Enhanced transfection efficiency and targeted delivery of self-assembling h-R3-dendriplexes in EGFR-overexpressing tumor cells

Nanomedicines functionalized with anti-EGFR ligands for active targeting in cancer therapy: Biological strategy, design and quality control

Recently, active targeting using nanocarriers with biological ligands has emerged as a novel strategy for improving the delivery of therapeutic and/or imaging agents to tumor cells. The presence of active targeting moieties on the surface of nanomedicines has been shown to play an important role in enhancing their accumulation in tumoral cells and tissues versus healthy ones. This property not only helps to increase the therapeutic index but also to minimize possible side effects of the designed nanocarriers. Since the overexpression of epidermal growth factor receptors (EGFR) is a common occurrence linked to the progression of a broad variety of cancers, the potential application of anti-EGFR immunotherapy and EGFR-targeting ligands in active targeting nanomedicines is getting increasing attention. Henceforth, the EGFR-targeted nanomedicines were extensively studied in vitro and in vivo but exhibited both satisfactory and disappointing results, depending on used protocols. This review is designed to give an overview of a variety of EGFR-targeting ligands available for nanomedicines, how to conjugate them onto the surface of nanoparticles, and the main analytical methods to confirm this successful conjugation.

Efficient Self-Assembled MicroRNA Delivery System Consisting of Cholesterol-Conjugated MicroRNA and PEGylated Polycationic Polymer for Tumor Treatment

MicroRNA (miR), a key molecule involved in endogenous RNA interference, is a promising therapeutic agent. In vivo delivery of miR, however, is a major factor limiting its application because its polyanionic nature and vulnerability to breakdown make delivery of miR to targeted lesions difficult. To overcome these challenges, we developed a self-assembled miR delivery system consisting of cholesterol-conjugated miR and polyethylene glycol-grafted polyethylene imine. Nanosized complexes of miR with polyethylene imine, which protected miR and its delivery into targeted lesions in vivo, were successfully synthesized by polyethylene glycol grafting. The hydrophobicity of cholesterol improved the structural stability of the complex, preventing the loss of miR. Here, we report the preparation of this self-assembled complex. We examined the delivery efficiency and validated the therapeutic efficacy of the complex. In conclusion, our miR delivery system shows considerable potential for effective in vivo delivery of miR.

Poly (amidoamine) (PAMAM) dendrimer mediated delivery of drug and pDNA/siRNA for cancer therapy

Poly (amidoamine) (PAMAM) dendrimers are well-defined, highly branched macromolecules with numerous active amine groups on the surface. Because of their unique properties, PAMAM dendrimers have steadily grown in popularity in drug delivery, gene therapy, medical imaging and diagnostic application. This review focuses on the recent developments on the application in PAMAM dendrimers as effective carriers for drug and gene (pDNA, siRNA) delivery in cancer therapy, including: a) PAMAM for anticancer drug delivery; b) PAMAM and gene therapy; c) PAMAM used in overcoming tumor multidrug resistance; d) PAMAM used for hybrid nanoparticles; and e) PAMAM linked or loaded in other nanoparticles.

A folate receptor-targeted lipoplex delivering interleukin-15 gene for colon cancer immunotherapy

Interleukin-15 has been implicated as a promising cytokine for cancer immunotherapy, while folate receptor α (FRα) has been shown to be a potentially useful target for colon cancer therapy. Herein, we developed F-PLP/pIL15, a FRα-targeted lipoplex loading recombinant interleukin-15 plasmid (pIL15) and studied its antitumor effects in vivo using a CT26 colon cancer mouse model. Compared with control (normal saline) treatment, F-PLP/pIL15 significantly suppressed tumor growth in regard to tumor weight (P < 0.001) and reduced tumor nodule formation (P < 0.001). Moreover, when compared to other lipoplex-treated mice, F-PLP/pIL15-treated mice showed higher levels of IL15 secreted in the serum (P < 0.001) and ascites (P < 0.01). These results suggested that the targeted delivery of IL15 gene might be associated with its in vivo antitumor effects, which include inducing tumor cell apoptosis, inhibiting tumor proliferation and promoting the activation of immune cells such as T cells and natural killer cells. Furthermore, hematoxylin and eosin staining of vital organs following F-PLP/pIL15 treatment showed no detectable toxicity, thus indicating that intraperitoneal administration may be a viable route of delivery. Overall, these results suggest that F-PLP/pIL15 may serve as a potential targeting preparation for colon cancer therapy.

In vitro studies of phospholipid-modified PAMAM-siMDR1 complexes for the reversal of multidrug resistance in human breast cancer cells

The application of RNAi therapeutics is promising in combating several major human diseases including malignant tumors. However, this approach is limited due to its delivery barriers. In this study, we designed a new carrier system loaded with a functional siRNA targeting MDR1 gene to reverse multi-drug resistance (MDR) in human breast cancer MCF-7/ADR cells. Phospholipid-modified PAMAM-siMDR1 complexes were designed on the external decoration of polyamidoamine (PAMAM) with phospholipid (PL) and the electrostatical interaction between PAMAM and siMDR1 to form hybrid nanocomplexes (PL-dendriplexes). Compared with siMDR1 and dendriplexes (PAMAM-siMDR1), this delivery system represented higher gene silencing efficiency, enhanced cellular uptake of siMDR1, decreased p-gp expression, raised cellular accumulation of doxorubicin (DOX) and inhibited the tumor cell migration. Moreover, the siMDR1 loaded PL-dendriplexes worked synergistically with paclitaxel (PTX) for treating MDR, leading to increased cell apoptosis and cell phase regulation. Overall, this study shows that the PL-dendriplexes hold great promise in reversing the drug-resistance in MCF-7/ADR cells.

Development of a gene carrier using a triblock co-polyelectrolyte with poly(ethylene imine)-poly(lactic acid)-poly(ethylene glycol)

The success of gene therapy mainly depends on the carriers for effective gene delivery. A non-viral vector using a cationic block co-polyelectrolyte, PEI-PLA-PEG polyethyleneimine-poly(lactic acid)-poly(ethylene glycol)) was developed as a potential gene carrier. The cationic PEI-PLA-PEG showed less toxicity compared to PEI and formed a gene nanocomplex (termed polyplex) by interaction with plasmid DNA or small interference RNA. The polyplex showed smaller particle size and greater positive zeta potential by increasing the high polymer nitrogen/DNA phosphate ratio. The polyplex with a nitrogen/DNA phosphate ratio of 16 or 32 demonstrated higher gene transfection by fluorescence imaging, flow cytometry measurement, and β-galactosidase activity. In particular, the polyplex with therapeutic histone deacetylase small interference RNA at nitrogen/DNA phosphate ratio 16 showed the most favorable properties with definite tumor growth inhibition. The synthetic PEI-PLA-PEG also showed less toxicity and would, therefore, be a great potential gene carrier, particularly given that small interference RNA delivery does not increase the charge density of small interference RNA due to the formation of a stable complex through conjugation with PLA-PEG.

Antibody h-R3-dendrimer mediated siRNA has excellent endosomal escape and tumor targeted delivery ability, and represents efficient siPLK1 silencing and inhibition of cell proliferation, migration and invasion

The major obstacle to developing siRNA delivery is their extracellular and intracellular barriers. Herein, a humanized anti-EGFR monoclonal antibody h-R3 was developed to modify the self-assembled binary complexes (dendriplexes) of PAMAM and siRNA via electrostatic interactions, and two common ligands HSA and EGF were used as a control. Compared to dendriplexes, h-R3/EGF/HSA-dendriplexes showed increased particle size, decreased zeta potentials and lower cytotoxicity. Moreover, h-R3-dendriplexes presented greater cellular uptake and excellent endosomal escape ability in HepG2 cells. Ex vivo fluorescence imaging revealed that h-R3-dendriplexes showed higher targeted delivery and gene expression in the tumors than dendriplexes, HSA-dendriplexes and EGF-dendriplexes, which was in agreement with confocal results of cryosections. Furthermore, h-R3-dendriplexes for siPLK1 delivery indicated efficient gene silencing, potentiated cell growth inhibition and cell apoptosis, and suppressed cellular migration/invasion. These results indicate that h-R3-dendriplexes represent a great potential to be used as efficient targeted siRNA delivery carriers.