Micelle-like Nanoparticles as Carriers for DNA and siRNA

Gene therapy represents a potential efficient approach of disease prevention and therapy. However, due to their poor <i>in vivo</i> stability, gene molecules need to be associated with delivery systems to overcome extracellular and intracellular barriers and allow access to the site of action. Cationic polymeric nanoparticles are popular carriers for small interfering RNA (siRNA) and DNA-based therapeutics for which efficient and safe delivery are important factors that need to be optimized. Micelle-like nanoparticles (MNP) (half micelles, half polymeric nanoparticles) can overcome some of the disadvantages of such cationic carriers by unifying in one single carrier the best of both delivery systems. In this review, we will discuss how the unique properties of MNP including self-assembly, condensation and protection of nucleic acids, improved cell association and gene transfection, and low toxicity may contribute to the successful application of siRNA- and DNA-based therapeutics into the clinic. Recent developments of MNP involving the addition of stimulus-sensitive functions to respond specifically to pathological or externally applied “triggers” (e.g., temperature, pH or enzymatic catalysis, light, or magnetic fields) will be discussed. Finally, we will overview the use of MNP as two-in-one carriers for the simultaneous delivery of different agents (small molecules, imaging agents) and nucleic acid combinations

d‑α-Tocopheryl Succinate/Phosphatidyl Ethanolamine Conjugated Amphiphilic Polymer-Based Nanomicellar System for the Efficient Delivery of Curcumin and To Overcome Multiple Drug Resistance in Cancer

Nanomedicines have emerged as a promising treatment strategy for cancer. Multiple drug resistance due to overexpression of various drug efflux transporters and upregulation of apoptotic inhibitory pathways in cancer cells are major barriers that limit the success of chemotherapy. Here, we developed a d-α-tocopherol (α-TOS)/lipid-based copolymeric nanomicellar system (VPM) by conjugating phosphatidyl ethanolamine (PE) and α-TOS with poly­(ethylene glycol) (PEG) via an amino acid linkage. The synthesized polymers were characterized by Fourier transform IR, gas-phase chromatography, and ¹H and ¹³C NMR spectroscopy. VPM exhibited mean hydrodynamic diameter of 141.0 ± 0.94 nm with low critical micelles concentrations (CMC) of 15 μM compared to plain PEG–PE micelles (PPM) with size of 23.9 ± 0.34 nm and CMC 20 μM. The bigger hydrophobic compartment in VPM resulted in improved loading of a potent chemotherapeutic drug, curcumin (Cur), and increased encapsulation efficiency (EE) (% drug loading 98.3 ± 1.92, and 85.3 ± 3.29; EE 14.8 ± 0.16 and 12.8 ± 0.09 for VPM and PPM, respectively). Curcumin loaded Vitamin E based micelles exhibited higher cytotoxicity compared to Curcumin loaded PEG-PE micelles in tested cancer cell lines. C-VPM demonstrated ∼3.2 and ∼2.7-fold higher ability to reverse multiple drug resistance compared to PPM and verapamil (concentration used 30 μM), respectively. In the in vivo study by using B16F10 implanted C57Bl6/J mice, C-VPM reduced the tumor volume and weight more efficiently than C-PPM by inducing apoptosis as analyzed by TUNEL assay on tumor cryosections. The newly developed polymeric micelles, VPM with improved drug loadability and ability to reverse the drug resistance could successfully be utilized as a nanocarrier system for hydrophobic chemotherapeutic agents for the treatment of drug-resistant solid tumors

Targeted Transferrin-Modified Polymeric Micelles: Enhanced Efficacy in Vitro and in Vivo in Ovarian Carcinoma

In this study, transferrin (Tf)-modified poly­(ethylene glycol)-phosphatidylethanolamine (mPEG-PE) micelles loaded with the poorly water-soluble drug, R547 (a potent and selective ATP-competitive cyclin-dependent kinase (CDK) inhibitor), were prepared and evaluated for their targeting efficiency and cytotoxicity in vitro and in vivo to A2780 ovarian carcinoma cells, which overexpress transferrin receptors (TfR). At 10 mM lipid concentration, both Tf-modified and plain micelles solubilized 800 μg of R547. Tf-modified micelles showed enhanced interaction with A2780 ovarian carcinoma cells in vitro. The involvement of TfR in endocytosis of Tf-modified micelles was confirmed by colocalization studies of micelle-treated cells with the endosomal marker Tf-Alexa488. We confirmed endocytosis of micelles in an intact form with micelles loaded with a fluorescent dye and additionally labeled with fluorescent lipid. The in vitro cytotoxicity and in vivo tumor growth inhibition studies in A2780-tumor bearing mice confirmed the enhanced efficacy of Tf-modified R547-loaded micelles compared to free drug solution and to nonmodified micelles. The results of this study demonstrate the potential application of Tf-conjugated polymeric micelles in the treatment of tumors overexpressing TfR

Comparison of micellar and liposomal formulations on modulating local periablational target proteins (HIF-1α and HSP70) 24 hr after RF ablation of R3230 tumor.

<p>(<b>A</b>) Micellar doxorubicin suppressed periablational HIF-1α expression to a greater degree than (<b>B</b>) liposomal doxorubicin 24 hr after RF ablation (40×). Similarly, (<b>C</b>) micellar quercetin suppressed ablation-induced periablational HSP70 expression in R3230 tumor at 24 hr compared to (<b>D</b>) liposomal quercetin (10×).</p

Confocal tiled Imaging for fluorescent surface area quantitation in R3230 tumors sacrificed at 4 hours post RF (10×).

<p>R3230 tumors were treated with RF alone, followed by IV injection of equal volumes of 3 fluorescent beads of different colors and sizes (purple 20 nm, red 100 nm, green 500 nm). Quantitation of tiled images of tumor sections (center, periablational rim and tumor margin) demonstrated fluorescent bead accumulation in the periablational rim, with greatest uptake of 20 nm beads (<b>D</b>) followed by the 100 nm (<b>C</b>) beads followed by the 500 nm beads (<b>B</b>) (p<0.05, all comparisons).</p

Gross and histopathologic outcomes for RFA/nanodrug combinations.

<p>*  = p<0.05 when compared to RF group.</p><p>** = P<0.05 when compared to adjuvant liposomal drug preparations.</p

Periablational intratumoral doxorubicin accumulation for liposomal and micellar nanocarriers combined with RF ablation over time.

<p>*  = p<0.05 when compared to the other treatment group.</p

Confocal Imaging of perivascular and interstitial fluorescent bead penetration in the periablational rim 24 hr after RF ablation of R3230 tumors (40×).

<p>R3230 tumors were treated with RF alone, followed by IV injection of 3 fluorescent beads of different colors and sizes (purple 20 nm, red 100 nm, green 500 nm). 40× images of the periablational rim reveal deeper penetration of the 20 nm beads into the intracellular spaces beyond the primary site of extravasation, outlining and mapping out the cells they are surrounding (<b>D,E</b>), whereas the majority of the 100 nm (<b>B</b>) remain confined to the primary site of extravasation. Even less extravasation is seen for the 500 nm beads (<b>C</b>).</p

Arginine-Based Biodegradable Ether–Ester Polymers with Low Cytotoxicity as Potential Gene Carriers

The success of gene therapy depends on safe and effective gene carriers. Despite being widely used, synthetic vectors based on poly­(ethylenimine) (PEI), poly­(l-lysine) (PLL), or poly­(l-arginine) (poly-Arg) are not yet fully satisfactory. Thus, both improvement of established carriers and creation of new synthetic vectors are necessary. A series of biodegradable arginine-based ether–ester polycations was developed, which consists of three main classes: amides, urethanes, and ureas. Compared to that of PEI, PLL, and poly-Arg, much lower cytotoxicity was achieved for the new cationic arginine-based ether–ester polymers. Even at polycation concentrations up to 2 mg/mL, no significant negative effect on cell viability was observed upon exposure of several cell lines (murine mammary carcinoma, human cervical adenocarcinoma, murine melanoma, and mouse fibroblast) to the new polymers. Interaction with plasmid DNA yielded compact and stable complexes. The results demonstrate the potential of arginine-based ether–ester polycations as nonviral carriers for gene therapy applications

Adjuvant nanoparticle anti-IL6 siRNA suppresses thermal ablation-induced hepatocyte proliferation in the untreated, distant hepatic lobe.

<p>Adjuvant MNP anti-IL6 siRNA given 15 minutes after hepatic thermal ablation <b>(C)</b> in C57Bl mice (n = 5–6 animals/arm) suppressed hepatocyte proliferation in the distant, untreated liver lobe (with CDC47 staining, mean ± standard deviation) compared to hepatic thermal ablation alone <b>(A, D,</b> p<0.01). Hepatic thermal ablation combined with MNP scrambled siRNA was not significantly different from either thermal ablation alone or ablation combined with MNP anti-IL6 siRNA <b>(B, D)</b>.</p