Enhanced antiproliferative activity of Herceptin (HER2)-conjugated gemcitabine-loaded chitosan nanoparticle in pancreatic cancer therapy

Manipulation of pH-Sensitive interactions between podophyllotoxin-chitosan for enhanced controlled drug release

Podophyllotoxin (PPT) offers a broad-spectrum of anticancer activities, but little has been reported for its controlled release. This work shows that by manipulating molecular interactions between PPT and Chitosan, efficient nanoscale capsulation of PPT can be realized. The drug encapsulation efficiency is as high as 52%, with a final particle drug loading in the order of 10% (wt/wt). It further demonstrates that changes in pH can also significantly affect the rate of drug release from the Chitosan nanoparticles. Upon contact with cancer cells, chitosan nanoparticles enable efficient internalization and drug release. In vitro evaluations with HepG-2 and MCF-7 cells indicate that the chitosan nanoparticle carriers can improve drug efficacy in comparison to free PPT, most likely by regulating the intrinsic apoptotic signaling pathway to induce apoptosis. Overall, PPT chitosan nanoparticles promise a safe and efficient drug delivery system for PPT.

Recent advances in drug delivery strategies for improved therapeutic efficacy of gemcitabine

Gemcitabine (2',2'-difluoro-2'-deoxycytidine; dFdC) is an efficacious anticancer agent acting against a wide range of solid tumors, including pancreatic, non-small cell lung, bladder, breast, ovarian, thyroid and multiple myelomas. However, short plasma half-life due to metabolism by cytidine deaminase necessitates administration of high dose, which limits its medical applicability. Further, due to its hydrophilic nature, it cannot traverse cell membranes by passive diffusion and, therefore, enters via nucleoside transporters that may lead to drug resistance. To circumvent these limitations, macromolecular prodrugs and nanocarrier-based formulations of Gemcitabine are gaining wide recognition. The nanoformulations based approaches by virtue of their controlled release and targeted delivery have proved to improve bioavailability, increase therapeutic efficacy and reduce adverse effects of the drug. Furthermore, the combination of Gemcitabine with other anticancer agents as well as siRNAs using nanocarriers has also been investigated in order to enhance its therapeutic potential. This review deals with challenges and recent advances in the delivery of Gemcitabine with particular emphasis on macromolecular prodrugs and nanomedicines.

Preclinical systemic toxicity evaluation of chitosan-solid lipid nanoparticle-encapsulated aspirin and curcumin in combination with free sulforaphane in BALB/c mice

Our previous studies have established the efficacy of chemopreventive regimens of aspirin and curcumin (CUR) encapsulated within solid lipid nanoparticles (SLNs) in combination with free sulforaphane (ACS combination) to prevent or delay the initiation and progression of pancreatic cancer, classified as one of the deadliest diseases with very low chances of survival upon diagnosis. Although toxicity of individual drugs and SLN has been studied previously, there are no studies in current literature that evaluate the potential toxicity of a combined regimen of ACS, especially when encapsulated within chitosan-SLNs (c-SLNs). Hence, objective of the current study was to investigate the potential toxic effects of ACS c-SLN combined chemopreventive regimens following acute (3 days), subacute (28 days), and subchronic (90 days) administrations by oral gavage in BALB/c mice. Mice were administered the following regimens: saline, blank c-SLN, low-dose ACS c-SLN (2+4.5+0.16 mg/kg), medium-dose ACS c-SLN (20+45+1.6 mg/kg), and high-dose ACS c-SLN (60+135+4.8 mg/kg). The potential toxicity was evaluated based on animal survival, body weight, hematology, blood chemistry, and organ histopathology. During 3-day, 28-day, and 90-day study periods, no animal deaths were observed. Treatment with ACS c-SLNs did not cause alteration in complete blood counts and blood chemistry data. Histopathological examination of various organ sections (pancreas, heart, liver, kidney, and brain) appeared normal. Based on the results of this study, no signs of toxicity in acute, subacute, and subchronic studies following oral administration of ACS c-SLNs were found indicating that the oral dosing regimens were safe at the levels tested for long-term administration to prevent the onset of pancreatic cancer.

Trastuzumab-grafted PAMAM dendrimers for the selective delivery of anticancer drugs to HER2-positive breast cancer

Approximately 20% of breast cancer cases are human epidermal growth factor receptor 2 (HER2)-positive. This type of breast cancer is more aggressive and tends to reoccur more often than HER2-negative breast cancer. In this study, we synthesized trastuzumab (TZ)-grafted dendrimers to improve delivery of docetaxel (DTX) to HER2-positive breast cancer cells. Bioconjugation of TZ on the surface of dendrimers was performed using a heterocrosslinker, MAL-PEG-NHS. For imaging of cancer cells, dendrimers were also conjugated to fluorescein isothiocyanate. Comparative in vitro studies revealed that these targeted dendrimers were more selective, and had higher antiproliferation activity, towards HER2-positive MDA-MB-453 human breast cancer cells than HER2-negative MDA-MB-231 human breast cancer cells. When compared with unconjugated dendrimers, TZ-conjugated dendrimers also displayed higher cellular internalization and induction of apoptosis against MDA-MB-453 cells. Binding of TZ to the dendrimer surface could help site-specific delivery of DTX and reduce systemic toxicity resulting from its lack of specificity. In addition, in vivo studies revealed that the pharmacokinetic profile of DTX was significantly improved by the conjugated nanosystem.

Functionalized magnetic dextran-spermine nanocarriers for targeted delivery of doxorubicin to breast cancer cells

In recent decades, targeted drug delivery systems for breast cancer treatment emerged as an ideal alternative and promising solution to reduce systemic side effects of chemotherapeutic agents. In this study, the preparation and characterization of cationic doxorubicin (DOX) loaded magnetic dextran-spermine (DEX-SP) nanocarriers (DEX-SP-DOX) by ionic gelation were fully investigated. Then, anti-HER2 as a monoclonal antibody (mAb) and targeting ligand was conjugated via EDC/NHS reagents. The binding was confirmed by Bradford assay and further assessments were carried out by size and zeta potential measurements. Cytotoxicity effect and internalization of magnetic nanocarriers were assessed by MTT and Prussian blue assays and transmission electron microscopy (TEM), respectively. DLS measurements indicated that the size of nanocarriers increased from 62 to 84 nm by conjugation of anti-HER2 to them. The in vitro release of DOX from mAb conjugated magnetic nanocarriers at pHs 5 and 7.4 was found to be 85 and 55.5%, respectively. The MTT and Prussian blue assays demonstrated enhanced and selective uptake of DEX-SP-DOX-mAb by SKBR cell (HER2 overexpressed cells) in comparison with unconjugated nanocarriers due to higher cellular binding. The TEM result also confirmed cellular internalization of DEX-SP-DOX-mAb magnetic nanocarriers. These results are very promising for targeted delivery of DOX to HER2 positive breast cancer cells.

In vivo drug delivery of gemcitabine with PEGylated single-walled carbon nanotubes

Gemcitabine (GEM) is an anticancer agent widely used in non-small cell lung and pancreatic cancers. The clinical use of GEM has been limited by its rapid metabolism and short plasma half-life. These restrictions lead to frequent administration of high drug doses which can cause severe side effects. Therefore, new delivery strategies are needed aiming toward improved therapeutic effects. Single-walled carbon nanotubes (SWCNTs) are emerging as promising carriers for drug delivery due to their unique properties including high drug loading capacities, notable cell membrane penetrability and prolonged circulation times. In this work, pristine SWCNTs were functionalized through carboxylation, acylation, amination, PEGylation and finally GEM conjugation. The prepared SWCNT-GEM and SWCNT-PEG-GEM conjugates were characterized by FTIR, NMR, DSC and TEM to confirm the successful functionalization. The amount of GEM bound to the conjugates was 43.14% (w/w) for the SWCNT-GEM and 37.32% for the SWCNT-PEG-GEM, indicating high loading capacity. MTT assay on the human lung carcinoma cell line (A549) and the human pancreatic carcinoma cell line (MIA PaCa-2) demonstrated that the SWCNT-GEM was more cytotoxic than SWCNT-PEG-GEM and GEM. The SWCNT-PEG-GEM conjugates afford higher efficacy in suppressing tumor growth than SWCNT-GEM and GEM in B6 nude mice. The results demonstrate that the new formulation of GEM is useful strategy for improving the antitumor efficacy of GEM.

Gemcitabine and Chlorotoxin Conjugated Iron Oxide Nanoparticles for Glioblastoma Therapy

Many small-molecule anti-cancer drugs have short blood half-lives and toxicity issues due to non-specificity. Nanotechnology has shown great promise in addressing these issues. Here, we report the development of an anti-cancer drug gemcitabine-conjugated iron oxide nanoparticle for glioblastoma therapy. A glioblastoma targeting peptide, chlorotoxin, was attached after drug conjugation. The nanoparticle has a small size (~32 nm) and uniform size distribution (PDI ≈ 0.1), and is stable in biological medium. The nanoparticle effectively enter cancer cells without losing potency compared to free drug. Significantly, the nanoparticle showed a prolonged blood half-life and the ability to cross the blood-brain barrier in wild type mice.

Theranostic reduction-sensitive gemcitabine prodrug micelles for near-infrared imaging and pancreatic cancer therapy

A biodegradable and reduction-cleavable gemcitabine (GEM) polymeric prodrug with in vivo near-infrared (NIR) imaging ability was reported. This theranostic GEM prodrug PEG-b-[PLA-co-PMAC-graft-(IR820-co-GEM)] was synthesized by ring-opening polymerization and "click" reaction. The as-prepared reduction-sensitive prodrug could self-assemble into prodrug micelles in aqueous solution confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). In vitro drug release studies showed that these prodrug micelles were able to release GEM in an intracellular-mimicking reductive environment. These prodrug micelles could be effectively internalized by BxPC-3 pancreatic cancer cells, which were observed by confocal laser scanning microscopy (CLSM). Meanwhile, a methyl thiazolyl tetrazolium (MTT) assay demonstrated that this prodrug exhibited high cytotoxicity against BxPC-3 cells. The in vivo whole-animal near-infrared (NIR) imaging results showed that these prodrug micelles could be effectively accumulated in tumor tissue and had a longer blood circulation time than IR820-COOH. The endogenous reduction-sensitive gemcitabine prodrug micelles with the in vivo NIR imaging ability might have great potential in image-guided pancreatic cancer therapy.

Monoclonal antibody-tagged polyethylenimine (PEI)/poly(lactide) (PLA) nanoparticles for the enhanced delivery of doxorubicin in HER-positive breast cancers

Poor therapeutic response and adverse side effects of chemotherapeutic agents are the major obstacles for effective chemotherapy against breast cancers.

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.

CD147 monoclonal antibody mediated by chitosan nanoparticles loaded with α-hederin enhances antineoplastic activity and cellular uptake in liver cancer cells

An antibody that specifically interacts with an antigen could be applied to an active targeting delivery system. In this study, CD147 antibody was coupled with α-hed chitosan nanoparticles (α-Hed-CS-NPs). α-Hed-CS-CD147-NPs were round and spherical in shape, with an average particle size of 148.23 ± 1.75 nm. The half-maximum inhibiting concentration (IC50) of α-Hed-CS-CD147-NPs in human liver cancer cell lines HepG2 and SMMC-7721 was lower than that of free α-Hed and α-Hed-CS-NPs. α-Hed-induced cell death was mainly triggered by apoptosis. The increase in intracellular accumulation of α-Hed-CS-CD147-NPs was also related to CD147-mediated internalization through the Caveolae-dependent pathway and lysosomal escape. The higher targeting antitumor efficacy of α-Hed-CS-CD147-NPs than that α-Hed-CS-NPs was attributed to its stronger fluorescence intensity in the tumor site in nude mice.

Enhanced delivery of Paclitaxel using electrostatically-conjugated Herceptin-bearing PEI/PLGA nanoparticles against HER-positive breast cancer cells

We have developed a novel nanoparticle delivery system fabricated from polyethylenimine (PEI) and poly(d,l-lactide-co-glycolide) (PLGA), which were able to deliver the chemotherapeutic agent Paclitaxel, while the biomacromolecule Herceptin acted as a targeting ligand that was conjugated onto the surfaces of the nanoparticles via electrostatic interactions. In this study, these electrostatically-conjugated Herceptin-bearing PEI/PLGA nanoparticles (eHER-PPNs) were optimized and employed as vectors to target HER2-positive breast cancer cells. The eHER-PPNs had an average diameter of ∼ 280 nm and a neutral surface charge (1.00 ± 0.73 mV), which remained stable under physiological conditions. The anticancer effects of eHER-PPNs were investigated in HER2-positive BT474 cells and HER2-negative MCF7 cells. The eHER-PPNs showed enhanced cytotoxicity that was dependent on the receptor expression levels and the incubation time. These conjugated nanoparticles deliver Paclitaxel more efficiently (p<0.001) than unmodified PPNs, Herceptin and the combined effects of these two monotherapies. Furthermore, the chemically-conjugated Herceptin-bearing PEI/PLGA nanoparticles (cHER-PPNs) were fabricated as a comparison. The eHER-PPNs exhibited lower cell viability (46.7%) than that of cHER-PPNs (65.1%). The targeting ability of eHER-PPNs was demonstrated through confocal microscopy images and flow cytometry, which showed that eHER-PPNs displayed higher cellular uptake efficiency (p<0.001) in comparison with cHER-PPNs. Therefore, eHER-PPNs could provide promising platforms for the delivery of therapeutic drugs against HER2-positive breast cancers.

Chitosan Nanoparticles for Nuclear Targeting: The Effect of Nanoparticle Size and Nuclear Localization Sequence Density

Many recently discovered therapeutic proteins exert their main function in the nucleus, thus requiring both efficient uptake and correct intracellular targeting. Chitosan nanoparticles (NPs) have attracted interest as protein delivery vehicles due to their biocompatibility and ability to escape the endosomes offering high potential for nuclear delivery. Molecular entry into the nucleus occurs through the nuclear pore complexes, the efficiency of which is dependent on NP size and the presence of nuclear localization sequence (NLS). Chitosan nanoparticles of different sizes (S-NPs ≈ 25 nm; L-NP ≈ 150 nm) were formulated, and they were modified with different densities of the octapeptide NLS CPKKKRKV (S-NPs, 0.25, 0.5, 2.0 NLS/nm(2); L-NPs, 0.6, 0.9, 2 NLS/nm(2)). Unmodified and NLS-tagged NPs were evaluated for their protein loading capacity, extent of cell association, cell uptake, cell surface binding, and finally nuclear delivery efficiency in L929 fibroblasts. To avoid errors generated with cell fractionation and nuclear isolation protocols, nuclear delivery was assessed in intact cells utilizing Förster resonance energy transfer (FRET) fluorometry and microscopy. Although L-NPs showed ≈10-fold increase in protein loading per NP when compared to S-NPs, due to higher cell association and uptake S-NPs showed superior protein delivery. NLS exerts a size and density dependent effect on nanoparticle uptake and surface binding, with a general reduction in NP cell surface binding and an increase in cell uptake with the increase in NLS density (up to 8.4-fold increase in uptake of High-NLS-L-NPs (2 NLS/nm(2)) compared to unmodified L-NPs). However, for nuclear delivery, unmodified S-NPs show higher nuclear localization rates when compared to NLS modified NPs (up to 5-fold by FRET microscopy). For L-NPs an intermediate NLS density (0.9 NLS/nm(2)) seems to provide highest nuclear localization (3.7-fold increase in nuclear delivery compared to High-NLS-L-NPs). Results indicate that a higher NLS density does not result in maximum protein nuclear localization and that a universal optimal density for NPs of different sizes does not exist.

Tumor targeting using polyamidoamine dendrimer-cisplatin nanoparticles functionalized with diglycolamic acid and herceptin

Polymer mediated drug delivery system represents a novel promising platform for tumor-targeting with reduced systemic side effects and improved chemotherapeutical efficacy. In this study, we report the preparation and characterization of herceptin targeted, diglycolamic acid (DGA) functionalized polyamidoamine (PAMAM) dendrimer as a potent drug carrier for cisplatin. DGA dendrimers carrying cisplatin demonstrated enhanced anticancer activity when targeted with herceptin. In vitro cell line studies with herceptin-DGA-G4-cisplatin in HER-2 +ve and HER-2 -ve human ovarian cancer cell lines showed that these nanoparticles possessed remarkable features such as lower IC50 value, improved S-phase arrest, and enhanced apoptosis due to increased cellular uptake and accumulation than the untargeted DGA-G4-cisplatin and free cisplatin. Furthermore, in vivo results in SCID mice bearing SKOV-3 tumor xenografts, herceptin-DGA-G4-cisplatin, appeared to be more effective in inducing tumor regression as compared to free cisplatin. Collectively, these results indicate that herceptin targeted DGA functionalized PAMAM-cisplatin conjugates serve as better anti-tumor agents than individual therapeutic agents.

Ultrasound contrast-enhanced imaging and in vitro antitumor effect of paclitaxel-poly(lactic-co-glycolic acid)-monomethoxypoly (ethylene glycol) nanocapsules with ultrasound-targeted microbubble destruction

A combination of diagnostic and therapeutic ultrasound (US) techniques may be able to provide the basis of specific therapeutic protocols, particularly for the treatment of tumors. Nanotechnology may aid the progression towards the use of US for tumor diagnosis and targeted therapy. The current study investigated in vivo and in vitro US contrast imaging using nanocapsules (NCs), and also US and US-targeted microbubble destruction (UTMD) therapy using drug-loaded NCs for pancreatic cancer in vitro. In the current study, the NCs were made from the polymer nanomaterial poly(lactic-co-glycolic acid)-monomethoxypoly(ethylene glycol) (PLGA-mPEG), encapsulated with paclitaxel (PTX), to create PTX-PLGA-mPEG NCs. The PTX-PLGA-mPEG NCs were used as a US contrast agent (UCA), which produced satisfactory US contrast-enhanced images in vitro and in vivo of the rabbit kidneys, with good contrast compared with lesions in the peripheral regions. However, clear contrast-enhanced images were not obtained using PTX-PLGA-mPEG NCs as a UCA, when imaging the superficial pancreatic tumors of nude mice in vivo. Subsequently, fluorescence and flow cytometry were used to measure the NC uptake rate of pancreatic tumor cells under various US or UTMD conditions. An MTT assay was used to evaluate the efficiency of PTX and PTX-PLGA-mPEG NCs in killing tumor cells following 24 or 48 h of US or UTMD therapy, compared with controls. The specific US or UTMD conditions had been previously demonstrated to be optimal through repeated testing, to determine the conditions by which cells were not impaired and the efficiency of uptake of nanoparticles was highest. The current study demonstrated high cellular uptake rates of PLGA-mPEG NCs and high tumor cell mortality with PTX-PLGA-mPEG NCs under US or UTMD optimal conditions. It was concluded that the use of NCs in US-mediated imaging and antitumor therapy may provide a novel application for US.

Gemcitabine loaded biodegradable PLGA nanospheres for in vitro pancreatic cancer therapy

Pancreatic cancer is the fourth leading cancer with 85% mortality rate in USA alone and it is prevalent in many other developed and developing countries. Clinically, gemcitabine is prescribed as the first line chemotherapeutic drug for pancreatic cancer treatment. Gemcitabine-loaded poly(lactide-co-glycolide) (PLGA) nanospheres were synthesized and their physico-chemical properties were evaluated. The FESEM images showed that the gemcitabine loaded and blank nanospheres were 180 nm and 200 nm, respectively. The optimized encapsulation efficiency of gemcitabine was 15%. It was observed that 100% of gemcitabine was released from the PLGA nanospheres for 41 days in phosphate buffered saline (PBS) at pH7.4. The uptake of nanospheres in MiaPaCa-2 cells was studied using sulforhodamine B loaded PLGA nanospheres and our results showed that the nanospheres were taken up within 3h. Furthermore, the cytotoxicity of PLGA nanospheres loaded with gemcitabine showed a relative decrease in IC50 in MiaPaCa-2 and ASPC-1 pancreatic cancer cells in comparison to free gemcitabine. The study demonstrates that this system hold promise to improve the therapeutic efficacy of gemcitabine in vitro.

Enhanced cytotoxicity and apoptosis-induced anticancer effect of silibinin-loaded nanoparticles in oral carcinoma (KB) cells

Silibinin (SIL) is a plant derived flavonoid isolated from the fruits and seeds of the milk thistle (Silybum marianum). Silibinin possesses a wide variety of biological applications including anticancer activities but poor aqueous solubility and poor bioavailability limit its potential and efficacy at the tumor sites. In the present study, silibinin was encapsulated in Eudragit® E (EE) nanoparticles in the presence of stabilizing agent polyvinyl alcohol (PVA) and its anticancer efficacy in oral carcinoma (KB) cells was studied. Silibinin loaded nanoparticles (SILNPs) were prepared by nanoprecipitation technique and characterized in terms of size distribution, morphology, surface charge, encapsulation efficiency and in vitro drug release. MTT assay revealed higher cytotoxic efficacy of SILNPs than free SIL in KB cells. Meanwhile, reactive oxygen species (ROS) determination revealed the significantly higher intracellular ROS levels in SILNPs treated cells compared to free SIL treated cells. Therefore, the differential cytotoxicity between SILNPs and SIL may be mediated by the discrepancy of intracellular ROS levels. Moreover, acridine orange (AO) and ethidium bromide (EB) dual staining and reduced mitochondrial membrane potential (MMP) confirmed the induction of apoptosis with nanoparticle treatment. Further, the extent of DNA damage (evaluated by comet assay) was significantly increased in SILNPs than free SIL in KB cells. Taken together, the present study suggests that silibinin-loaded nanoparticles can be used as an effective drug delivery system to produce a better chemopreventive response for the treatment of cancer.

Rapid hybridization of chitosan-gold-antibodies via metal-free click in water-based systems: a model approach for naked-eye detectable antigen sensors

A surface plasmon resonance (SPR) expression after hybridization of chitosan-gold nanoparticle-antibody (CS-AuNPs-Ab) based on: i) metal-free click chemistry, and, ii) in water system as an approach for a rapid antigen sensing, is proposed. The chitosan-hydroxybenzyl triazole complex enables us to carry out the conjugation of mPEG and trifluoromethylated oxanorbornadiene (OND) in water. CS-mPEG-OND further allows metal-free click to hybridize chitosan (CS) with azido-modified gold nanoparticles (azido-AuNPs) in aqueous solution at room temperature. The CS-mPEG-OND conjugated with LipL32 antibody (Ab) not only effectively binds with LipL32 antigen (Ag) but also performs the cycloaddition with azido-AuNPs to display a change in color within 2 min. The phenomenon leads to a simple and efficient naked-eye antigen detection technique.

Polymer nanoparticles for drug and small silencing RNA delivery to treat cancers of different phenotypes

Advances in nanotechnology have provided powerful and efficient tools in the development of cancer diagnosis and therapy. There are numerous nanocarriers that are currently approved for clinical use in cancer therapy. In recent years, biodegradable polymer nanoparticles have attracted a considerable attention for their ability to function as a possible carrier for target-specific delivery of various drugs, genes, proteins, peptides, vaccines, and other biomolecules in humans without much toxicity. This review will specifically focus on the recent advances in polymer-based nanocarriers for various drugs and small silencing RNA's loading and delivery to treat different types of cancer.

Comparative evaluation of novel biodegradable nanoparticles for the drug targeting to breast cancer cells

Nanomedicine formulations such as biodegradable nanoparticles (nps) and liposomes offer several advantages over traditional routes of administration: due to their small size, nanocarriers are able to selectively accumulate inside tumours or inflammatory tissues, resulting in improved drug efficacy and reduced side effects. To further augment targeting ability of nanoparticles towards tumour cells, specific ligands or antibodies that selectively recognise biomarkers over-expressed on cancer cells, can be attached to the surface either by chemical bond or by hydrophilic/hydrophobic interactions. In the present work, Herceptin (HER), a monoclonal antibody (mAb) able to selectively recognise HER-2 over-expressing tumour cells (such as breast and ovarian cancer cells), was absorbed on the surface of nanoparticles through hydrophilic/hydrophobic interactions. Nps were prepared by a modified single emulsion solvent evaporation method with five different polymers: three commercial polyesters (poly(ε-caprolactone) (PCL), poly (D,L-lactide) (PLA) and poly (D,L-lactide-co-.glycolide) (PLGA)) and two novel biodegradable polyesterurethanes (PURs) based on Poly(ε-caprolactone) blocks, synthesised with different chain extenders (1,4-cyclohexane dimethanol (CDM) and N-Boc-serinol). Polyurethanes were introduced as matrix-forming materials for nanoparticles due to their high chemical versatility, which allows tailoring of the materials final properties by properly selecting the reagents. All nps exhibited a small size and negative surface charge, suitable for surface functionalisation with mAb through hydrophilic/hydrophobic interactions. The extent of cellular internalisation was tested on two different cell lines: MCF-7 and SK-BR-3 breast cancer cells showing a normal and a high expression of the HER-2 receptor, respectively. Paclitaxel, a model anti-neoplastic drug, was encapsulated inside all nps, and release profiles and cytotoxicity on SK-BR-3 cells were also assessed. Interestingly, PUR nps were superior to commercial polyester-based nps in terms of higher cellular internalisation and cytotoxic activity on the tested cell lines. Results obtained warrants further investigation on the application of these PUR nps for controlled drug delivery and targeting.

Self-assembling, amphiphilic polymer-gemcitabine conjugate shows enhanced antitumor efficacy against human pancreatic adenocarcinoma

The therapeutic efficacy of gemcitabine is severely compromised due to its rapid plasma metabolism. Moreover, its hydrophilicity poses a challenge for its efficient entrapment in nanosized delivery systems and to provide a sustained release profile. In this study, gemcitabine was covalently conjugated to poly(ethylene glycol)-block-poly(2-methyl-2-carboxyl-propylene carbonate) (PEG-PCC) which could self-assemble into micelles of 23.6 nm. These micelles afforded protection to gemcitabine from plasma metabolism as evident by negligible amount of gemcitabine and its metabolite dFdU detected in the plasma after 24 h. A controlled release of gemcitabine from the micelles was observed with 53.89% drug release in 10 days in the presence of protease enzyme Cathepsin B. Gemcitabine conjugated micelles were cytotoxic, showed internalization, and induced cell apoptosis in MIA PaCa-2 and L3.6pl pancreatic cancer cell lines. These micelles efficiently inhibited tumor growth when injected intravenously into MIA PaCa-2 cell derived xenograft tumor bearing NSG mice at a dose of 40 mg/kg in terms of reduced tumor volume and tumor weight (0.38 g vs 0.58 g). TUNEL assay revealed that gemcitabine conjugated micelles induced a much higher extent of apoptosis in the tumor tissues compared to free gemcitabine. In conclusion, gemcitabine conjugated micelles were able to enhance the drug payload, protect it from rapid plasma metabolism, and provide a sustained release and showed enhanced antitumor activity, and thus have the potential to provide a better therapeutic alternative for treating pancreatic cancer.

Receptor-based targeting of therapeutics

Receptor-based targeting of therapeutics may be a fascinating proposition to improve the therapeutic efficacy of encapsulated drugs. The development of safe and effective nanomedicines is a prerequisite in the current nanotechnological scenario. Currently, the surface engineering of nanocarriers has attracted great attention for targeted therapeutic delivery by selective binding of targeting ligand to the specific receptors present on the surface of cells. In this review, we have discussed the current status of various receptors such as transferrin, lectoferrin, lectin, folate, human EGF receptor, scavenger, nuclear and integrin, which are over-expressed on the surface of cancer cells; along with the relevance of targeted delivery systems such as nanoparticles, polymersomes, dendrimers, liposomes and carbon nanotubes. The review also focuses on the effective utilization of receptor-based targeted delivery systems for the management of cancer in effective ways by minimizing the drug-associated side effects and improving the therapeutic efficacy of developed nano-architectures.

The novel albumin-chitosan core-shell nanoparticles for gene delivery: preparation, optimization and cell uptake investigation

Natural polymers and proteins such as chitosan (CS) and albumin (Alb) have recently attracted much attention both in drug delivery and gene delivery. The underlying rationale is their unique properties such as biodegradability, biocompatibility and controlled release. This study aimed to prepare novel albumin-chitosan-DNA (Alb-CS-DNA) core-shell nanoparticles as a plasmid delivery system and find the best conditions for their preparation. Phase separation method and ionic interaction were used for preparation of Alb nanoparticles and Alb-CS-DNA core-shell nanoparticles, respectively. The effects of three important independent variables (1) CS/Alb mass ratio, (2) the ratios of moles of the amine groups of cationic polymers to those of the phosphate groups of DNA (N/P ratio), and (3) Alb concentration, on the nanoparticle size and loading efficiency of the plasmid were investigated and optimized through Box-Behnken design of response surface methodology (RSM). The optimum conditions were found to be CS/Alb mass ratio = 3, N/P ratio = 8.24 and Alb concentration = 0.1 mg/mL. The most critical factors for the size of nanoparticles and loading efficiency were Alb concentration and N/P ratio. The optimized nanoparticles had an average size of 176 ± 3.4 nm and loading efficiency of 80 ± 3.9 %. Cytotoxicity experiments demonstrated that the prepared nanoparticles were not toxic. The high cellular uptake of nanoparticles (~85 %) was shown by flow cytometry and fluorescent microscopy.

Trastuzumab-conjugated vitamin E TPGS liposomes for sustained and targeted delivery of docetaxel

OBJECTIVES

In this study, the authors developed D-α-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS or simply TPGS) liposomes and further conjugated them to trastuzumab for controlled and targeted delivery of docetaxel (DTX) as a model hydrophobic drug.

METHODS

DTX- or coumarin-6-loaded liposomes were prepared by solvent injection method and characterized for size and size distribution, surface charge, surface chemistry and drug encapsulation efficiency and drug release profile. SK-BR-3 cells were employed as an in vitro model for HER2-positive breast cancer and assessed for their cellular uptake and cytotoxicity of the two liposomal formulations. In vivo pharmacokinetics (PK) was investigated in Sprague-Dawley rats.

RESULTS

The IC(50) value was found to be 20.23 ± 1.95, 3.74 ± 0.98, 0.08 ± 0.4 μg/ml for the marketed preparation of DTX, TPGS liposomes and trastuzumab-conjugated TPGS liposomes, respectively after 24 h incubation with SK-BR-3 cells. In vivo PK experiments showed that i.v. administration of trastuzumab-conjugated liposomes achieved 1.9 and 10 times longer half-life, respectively than PEG-coated liposomes and DTX. The area under the curve (AUC) was increased by 3.47- and 1.728-fold, respectively.

CONCLUSION

The trastuzumab-conjugated vitamin E TPGS-coated liposomes showed greater potential for sustained and targeted chemotherapy in the treatment of HER2 overexpressing breast cancer.

Systemic delivery of gemcitabine triphosphate via LCP nanoparticles for NSCLC and pancreatic cancer therapy

Nucleoside analogs are a significant class of anti-cancer agent. As prodrugs, they terminate the DNA synthesis upon transforming to their active triphosphate metabolites. We have encapsulated a biologically activate nucleotide analog (i.e. gemcitabine triphosphate (GTP)), instead of the nucleoside (i.e. gemcitabine) derivative, into a novel Lipid/Calcium/Phosphate nanoparticle (LCP) platform. The therapeutic efficacy of LCP-formulated GTP was evaluated in a panel of human non-small-cell lung cancer (NSCLC) and human pancreatic cancer models after systemic administrations. GTP-loaded LCPs induced cell death and arrested the cell cycle in the S phase. In vivo efficacy studies showed that intravenously injected GTP-loaded LCPs triggered effective apoptosis of tumor cells, significant reduction of tumor cell proliferation and cell cycle progression, leading to dramatic inhibition of tumor growth, with little in vivo toxicity. Broadly speaking, the current study offers preclinical proof-of-principle that many active nucleotide or phosphorylated nucleoside analogs could be encapsulated in the LCP nanoplatform and delivered systemically for a wide variety of therapeutic applications.

Methods for conjugating antibodies to nanocarriers

Antibodies are one of the most commonly used targeting ligands for nanocarriers, mainly because they are specific, have a strong binding affinity, and are available for a number of disease biomarkers. The bioconjugation chemistry can be a crucial factor in determining the targeting efficiency of drug delivery and should be chosen on a case-by-case basis. An antibody consists of a number of functional groups which offer many flexible options for bioconjugation. This chapter focuses on discussing some of the approaches including periodate oxidation, carbodiimide, maleimide, and heterofunctional linkers, for conjugating antibodies to different nanocarriers. The advantages and limitations are described herein. Specific examples are selected to demonstrate the experimental procedures and to illustrate the potential for applying to other nanocarrier system.

Site specific/targeted delivery of gemcitabine through anisamide anchored chitosan/poly ethylene glycol nanoparticles: an improved understanding of lung cancer therapeutic intervention

Gemcitabine (2', 2'-difluorodeoxycytidine) is a deoxycytidine analog with significant antitumor activity against variety of cancers including non-small cell lung cancer. However, rapid metabolism and shorter half-life of drug mandate higher dose and frequent dosing schedule which subsequently results into higher toxicity. Therefore, there is a need to design a vector which can reduce the burden of frequent dosing and higher toxicity associated with the use of gemcitabine. In this study, we investigated the possibility of improving the targeting potential by employing the surface modification on Chitosan/poly(ethylene glycol) (CTS/PEG) Nanoparticles. We demonstrate formulation and characterization of chitosan/poly(ethylene glycol)-anisamide (CTS/PEG-AA) and compared its efficiency with CTS/PEG and free gemcitabine. Our results reveal its sizeable compatibility, comparatively less organ toxicity and higher antitumor activity in vitro as well as in vivo. This wealth of information surfaces the potential of CTS/PEG-AA nanoparticles as a potent carrier for drug delivery. In brief, this novel carrier opens new avenues for drug delivery which better meets the needs of anticancer research.

Functionalized magnetic nanoparticles as vehicles for the delivery of the antitumor drug gemcitabine to tumor cells. Physicochemical in vitro evaluation

Gemcitabine is a chemotherapy drug used in different carcinomas, although because it displays a short biological half-life, its plasmatic levels can quickly drop below the effective threshold. Nanoparticle-based drug delivery systems can provide an alternative approach for regulating the bioavailability of this and most other anticancer drugs. In this work we describe a new model of composite nanoparticles consisting of a core of magnetite nanoparticles, coated with successive layers of high molecular weight poly(acrylic acid) and chitosan, and a final layer of folic acid. The possibility of using these self-assembled nanostructures for gemcitabine vehiculization is explored. First, the surface charge of the composite particles is studied by means of electrophoretic mobility measurements as a function of pH for poly(acrylic acid) (carbopol) of different molecular weights. The adsorption of folic acid, aimed at increasing the chances of the particles to pass the cell membrane, is followed up by optical absorbance measurements, which were also employed for drug adsorption determinations. As a main result, it is shown that gemcitabine adsorbs onto the surface of chitosan/carbopol-coated magnetite nanoparticles. In vitro experiments show that the functionalized magnetic nanoparticles are able to deliver the drug to the nuclei of liver, colon and breast tumor cells.

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.