Pharmaceutical Nanotechnology (v.2, #4)

Editorial: by Ijeoma Uchegbu (171-171).

Despite its potent in vitro anti-cancer activity, the vitamin E extract tocotrienol has its therapeutic potential hampered by its poor bioavailability and by its inability to reach tumors in a specific way after intravenous administration. One possibility to overcome this issue would be to entrap tocotrienol within vesicles bearing transferrin, whose receptors are present in abundance on many cancer cell types. In this study, we demonstrated that the systemic administration of tocotrienol entrapped within transferrin-bearing vesicles led to tumor suppression of 20% of A431 epidermoid carcinoma tumors and 50% of B16-F10 melanoma tumors at the end of the treatment. The survival of animals treated with these vesicles was improved by more than 20 days in comparison with the controls, for the two cancer models tested. Animals did not show any secondary effects following administration of the treatment. The entrapment of tocotrienol within transferrin-bearing vesicles is therefore a promising therapeutic strategy, which could result in tumor suppression after systemic administration of this delivery system.

Star Shaped Poly(ethylene glycols) Yield Biocompatible Gene Delivery Systems by Jayanant Iemsam-Arng, Xiao Kong, Andreas G. Schatzlein, Ijeoma F. Uchegbu (182-195).
Cationic gene delivery molecules are relatively cytotoxic [50% cell survival concentrations (IC50) < 0.05 mg mL-1], limiting their use clinically. We hypothesise that a low molecular weight polymer with reduced amine content would yield biocompatible gene therapy nanoparticles with DNA. We synthesised and characterised an amine terminated poly(ethylene glycol) – (PEG) based polymer - tetra-O,O,O,O-[poly(ethyleneglycol-O-2- ethyleneimine)-graft-N-(2-ethylamine)-]-pentaerythritol (4-arm-PEG-ethylamine - 4APEA) and subjected 4APEA to physicochemical and biological testing. 4APEA was relatively non-toxic against the A431 cell line (IC50 of 4.76 A± 0.27 mg mL-1), formed 200 nm positively charged nanoparticles with DNA and transfected the A431 cell line with a similar efficacy to the less biocompatible poly(ethylenimine) (PEI, IC50 = 0.002 mg mL-1). On intravenous injection of 4APEA – DNA nanoparticles, significantly more DNA was found in the lungs and liver when compared to the injection of DNA alone. When 4APEA, 4APEA -TNF-alpha DNA nanoparticles and TNF-alpha DNA alone were intravenously injected to MiaPaCa tumour bearing mice, only the 4APEA - TNF-alpha DNA nanoparticles were tumouricidal, with tumour volumes significantly different from untreated controls. A new PEG derivative 4APEA is 1000 time less toxic than PEI in the A431 cell line, has comparable cell transfection capability to PEI in this cell line and produces tumouricidal nanoparticles when complexed with TNF-alpha.

Ligands with Delocalized Charge Density and Hydrophobicity Significantly Affect the Transfection Efficacy of the PAMAM Dendrimer by Santosh Yadav, Ayushi Priyam, Manohar Mahato, Smriti R. Deka, Ashwani K. Sharma (196-207).
Polyamidoamine dendrimers (PAMAM) are being used as efficient vectors for delivery of nucleic acids to the cells. However, these dendrimers cause a significant amount of cytotoxicity. In order to improve its transfection efficiency and cell viability, surface amine groups of PAMAM were converted into guanidinium (Gn) and tetramethylguanidinium (TMG) moieties. These modified PAMAM dendrimers interacted with negatively charged plasmid DNA efficiently and formed stable complexes as revealed by dynamic light scattering analysis. PAMAM/pDNA, PAMAM-TMG/pDNA and PAMAM-Gn/pDNA complexes were found to be in the range of 175-250 nm with zeta potential in the range of +21-37 mV. Further, these modified dendrimers did not display toxicity rather it decreased a bit when tested in HEK293, HeLa and MCF-7 cells. Among these modified dendrimers, PAMAM-Gn/pDNA complex displayed the highest transfection efficiency in both the cell lines HEK293 and MCF-7.

Efficacy of Loteprednol Etabonate Drug Delivery System in Suppression of in vitro Retinal Pigment Epithelium Activation by Anjali Hirani, Yong W. Lee, Yashwant Pathak, Vijaykumar Sutariya (208-216).
Choroidal neovascularization (CNV) is the growth of abnormal blood vessels in the choroid layer of the eye; it is a pathophysiological characteristic of wet age-related macular degeneration (AMD). Current clinical treatment utilizes frequent intravitreal injections, which can result in retinal detachment and increased ocular pressure. The purpose of the current study is to develop a novel drug delivery system of loteprednol etabonateencapsulated PEGylated PLGA nanoparticles incorporated into the PLGA-PEG-PLGA thermoreversible gel for treatment of AMD. The proposed drug delivery system was characterized for drug release, cytotoxicity studies and vascular endothelial growth factor (VEGF) suppression efficacy studies using ARPE-19 cells. The nanoparticles showed uniform size distribution with mean size of 168.60A±23.18 nm and exhibited sustained drug release. Additionally, the proposed drug delivery system was non-cytotoxic to ARPE-19 cells and significantly reduced VEGF expression as compared to loteprednol etabonate solution. These results suggest the proposed drug delivery system can be used for further work in an animal model of experimental AMD with reduced intravitreal administration frequency.

Preparation and Characterization of MKT-077 Nanoparticles for Treatment of Alzheimer's Disease and Other Tauopathies by Umesh K. Jinwal, Aditya Grover, Malathi Narayan, Anjali Hirani, Vijaykumar Sutariya (217-226).
Alzheimer's disease is one of the most common causes of dementia and death in elderly populations. However, therapeutic intervention in Alzheimer's disease is limited by the blood-brain barrier, which not only protects the brain by limiting the permeation of potential toxins into neural tissue but also by blocking certain drugs aimed at neurological disorders. MKT-077 is one such drug, which has shown promise in reducing Alzheimer's disease- related pathology in cellular models but has limited brain permeation due to blockage by the blood-brain barrier. Herein, we describe the formulation and characterization of brain-targeted PEG-PLGA nanoparticles coated in 2% w/v glutathione to get higher blood-brain barrier permeation. Average nanoparticle size was found to be 230nm, suitable for intravenous administration and brain permeation. The nanoparticles showed steady, sustained release of MKT-077 in in vitro settings. Transwell in vitro blood-brain barrier model permeation studies showed the permeation of nanoparticles across the Transwell model to be greater than drug solution over 48 hours. The proposed model shows promise as a potential therapy against Alzheimer's disease and other tauopathies.

Solid lipid nanoparticles of a lipophilic cosmeceutical molecule, 18β- glycyrrhetinic acid were prepared by emulsion-solvent evaporation technique, using methanol as solvent, stearic acid as lipid and tween 80 as surfactant. The solid lipid nanoparticle preparation was optimized by response surface methodology using Box Behnken design. Under optimum level of stearic acid (0.68%), tween 80 (0.5%) and 18β-glycyrrhetinic acid (32.4%) the encapsulation efficiency of nanoparticles reached 68.81%, mean particle size 414 nm, and polydispersity index 0.76 were obtained. The prepared nanoparticles were rod shaped (nanorods) when observed under scanning electron microscope. The in vitro release of 18β-glycyrrhetinic acid from the nanoparticles followed initial burst release then lag phase and finally sustained release. The prepared nano-cosmeceuticals have interesting perspectives in the development of newer skincare cosmetic preparation with improved skincare properties.