Nanoparticulate drug delivery systems for cancer chemotherapy

Visual targeted therapy of hepatic cancer using homing peptide modified calcium phosphate nanoparticles loading doxorubicin guided by T1 weighted MRI

Effective treatment and real-time monitoring of hepatic cancer are essential. A multifunctional calcium phosphate nanoparticles loading chemotherapeutic agent doxorubicin and magnetic resonance imaging contrast agent diethylenetriaminepentaacetic acid gadolinium (A54-CaP/Gd-DTPA/DOX) was developed for visual targeted therapy of hepatic cancer via T1-weighted MRI in real-time. A54-CaP/Gd-DTPA/DOX exhibited a higher longitudinal relaxivity (6.02 mM^-1 s^-1) than commercial MR contrast agent Gd-DTPA (3.3765 mM^-1 s^-1). The DOX release from the nanoparticles exhibited a pH dependent behavior. The cellular uptake results showed that the internalization of A54-CaP/Gd-DTPA/DOX into BEL-7402 cells was1.9-fold faster than that of HepG2 cells via A54 binding. In vivo experiments presented that A54-CaP/Gd-DTPA/DOX had higher distribution and longer retention time in tumor tissue than CaP/Gd-DTPA/DOX and free DOX, and also displayed great antitumor efficacy (95.38% tumor inhibition rate) and lower toxicity. Furthermore, the Gd-DTPA entrapped in the nanoparticles could provide T1-weighted MRI for real-time monitoring the progress of tumor treatment.

Dual Receptor Targeting Cell Penetrating Peptide Modified Liposome for Glioma and Breast Cancer Postoperative Recurrence Therapy

PURPOSE

Cell penetrating peptides (CPPs) were widely used as motifs for drug delivery to tumor. In former study, an RGD reverse sequence dGR was used to develop active-targeting liposome R8dGR-Lip, which showed well penetrating ability and treatment efficiency on glioma model. However, recurrence after tumor resection caused by post-operative residual cancer cells was a huge obstacle in tumor treatment. In consideration of the effective anti-cancer effect of PTX-R8dGR-Lip when treating glioma in former study, we decide to evaluate its pharmacodynamics on tumor resection models, which were more invasive and resistant.

METHOD

In vitro, the effectiveness of PTX-R8dGR-Lip in reducing tumor initiating cell (TIC) was investigated using mammosphere formation. In vivo, the inhibition efficiency of PTX-R8dGR-Lip on C6 glioma recurrence and 4 T1 breast cancer recurrence model were evaluated, including tumor bioluminescence imaging, survival rate and immumohistochemical staining, etc..

RESULTS

C6 mammosphere formation rate of PTX-R8dGR-Lip group was 48.06 ± 2.72%, and 4 T1 mammosphere formation rate of PTX-R8dGR-Lip group was 39.51 ± 4.02% when PBS group was set as 100%. C6 and 4 T1 bioluminescent tumor resected model were established, then effectiveness of different PTX-loaded preparations were evaluated on these two models. PTX-R8dGR-Lip could obviously inhibit tumor recurrence, prolong survival rate and reduce tumor tissue invasion.

CONCLUSION

PTX-R8dGR-Lip could reduce post-operative recurrence rate, prolong survival time, and decrease the proliferation of residual cancer cells through regulating the expression of recurrence-related cytokines.

Progress and challenges towards targeted delivery of cancer therapeutics

Targeted delivery approaches for cancer therapeutics have shown a steep rise over the past few decades. However, compared to the plethora of successful pre-clinical studies, only 15 passively targeted nanocarriers (NCs) have been approved for clinical use and none of the actively targeted NCs have advanced past clinical trials. Herein, we review the principles behind targeted delivery approaches to determine potential reasons for their limited clinical translation and success. We propose criteria and considerations that must be taken into account for the development of novel actively targeted NCs. We also highlight the possible directions for the development of successful tumor targeting strategies.

Targeted delivery strategies based on nanocarriers have immense potential to change cancer care but current strategies have been shown only limited translation in the clinic. Here, the authors survey the challenge, progress and opportunities towards targeted delivery of cancer therapeutics.

Tumor Microenvironment on a Chip: The Progress and Future Perspective

Tumors develop in intricate microenvironments required for their sustained growth, invasion, and metastasis. The tumor microenvironment plays a critical role in the malignant or drug resistant nature of tumors, becoming a promising therapeutic target. Microengineered physiological systems capable of mimicking tumor environments are one emerging platform that allows for quantitative and reproducible characterization of tumor responses with pathophysiological relevance. This review highlights the recent advancements of engineered tumor microenvironment systems that enable the unprecedented mechanistic examination of cancer progression and metastasis. We discuss the progress and future perspective of these microengineered biomimetic approaches for anticancer drug prescreening applications.

Statins anticancer targeted delivery systems: re-purposing an old molecule

OBJECTIVES

Exploring the use of statins as anticancer agents and exploiting different drug delivery systems in targeting these molecules to cancerous sites. Literature review was performed to investigate the use of statins in cancer treatment in one hand, and the different pharmaceutical approaches to deliver and target these drugs to their site of action.

KEY FINDINGS

Statins were used for decades as antihypercholestrolemic drugs but recently have been proven potential for broad anticancer activities. The incorporation of statins in nanoparticulate drug delivery systems not only augmented the cytotoxicity of statins but also overcame the resistance of cancerous cells against the traditional chemotherapeutic agents. Statins-loaded nanoparticles could be easily tampered to target the cancerous cells and consequently minimal drug amount could be utilized.

SUMMARY

This review reconnoitered the different endeavors to incorporate statins in various nanoparticles and summarized the successful effects in targeting cancerous cells and reducing their proliferation without the side effects of commonly used chemotherapeutic agents.

Nanomedicine as a potent strategy in melanoma tumor microenvironment

Melanoma originated from melanocytes is the most aggressive type of skin cancer. Despite considerable progresses in clinical treatment with the discovery of BRAF or MEK inhibitors and monoclonal antibodies, the durability of response to treatment is often limited to the development of acquired resistance and systemic toxicity. The limited success of conventional treatment highlights the importance of understanding the role of melanoma tumor microenvironment in tumor developement and drug resistance. Nanoparticles represent a promising strategy for the development of new cancer treatments able to improve the bioavailability of drugs and increase their penetration by targeting specifically tumors cells and/or tumor environment. In this review, we will discuss the main influence of tumor microenvironment in melanoma growth and treatment outcome. Furthermore, third generation loaded nanotechnologies represent an exciting tool for detection, treatment, and escape from possible mechanism of resistance mediated by tumor microenvironment, and will be highlighted in this review.

Nanotechnology Applications for Diffuse Intrinsic Pontine Glioma

Diffuse intrinsic pontine gliomas (DIPGs) are invariably fatal tumors found in the pons of elementary school aged children. These tumors are grade II-IV gliomas, with a median survival of less than 1 year from diagnosis when treated with standard of care (SOC) therapy. Nanotechnology may offer therapeutic options for the treatment of DIPGs. Multiple nanoparticle formulations are currently being investigated for the treatment of DIPGs. Nanoparticles based upon stable elements, polymer nanoparticles, and organic nanoparticles are under development for the treatment of brain tumors, including DIPGs. Targeting of nanoparticles is now possible as delivery techniques that address the difficulty in crossing the blood brain barrier (BBB) are developed. Theranostic nanoparticles, a combination of therapeutics and diagnostic nanoparticles, improve imaging of the cancerous tissue while delivering therapy to the local region. However, additional time and attention should be directed to developing a nanoparticle delivery system for treatment of the uniformly fatal pediatric disease of DIPG.

Tumor-targeted delivery of sunitinib base enhances vaccine therapy for advanced melanoma by remodeling the tumor microenvironment

Development of an effective treatment against advanced tumors remains a major challenge for cancer immunotherapy. We have previously developed a potent mannose-modified lipid calcium phosphate (LCP) nanoparticle (NP)-based Trp2 vaccine for melanoma therapy, but because this vaccine can induce a potent anti-tumor immune response only during the early stages of melanoma, poor tumor growth inhibition has been observed in more advanced melanoma models, likely due to the development of an immune-suppressive tumor microenvironment (TME). To effectively treat this aggressive tumor, a multi-target receptor tyrosine kinase inhibitor, sunitinib base, was efficiently encapsulated into a targeted polymeric micelle nano-delivery system (SUNb-PM), working in a synergistic manner with vaccine therapy in an advanced mouse melanoma model. SUNb-PM not only increased cytotoxic T-cell infiltration and decreased the number and percentage of MDSCs and Tregs in the TME, but also induced a shift in cytokine expression from Th2 to Th1 type while remodeling the tumor-associated fibroblasts, collagen, and blood vessels in the tumor. Additionally, inhibition of the Stat3 and AKT signaling pathways by SUNb-PM may induce tumor cell apoptosis or decrease tumor immune evasion. Our findings indicated that targeted delivery of a tyrosine kinase inhibitor to tumors can be used in a novel synergistic way to enhance the therapeutic efficacy of existing immune-based therapies for advanced melanoma.

Improved Targeting of Cancers with Nanotherapeutics

Targeted cancer nanotherapeutics offers numerous opportunities for the selective uptake of toxic chemotherapies within tumors and cancer cells. The unique properties of nanoparticles, such as their small size, large surface-to-volume ratios, and the ability to achieve multivalency of targeting ligands on their surface, provide superior advantages for nanoparticle-based drug delivery to a variety of cancers. This review highlights various key concepts in the design of targeted nanotherapeutics for cancer therapy, and discusses physicochemical parameters affecting nanoparticle targeting, along with recent developments for cancer-targeted nanomedicines.

Nanomedicine Magic Bullet for Human Cancer

Nanotechnology is the new tool that has changed healthcare, engineering, and space science. The technology involves nanoparticles that are effectively a bridge between bulk materials and atomic or molecular structures. The properties of materials change its surface plasmon resonance in metals, supermagnetism in magnetic materials as their size approaches to nanoscale. Taking in to account of their small sizes (less than 100nm) and their miraculous properties, unlike their precursor bulk material, nanoparticles are exploited to create new diagnostics and therapeutics with respect to several human diseases. Nanomedicine is generating a new generation of innovative revolution in nanoscale drug delivery strategies, site-specific drug delivery, and personalized therapy in cancer by releasing the drug at a specific site. This chapter discusses the evolution of nanomedicine to several advancements in the field of nanoparticle technologies, targeting and controlled release strategies, with the desire of generating robust and efficient nanotherapeutic tools against cancer.

EGFR as a Target for Glioblastoma Treatment: An Unfulfilled Promise

The receptor for epidermal growth factor (EGFR) is a prime target for cancer therapy across a broad variety of tumor types. As it is a tyrosine kinase, small molecule tyrosine kinase inhibitors (TKIs) targeting signal transduction, as well as monoclonal antibodies against the EGFR, have been investigated as anti-tumor agents. However, despite the long-known enigmatic EGFR gene amplification and protein overexpression in glioblastoma, the most aggressive intrinsic human brain tumor, the potential of EGFR as a target for this tumor type has been unfulfilled. This review analyses the attempts to use TKIs and monoclonal antibodies against glioblastoma, with special consideration given to immunological approaches, the use of EGFR as a docking molecule for conjugates with toxins, T-cells, oncolytic viruses, exosomes and nanoparticles. Drug delivery issues associated with therapies for intracerebral diseases, with specific emphasis on convection enhanced delivery, are also discussed.

Liposomal drug delivery systems for targeted cancer therapy: is active targeting the best choice?

Liposomes are biodegradable and biocompatible self-forming spherical lipid bilayer vesicles. They can encapsulate and deliver one or more hydrophobic and hydrophilic therapeutic agents with poor therapeutic indices to tumor sites. Properties such as lipid bilayer fluidity, charge, size and surface hydration can be modified to extend liposome circulation time in the bloodstream and enhance efficacy. The focus of this review is on ligand-conjugated liposomes and their potential application in tumor-targeted delivery. Ligand-conjugated liposomes are designed to target receptors which are overexpressed on tumor cells to decrease drugs side effects by enhancing their selective delivery to tumor site. Despite the extensive research in this area, no small molecule ligand-conjugated liposome has been approved up to date for cancer therapy.

Improvement of pyrazolo[3,4-d]pyrimidines pharmacokinetic properties: nanosystem approaches for drug delivery

Pyrazolo[3,4-d]pyrimidines are a class of compounds with a good activity against several cancer cell lines. Despite the promising anticancer activity, these molecules showed a poor aqueous solubility. This issue could threat the future development of pyrazolo[3,4-d]pyrimidines as clinical drug candidates. With the aim of improving their solubility profile and consequently their pharmacokinetic properties, we have chosen four compounds (1–4) on the base of their anti-neuroblastoma activity and we have developed albumin nanoparticles and liposomes for the selected candidates. Albumin nanoparticles and liposomes were prepared and characterized regarding size and ζ-potential distribution, polidispersity index, entrapment efficiency and activity against SH-SY5Y human neuroblastoma cell line. The most promising nanosystem, namely LP-2, was chosen to perform further studies: confocal microscopy, stability and drug release in physiological conditions, and biodistribution. Altogether, the obtained data strongly indicate that the encapsulation of pyrazolo[3,4-d]pyrimidines in liposomes represent an effective method to overcome the poor water solubility.

Porphyrin Nanodroplets: Sub-micrometer Ultrasound and Photoacoustic Contrast Imaging Agents

A novel class of all-organic nanoscale porphyrin nanodroplet agents is presented which is suitable for multimodality ultrasound and photoacoustic molecular imaging. Previous multimodality photoacoustic-ultrasound agents are either not organic, or not yet demonstrated to exhibit enhanced accumulation in leaky tumor vasculature, perhaps because of large diameters. In the current study, porphyrin nanodroplets are created with a mean diameter of 185 nm which is small enough to exhibit the enhanced permeability and retention effect. Porphyrin within the nanodroplet shell has strong optical absorption at 705 nm with an estimated molar extinction coefficient >5 × 10(9) m(-1) cm(-1) , allowing both ultrasound and photoacoustic contrast in the same nanoparticle using all organic materials. The potential of nanodroplets is that they may be phase-changed into microbubbles using high pressure ultrasound, providing ultrasound contrast with single-bubble sensitivity. Multispectral photoacoustic imaging allows visualization of nanodroplets when injected intratumorally in an HT1080 tumor in the chorioallantoic membrane of a chicken embryo. Intravital microscopy imaging of Hep3-GFP and HT1080-GFP tumors in chicken embryos determines that nanodroplets accumulated throughout or at the periphery of tumors, suggesting that porphyrin nanodroplets may be useful for enhancing the visualization of tumors with ultrasound and/or photoacoustic imaging.

Design of Nanoparticle-Based Carriers for Targeted Drug Delivery

Nanoparticles have shown promise as both drug delivery vehicles and direct antitumor systems, but they must be properly designed in order to maximize efficacy. Computational modeling is often used both to design new nanoparticles and to better understand existing ones. Modeled processes include the release of drugs at the tumor site and the physical interaction between the nanoparticle and cancer cells. In this article, we provide an overview of three different targeted drug delivery methods (passive targeting, active targeting and physical targeting), compare methods of action, advantages, limitations, and the current stage of research. For the most commonly used nanoparticle carriers, fabrication methods are also reviewed. This is followed by a review of computational simulations and models on nanoparticle-based drug delivery.

Peptide-like Polymers Exerting Effective Glioma-Targeted siRNA Delivery and Release for Therapeutic Application

Lipopolymer 49, a solid-phase synthesized T-shaped peptide-like oligoamide containing two central oleic acids, 20 aminoethane, and two terminal cysteine units, is identified as very potent and biocompatible small interfering RNA (siRNA) carrier for gene silencing in glioma cells. This carrier is combined with a novel targeting polymer 727, containing a precise sequence of Angiopep 2 targeting peptide, linked with 28 monomer units of ethylene glycol, 40 aminoethane, and two terminal cysteines in siRNA complex formation. Angiopep-polyethylene glycol (PEG)/siRNA polyplexes exhibit good nanoparticle features, effective glioma-targeting siRNA delivery, and intracellular siRNA release, resulting in an outstanding gene downregulation both in glioma cells and upon intravenous delivery in glioma model nude mice without significant biotoxicity. Therefore, this novel siRNA delivery system is expected to be a promising strategy for targeted and safe glioma therapy.

Nanoparticles coated with the tumor-penetrating peptide iRGD reduce experimental breast cancer metastasis in the brain

Metastasis is the main killer in cancer; consequently, there is great interest in novel approaches to prevent and treat metastatic disease. Brain metastases are particularly deadly, as the protection of the blood-brain barrier obstructs the passage of common anticancer drugs. This study used magnetic resonance imaging (MRI) to investigate the therapeutic effects of nanoparticles coated with a tumor-penetrating peptide (iRGD) against a preclinical model of breast cancer brain metastasis. Single doses of iRGD nanoparticle were administered intravenously, and the effect on tumor growth was observed over time. iRGD nanoparticles, when applied in the early stages of metastasis development, strongly inhibited tumor progression. Overall, this study demonstrated for the first time that a single dose of iRGD nanoparticle can have a significant effect on metastatic tumor progression and nonproliferative cancer cell retention when applied early in course of tumor development. These data suggest that iRGD nanoparticles may be useful in preventatively reducing metastasis after a cancer diagnosis has been established.

KEY MESSAGES

bSSFP MRI can be used to track nonproliferative iron-labeled cells and tumor development over time. iRGD-NW, when applied early, has a significant effect on metastatic tumor progression. Retained signal voids represent a subpopulation of nonproliferating tumor cells. Reduced cell retention and tumor burden show a role for iRGD-NW in metastasis prevention. iRGD target is universally expressed; thus, iRGD-NW should be clinically translatable.

Supramolecularly engineered phospholipids constructed by nucleobase molecular recognition: upgraded generation of phospholipids for drug delivery

Supramolecularly engineered phospholipids and liposomes based on complementary hydrogen bonding of nucleosides have been developed.

Despite of great advances of phospholipids and liposomes in clinical therapy, very limited success has been achieved in the preparation of smart phospholipids and controlled-release liposomes for in vivo drug delivery and clinical trials. Here we report a supramolecular approach to synthesize novel supramolecularly engineered phospholipids based on complementary hydrogen bonding of nucleosides, which greatly reduces the need of tedious chemical synthesis, including reducing the strict requirements for multistep chemical reactions, and the purification of the intermediates and the amount of waste generated relative more traditional approaches. These upgraded phospholipids self-assemble into liposome-like bilayer structures in aqueous solution, exhibiting fast stimuli-responsive ability due to the hydrogen bonding connection. In vitro and in vivo evaluations show the resulted supramolecular liposomes from nucleoside phospholipids could effectively transport drug into tumor tissue, rapidly enter tumor cells, and controllably release their payload in response to an intracellular acidic environment, thus resulting in a much higher antitumor activity than conventional liposomes. The present supramolecularly engineered phospholipids represent an important evolution in comparison to conventional covalent-bonded phospholipid systems.

Nanotechnology-Based Drug Delivery Systems for Melanoma Antitumoral Therapy: A Review

Melanoma (MEL) is a less common type of skin cancer, but it is more aggressive with a high mortality rate. The World Cancer Research Fund International (GLOBOCAN 2012) estimates that there were 230,000 new cases of MEL in the world in 2012. Conventional MEL treatment includes surgery and chemotherapy, but many of the chemotherapeutic agents used present undesirable properties. Drug delivery systems are an alternative strategy by which to carry antineoplastic agents. Encapsulated drugs are advantageous due to such properties as high stability, better bioavailability, controlled drug release, a long blood circulation time, selective organ or tissue distribution, a lower total required dose, and minimal toxic side effects. This review of scientific research supports applying a nanotechnology-based drug delivery system for MEL therapy.

Targeted dextran-b-poly(ε-caprolactone) micelles for cancer treatments

In this study, targeted amphiphilic dextran-b-poly(ε-caprolactone) (Dex-PCL) was synthesized and used for efficient intracellular drug delivery.

RNA biomarker release with ultrasound and phase-change nanodroplets

Microbubbles driven by ultrasound are capable of permeabilizing cell membranes and allowing biomarkers or therapeutics to exit from or enter cancer cells, respectively. Unfortunately, the relatively large size of microbubbles prevents extravasation. Lipid-based perfluorobutane microbubbles can be made seven-fold smaller by pressurization, creating 430-nm nanodroplets. The present study compares microbubbles and nanodroplets with respect to their ability to enhance miR-21 and mammaglobin mRNA release from cultured ZR-75-1 cells. Mammaglobin mRNA and miR-21 release increased with escalating concentrations of nanodroplets up to, respectively, 25- and 42-fold with 2% nanodroplets (v/v), compared with pre-ultrasound levels, whereas cell viability decreased to 62.4%. Sonication of ZR-75-1 cells incubated with microbubbles or nanodroplets caused relatively similar levels of cell death and miR-21 release, suggesting that nanodroplets are similar to microbubbles in enhancing cell permeability, but may be more advantageous because of their smaller size, which may allow extravasation through leaky tumor vasculature.

Co-delivery of Sildenafil (Viagra(®)) and Crizotinib for synergistic and improved anti-tumoral therapy

PURPOSE

Cancer multi-drug resistance is a major issue associated with current anti-tumoral therapeutics. In this work, Crizotinib an anti-tumoral drug approved for the treatment of non-small lung cancer in humans, and Sildenafil (Viagra(®)), were loaded into micellar carriers to evaluate the establishment of a possible synergistic anti-tumoral effect in breast cancer cells.

METHODS

Micellar carriers comprised by PEG-PLA block co-polymers were formulated by the solvent displacement method in which the simultaneous encapsulation of Crizotinib and Sildenafil was promoted. Encapsulation efficiency was analyzed by a new UPLC method validated for this combination of compounds. Micelle physicochemical characterization and cellular uptake were characterized by light scattering and confocal microscopy. The bio- and hemocompatibility of the carriers was also evaluated. MCF-7 breast cancer cells were used to investigate the synergistic anti-tumoral effect.

RESULTS

Our results demonstrate that this particular combination induces massive apoptosis of breast cancer cells. The co-delivery of Crizotinib and Sildenafil was only possible due to the high encapsulation efficiency of the micellar systems (>70%). The micelles with size ranging between 93 and 127 nm were internalized by breast cancer cells and subsequently released their payload in the intracellular compartment. The results obtained demonstrated that the delivery of both drugs by micellar carriers led to a 2.7 fold increase in the anti-tumoral effect, when using only half of the concentration that is required when free drugs are administered.

CONCLUSIONS

Altogether, co-delivery promoted a synergistic effect and demonstrated for the first time the potential of PEG-PLA-Crizotinib-Sildenafil combination for application in cancer therapy.

Hydrophobic drug-triggered self-assembly of nanoparticles from silk-elastin-like protein polymers for drug delivery

Silk-elastin-like protein polymers (SELPs) combine the mechanical and biological properties of silk and elastin. These properties have led to the development of various SELP-based materials for drug delivery. However, SELPs have rarely been developed into nanoparticles, partially due to the complicated fabrication procedures, nor assessed for potential as an anticancer drug delivery system. We have recently constructed a series of SELPs (SE8Y, S2E8Y, and S4E8Y) with various ratios of silk to elastin blocks and described their capacity to form micellar-like nanoparticles upon thermal triggering. In this study, we demonstrate that doxorubicin, a hydrophobic antitumor drug, can efficiently trigger the self-assembly of SE8Y (SELPs with silk to elastin ratio of 1:8) into uniform micellar-like nanoparticles. The drug can be loaded in the SE8Y nanoparticles with an efficiency around 6.5% (65 ng doxorubicin/μg SE8Y), S2E8Y with 6%, and S4E8Y with 4%, respectively. In vitro studies with HeLa cell lines demonstrate that the protein polymers are not cytotoxic (IC50 > 200 μg/mL), while the doxorubicin-loaded SE8Y nanoparticles showed a 1.8-fold higher cytotoxicity than the free drug. Confocal laser scanning microscopy (CLSM) and flow cytometry indicate significant uptake of the SE8Y nanoparticles by the cells and suggest internalization of the nanoparticles through endocytosis. This study provides an all-aqueous, facile method to prepare nanoscale, drug-loaded SELPs packages with potential for tumor cell treatments.

A study on enhanced intestinal permeability of clarithromycin nanoparticles

The main objective of the present study was to determine the permeability of clarithromycin (CLA)-PLGA nanoparticles using single-pass intestinal perfusion technique in rats. Clarithromycin nanoparticles were prepared by nano-precipitation according to the modified quasi emulsion solvent diffusion technique and evaluated for their physicochemical characteristics. Permeability coefficients (Peff) in anaesthetized rats were determined at 3 different concentrations. Drug solution or suspensions in PBS was perfused through a cannulated jejunal segment and samples were taken from outlet tubing at different time points up to 90 min. Microbiological assay of CLA and phenol red in the samples were analyzed using an agar well diffusion procedure and HPLC method respectively. The average particle size of prepared nanoparticles was 305 ± 134 nm. The mean Peff of CLA solution in concentrations of 150, 250 and 400 µg/mL was found to be 1.20 (±0.32) ×10-3, 9.62 (±0.46) ×10-4, and 1.36 (±0.95) ×10-3 cm/sec, respectively. The corresponding values for the same concentration of nanoparticles were found to be 2.74 (±0.73) ×10-3, 2.45 (±0.88) ×10-3, and 3.68 (±0.46) ×10-3 cm/s, respectively. The two-tailed Student’s t-test showed that the intestinal permeability of CLA nanoparticle suspensions in prepared concentrations were significantly increased in comparison with its solution.

Cancer nanotechnology: the impact of passive and active targeting in the era of modern cancer biology

Cancer nanotherapeutics are progressing at a steady rate; research and development in the field has experienced an exponential growth since early 2000's. The path to the commercialization of oncology drugs is long and carries significant risk; however, there is considerable excitement that nanoparticle technologies may contribute to the success of cancer drug development. The pace at which pharmaceutical companies have formed partnerships to use proprietary nanoparticle technologies has considerably accelerated. It is now recognized that by enhancing the efficacy and/or tolerability of new drug candidates, nanotechnology can meaningfully contribute to create differentiated products and improve clinical outcome. This review describes the lessons learned since the commercialization of the first-generation nanomedicines including DOXIL® and Abraxane®. It explores our current understanding of targeted and non-targeted nanoparticles that are under various stages of development, including BIND-014 and MM-398. It highlights the opportunities and challenges faced by nanomedicines in contemporary oncology, where personalized medicine is increasingly the mainstay of cancer therapy. We revisit the fundamental concepts of enhanced permeability and retention effect (EPR) and explore the mechanisms proposed to enhance preferential "retention" in the tumor, whether using active targeting of nanoparticles, binding of drugs to their tumoral targets or the presence of tumor associated macrophages. The overall objective of this review is to enhance our understanding in the design and development of therapeutic nanoparticles for treatment of cancers.

Delivery of therapeutic agents by nanoparticles made of grapefruit-derived lipids

Although the use of nanotechnology for the delivery of a wide range of medical treatments has potential to reduce adverse effects associated with drug therapy, tissue-specific delivery remains challenging. Here we show that nanoparticles made of grapefruit-derived lipids, which we call grapefruit-derived nanovectors (GNVs), can transport chemotherapeutic agents, siRNA, DNA expression vectors and proteins to different types of cells. We demonstrate the in vivo targeting specificity of GNVs by co-delivering therapeutic agents with folic acid, which in turn leads to significantly increasing targeting efficiency to cells expressing folate receptors. The therapeutic potential of GNVs was further demonstrated by enhancing the chemotherapeutic inhibition of tumor growth in two tumor animal models. GNVs are less toxic than nanoparticles made of synthetic lipids and, when injected intravenously into pregnant mice, do not pass the placental barrier, suggesting they may be a useful tool for drug delivery.

Nanoparticle systems as tools to improve drug delivery and therapeutic efficacy

Nanoparticle-based drug delivery systems are appealing because, among other properties, they are easily manufactured and have the capacity to encapsulate a wide variety of drugs, many of which are not directly miscible with water. This review classifies nanoparticles into three broad categories based upon material composition: bio-inspired systems, synthetic systems, and inorganic systems. Each has distinct properties suitable for drug delivery applications, including their structure, composition, and pharmacokinetics (including clearance and uptake mechanisms), making each uniquely suitable for certain types of drugs. Furthermore, nanoparticles can be customized, making them ideal for a variety of applications. Advantages and disadvantages of the different systems are discussed. Strategies for improving nanoparticle efficacy include adding targeting agents on the nanoparticle surface, altering the degradation profile to control drug release, or PEGylating the surface to increase circulation times and reduce immediate clearance by the kidneys. The future of nanoparticle systems seems to be focused on further improving overall patient outcome by increasing delivery accuracy to the target area.

The inclusion complex of 4-hydroxynonenal with a polymeric derivative of β-cyclodextrin enhances the antitumoral efficacy of the aldehyde in several tumor cell lines and in a three-dimensional human melanoma model

4-Hydroxynonenal (HNE) is the most studied end product of the lipoperoxidation process, by virtue of its relevant biological activity. The antiproliferative and proapoptotic effects of HNE have been widely demonstrated in a great variety of tumor cell types in vitro. Thus, it might represent a promising new molecule in anticancer therapy strategies. However, the extreme reactivity of this aldehyde, as well as its insolubility in water, a limiting factor for drug bioavailability, and its rapid degradation by specific enzymes represent major obstacles to its possible in vivo application. Various strategies can used to overcome these problems. One of the most attractive strategies is the use of nanovehicles, because loading drugs into nanosized structures enhances their stability and solubility, thus improving their bioavailability and their antitumoral effectiveness. Several natural or synthetic polymers have been used to synthesize nanosized structures and, among them, β-cyclodextrin (βCD) polymers are playing a very important role in drug formulation by virtue of the ability of βCD to form inclusion compounds with a wide range of solid and liquid molecules by molecular complexation. Moreover, several βCD derivatives have been designed to improve their physicochemical properties and inclusion capacities. Here we report that the inclusion complex of HNE with a derivative of βCD, the βCD-poly(4-acryloylmorpholine) conjugate (PACM-βCD), enhances the aldehyde stability. Moreover, the inclusion of HNE in PACM-βCD potentiates its antitumor effects in several tumor cell lines and in a more complex system, such as a human reconstructed skin carrying melanoma tumor cells.

Optimization of parameters for preparation of docetaxel-loaded PLGA nanoparticles by nanoprecipitation method

The purpose of this study was to develop docetaxel-poly (lactide-co-glycolide) (PLGA) loaded nanoparticles by using nanoprecipitation method and optimize the relative parameters to obtain nanoparticles with higher encapsulation efficiency and smaller size. The physicochemical characteristics of nanoparticles were studied. The optimized parameters were as follows: the oil phase was mixture of acetone and ethanol, concentration of tocopheryl polyethylene glycol succinate (TPGS) was 0.2%, the ratio of oil phase to water phase was 1:5, and the theoretical drug concentration was 5%. The optimized nanoparticles were spherical with size between 130 and 150 nm. The encapsulation efficiency was (40.83±2.1)%. The in vitro release exhibited biphasic pattern. The results indicate that docetaxel-PLGA nanoparticles were successfully fabricated and may be used as the novel vehicles for docetaxel, which would replace Taxotere® and play great roles in future.

Targeted antiepidermal growth factor receptor (cetuximab) immunoliposomes enhance cellular uptake in vitro and exhibit increased accumulation in an intracranial model of glioblastoma multiforme

Therapeutic advances do not circumvent the devastating fact that the survival rate in glioblastoma multiforme (GBM) is less than 5%. Nanoparticles consisting of liposome-based therapeutics are provided against a variety of cancer types including GBM, but available liposomal formulations are provided without targeting moieties, which increases the dosing demands to reach therapeutic concentrations with risks of side effects. We prepared PEGylated immunoliposomes (ILs) conjugated with anti-human epidermal growth factor receptor (EGFR) antibodies Cetuximab (α-hEGFR-ILs). The affinity of the α-hEGFR-ILs for the EGF receptor was evaluated in vitro using U87 mg and U251 mg cells and in vivo using an intracranial U87 mg xenograft model. The xenograft model was additionally analyzed with respect to permeability to endogenous albumin, tumor size, and vascularization. The in vitro studies revealed significantly higher binding of α-hEGFR-ILs when compared with liposomes conjugated with isotypic nonimmune immunoglobulin. The uptake and internalization of the α-hEGFR-ILs by U87 mg cells were further confirmed by 3D deconvolution analyses. In vivo, the α-hEGFR-ILs accumulated to a higher extent inside the tumor when compared to nonimmune liposomes. The data show that α-hEGFR-ILs significantly enhance the uptake and accumulation of liposomes in this experimental model of GBM suggestive of improved specific nanoparticle-based delivery.

Small peptide-modified nanostructured lipid carriers distribution and targeting to EGFR-overexpressing tumor in vivo

Ala-Glu-Tyr-Leu-Arg (AEYLR) was identified as a small peptide ligand targeting epidermal growth factor receptors (EGFR) in vitro in our previous study. The in vivo targeting ability of AEYLR and AEYLR-conjugated nanostructured lipid carriers (NLC) was studied in this paper. Near-infrared fluorescent (NIFR) dye 1,1'-dioctadecyltetramethyl indotricarbocyanine iodide (DiR)-loaded and AEYLR-modified NLC (A-D-NLC) were prepared. The average diameter, zeta potential, coupling efficiency between AEYLR and NLC and the amount of DiR released from A-D-NLC were used to evaluate their in vivo characteristics. AEYLR was labeled by Cy7 and A549 xenograft tumor-bearing mice model were establish. The in vivo distribution in tumor-bearing mice of A-D-NLC and Cy7-AEYLR was examined using NIRF imaging experiments at different times post-injection. AEYLR and AEYLR-conjugated NLC showed obvious targeting to A549 xenograft tumor compared with the control group. These results suggested that AEYLR-modified NLC could be considered as a promising targeted delivery system for combination cancer chemotherapy to improve therapeutic efficacy and to minimize adverse effects.

Exosomes are endogenous nanoparticles that can deliver biological information between cells

Exosomal particular size of 30-100 nm matches the size criterion for nanoparticles, and opens up the possibility of using exosomes as a nanoparticle drug carrier. More importantly, exosomes released from different types of host cells have different biological effects and targeting specificities. Therefore, depending on the therapeutic goal, different types of exosomes can be combined with specific drugs and serve as carriers so that personalized medicine needs are met. In addition, exosomes do not appear to have cytotoxicity. Based on the perceived advantages of exosomes, they may well serve as a next generation drug delivery mechanism that combines nanoparticle size with a non-cytotoxic effect, target specificity, and a high drug carrying capacity, to make them useful in the treatment of a variety of diseases. This review will focus on exosomes as a biological nanoparticle drug carrier with emphasis on their immune-regulatory activities.

Development of the vault particle as a platform technology

Vaults are naturally occurring nanoparticles found widely in eukaryotes. The particles can be produced in large quantities and are assembled in situ from multiple copies of the single structural protein following expression. Using molecular engineering, recombinant vaults can be functionally modified and targeted, and their contents can be controlled by packaging. Here, we review the development of engineered vaults as a platform for a wide variety of therapeutic applications and we examine future directions for this unique nanoparticle system.

5-Fluorouracil nanoparticles inhibit hepatocellular carcinoma via activation of the p53 pathway in the orthotopic transplant mouse model

Biodegradable polymer nanoparticle drug delivery systems provide targeted drug delivery, improved pharmacokinetic and biodistribution, enhanced drug stability and fewer side effects. These drug delivery systems are widely used for delivering cytotoxic agents. In the present study, we synthesized GC/5-FU nanoparticles by combining galactosylated chitosan (GC) material with 5-FU, and tested its effect on liver cancer in vitro and in vivo. The in vitro anti-cancer effects of this sustained release system were both dose- and time-dependent, and demonstrated higher cytotoxicity against hepatic cancer cells than against other cell types. The distribution of GC/5-FU in vivo revealed the greatest accumulation in hepatic cancer tissues. GC/5-FU significantly inhibited tumor growth in an orthotropic liver cancer mouse model, resulting in a significant reduction in tumor weight and increased survival time in comparison to 5-FU alone. Flow cytometry and TUNEL assays in hepatic cancer cells showed that GC/5-FU was associated with higher rates of G0-G1 arrest and apoptosis than 5-FU. Analysis of apoptosis pathways indicated that GC/5-FU upregulates p53 expression at both protein and mRNA levels. This in turn lowers Bcl-2/Bax expression resulting in mitochondrial release of cytochrome C into the cytosol with subsequent caspase-3 activation. Upregulation of caspase-3 expression decreased poly ADP-ribose polymerase 1 (PARP-1) at mRNA and protein levels, further promoting apoptosis. These findings indicate that sustained release of GC/5-FU nanoparticles are more effective at targeting hepatic cancer cells than 5-FU monotherapy in the mouse orthotropic liver cancer mouse model.

An Algorithm for the Preclinical Screening of Anticancer Drugs Effective against Brain Tumors

The anticancer drugs screening program is a long and expensive process. It is estimated that only 5% of drugs entering clinical trials are approved by the FDA. Moreover, many of the drugs that enter clinical trials are often of limited use in clinical practice, and most cancers remain untreatable. Brain tumors are particularly difficult to treat due to the presence of the blood brain barrier that limits the penetration of anticancer drugs. Additionally the isolation from most brain tumors of putative cancer stem cells and novel models of cancer stem cell biology suggest that anticancer drugs should be delivered for prolonged time and at higher concentrations to deplete any potential tumorigenic cell. In this paper, current concepts of cancer stem cell biology and novel concepts of anticancer drugs screening are integrated to develop a seven-steps algorithm as a guideline for the preclinical evaluation of active compounds for the treatment of brain tumors. The flexibility of the algorithm allows the inclusion of alternative studies to exhaustively investigate anticancer drugs and creates multiple opportunities where decisions to engage or not in early clinical trials can be made providing a useful tool for translational research in neurooncology.

Breakdown of the blood-ocular barrier as a strategy for the systemic use of nanosystems

Several drug delivery systems have been proposed to overcome physiological barriers, improving ocular bioavailability. Systemic routes are seldom used due to the blood-ocular barrier. Novel drug delivery systems based on nanotechnology techniques have been developed to overcome ocular physiological barriers. This non-systematic review suggests the utilization of a transitory blood-ocular breakdown to allow the access of drugs by nanotechnology drug delivery systems via the systemic route. We discuss the possible ways to cause the breakdown of the blood-ocular barrier: acute inflammation caused by intraocular surgery, induced ocular hypotony, and the use of inflammatory mediators. The suitability of use of the systemic route and its toxic effects are also discussed in this article.

Prodrug strategy for PSMA-targeted delivery of TGX-221 to prostate cancer cells

TGX-221 is a potent, selective, and cell membrane permeable inhibitor of the PI3K p110β catalytic subunit. Recent studies showed that TGX-221 has antiproliferative activity against PTEN-deficient tumor cell lines including prostate cancers. The objective of this study was to develop an encapsulation system for parenterally delivering TGX-221 to the target tissue through a prostate-specific membrane aptamer (PSMAa10) with little or no side effects. In this study, PEG-PCL micelles were formulated to encapsulate the drug, and a prodrug strategy was pursued to improve the stability of the carrier system. Fluorescence imaging studies demonstrated that the cellular uptake of both drug and nanoparticles was significantly improved by targeted micelles in a PSMA positive cell line. The area under the plasma concentration time curve of the micelle formulation in nude mice was 2.27-fold greater than that of the naked drug, and the drug clearance rate was 6.16-fold slower. These findings suggest a novel formulation approach for improving site-specific drug delivery of a molecular-targeted prostate cancer treatment.

Targeted polymeric therapeutic nanoparticles: design, development and clinical translation

Polymeric materials have been used in a range of pharmaceutical and biotechnology products for more than 40 years. These materials have evolved from their earlier use as biodegradable products such as resorbable sutures, orthopaedic implants, macroscale and microscale drug delivery systems such as microparticles and wafers used as controlled drug release depots, to multifunctional nanoparticles (NPs) capable of targeting, and controlled release of therapeutic and diagnostic agents. These newer generations of targeted and controlled release polymeric NPs are now engineered to navigate the complex in vivo environment, and incorporate functionalities for achieving target specificity, control of drug concentration and exposure kinetics at the tissue, cell, and subcellular levels. Indeed this optimization of drug pharmacology as aided by careful design of multifunctional NPs can lead to improved drug safety and efficacy, and may be complimentary to drug enhancements that are traditionally achieved by medicinal chemistry. In this regard, polymeric NPs have the potential to result in a highly differentiated new class of therapeutics, distinct from the original active drugs used in their composition, and distinct from first generation NPs that largely facilitated drug formulation. A greater flexibility in the design of drug molecules themselves may also be facilitated following their incorporation into NPs, as drug properties (solubility, metabolism, plasma binding, biodistribution, target tissue accumulation) will no longer be constrained to the same extent by drug chemical composition, but also become in-part the function of the physicochemical properties of the NP. The combination of optimally designed drugs with optimally engineered polymeric NPs opens up the possibility of improved clinical outcomes that may not be achievable with the administration of drugs in their conventional form. In this critical review, we aim to provide insights into the design and development of targeted polymeric NPs and to highlight the challenges associated with the engineering of this novel class of therapeutics, including considerations of NP design optimization, development and biophysicochemical properties. Additionally, we highlight some recent examples from the literature, which demonstrate current trends and novel concepts in both the design and utility of targeted polymeric NPs (444 references).

Vaults engineered for hydrophobic drug delivery

The vault nanoparticle is one of the largest known ribonucleoprotein complexes in the sub-100 nm range. Highly conserved and almost ubiquitously expressed in eukaryotes, vaults form a large nanocapsule with a barrel-shaped morphology surrounding a large hollow interior. These properties make vaults an ideal candidate for development into a drug delivery vehicle. In this study, the first example of using vaults towards this goal is reported. Recombinant vaults are engineered to encapsulate the highly insoluble and toxic hydrophobic compound all-trans retinoic acid (ATRA) using a vault-binding lipoprotein complex that forms a lipid bilayer nanodisk. These recombinant vaults offer protection to the encapsulated ATRA from external elements. Furthermore, a cryo-electron tomography (cryo-ET) reconstruction shows the vault-binding lipoprotein complex sequestered within the vault lumen. Finally, these ATRA-loaded vaults show enhanced cytotoxicity against the hepatocellular carcinoma cell line HepG2. The ability to package therapeutic compounds into the vault is an important achievement toward their development into a viable and versatile platform for drug delivery.