Soma Patnaik

Recent trends in non-viral vector-mediated gene delivery.

Nucleic acids‐based next generation biopharmaceuticals (i.e., pDNA, oligonucleotides, short interfering RNA) are potential pioneering materials to cope with various incurable diseases. However, several biological barriers present a challenge for efficient gene delivery. On the other hand, developments in nanotechnology now offer numerous non‐viral vectors that have been fabricated and found capable of transmitting the biopharmaceuticals into the cell and even into specific subcellular compartments like mitochondria. This overview illustrates cellular barriers and current status of non‐viral gene vectors, i.e., lipoplexes, liposomes, polyplexes, and nanoparticles, to relocate therapeutic DNA‐based nanomedicine into the target cell. Despite the awesome impact of physical methods (i.e., ultrasound, electroporation), chemical methods have been shown to accomplish high‐level and safe transgene expression. Further comprehension of barriers and the mechanism of cellular uptake will facilitate development of nucleic acids‐based nanotherapy for alleviation of various disorders.

Novel polyethylenimine-derived nanoparticles for in vivo gene delivery

Introduction: Branched and linear polyethylenimines (PEIs) are cationic polymers that have been used to deliver nucleic acids both in vitro and in vivo. Owing to the high cationic charge, the branched polymers exhibit high transfection efficiency, and particularly PEI of molecular weight 25 kDa is considered as a gold standard in gene delivery. These polymers have been extensively studied and modified with different ligands so as to achieve the targeted delivery. Areas covered: The application of PEI in vivo promises to take the polymer-based vector to the next level wherein it can undergo clinical trials and subsequently could be used for delivery of therapeutics in humans. This review focuses on the various recent developments that have been made in the field of PEI-based delivery vectors for delivery of therapeutics in vivo. Expert opinion: The efficacy of PEI-based delivery vectors in vivo is significantly high and animal studies demonstrate that such systems have a potential in humans. However, we feel that though PEI is a promising vector, further studies involving PEI in animal models are needed so as to get a detailed toxicity profile of these vectors. Also, it is imperative that the vector reaches the specific organ causing little or no undesirable effects to other organs.

Imidazolyl-PEI modified nanoparticles for enhanced gene delivery.

The derivatives of polyethylenimine (PEI 25 and 750kDa) were synthesized by partially substituting their amino groups with imidazolyl moieties. The series of imidazolyl-PEIs thus obtained were cross-linked with polyethylene glycol (PEG) to get imidazolyl-PEI-PEG nanoparticles (IPP). The component of hydrophobicity was introduced by grafting the lauryl groups in the maximal substituted IPP nanoparticles (IPPL). The nanoparticles were characterized with respect to DNA interaction, hydrodynamic diameter, zeta potential, in vitro cytotoxicity and transfection efficiency on model cell lines. The IPP and IPPL nanoparticles formed a loose complex with DNA compared to the corresponding native PEI, leading to more efficient unpackaging of DNA. The DNA loading capacity of IPP and IPPL nanoparticles was also lower compared to PEI. The imidazolyl substitution improved the gene delivery efficiency of PEI (750kDa) by nine- to ten-fold and PEI (25kDa) by three- to four-fold. At maximum transfection efficiency, the zeta potential of nanoparticles was positive after forming a complex with DNA. The maximum level of reporter gene expression was mediated by IPPL nanoparticles in both the series. The cytotoxicity, another pertinent problem with cationic polymers, was also negligible in case of IPP and IPPL nanoparticles.

Development and characterization of itraconazole-loaded solid lipid nanoparticles for ocular delivery

Abstract The purpose of this study was to investigate the feasibility of entrapping water-insoluble drug itraconazole into solid lipid nanoparticles (SLNs) for topical ocular delivery. The drug-loaded SLNs were prepared from stearic acid and palmitic acid using different concentrations of polyvinyl alcohol employed as emulsifier. SLNs were prepared by the melt-emulsion sonication and low temperature-solidification method and characterized for particle size, zeta potential, drug loading and drug entrapment efficiency. The mean particle size of SLNs prepared with stearic acid ranged from 139 to 199 nm, while the SLNs prepared with palmitic acid had particle size in the range of 126–160 nm. The SLNs were spherical in shape. Stearic acid-SLNs showed higher entrapment of drug compared with palmitic acid-SLNs. Differential scanning calorimetry (DSC) and X-ray diffraction measurements showed decrease in crystallinity of drug in the SLN formulations. The modified Franz-diffusion cell and freshly excised goat corneas were used to test drug corneal permeability. Permeation of itraconazole from stearic acid-SLNs was higher than that obtained with palmitic acid-SLNs. The SLNs showed clear zone of inhibition against Aspergillus flavus indicating antimicrobial efficacy of formulations.

PEI-alginate nanocomposites: Efficient non-viral vectors for nucleic acids

Branched polyethylenimine (PEI, 25 kDa) was ionically interacted with varying amount of alginic acid to block different proportion (2.6-5.7%) of amines in PEI to form a series of nanocomposites, PEI-Al. These nanocomposites, upon interaction with DNA, protected it against DNase I. Among various complexes evaluated, PEI-Al(4.8%)/DNA displayed the highest transfection efficiency in HEK293, COS-1 and HeLa cells that was approximately 2-8-folds higher than Superfect, Fugene, PEI (750 kDa)-Al(6.26%) and PEI alone. The projected nanocomposites were nearly non-toxic to cells in vitro. Furthermore, the concentration of PEI-Al(4.8%) needed to deliver GFP-specific siRNA in COS-1 cells was 20 times lower than PEI (750 kDa)-Al(6.26%). Intracellular trafficking of PEI-Al(4.8%) with or without complexed DNA in HeLa cells shows that both appear in the nucleus after 1 h.

Cross-linked polyethylenimine-hexametaphosphate nanoparticles to deliver nucleic acids therapeutics.

UNLABELLED Branched polyethylenimine (PEI; 25 kDa) as a nonviral vector exhibits high transfection efficiency and is a potential candidate for efficient gene delivery. However, the cytotoxicity of PEI limits its application in vivo. PEI was ionically interacted with hexametaphosphate, a compact molecule with high anionic charge density, to obtain nanoparticles (PEI-HMP). Nanoparticles were assessed for their efficacy in protecting complexed DNA against nucleases. The intracellular trafficking of nanoparticles was monitored by confocal microscopy. The cytotoxicity and transfection efficiency of PEI-HMP nanoparticles were evaluated in vitro. In vitro transfection efficiency of PEI-HMP (7.7%) was approximately 1.3- to 6.4-folds higher than that of the commercial reagents GenePORTER 2, Fugene, and Superfect. Also, PEI-HMP (7.7%) delivered green fluorescent protein (GFP)-specific small interfering ribonucleic acid (siRNA) in culture cells leading to >80% suppression in GFP gene expression. PEI-HMP nanoparticles protected complexed DNA against DNase for at least 2 hours. A time-course uptake of PEI-HMP (7.7%) nanoparticles showed the internalization of nanoparticles inside the cell nucleus in 2 hours. Thus, PEI-HMP nanoparticles efficiently transfect cells with negligible cytotoxicity and show great promise as nonviral vectors for gene delivery. FROM THE CLINICAL EDITOR Branched polyethylenimine (PEI) as a non-viral vector exhibits high transfection efficiency for gene delivery, but its cytotoxicity limits its applications. PEI hexametaphosphate nanoparticles (PEI-HMP) demonstrated a 1.3-6.4 folds higher transfection rate compared to commercial reagents. Overall, PEI-HMP nanoparticles efficiently transfect cells with negligible cytotoxicity and show great promise as non-viral vectors for gene delivery.

Polyethylenimine derived nanoparticles for efficient gene delivery

Introduction of therapeutic genes into the cells of an organism in a safe and efficient way has become a challenging task in non-viral mediated gene therapy. Here, branched polyethylenimine (bPEI, 25 kDa) was converted into nanoparticles through electrostatic interactions with anionic polysaccharides (e.g. alginic acid, Al and hyaluronic acid, HA). A small library of PEI-Al and PEI-HA nanoparticles was synthesized by varying the amounts of anionic polysaccharides and evaluated in terms of their size, surface charge, cytotoxicity, transfection efficiency, etc. Both the series of nanoparticles exhibited higher cell viability and transfection efficiency as compared to native PEI and the standard transfection reagents. In vivo targeting efficacy of PEI-HA(4.6%) nanoparticles was examined in tumor induced mice.

Nanoparticle-Based Vectors for Gene Delivery

Gene therapy holds a great potential for treating and correcting inherited as well as acquired diseases that rely on the transfer of nucleic acids-based materials into mammalian cells. A plethora of vector systems, based on biological (viral), physical and chemical (non-viral) methods, have been developed for the efficient delivery of these biopharmaceuticals, however, these have encountered several biological barriers, which present a challenge to clinical application of gene therapy. Recent developments in nanotechnology has thrown some light by offering efficient systems capable of carrying cargo to targeted sites without affecting the cellular environment. Here, the authors have reviewed various cellular barriers and current status of the chemical vectors to transfer nucleic acids-based therapeutics into the mammalian cells and to down regulate endogenous genes.