Kailash C. Gupta

Curcumin-Loaded Nanoparticles Potently Induce Adult Neurogenesis and Reverse Cognitive Deficits in Alzheimer’s Disease Model via Canonical Wnt/β-Catenin Pathway

Neurogenesis, a process of generation of new neurons, is reported to be reduced in several neurodegenerative disorders including Alzheimers disease (AD). Induction of neurogenesis by targeting endogenous neural stem cells (NSC) could be a promising therapeutic approach to such diseases by influencing the brain self-regenerative capacity. Curcumin, a neuroprotective agent, has poor brain bioavailability. Herein, we report that curcumin-encapsulated PLGA nanoparticles (Cur-PLGA-NPs) potently induce NSC proliferation and neuronal differentiation in vitro and in the hippocampus and subventricular zone of adult rats, as compared to uncoated bulk curcumin. Cur-PLGA-NPs induce neurogenesis by internalization into the hippocampal NSC. Cur-PLGA-NPs significantly increase expression of genes involved in cell proliferation (reelin, nestin, and Pax6) and neuronal differentiation (neurogenin, neuroD1, neuregulin, neuroligin, and Stat3). Curcumin nanoparticles increase neuronal differentiation by activating the Wnt/β-catenin pathway, involved in regulation of neurogenesis. These nanoparticles caused enhanced nuclear translocation of β-catenin, decreased GSK-3β levels, and increased promoter activity of the TCF/LEF and cyclin-D1. Pharmacological and siRNA-mediated genetic inhibition of the Wnt pathway blocked neurogenesis-stimulating effects of curcumin. These nanoparticles reverse learning and memory impairments in an amyloid beta induced rat model of AD-like phenotypes, by inducing neurogenesis. In silico molecular docking studies suggest that curcumin interacts with Wif-1, Dkk, and GSK-3β. These results suggest that curcumin nanoparticles induce adult neurogenesis through activation of the canonical Wnt/β-catenin pathway and may offer a therapeutic approach to treating neurodegenerative diseases such as AD, by enhancing a brain self-repair mechanism.

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.

Polyethylenimine nanoparticles as efficient transfecting agents for mammalian cells

Two cross-linkers based on polyethylene glycol (PEG) (MW=6 and 8 kDa), were synthesized for self-assembling and formation of nanoparticles of branched, high molecular weight polyethylenimine (PEI). Cross-linking was realized in two ways, viz., ionic as well as covalent. Ionic cross-linking was accomplished by using PEG-bis (phosphate) whereas, the covalent one was achieved by using PEG-bis (p-nitrophenylcarbonate). A range of nanoparticles of PEI was prepared by varying the degree of cross-linking (i.e. the amount of cross-linkers used). PEI-PEG nanoparticles were characterized by dynamic light scattering and transmission electron microscopy and found to be in the range of approximately 18-75 nm (hydrodynamic radii) with almost uniform population. Subsequently, these particles were used for DNA binding assay and zeta-potential measurements, taking native PEI-PEG nanoparticles as reference. As expected, the zeta potential values decreased, on increasing the percentage of cross-linking as well as on complexation with DNA. Further, PEI-PEG nanoparticles were investigated for their transfecting efficacy on COS-1 cells. It was found that PEI-PEG nanoparticles were 5- to 16-fold more efficient as transfecting agents compared to lipofectin and PEI itself. The toxicity of PEI-PEG nanoparticles was found to be reduced considerably in comparison to PEI polymer, as determined by MTT colorimetric assay. Out of the various systems prepared, PEI-PEG8000 (5% ionic) nanoparticles were found to be the most efficient transfecting agent for in vitro transfection.

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.

Gene Expression, Biodistribution, and Pharmacoscintigraphic Evaluation of Chondroitin Sulfate−PEI Nanoconstructs Mediated Tumor Gene Therapy

Tumor-specific gene delivery constitutes a primary challenge in nonviral mediated gene therapy. In this investigation, branched polyethylenimine (bPEI, 25 kDa) was modified by forming nanoconstructs with a natural polysaccharide, chondroitin sulfate (CS), to impart site-specific property. A library of CS-PEI (CP) nanoconstructs was fabricated by altering the content of CS and evaluated in terms of size, surface charge, morphology, pDNA loading efficiency, pDNA release assay, pDNA protection study, cytotoxicity, and transfection efficiency. In vitro transfection efficiency of CP nanoconstructs was examined in HEK293, HEK293T, HepG2, and HeLa cell lines, while their cytotoxicity was investigated in HepG2 and HeLa cells. DNase I protection assay showed that the plasmid was protected from degradation over a period of time. The CP nanoconstructs possess significantly lower toxicity and enhanced transfection efficiency compared to PEI (25 kDa) and commercial transfection reagents (i.e., superfect, fugene, and GenePORTER 2). Further, the CP nanoconstructs were also found to transfect cells in serum-containing medium. In vivo studies were carried out with pDNA loaded CP-3 nanoconstruct after intravenous (iv) injection in Ehrlich ascites tumor (EAT)-bearing mice. The outcome revealed higher concentration of CP-3 nanoconstruct in tumor mass. These findings demonstrate that CP nanoconstructs could be exploited as carriers for nanomedicine for efficient management of solid tumor.

Nano-vectors for efficient liver specific gene transfer

Recent progress in nanotechnology has triggered the site specific drug/gene delivery research and gained wide acknowledgment in contemporary DNA therapeutics. Amongst various organs, liver plays a crucial role in various body functions and in addition, the site is a primary location of metastatic tumor growth. In past few years, a plethora of nano-vectors have been developed and investigated to target liver associated cells through receptor mediated endocytosis. This emerging paradigm in cellular drug/gene delivery provides promising approach to eradicate genetic as well as acquired diseases affecting the liver. The present review provides a comprehensive overview of potential of various delivery systems, viz., lipoplexes, liposomes, polyplexes, nanoparticles and so forth to selectively relocate foreign therapeutic DNA into liver specific cell type via the receptor mediated endocytosis. Various receptors like asialoglycoprotein receptors (ASGP-R) provide unique opportunity to target liver parenchymal cells. The results obtained so far reveal tremendous promise and offer enormous options to develop novel DNA-based pharmaceuticals for liver disorders in near future.

Trans-Blood Brain Barrier Delivery of Dopamine-Loaded Nanoparticles Reverses Functional Deficits in Parkinsonian Rats

Sustained and safe delivery of dopamine across the blood brain barrier (BBB) is a major hurdle for successful therapy in Parkinsons disease (PD), a neurodegenerative disorder. Therefore, in the present study we designed neurotransmitter dopamine-loaded PLGA nanoparticles (DA NPs) to deliver dopamine to the brain. These nanoparticles slowly and constantly released dopamine, showed reduced clearance of dopamine in plasma, reduced quinone adduct formation, and decreased dopamine autoxidation. DA NPs were internalized in dopaminergic SH-SY5Y cells and dopaminergic neurons in the substantia nigra and striatum, regions affected in PD. Treatment with DA NPs did not cause reduction in cell viability and morphological deterioration in SH-SY5Y, as compared to bulk dopamine-treated cells, which showed reduced viability. Herein, we report that these NPs were able to cross the BBB and capillary endothelium in the striatum and substantia nigra in a 6-hydroxydopamine (6-OHDA)-induced rat model of PD. Systemic intravenous administration of DA NPs caused significantly increased levels of dopamine and its metabolites and reduced dopamine-D2 receptor supersensitivity in the striatum of parkinsonian rats. Further, DA NPs significantly recovered neurobehavioral abnormalities in 6-OHDA-induced parkinsonian rats. Dopamine delivered through NPs did not cause additional generation of ROS, dopaminergic neuron degeneration, and ultrastructural changes in the striatum and substantia nigra as compared to 6-OHDA-lesioned rats. Interestingly, dopamine delivery through nanoformulation neither caused alterations in the heart rate and blood pressure nor showed any abrupt pathological change in the brain and other peripheral organs. These results suggest that NPs delivered dopamine into the brain, reduced dopamine autoxidation-mediated toxicity, and ultimately reversed neurochemical and neurobehavioral deficits in parkinsonian rats.

Engineered Polyallylamine Nanoparticles for Efficient In Vitro Transfection

PurposeCationic polymers (i.e. polyallylamine, poly-L-lysine) having primary amino groups are poor transfection agents and possess high cytotoxicity index when used without any chemical modification and usually entail specific receptor mediated endocytosis or lysosomotropic agents to execute efficient gene delivery. In this report, primary amino groups of polyallylamine (PAA, 17xa0kDa) were substituted with imidazolyl functions, which are presumed to enhance endosomal release, and thus enhance its gene delivery efficiency and eliminate the requirement of external lysosomotropic agents. Further, systems were cross-linked with polyethylene glycol (PEG) to prepare PAA-IAA-PEG (PIP) nanoparticles and evaluated them in various model cell lines.Materials and MethodsThe efficacy of PIP nanoparticles in delivering a plasmid encoding enhanced green fluorescent protein (EGFP) gene was assessed in COS-1, N2a and HEK293 cell lines, while their cytotoxicity was investigated in COS-1 and HEK293 cell lines. The PAA was chemically modified using imidazolyl moieties and ionically cross-linked with PEG to engineer nanoparticles. The extent of substitution was determined by ninhydrin method. The PIP nanoparticles were further characterized by measuring the particle size (dynamic light scattering and transmission electron microscopy), surface charge (zeta potential), DNA accessibility and buffering capacity. The cytotoxicity was examined using the MTT method.ResultsIn vitro transfection efficiency of synthesized nanoparticles is increased up to several folds compared to native polymer even in the presence of serum, while maintaining the cell viability over 100% in COS-1 cells. Nanoparticles possess positive zeta potential between 5.6–13xa0mV and size range of 185–230xa0nm in water. The accessibility experiment demonstrated that nanoparticles with higher degree of imidazolyl substitution formed relatively loose complexes with DNA. An acid-base titration showed enhanced buffering capacity of modified PAA.ConclusionsThe PIP nanoparticles reveal tremendous potential as novel delivery system for achieving improved transfection efficiency, while keeping the cells at ease.

Effect of homobifunctional crosslinkers on nucleic acids delivery ability of PEI nanoparticles.

Polyethylenimine (PEI), a widely used cationic polymeric vector with high transfection efficiency, was converted into nanoparticles by introducing ionic and covalent crosslinkers with varying proportion of 1,6-hexanebisphosphate (HP), adipic acid (AA) and 1,4-butane dialdehyde (BA) to obtain a small library of HP-PEI (HPP), AA-PEI (AAP) and BA-PEI (BAP) nanoparticles, respectively. Particles were characterized by spectroscopic technique as well as physicochemical parameters such as size, morphology, surface charge, effect of crosslinking on buffering capacity and DNA binding ability. The entire series of nanoparticles were compared for their cytoxicity and ability to deliver genes in various cell lines. Among various nanoparticles, AAP-3 nanoparticle/DNA complex exhibited higher transfection efficiency (1.5-7.8 folds) than the native PEI (25kDa) and commercially available transfection reagents, such as GenePorter, GenePorter2, Fugene and Superfect, with cell viability >85%. The highest cell viability was observed with BAP nanoparticles (>95%). Importantly, the transfection activity of nanoparticle/DNA complexes was preserved in the presence of serum. Transfection with GFP-siRNA inhibited expression of transfected GFP gene by approximately 81-92%. All nanoparticle types (HPP, AAP and BAP) required a comparable time for entry into cells and subsequent intracellular passage from the cytoplasm to the nucleus. Intravenous delivery of (99)Tc labeled BAP-2/DNA complex to female Balb/c mice revealed the presence of the complex in most of the organs with the highest retention in liver. In conclusion, HPP, AAP and BAP nanoparticles are safe for efficient gene delivery.

Synthesis of PLGA nanoparticles of tea polyphenols and their strong in vivo protective effect against chemically induced DNA damage.

In spite of proficient results of several phytochemicals in preclinical settings, the conversion rate from bench to bedside is not very encouraging. Many reasons are attributed to this limited success, including inefficient systemic delivery and bioavailability under in vivo conditions. To achieve improved efficacy, polyphenolic constituents of black (theaflavin [TF]) and green (epigallocatechin-3-gallate [EGCG]) tea in poly(lactide-co-glycolide) nanoparticles (PLGA-NPs) were entrapped with entrapment efficacy of ~18% and 26%, respectively. Further, their preventive potential against 7,12-dimethylbenzanthracene (DMBA)-induced DNA damage in mouse skin using DNA alkaline unwinding assay was evaluated. Pretreatment (topically) of mouse skin with either TF or EGCG (100 μg/mouse) doses exhibits protection of 45.34% and 28.32%, respectively, against DMBA-induced DNA damage. However, pretreatment with TF-loaded PLGA-NPs protects against DNA damage 64.41% by 1/20th dose of bulk, 71.79% by 1/10th dose of bulk, and 72.46% by 1/5th dose of bulk. Similarly, 51.28% (1/20th of bulk), 57.63% (1/10th of bulk), and 63.14% (1/5th of bulk) prevention was noted using EGCG-loaded PLGA-NP doses. These results showed that tea polyphenol-loaded PLGA-NPs have ~30-fold dose-advantage than bulk TF or EGCG doses. Additionally, TF- or EGCG-loaded PLGA-NPs showed significant potential for induction of DNA repair genes (XRCC1, XRCC3, and ERCC3) and suppression of DNA damage responsive genes (p53, p21, MDM2, GADD45α, and COX-2) as compared with respective bulk TF or EGCG doses. Taken together, TF- or EGCG-loaded PLGA-NPs showed a superior ability to prevent DMBA-induced DNA damage at much lower concentrations, thus opening a new dimension in chemoprevention research.