functionalized polymer nanoparticle leading to memory recovery in Alzheimer's disease-like transgenic mouse model

Alzheimer's disease (AD) is a neurodegenerative disorder related, in part, to the accumulation of amyloid-β peptide (Aβ) and especially the Aβ peptide 1-42 (Aβ_1-42). The aim of this study was to design nanocarriers able to: (i) interact with the Aβ_1-42 in the blood and promote its elimination through the "sink effect" and (ii) correct the memory defect observed in AD-like transgenic mice. To do so, biodegradable, PEGylated nanoparticles were surface-functionalized with an antibody directed against Aβ_1-42. Treatment of AD-like transgenic mice with anti-Aβ_1-42-functionalized nanoparticles led to: (i) complete correction of the memory defect; (ii) significant reduction of the Aβ soluble peptide and its oligomer level in the brain and (iii) significant increase of the Aβ levels in plasma. This study represents the first example of Aβ_1-42 monoclonal antibody-decorated nanoparticle-based therapy against AD leading to complete correction of the memory defect in an experimental model of AD.

Safety and efficacy of intra-arterial hepatic chemotherapy with doxorubicin-loaded nanoparticles in hepatocellular carcinoma

Background

Doxorubicin Transdrug (DT), a nanoformulation of doxorubicin, was demonstrated to overcome the chemoresistance of hepatocellular carcinoma (HCC) in preclinical models. Its efficacy and safety were thus investigated in phase I and randomised phase II trials in unresectable HCC.

Patients and methods

Phase I was a single dose of DT through the hepatic intra-arterial (HIA) route, dose-escalating 3+3 trial, evaluating five-dose levels from 10 to 40 mg/m² with maximal tolerated dose (MTD) as primary endpoint. The multicentre phase II trial randomly assigned (2:1 ratio) patients to receive either 30 mg/m² of DT through HIA route every 4 weeks for up to three courses or best standard of care (BSC). Progression-free survival (PFS) rate at 3 months was the primary endpoint. Overall survival (OS) and disease control rate (DCR) were secondary endpoints.

Results

In phase I, haematological and respiratory limited toxicities were reported at 35 and 40 mg/m², giving MTD at 30 mg/m². Partial response rate was 10%, and stable disease 70%. Phase II was discontinued due to three severe acute respiratory distress events in the DT group while 17 patients had received 30 mg/m² DT and 11 BSC. At 3 months, PFS was 64% (95% CI 31 to 89) vs 75% (95% CI 35 to 97), and DCR 35% vs 27% in DT and BSC, respectively (p=NS). Median OS was 32.6 months (95% CI 8.2 to 34.1) in DT group and 15 months (95% CI 8.0 to 18.8) in BSC group (p<0.05).

Conclusion

DT increased OS in unresectable HCC but induced severe respiratory distress. Efficacy data deserve further investigation using a safer dosing and schedule regimen.

Trial registration number

EUDRACT 2006-004088-77; Results.

MDR in cancer: Addressing the underlying cellular alterations with the use of nanocarriers

Multidrug resistance (MDR) is associated with a wide range of pathological changes at different cellular and intracellular levels. Nanoparticles (NPs) have been extensively exploited as the carriers of MDR reversing payloads to resistant tumor cells. However, when properly formulated in terms of chemical composition and physicochemical properties, NPs can serve as beyond delivery systems and help overcome MDR even without carrying a load of chemosensitizers or MDR reversing molecular cargos. Whether serving as drug carriers or beyond, a wise design of the nanoparticulate systems to overcome the cellular and intracellular alterations underlying the resistance is imperative. Within the current review, we will initially discuss the cellular changes occurring in resistant cells and how such changes lead to chemotherapy failure and cancer cell survival. We will then focus on different mechanisms through which nanosystems with appropriate chemical composition and physicochemical properties can serve as MDR reversing units at different cellular and intracellular levels according to the changes that underlie the resistance. Finally, we will conclude by discussing logical grounds for a wise and rational design of MDR reversing nanoparticulate systems to improve the cancer therapeutic approaches.

Cellular uptake of nanoparticles: journey inside the cell

Nanoscale materials are increasingly found in consumer goods, electronics, and pharmaceuticals. While these particles interact with the body in myriad ways, their beneficial and/or deleterious effects ultimately arise from interactions at the cellular and subcellular level. Nanoparticles (NPs) can modulate cell fate, induce or prevent mutations, initiate cell-cell communication, and modulate cell structure in a manner dictated largely by phenomena at the nano-bio interface. Recent advances in chemical synthesis have yielded new nanoscale materials with precisely defined biochemical features, and emerging analytical techniques have shed light on nuanced and context-dependent nano-bio interactions within cells. In this review, we provide an objective and comprehensive account of our current understanding of the cellular uptake of NPs and the underlying parameters controlling the nano-cellular interactions, along with the available analytical techniques to follow and track these processes.

Chemoresistance and chemosensitization in cholangiocarcinoma

One of the main difficulties in the management of patients with advanced cholangiocarcinoma (CCA) is their poor response to available chemotherapy. This is the result of powerful mechanisms of chemoresistance (MOC) of quite diverse nature that usually act synergistically. The problem is often worsened by altered MOC gene expression in response to pharmacological treatment. Since CCA includes a heterogeneous group of cancers their genetic signature coding for MOC genes is also diverse; however, several shared traits have been defined. Some of these characteristics are shared with other types of liver cancer, namely hepatocellular carcinoma and hepatoblastoma. An important goal in modern oncologic pharmacology is to develop novel strategies to overcome CCA chemoresistance either by increasing drug specificity, such as in targeted therapies aimed to inhibit receptors with tyrosine kinase activity, or to increase the amounts of active agents inside CCA cells by enhancing drug uptake or reducing efflux through export pumps. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Aptamer-functionalized hybrid nanoparticle for the treatment of breast cancer

PURPOSE

Resistance to chemotherapeutic agents such as doxorubicin is a major reason for cancer treatment failure. At present the treatment option for metastatic breast cancer is very poor. Therefore, development of an effective therapeutic strategy to circumvent MDR of metastatic breast cancer is highly anticipated. The MDR of metastatic breast cancer cells was accompanied with the overexpression of P-gp transporter. Even though the overexpression of P-gp could be minimized by silencing with siRNA, the question is how they can be selectively targeted to the cancer cells. We propose that aptamer surface labeling of the nanoparticles could enhance the selectively delivery of p-gp siRNA into the metastatic breast cancer cells. Our hypothesis is that conjugating nanoparticles with a cancer cell specific aptamer should allow selective delivery of therapeutic drugs to tumor cells leading to enhanced cellular toxicity and antitumor effect as compared to unconjugated nanoparticles. The primary objective of this study is to develop a targeted nanocarrier delivery system for siRNA into breast cancer cells.

DESIGN METHODS

For targeted delivery, Aptamer A6 has been used which can bind to Her-2 receptors on breast cancer cells. For aptamer binding to particle surface, maleimide-terminated PEG-DSPE (Mal-PEG) was incorporated into the nanoparticles. Initially, three blank hybrid nanoparticles (i.e. F21, F31, and F40) out of nine different formulations prepared by high pressure homogenization (HPH) using different amount of DOTAP, cholesterol, PLGA or PLGA-PEG and Mal-PEG were chosen. Then protamine sulfate-condensed GAPDH siRNA (TRITC conjugated; red) or P-gp siRNA was encapsulated into those nanoparticles. Finally, the particles were incubated with aptamer A6 (FITC conjugated; green) for surface labeling.

RESULTS

Aptamer labeled-nanoparticles having PLGA are smaller in size than those having PLGA-PEG. Surface charge was reduced when the particles were labeled with aptamer. Cell transfection was increased significantly in Her-2 (+) SKBR-3 and 4T1-R cells but not in Her-2 poorly expressed MDA MB-231 and MCF-7 cells. The knockdown of P-gp was increased significantly when the particles were labeled with aptamer. No significant cellular toxicity was observed for any of these formulations.

CONCLUSION

This preliminary study concludes that aptamer-functionalized hybrid nanoparticles could be used to deliver P-gp targeted siRNA into the breast cancer cells to overcome chemoresistance.

Targeted Drug Delivery in Cancer Therapy

Chemotherapy has been the main modality of treatment for cancer patients; however, its success rate remains low, primarily due to limited accessibility of drugs to the tumor tissue, their intolerable toxicity, development of multi-drug resistance, and the dynamic heterogeneous biology of the growing tumors. Better understanding of tumor biology in recent years and new targeted drug delivery approaches that are being explored using different nanosystems and bioconjugates provide optimism in developing successful cancer therapy. This article reviews the possibilities and challenges for targeted drug delivery in cancer therapy.

Cellular uptake and intracellular degradation of poly(alkyl cyanoacrylate) nanoparticles

Background

Poly(alkyl cyanoacrylate) (PACA) nanoparticles have shown promise as drug carriers both to solid tumors and across the blood–brain barrier. Efficient drug delivery requires both high cellular uptake of the nanoparticles and release of the drug from the nanoparticles. Release of hydrophobic drugs from PACA nanoparticles is primarily governed by nanoparticle degradation, and this process has been poorly studied at the cellular level. Here we use the hydrophobic model drug Nile Red 668 (NR668) to investigate intracellular degradation of PACA nanoparticles by measuring changes in NR668 fluorescence emission and lifetime, as the spectral properties of NR668 depend on the hydrophobicity of the dye environment. We also assess the potential of poly(butyl cyanoacrylate) (PBCA) and poly(octyl cyanoacrylate) (POCA) nanoparticles for intracellular drug delivery in the prostate cancer cell line PC3 and rat brain endothelial cell line RBE4 and the role of endocytosis pathways in PACA nanoparticle uptake in those cell lines.

Results

Fluorescence lifetime imaging, emission spectra analysis and Förster resonance energy transfer indicated that the intracellular degradation was in line with the degradation found by direct methods such as gas chromatography and scanning electron microscopy, showing that PBCA has a faster degradation rate compared to POCA. The combined P(BCA/OCA) nanoparticles had an intermediate degradation rate. The uptake of POCA and PBCA nanoparticles was much higher in RBE4 than in PC3 cells. Endocytosis inhibition studies showed that both clathrin- and caveolin-mediated endocytosis were involved in PACA nanoparticle uptake, and that the former played a predominant role, particularly in PC3 cells.

Conclusions

In the present study, we used three different optical techniques to show that within a 24-hour period PBCA nanoparticles degraded significantly inside cells, releasing their payload into the cytosol, while POCA nanoparticles remained intact. This indicates that it is possible to tune the intracellular drug release rate by choosing appropriate monomers from the PACA family or by using hybrid PACA nanoparticles containing different monomers. In addition, we showed that the uptake of PACA nanoparticles depends not only on the monomer material, but also on the cell type, and that different cell lines can use different internalization pathways.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-015-0156-7) contains supplementary material, which is available to authorized users.

How can nanomedicines overcome cellular-based anticancer drug resistance?

This review discusses the mechanisms of anticancer drug resistance according to its cellular level of action and outlines the nanomedicine-based strategies adopted to overcome it.

Patrick Couvreur: inspiring pharmaceutical innovation

Patrick Couvreur speaks to Hannah Stanwix, Managing Comissioning Editor: Professor Patrick Couvreur received his pharmacy degree from the Université Catholique de Louvain (Louvain-la-Neuve, Belgium) in 1972. He holds a PhD in pharmaceutical technology from the same university and completed a postdoctoral fellowship at the Eidgenössische Technische Hochschule (Zürich, Switzerland). Since 1984, Professor Couvreur has been Full Professor of Pharmacy at the Paris-Sud University (Paris, France) and was holder of the Chair of Innovation Technologique at the prestigious Collège de France (Paris, France). He has published more than 450 peer-reviewed articles and has an H-index of 73, with over 19,000 citations. Professor Coureur has been recognized by numerous national and international awards, including the 2004 Pharmaceutical Sciences World Congress Award, the prestigious Host Madsen Medal, the Prix Galien, the European Pharmaceutical Scientist Award 2011 from the European Federation of Pharmaceutical Sciences, the Médaille de l’Innovation from the Centre National de la Recherche Scientifique, and recently the European Inventor Award 2013 from the European Patent Office.

Nanocarriers for antibiotics: a promising solution to treat intracellular bacterial infections

In the field of antibiotherapy, intracellular infections remain difficult to eradicate mainly due to the poor intracellular penetration of most of the commonly used antibiotics. Bacteria have quickly understood that their intracellular localisation allows them to be protected from the host immune system, but also from the action of antimicrobial agents. In addition, in most cases pathogens nestle in professional phagocytic cells, and can even use them as a 'Trojan horse' to induce a secondary site of infection thereby causing persistent or recurrent infections. Thus, new strategies had to be considered in order to counteract these problems. Amongst them, nanocarriers loaded with antibiotics represent a promising approach. Nowadays, it is possible to encapsulate, incorporate or even conjugate biologically active molecules into different families of nanocarriers such as liposomes or nanoparticles in order to deliver antibiotics intracellularly and hence to treat infections. This review gives an overview of the variety of nanocarriers developed to deliver antibiotics directly into infected cells.

Efficacy of Cisplatin-loaded polybutyl cyanoacrylate nanoparticles on the glioblastoma

Glioblastoma is known as one of the most aggressive human cancers. To gain access of the brain, therapeutic agents must overcome blood-brain barrier (BBB). In this study, Cisplatin (Cispt)-loaded polybutylcyanoacrylate (PBCA) nanoparticles (NPs) were prepared through miniemulsion polymerization technique. They were coated with polysorbate 80 to cross the BBB of glioblastoma-bearing rats. Prepared NPs were characterized with respect to their size, size distribution, zeta potential, drug loading and encapsulation efficiency, cytotoxicity effects, drug release, and stability pattern. Size and zeta potential of nanodrug were found to be 489 nm and -20 mV, while drug loading and encapsulation efficiency were determined to be 5% and 25%, respectively. Release studies demonstrated high retention capability of nanodrug in that 3.18% of Cispt was released from NPs in a period of 51 h. NPs presented acceptable stability after 2 months and lyophilization. Mean survival time in nanodrug receivers was 19.6 days, while it was 17.5 days for free drug receivers. Histological studies demonstrated efficacy of PBCA NPs in reducing side effects. Finally, such preparation can be considered as a promising nanocarrier for other types of tumor.

Nanotechnology for targeted cancer therapy

Cancer nanotechnology is currently under intense development for applications in cancer imaging, molecular diagnosis and targeted therapy. The basic rationale is that nanometer-sized particles, such as biodegradable micelles, semiconductor quantum dots and iron oxide nanocrystals, have functional or structural properties that are not available from either molecular or macroscopic agents. When linked with biotargeting ligands, such as monoclonal antibodies, peptides or small molecules, these nanoparticles are used to target malignant tumors with high affinity and specificity. In the 'mesoscopic' size range of 5-100 nm in diameter, nanoparticles also have large surface areas and functional groups for conjugating to multiple diagnostic (e.g., optical, radioisotopic or magnetic) and therapeutic (e.g., anticancer) agents. Recent advances have led to multifunctional nanoparticle probes for molecular and cellular imaging, nanoparticle drugs for targeted therapy, and integrated nanodevices for early cancer detection and screening. These developments have opened exciting opportunities for personalized oncology in which cancer detection, diagnosis and therapy are tailored to each individual's molecular profile, and also for predictive oncology, in which genetic/molecular information is used to predict tumor development, progression and clinical outcome.

Exploiting nanotechnology to overcome tumor drug resistance: Challenges and opportunities

Tumor cells develop resistance to chemotherapeutic drugs through multiple mechanisms. Overexpression of efflux transporters is an important source of drug resistance. Efflux transporters such as P-glycoprotein reduce intracellular drug accumulation and compromise drug efficacy. Various nanoparticle-based approaches have been investigated to overcome efflux-mediated resistance. These include the use of formulation excipients that inhibit transporter activity and co-delivery of the anticancer drug with a specific inhibitor of transporter function or expression. However, the effectiveness of nanoparticles can be diminished by poor transport in the tumor tissue. Hence, adjunct therapies that improve the intratumoral distribution of nanoparticles may be vital to the successful application of nanotechnology to overcome tumor drug resistance. This review discusses the mechanisms of tumor drug resistance and highlights the opportunities and challenges in the use of nanoparticles to improve the efficacy of anticancer drugs against resistant tumors.

Anthracycline Nano-Delivery Systems to Overcome Multiple Drug Resistance: A Comprehensive Review

Anthracyclines (doxorubicin, daunorubicin, and idarubicin) are very effective chemotherapeutic drugs to treat many cancers; however, the development of multiple drug resistance (MDR) is one of the major limitations for their clinical applications. Nano-delivery systems have emerged as the novel cancer therapeutics to overcome MDR. Up until now, many anthracycline nano-delivery systems have been developed and reported to effectively circumvent MDR both in-vitro and in-vivo, and some of these systems have even advanced to clinical trials, such as the HPMA-doxorubicin (HPMA-DOX) conjugate. Doxil, a DOX PEGylated liposome formulation, was developed and approved by FDA in 1995. Unfortunately, this formulation does not address the MDR problem. In this comprehensive review, more than ten types of developed anthracycline nano-delivery systems to overcome MDR and their proposed mechanisms are covered and discussed, including liposomes; polymeric micelles, conjugate and nanoparticles; peptide/protein conjugates; solid-lipid, magnetic, gold, silica, and cyclodextrin nanoparticles; and carbon nanotubes.

[Nanotechnologies for designing new medicines]

The use of nanotechnologies for the targeted delivery of therapeutic agents is a research strategy which can lead to more efficacious drugs fulfilling unmet medical needs. The morphology, supramolecular organization and properties of first, second and third generation nanocarriers used for the targeted delivery of drugs are discussed. These different nanocarriers (liposomes, nanoparticles, polymers, etc.) may: (I) protect the drug from degradation by the biological environment; (II) allow the controlled delivery of the active molecule by an external stimulus; (III) avoid the recognition of the drug by the reticulo-endothelial system; (IV) overcome multidrug resistance mechanisms of cancer cells and finally (V) very specifically target the therapeutic agent to the diseased cell by means of selective ligands. Some therapeutic applications of these different types of nanocarriers are discussed, especially in the field of cancer therapy. Finally, the future challenges and perspectives of nanotechnologies, especially for  "theragnostic" and gene therapy are briefly discussed.

Emerging nanodelivery strategies of RNAi molecules for colon cancer therapy: preclinical developments

Although local colonic delivery is achievable through several strategies, colon cancer is still considered one of the leading causes of death worldwide. Failure of chemotherapeutics to exhibit efficient anticancer activity might be attributed to the development of multidrug resistance (MDR) mechanisms including the overexpression of certain oncogenes such as MDR1/P-gp. One of the major reasons for the shortcoming of P-gp inhibitors in clinic is the nonspecific distribution of them to nontarget organs, which leads to reduced elimination and increased toxicity of its substrates including anticancer agents. Numerous studies have demonstrated the effectiveness of gene-silencing approaches in reversing the P-gp-mediated MDR. However, none have reached clinical trials yet. Several drug-delivery systems have been investigated primarily to address P-gp and the observed improved anticancer efficacy suggests that nanomedicine provides new opportunities to overcome MDR in cancer. In this review, novel therapeutic strategies for colon cancer therapy will be discussed in the context of P-gp inhibition by low-molecular-weight agents and RNAi molecules.

Reversion of multidrug resistance by co-encapsulation of doxorubicin and curcumin in chitosan/poly(butyl cyanoacrylate) nanoparticles

Co-encapsulated doxorubicin (DOX) and curcumin (CUR) in poly(butyl cyanoacrylate) nanoparticles (PBCA-NPs) were prepared with emulsion polymerization and interfacial polymerization. The mean particle size and mean zeta potential of CUR-DOX-PBCA-NPs were 133 ± 5.34 nm in diameter and +32.23 ± 4.56 mV, respectively. The entrapment efficiencies of doxorubicin and curcumin were 49.98 ± 3.32% and 94.52 ± 3.14%, respectively. Anticancer activities and reversal efficacy of the formulations and various combination approaches were assessed using 3-[4,5-dimethylthiazol-2-yl] 2,5-diphenyltetrazolium bromide assay and western blotting. The results showed that the dual-agent loaded PBCA-NPs system had the similar cytotoxicity to co-administration of two single-agent loaded PBCA-NPs (DOX-PBCA-NPs+CUR-PBCA-NPs), which was slightly higher than that of the free drug combination (DOX+CUR) and one free drug/another agent loaded PBCA-NPs combination (DOX+CUR-PBCA-NPs or CUR+DOX-PBCA-NPs). The simultaneous administration of doxorubicin and curcumin achieved the highest reversal efficacy and down-regulation of P-glycoprotein in MCF-7/ADR cell lines, an MCF-7 breast carcer cell line resistant to adriamycin. Multidrug resistance can be enhanced by combination delivery of encapsulated cytotoxic drugs and reversal agents.

Entrapment of epirubicin in poly(butyl cyanoacrylate) colloidal nanospheres by nanoprecipitation: formulation development and in vitro studies on cancer cell lines

This report describes the preparation of poly(butyl cyanoacrylate) nanospheres loaded with epirubicin by nanoprecipitation, their characterization and in vitro evaluation of the drug uptake and cytotoxicity on cancer cell lines. The epirubicin-loaded nanospheres were prepared by nanoprecipitation using presynthesized polymer and dextran 40 as a colloidal stabilizer at different pH and initial drug concentrations. The nanospheres were characterized for particle morphology, size distribution, zeta-potential and drug loading. Epirubicin-loaded particles with diameters around 350 nm were obtained. Drug loading depended on the pH and epirubicin concentration. Epirubicin was more cytotoxic when loaded in nanospheres. Drug release was studied by dialysis method. Cytotoxicity and drug uptake experiments were performed on HeLa and A549 cell lines. It was found that addition of polysorbate 80 could increase cytotoxicity. The cytotoxicity was found to correlate with the drug uptake by cells. The findings reported here demonstrate that epirubicin-loaded nanospheres of poly(butyl cyanoacrylate) can be successfully prepared by the nanoprecipitation approach as alternative to the well-known polymerization-based methods. It is found that the epirubicin-loaded nanospheres are more cytotoxic than the free drug to human carcinoma cell lines in vitro. The higher cytotoxicity of the obtained epirubicin formulations, compared with the free drug, is due to enhanced cellular internalization of epirubicin.

Redox-responsive nanoparticles from the single disulfide bond-bridged block copolymer as drug carriers for overcoming multidrug resistance in cancer cells

Multidrug resistance (MDR) is a major impediment to the success of cancer chemotherapy. The intracellular accumulation of drug and the intracellular release of drug molecules from the carrier could be the most important barriers for nanoscale carriers in overcoming MDR. We demonstrated that the redox-responsive micellar nanodrug carrier assembled from the single disulfide bond-bridged block polymer of poly(ε-caprolactone) and poly(ethyl ethylene phosphate) (PCL-SS-PEEP) achieved more drug accumulation and retention in MDR cancer cells. Such drug carrier rapidly released the incorporated doxorubicin (DOX) in response to the intracellular reductive environment. It therefore significantly enhanced the cytotoxicity of DOX to MDR cancer cells. It was demonstrated that nanoparticular drug carrier with either poly(ethylene glycol) or poly(ethyl ethylene phosphate) (PEEP) shell increased the influx but decreased the efflux of DOX by the multidrug resistant MCF-7/ADR breast cancer cells, in comparison with the direct incubation of MCF-7/ADR cells with DOX, which led to high cellular retention of DOX. Nevertheless, nanoparticles bearing PEEP shell exhibited higher affinity to the cancer cells. The shell detachment of the PCL-SS-PEEP nanoparticles caused by the reduction of intracellular glutathione significantly accelerated the drug release in MCF-7/ADR cells, demonstrated by the flow cytometric analyses, which was beneficial to the entry of DOX into the nuclei of MCF-7/ADR cells. It therefore enhanced the efficiency in overcoming MDR of cancer cells, which renders the redox-responsive nanoparticles promising in cancer therapy.

Polyanionic carbohydrate doxorubicin-dextran nanocomplex as a delivery system for anticancer drugs: in vitro analysis and evaluations

This study deals with the preparation and investigation of a nanoscale delivery system for the anticancer drug doxorubicin (DOX) using its complexation with polyanionic carbohydrate dextran sulfate (DS). Dynamic light scattering, SEM, and zeta potential determination were used to characterize nanocomplexes. DOX-DS complexation was studied in the presence of ethanol as a hydrogen-bond disrupting agent, NaCl as an electrostatic shielding agent, and chitosan as a positively charged polymer. Thermodynamics of DOX-DS interaction was studied using isothermal titration calorimetry (ITC). A dialysis method was applied to investigate the release profile of DOX from DOX-DS nanocomplexes. Spherical and smooth-surfaced DOX-DS nanocomplexes (250–500 nm) with negative zeta potential were formed at a DS/DOX (w/w) ratio of 0.4–0.6, with over 90% drug encapsulation efficiency. DOX when complexed with DS showed lower fluorescence emission and 480 nm absorbance plus a 15 nm bathometric shift in its visible absorbance spectrum. Electrostatic hydrogen bonding and π-π stacking interactions are the main contributing interactions in DOX-DS complexation. Thermal analysis of DOX-DS complexation by ITC revealed that each DOX molecule binds with 3 DS glycosyl monomers. Drug release profile of nanocomplexes showed a fast DOX release followed by a slow sustained release, leading to release of 32% of entrapped DOX within 15 days. DOX-DS nanocomplexes may serve as a drug delivery system with efficient drug encapsulation and also may be taken into consideration in designing DOX controlled-release systems.

Nanomedicinal strategies to treat multidrug-resistant tumors: current progress

Multidrug resistance (MDR) is a major impediment to the success of cancer chemotherapy. P-glycoprotein is an important and the best-known membrane transporter involved in MDR. Several strategies have been used to address MDR, especially P-glycoprotein-mediated drug resistance in tumors. However, clinical success has been limited, largely due to issues regarding lack of efficacy and/or safety. Nanoparticles have shown the ability to target tumors based on their unique physical and biological properties. To date, nanoparticles have been investigated primarily to address P-glycoprotein and the observed improved anticancer efficacy suggests that nanomedicinal strategies provide a new opportunity to overcome MDR. This article focuses on nanotechnology-based formulations and current nanomedicine approaches to address MDR in tumors and discusses the proposed mechanisms of action.

Evaluating the potential of polymer nanoparticles for oral delivery of paclitaxel in drug-resistant cancer

The present study was designed to explore the ability of polymeric nanoparticles to restore drug sensitivity to P-glycoprotein over-expressing cancer cells. A multidrug-resistant cell line 2780 AD and its sensitive parent cell line A2780 were studied in cell culture and as a xenografted tumour model. Paclitaxel was incorporated in poly(lactide-co-glycolide) nanoparticles of average diameter 125 nm stabilised by a positively charged surfactant. The nanoparticulate formulation was shown to be about sevenfold more potent than free paclitaxel against cell line A2780 and the poly(lactic-co-glycolic acid) (PLGA) nanoparticles alone were nontoxic to the cells at the concentrations required to deliver the drug. Whilst the oral formulation of paclitaxel was not as potent as the free drug in the A2780 xenografts, it showed significant activity against 2780 AD tumours, which are resistant to the maximum tolerated intravenous dose of paclitaxel. The efficacy of orally delivered paclitaxel in this drug-resistant model supports the concept of exploring nanoparticles for improved drug delivery.

Development and in vitro characterization of galactosylated low molecular weight chitosan nanoparticles bearing doxorubicin

The aim of the present research was to evaluate the potential of galactosylated low molecular weight chitosan (Gal-LMWC) nanoparticles bearing positively charged anticancer, doxorubicin (DOX) for hepatocyte targeting. The chitosan from crab shell was depolymerized, and the lactobionic acid was coupled with LMWC using carbodiimide chemistry. The depolymerized and galactosylated polymers were characterized. Two types of Gal-LMWC(s) with variable degree of substitution were employed to prepare the nanoparticles using ionotropic gelation with pentasodium tripolyphosphate anions. Factors affecting nanoparticles formation were discussed. The nanoparticles were characterized by transmission electron microscopy and photon correlation spectroscopy and found to be spherical in the size range 106-320 nm. Relatively higher percent DOX entrapment was obtained for Gal-LMWC(s) nanoparticles than for LMWC nanoparticles. A further increase in drug entrapment was found with nanoparticles prepared by Gal-LMWC with higher degree of substitution. A hypothesis which correlates the ionic concentration of DOX in nanoparticles preparation medium and percent DOX entrapment in cationic polymer has been proposed to explain the enhanced DOX entrapment. In-vitro drug release study demonstrated an initial burst release followed by a sustained release. The targeting potential of the prepared nanoparticles was assessed by in vitro cytotoxicity study using the human hepatocellular carcinoma cell line (HepG(2)) expressing the ASGP receptors on their surfaces. The enthusiastic results showed the feasibility of Gal-LMWC(s) to entrap the cationic DOX and targeting potential of developed Gal-LMWC(s) nanoparticles to HepG(2) cell line.

Secondary cytotoxicity mediated by alveolar macrophages: a contribution to the total efficacy of nanoparticles in lung cancer therapy?

Local treatment of lung cancer using inhalable nanoparticles (NPs) is an emerging and promising treatment option. The aim of this study was to investigate the activation of alveolar macrophages by poly (isobutyl cyanoacrylate) (BIPCA) NPs and the consequences of this activation on H460 lung cancer cells. A methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay was used to determine the primary cytotoxicity, that is, the immediate and direct cytotoxicity of doxorubicin (DOX)-loaded NPs on both cell lines. Macrophages were then treated using EC(50) concentrations of different treatments and co-cultured in a two-compartment system with H460 lung cancer cells. These treatments included DOX solution, blank NPs, and DOX-loaded NPs. The results showed that alveolar macrophages exposed to blank or DOX-loaded NPs showed cytotoxicity against cancer cells after 8 and 24h; this behavior was not expressed by naïve macrophages or macrophages treated with DOX solution. Sample analysis indicated that macrophages have the ability to release back fragments of NPs that were previously phagocytized. Further investigations showed that NPs can induce an increase in the excretion of Th1 cytokines namely, monocytes chemoattractant protein-1 (MCP-1), macrophages inflammatory protein (MIP-1), tumor necrosis factor alpha (TNF-alpha), and interferon gamma (IFN-gamma). The Th1 cytokines released by the alveolar macrophages might explain the significant secondary cytotoxicity effect on H460 cancer cells. Secondary cytotoxicity mediated by macrophages might compliment the direct cytotoxic effect that NPs have on cancer cells.