Efficiency of Dispatch and Infiltrator cardiac infusion catheters in arterial localization of nanoparticles in a porcine coronary model of restenosis

Assessing the Effect of Training Sampling Design on the Performance of Machine Learning Classifiers for Land Cover Mapping Using Multi-Temporal Remote Sensing Data and Google Earth Engine

Machine learning classifiers are being increasingly used nowadays for Land Use and Land Cover (LULC) mapping from remote sensing images. However, arriving at the right choice of classifier requires understanding the main factors influencing their performance. The present study investigated firstly the effect of training sampling design on the classification results obtained by Random Forest (RF) classifier and, secondly, it compared its performance with other machine learning classifiers for LULC mapping using multi-temporal satellite remote sensing data and the Google Earth Engine (GEE) platform. We evaluated the impact of three sampling methods, namely Stratified Equal Random Sampling (SRS(Eq)), Stratified Proportional Random Sampling (SRS(Prop)), and Stratified Systematic Sampling (SSS) upon the classification results obtained by the RF trained LULC model. Our results showed that the SRS(Prop) method favors major classes while achieving good overall accuracy. The SRS(Eq) method provides good class-level accuracies, even for minority classes, whereas the SSS method performs well for areas with large intra-class variability. Toward evaluating the performance of machine learning classifiers, RF outperformed Classification and Regression Trees (CART), Support Vector Machine (SVM), and Relevance Vector Machine (RVM) with a >95% confidence level. The performance of CART and SVM classifiers were found to be similar. RVM achieved good classification results with a limited number of training samples.

Nanoparticle-Based Mycosis Vaccine

Many diseases that were considered major affliction of mankind in the past have been successfully eradicated with introduction of appropriate vaccine strategies. In order to expedite new challenges coming up to deal with various infectious diseases, nano-particulate-based subunit vaccines seem to be the demand of ordeal. The nano-vaccines can find better scope for the diseases that were not rampant in the semi-advanced world few years back. For example in present-day circumstances that corroborate with advancement in the field of medical sciences in terms of cancer chemotherapy, organ transplantation, therapy of autoimmune diseases, etc.; along with prevalence of altogether unheard diseases such as HIV infection, people are at risk of infliction with many more pathogens. In this regard, development of an effective prophylactic strategy against many opportunistic infections primarily caused by fungal pathogens needs better understanding of host pathogen relation and role of active immunity against pathogenic fungi. In the present study, we have tried to decipher effectiveness of a nano-sized vaccine delivery system in imparting protection against fungal pathogens.

Local Endovascular Delivery, Gene Therapy, and Cell Transplantation for Peripheral Arterial Disease

Advances in catheter technology, gene identification, and cell biology may provide novel treatment options for patients with peripheral arterial disease (PAD) who are not candidates for standard revascularization procedures. Animal studies and recent results in human beings suggest that transfer of growth factors or regulatory genes and transplantation of progenitor cells may provide novel therapy options by inducing therapeutic angiogenesis or by inhibiting restenosis. This review will discuss the development of a variety of catheters for localized endovascular delivery, as well as the various cellular and genetic strategies that exist to restore blood flow to ischemic tissue and to reduce neointimal hyperplasia.

Nanocarrier mediated delivery of siRNA/miRNA in combination with chemotherapeutic agents for cancer therapy: current progress and advances

Chemotherapeutic agents have certain limitations when it comes to treating cancer, the most important being severe side effects along with multidrug resistance developed against them. Tumor cells exhibit drug resistance due to activation of various cellular level processes viz. activation of drug efflux pumps, anti-apoptotic defense mechanisms, etc. Currently, RNA interference (RNAi) based therapeutic approaches are under vibrant scrutinization to seek cancer cure. Especially small interfering RNA (siRNA) and micro RNA (miRNA), are able to knock down the carcinogenic genes by targeting the mRNA expression, which underlies the uniqueness of this therapeutic approach. Recent research focus in the regime of cancer therapy involves the engagement of targeted delivery of siRNA/miRNA in combinations with other therapeutic agents (such as gene, DNA or chemotherapeutic drug) for targeting permeability glycoprotein (P-gp), multidrug resistant protein 1 (MRP-1), B-cell lymphoma (BCL-2) and other targets that are mainly responsible for resistance in cancer therapy. RNAi-chemotherapeutic drug combinations have also been found to be effective against different molecular targets as well and can increase the sensitization of cancer cells to therapy several folds. However, due to stability issues associated with siRNA/miRNA suitable protective carrier is needed and nanotechnology based approaches have been widely explored to overcome these drawbacks. Furthermore, it has been univocally advocated that the co-delivery of siRNA/miRNA with other chemodrugs significantly enhances their capability to overcome cancer resistance compared to naked counterparts. The objective of this article is to review recent nanocarrier based approaches adopted for the delivery of siRNA/miRNA combinations with other anticancer agents (siRNA/miRNA/pDNA/chemodrugs) to treat cancer.

Inhibition of Apoptosis Through Localized Delivery of Rapamycin-Loaded Nanoparticles Prevented Neointimal Hyperplasia and Reendothelialized Injured Artery

Background— A significant fraction of vascular smooth muscle cells (VSMCs) undergo rapid apoptosis after balloon angioplasty. In this study, we tested the hypothesis that protecting VSMCs from undergoing apoptosis prevents the cascade of events that lead to intimal hyperplasia.

Methods and Results— Rapamycin-loaded gel-like nanoparticles (mean diameter, 54�5 nm) were infused locally in a rat carotid artery model of vascular injury. The drug has both antiapoptotic and antiproliferative effects on VSMCs and hence was selected for the current study. Localized delivery of nanoparticles sustained the drug level in the target artery for >2 weeks; demonstrated significant inhibition of hyperplasia (intima/media ratio, 1.5�0.02 versus 2.7�0.6; P <0.01); and most importantly, reendothelialized the injured artery (endothelium coverage: treated 82% versus control 28%). We also demonstrated inhibition of activation of caspase-3/7 enzymes in the treated artery, preventing VSMCs from undergoing apoptosis and subsequent infiltration of macrophages.

Conclusions— It may be postulated that the localized delivery of rapamycin inhibited apoptosis of VSMCs, minimizing the inflammatory response to the injury and, thus, creating conditions conducive to vascular repair (reendothelialization). Unlike stenting, which can lead to thrombosis and increased risk for in-stent restenosis, our approach could eliminate or minimize long-term complications because the injured artery undergoes a natural process of reendothelialization.

Polymeric nanoparticles for siRNA delivery and gene silencing

Gene silencing using small interfering RNA (siRNA) has several potential therapeutic applications. In the present study, we investigated nanoparticles formulated using the biodegradable polymer, poly(d,l-lactide-co-glycolide) (PLGA) for siRNA delivery. A cationic polymer, polyethylenimine (PEI), was incorporated in the PLGA matrix to improve siRNA encapsulation in PLGA nanoparticles. PLGA-PEI nanoparticles were formulated using double emulsion-solvent evaporation technique and characterized for siRNA encapsulation and in vitro release. The effectiveness of siRNA-loaded PLGA-PEI nanoparticles in silencing a model gene, fire-fly luciferase, was investigated in cell culture. Presence of PEI in PLGA nanoparticle matrix increased siRNA encapsulation by about 2-fold and also improved the siRNA release profile. PLGA-PEI nanoparticles carrying luciferase-targeted siRNA enabled effective silencing of the gene in cells stably expressing luciferase as well as in cells that could be induced to overexpress the gene. Quantitative studies indicated that presence of PEI in PLGA nanoparticles resulted in 2-fold higher cellular uptake of nanoparticles while fluorescence microscopy studies showed that PLGA-PEI nanoparticles delivered the encapsulated siRNA in the cellular cytoplasm; both higher uptake and greater cytosolic delivery could have contributed to the gene silencing effectiveness of PLGA-PEI nanoparticles. Serum stability and lack of cytotoxicity further add to the potential of PLGA-PEI nanoparticles in gene silencing-based therapeutic applications.

Vitamin E TPGS-emulsified poly(lactic-co-glycolic acid) nanoparticles for cardiovascular restenosis treatment

AIMS

Paclitaxel is one of the most effective antiproliferative agents and it has been applied in the development of drug-eluting stents. There are difficulties, however, in using paclitaxel in clinical applications owing to its poor solubility and side effects. We have synthesized nanoparticles of biodegradable polymers for the effective and sustainable delivery of paclitaxel and other antiproliferative agents for restenosis treatment.

METHODS & RESULTS

Paclitaxel-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles were prepared by a modified solvent extraction/evaporation method with D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) or polyvinyl alcohol (PVA) as an emulsifier. Drug-loaded nanoparticles were characterized for size and size distribution, surface morphology, surface charge, drug-encapsulation efficiency and in vitro drug-release kinetics. Cellular uptake of fluorescent nanoparticles was investigated in vitro in coronary artery smooth muscle cells and in vivo in the carotid arteries of rabbits. The antiproliferative effects of the nanoparticle formulations were assessed in vitro in close comparison with Taxol((R)). Both the PVA- and TPGS-emulsified nanoparticles have similar size and size distribution, surface morphology and dispersion stability and showed great advantages over paclitaxel in in vitro cellular uptake and cytotoxicity than Taxol. The TPGS-emulsified nanoparticle formulation has higher drug-encapsulation efficiency, cellular uptake and cytotoxicity than the PVA-emulsified nanoparticle formulation. IC(50) in 24-h culture with coronary artery smooth muscle cells is 748 ng/ml for paclitaxel, 708 ng/ml for PVA-emulsified nanoparticles and 474 ng/ml for TPGS-emulsified nanoparticles, respectively.

CONCLUSION

TPGS-emulsified PLGA nanoparticles have great potential for the effective and sustainable delivery of antiproliferative agents and for the development of nanoparticle-coated stents, which may become the third generation of cardiovascular stents.

Nanotechnology in cardiovascular medicine

Nanotechnology is a new field of science and technology that has already had significant impact in the development of novel products in industry. In medicine, application of nanotechnology has the potential to develop new imaging agents, pharmaceutical drugs and medical devices with unique physical and chemical properties. This article reviews the potential for various nanoparticles in cardiovascular imaging and therapeutics, nanoporous structures for sensing and implant based drug delivery, and self-assembled monolayers for surface modification and implant based drug delivery.

Engineered nanoparticles as precise drug delivery systems

With the remarkable development of nanotechnology in recent years, new drug delivery approaches based on the state-of-the-art nanotechnology have been receiving significant attention. Nanoparticles, an evolvement of nanotechnology, are increasingly considered as a potential candidate to carry therapeutic agents safely into a targeted compartment in an organ, particular tissue or cell. These particles are colloidal structures with a diameter smaller than 1,000 nm, and therefore can penetrate through diminutive capillaries into the cell's internal machinery. This innovative delivery technique might be a promising technology to meet the current challenges in drug delivery. When loaded with a gene or drug agent, nanoparticles can become nanopills, which can effectively treat problematical diseases such as cancer. This article summarizes different types of nanoparticles drug delivery systems under investigation and their prospective therapeutic applications. Also, this article presents a closer look at the advances, current challenges, and future direction of nanoparticles drug delivery systems.

Local endovascular delivery, gene therapy, and cell transplantation for peripheral arterial disease

Advances in catheter technology, gene identification, and cell biology may provide novel treatment options for patients with peripheral arterial disease (PAD) who are not candidates for standard revascularization procedures. Animal studies and recent results in human beings suggest that transfer of growth factors or regulatory genes and transplantation of progenitor cells may provide novel therapy options by inducing therapeutic angiogenesis or by inhibiting restenosis. This review will discuss the development of a variety of catheters for localized endovascular delivery, as well as the various cellular and genetic strategies that exist to restore blood flow to ischemic tissue and to reduce neointimal hyperplasia.

Nanotech approaches to drug delivery and imaging

Nanotechnology, a multidisciplinary scientific undertaking, involves creation and utilization of materials, devices or systems on the nanometer scale. The field of nanotechnology is currently undergoing explosive development on many fronts. The technology is expected to create innovations and play a critical role in various biomedical applications, not only in drug delivery, but also in molecular imaging, biomarkers and biosensors. Target-specific drug therapy and methods for early diagnosis of pathologies are the priority research areas where nanotechnology would play a vital role. This review considers different nanotechnology-based drug delivery and imaging approaches, and their economic impact on pharmaceutical and biomedical industries.

Fluorescence and electron microscopy probes for cellular and tissue uptake of poly(D,L-lactide-co-glycolide) nanoparticles

Nanoparticles formulated from poly(D,L-lactide-co-glycolide) (PLGA) and poly(lactide) (PLA) are being extensively investigated for different therapeutic applications such as for sustained drug, vaccine, and gene delivery. For many of these applications, it is necessary to study the intracellular distribution as well as the tissue uptake of nanoparticles to optimize the efficacy of the encapsulated therapeutic agent. Fluorescence and electron microscopic techniques are usually used for the above purposes. Colloidal gold particles and fluorescent polystyrene, which are generally used as model particles for electron and fluorescence microscopy, respectively, may not be suitable alternatives to PLGA/PLA nanoparticles for these studies mainly because of the differences in their physical properties and also because they do not contain any therapeutic agent. The aim of the present study was to develop and characterize PLGA nanoparticle formulations that would be suitable for confocal/fluorescence and transmission electron microscopic (TEM) studies. Towards this objective, PLGA nanoparticles containing 6-coumarin as a fluorescent marker and osmium tetroxide as an electron microscopic marker with bovine serum albumin (BSA) as a model protein were formulated. Different physical properties of marker-loaded nanoparticles such as particle size, zeta potential, residual PVA content and protein-loading were compared with those of unloaded nanoparticles and were found to be not significantly different. Furthermore, marker-loaded nanoparticle formulations were non-toxic to the cells as unloaded nanoparticles. Nanoparticles loaded with 6-coumarin were found to be useful for studying intracellular nanoparticle uptake and distribution using confocal microscopy while osmium tetroxide-loaded nanoparticles were found to be useful for studying nanoparticle uptake and distribution in cells and tissue using TEM. It was concluded that 6-coumarin and osmium tetroxide could serve as useful fluorescence and electron microscopy probes, respectively, for incorporation into nanoparticles to study their cellular and tissue distribution.

Biodegradable nanoparticles for drug and gene delivery to cells and tissue

Biodegradable nanoparticles formulated from poly (D,L-lactide-co-glycolide) (PLGA) have been extensively investigated for sustained and targeted/localized delivery of different agents including plasmid DNA, proteins and peptides and low molecular weight compounds. Research about the mechanism of intracellular uptake of nanoparticles, their trafficking and sorting into different intracellular compartments, and the mechanism of enhanced therapeutic efficacy of nanoparticle-encapsulated agent at cellular level is more recent and is the primary focus of the review. Recent studies in our laboratory demonstrated rapid escape of PLGA nanoparticles from the endo-lysosomal compartment into cytosol following their uptake. Based on the above mechanism, various potential applications of nanoparticles for delivery of therapeutic agents to the cells and tissue are discussed.

Dynamics of endocytosis and exocytosis of poly(D,L-lactide-co-glycolide) nanoparticles in vascular smooth muscle cells

PURPOSE

The purpose of this work was to characterize the process of endocytosis, exocytosis, and intracellular retention of poly (D,L-lactide-co-glycolide) nanoparticles in vitro using human arterial vascular smooth muscle cells (VSMCs).

METHODS

Nanoparticles containing bovine serum albumin (BSA) as a model protein and 6-coumarin as a fluorescent marker were formulated by a double emulsion-solvent evaporation technique. The endocytosis and exocytosis of nanoparticles in VSMCs were studied using confocal microscopy and their intracellular uptake and retention were determined quantitatively using high-performance liquid chromatography.

RESULTS

Cellular uptake of nanoparticles (mean particle size 97 +/- 3 nm) was a concentration-, time-, and energy-dependent endocytic process. Confocal microscopy demonstrated that nanoparticles were internalized rapidly, with nanoparticles seen inside the cells as early as within 1 min after incubation. The nanoparticle uptake increased with incubation time in the presence of nanoparticles in the medium; however, once the extracellular nanoparticle concentration gradient was removed, exocytosis of nanoparticles occurred with about 65% of the internalized fraction undergoing exocytosis in 30 min. Exocytosis of nanoparticles was slower than the exocytosis of a fluid phase marker, Lucifer yellow. Furthermore, the exocytosis of nanoparticles was reduced after the treatment of cells with the combination of sodium azide and deoxyglucose, suggesting that exocytosis of nanopartides is an energy-dependent process. The nanoparticle retention increased with increasing nanoparticle dose in the medium but the effect was relatively less significant with the increase in incubation time. Interestingly, the exocytosis of nanoparticles was almost completely inhibited when the medium was depleted of serum. Further studies suggest that the addition of BSA in the serum free medium with or without platelet derived growth factor (PDGF) induced exocytosis of nanoparticles. The above result suggests that the protein in the medium is either adsorbed onto nanoparticles and/or carried along with nanoparticles inside the cells, which probably interacts with the exocytic pathway and leads to greater exocytosis of nanoparticles.

CONCLUSIONS

The study demonstrated that endocytosis and exocytosis of nanoparticles are dynamic and energy-dependent processes. Better understanding of the mechanisms of endocytosis and exocytosis, studies determining the effect of nanoparticle formulation and composition that may affect both the processes, and characterization of intracellular distribution of nanoparticles with surface modifications would be useful in exploring nanoparticles for intracellular delivery of therapeutic agents.

Size-dependency of nanoparticle-mediated gene transfection: studies with fractionated nanoparticles

Nanoparticles formulated from biodegradable polymers such as poly (lactic acid) and poly (D,L-lactide-co-glycolide) (PLGA) are being extensively investigated as non-viral gene delivery systems due to their sustained release characteristics and biocompatibility. PLGA nanoparticles for DNA delivery are mainly formulated using an emulsion-solvent evaporation technique. However, this formulation procedure results in the formation of particles with heterogeneous size distribution. The objective of the present study was to determine the relative transfectivity of the smaller- and the larger-sized fractions of nanoparticles in cell culture. PLGA nanoparticles containing a plasmid DNA encoding luciferase protein as a marker were formulated by a multiple emulsion-solvent evaporation method (mean particle diameter = 97 +/- 3 nm) and were fractionated using a membrane (pore size: 100 nm) filtration technique. The particles that passed through the membrane were designated as the smaller-sized nanoparticles (mean diameter = 70 +/- 2 nm) and the fraction that was retained on the membrane as the larger-sized nanoparticles (mean diameter = 202 +/- 9 nm). The smaller-sized nanoparticles showed a 27-fold higher transfection than the larger-sized nanoparticles in COS-7 cell line and a 4-fold higher transfection in HEK-293 cell line. The surface charge (zeta potential), cellular uptake, and the DNA release were almost similar for the two fractions of nanoparticles, suggesting that some other yet unknown factor(s) is responsible for the observed differences in the transfection levels. The results suggest that the particle size is an important factor, and that the smaller-sized fraction of the nanoparticle formulation predominantly contributes towards their transfection.

Residual polyvinyl alcohol associated with poly (D,L-lactide-co-glycolide) nanoparticles affects their physical properties and cellular uptake

Polyvinyl alcohol (PVA) is the most commonly used emulsifier in the formulation of poly lactide and poly (D,L-lactide-co-glycolide) (PLGA) polymeric nanoparticles. A fraction of PVA remains associated with the nanoparticles despite repeated washing because PVA forms an interconnected network with the polymer at the interface. The objective of this study was to determine the parameters that influence the amount of residual PVA associated with PLGA nanoparticles and its effect on the physical properties and cellular uptake of nanoparticles. Nanoparticles were formulated by a multiple emulsion-solvent evaporation technique using bovine serum albumin (BSA) as a model protein. The parameters that affected the amount of residual PVA include the concentration of PVA and the type of organic solvent used in the emulsion. The residual PVA, in turn, influenced different pharmaceutical properties of nanoparticles such as particle size, zeta potential, polydispersity index, surface hydrophobicity, protein loading and also slightly influenced the in vitro release of the encapsulated protein. Importantly, nanoparticles with higher amount of residual PVA had relatively lower cellular uptake despite their smaller particle size. It is proposed that the lower intracellular uptake of nanoparticles with higher amount of residual PVA could be related to the higher hydrophilicity of the nanoparticle surface. In conclusion, the residual PVA associated with nanoparticles is an important formulation parameter that can be used to modulate the pharmaceutical properties of PLGA nanoparticles.