Properties of a peptide containing DL-lactide/glycolide copolymer nanospheres prepared by novel emulsion solvent diffusion methods

Preparation and evaluation of sustained release formulation of PLGA using a new injection system based on ink-jet injection technology

We developed a method for the preparation of PLGA particles exhibiting long-term sustained-release of entrapped drugs. The fine droplet drying (FDD) technology using a new injection system based on ink-jet injection technology was adapted as the preparation method. PLGA microspheres containing TRITC-dextran, acetaminophen, and albumin as model drugs were prepared by the FDD technology. The resultant microspheres were uniform in size, with average particle sizes ranging from 16.3 to 33.0 μm and SPAN factors ranging from 0.49 to 0.77. The encapsulation efficiency of drugs showed high values ranging from 75 to 99 wt% of the total amount of water-soluble drug contained in the particles. In an investigation of the optimal operation conditions of the FDD technology, the dew point temperature of the dryer air stream was found to be an important factor for controlling the initial burst of the prepared particles. The TRITC-dextran-containing PLGA microspheres were confirmed to exhibit long-term sustained release for about 90 days, and the mechanism was found to be PLGA degradation rate-limiting. Based on these results, we concluded that long-term sustained-released PLGA particles can be prepared by using FDD technology under a suitable drying condition for controlling the initial burst.

Pitavastatin-Incorporated Nanoparticles for Chronic Limb Threatening Ischemia: A Phase I/IIa Clinical Trial

AIM

To assess the results of a phase I/IIa open-label dose-escalation clinical trial of 5-day repeated intramuscular administration of pitavastatin-incorporated poly (lactic-co-glycolic acid) nanoparticles (NK-104-NP) in patients with chronic limb threatening ischemia (CLTI).

METHODS

NK-104-NP was formulated using an emulsion solvent diffusion method. NK-104-NP at four doses (nanoparticles containing 0.5, 1, 2, and 4 mg of pitavastatin calcium, n=4 patients per dose) was investigated in a dose-escalation manner and administered intramuscularly into the ischemic limbs of 16 patients with CLTI. The safety and therapeutic efficacy of treatment were investigated over a 26-week follow-up period.

RESULTS

No cardiovascular or other serious adverse events caused by NK-104-NP were detected during the follow-up period. Improvements in Fontaine and Rutherford classifications were noted in five patients (one, three, and one in the 1-, 2-, and 4-mg dose groups, respectively). Pharmacokinetic parameters including the maximum serum concentration and the area under the blood concentration-time curve increased with pitavastatin treatment in a dose-dependent manner. The area under the curve was slightly increased at day 5 compared with that at day 1 of treatment, although the difference was not statistically significant.

CONCLUSIONS

This is the first clinical trial of pitavastatin-incorporated nanoparticles in patients with CLTI. Intramuscular administration of NK-104-NP to the ischemic limbs of patients with CLTI was safe and well tolerated and resulted in improvements in limb function.

Extracellular vesicles synchronize cellular phenotypes of differentiating cells

During embryonic development, cells differentiate in a coordinated manner, aligning their fate decisions and differentiation stages with those of surrounding cells. However, little is known about the mechanisms that regulate this synchrony. Here we show that cells in close proximity synchronize their differentiation stages and cellular phenotypes with each other via extracellular vesicle (EV)-mediated cellular communication. We previously established a mouse embryonic stem cell (ESC) line harbouring an inducible constitutively active protein kinase A (CA-PKA) gene and found that the ESCs rapidly differentiated into mesoderm after PKA activation. In the present study, we performed a co-culture of Control-ESCs and PKA-ESCs, finding that both ESC types rapidly differentiated in synchrony even when PKA was activated only in PKA-ESCs, a phenomenon we named 'Phenotypic Synchrony of Cells (PSyC)'. We further demonstrated PSyC was mediated by EVs containing miR-132. PKA-ESC-derived EVs and miR-132-containing artificial nano-vesicles similarly enhanced mesoderm and cardiomyocyte differentiation in ESCs and ex vivo embryos, respectively. PSyC is a new form of cell-cell communication mediated by the EV regulation of neighbouring cells and could be broadly involved in tissue development and homeostasis.

Nanoparticle-Mediated Delivery of Pitavastatin to Monocytes/Macrophages Inhibits Angiotensin II-Induced Abdominal Aortic Aneurysm Formation in Apoe－/－ Mice

Aim: Abdominal aortic aneurysm (AAA) is a lethal and multifactorial disease. To prevent a rupture and dissection of enlarged AAA, prophylactic surgery and stenting are currently available. There are, however, no medical therapies preventing these complications of AAA. Statin is one of the candidates, but its efficacy on AAA formation/progression remains controversial. We have previously demonstrated that nanoparticles (NPs) incorporating pitavastatin (Pitava-NPs)—clinical trials using these nanoparticles have been already conducted—suppressed progression of atherosclerosis in apolipoprotein E-deficient ( Apoe^−/− ) mice. Therefore, we have tested a hypothesis that monocytes/macrophages-targeting delivery of pitavastatin prevents the progression of AAA.

Methods: Angiotensin II was intraperitoneally injected by osmotic mini-pumps to induce AAA formation in Apoe^−/− mice. NPs consisting of poly(lactic-co-glycolic acid) were used for in vivo delivery of pitavastatin to monocytes/macrophages.

Results: Intravenously administered Pitava-NPs (containing 0.012 mg/kg/week pitavastatin) inhibited AAA formation accompanied with reduction of macrophage accumulation and monocyte chemoattractant protein-1 (MCP-1) expression. Ex vivo molecular imaging revealed that Pitava-NPs not only reduced macrophage accumulation but also attenuated matrix metalloproteinase activity in the abdominal aorta, which was underpinned by attenuated elastin degradation.

Conclusion: These results suggest that Pitava-NPs inhibit AAA formation associated with reduced macrophage accumulation and MCP-1 expression. This clinically feasible nanomedicine could be an innovative therapeutic strategy that prevents devastating complications of AAA.

Preparation and in vitro tumor growth inhibitory effect of oligo (L-lactate) nanoparticles

Oligo L-lactates (oligolactates) that have low molecular weights less than 2000 have been reported to inhibit tumor growth and extend the survival of experimental animals. Because oligolactates are scarcely soluble in water, they require a solvent or a solubilizing agent, such as a surfactant, to be dissolved in water. However, these agents are generally cytotoxic, an in vitro assay appropriate to evaluate the inhibitory effect on tumor growth has not been developed yet. Here, we prepared a solid nanodispersion of oligolactates using an oil-in-water emulsion solvent evaporation method to evaluate its tumor inhibitory activity in vitro without a solvent or surfactant. Polyol solutions containing polyvinyl alcohol (PVA) were used as a continuous phase. The formation of nanoparticles depended on the concentrations of polyol and PVA in the continuous phase. The nanoparticles with a particle size of approximately 100 nm were obtained using 10-15% PVA and 60% propylene glycol. The obtained aqueous nanodispersion of oligolactates inhibited the growth of B16-BL6 melanoma cells in vitro, whereas the medium alone did not affect tumor cell growth. Therefore, oligo(L-lactate) nanoparticles may be useful in the research and development of oligolactates as a remedy for cancer.

Preparation of silver-decorated Soluplus® nanoparticles and antibacterial activity towards S. epidermidis biofilms as characterized by STEM-CL spectroscopy

Biofilm infections present a serious problem because antibacterial drugs are not effective against mature biofilms or biofilms formed by drug-resistant bacteria. To address this issue, we developed a drug delivery system based on metal-decorated polymeric particles. Polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus®) is an amphiphilic polymer used in biomedical formulations, while silver nanoparticles are widely acknowledged to have high antibacterial activity. We prepared silver-decorated Soluplus® micelle nanoparticles with high antibacterial activity using the emulsion solvent diffusion method. Decoration of Soluplus® micelles with silver nanoparticles was found to increase their antibacterial activity. Scanning transmission electron microscopy-cathodoluminescence (STEM-CL) spectroscopy allows imaging of the spatial distribution of labeled targets and the chemical identification of materials. However, STEM-CL spectroscopy of fragile polymer materials is challenging. We optimized the STEM-CL spectroscopy technique to determine the distribution of silver nanoparticles in Soluplus® micelles. Additionally, the surface plasmon properties of the silver nanoparticles were successfully characterized without deactivation. The developed silver-decorated Soluplus® nanoparticles were effective against biofilm infections and have the potential to be applied for other biofilm-related diseases. Additionally, the optimized STEM-CL spectroscopy technique is expected to contribute to the analysis and imaging of fragile polymer materials, as well as other soft materials such as cells and tissues.

Therapeutic Arteriogenesis/Angiogenesis for Peripheral Arterial Disease by Nanoparticle-Mediated Delivery of Pitavastatin into Vascular Endothelial Cells

Two decades have passed since therapeutic angiogenesis was proposed to promote reparative collateral growth as an alternative therapy for ischemic diseases in patients for whom neither surgical revascularization nor endovascular therapy was suitable. When therapeutic angiogenesis first began, local administration was conducted using recombinant growth factor proteins or gene-encoding growth factors for endothelial cells. Since then, autologous stem cells and endothelial progenitor cell transplantation therapy have been developed. Although many clinical trials have been performed on patients, most therapies have not yet become standard treatments. We have developed a nanoparticle (NP)-mediated, drug-targeting delivery system using bioabsorbable poly-lactic/glycolic acid (PLGA) NPs. In several animal models, pitavastatin-incorporated (Pitava)-NPs showed significant therapeutic effects on critical limb ischemia. Because PLGA NPs are delivered selectively to vascular endothelial cells after intramuscular administration, it is suggested that therapeutic angiogenesis/arteriogenesis plays an important role in the mechanism by which Pitava-NPs exert beneficial therapeutic effects. To translate this to clinical medicine, we have performed studies and produced Pitava-NPs in compliance with good laboratory practice/good manufacturing practice regulations, and completed a phase I/II clinical trial, reporting the safety and efficacy of Pitava-NP intramuscular injection for patients with critical limb ischemia. This review will focus on therapeutic angiogenesis/arteriogenesis for peripheral arterial disease induced by Pitava-NPs.

Peroxisome proliferator-activated receptor-gamma targeting nanomedicine promotes cardiac healing after acute myocardial infarction by skewing monocyte/macrophage polarization in preclinical animal models

Aims

Monocyte-mediated inflammation is a major mechanism underlying myocardial ischaemia-reperfusion (IR) injury and the healing process after acute myocardial infarction (AMI). However, no definitive anti-inflammatory therapies have been developed for clinical use. Pioglitazone, a peroxisome proliferator-activated receptor-gamma (PPARγ) agonist, has unique anti-inflammatory effects on monocytes/macrophages. Here, we tested the hypothesis that nanoparticle (NP)-mediated targeting of pioglitazone to monocytes/macrophages ameliorates IR injury and cardiac remodelling in preclinical animal models.

Methods and results

We formulated poly (lactic acid/glycolic acid) NPs containing pioglitazone (pioglitazone-NPs). In a mouse IR model, these NPs were delivered predominantly to circulating monocytes and macrophages in the IR heart. Intravenous treatment with pioglitazone-NPs at the time of reperfusion attenuated IR injury. This effect was abrogated by pre-treatment with the PPARγ antagonist GW9662. In contrast, treatment with a pioglitazone solution had no therapeutic effects on IR injury. Pioglitazone-NPs inhibited Ly6Chigh inflammatory monocyte recruitment as well as inflammatory gene expression in the IR hearts. In a mouse myocardial infarction model, intravenous treatment with pioglitazone-NPs for three consecutive days, starting 6 h after left anterior descending artery ligation, attenuated cardiac remodelling by reducing macrophage recruitment and polarizing macrophages towards the pro-healing M2 phenotype. Furthermore, pioglitazone-NPs significantly decreased mortality after MI. Finally, in a conscious porcine model of myocardial IR, pioglitazone-NPs induced cardioprotection from reperfused infarction, thus providing pre-clinical proof of concept.

Conclusion

NP-mediated targeting of pioglitazone to inflammatory monocytes protected the heart from IR injury and cardiac remodelling by antagonizing monocyte/macrophage-mediated acute inflammation and promoting cardiac healing after AMI.

Optimization of ionic liquid-incorporated PLGA nanoparticles for treatment of biofilm infections

Ionic liquids (ILs) containing imidazolium cations have a number of useful properties, such as high permeability to cells, high antimicrobial activity, and good biocompatibility. With the aid of ILs, transdermal delivery, solubilization of poorly soluble drugs were developed and therapeutic effects were improved. In this work, 1‑butyl‑3‑methylimidazolium hexafluorophosphate-incorporated, chitosan-modified, submicron-sized poly(dl‑lactide‑co‑glycolide) (PLGA) nanoparticles (NPs) were prepared using the emulsion solvent diffusion method for the treatment of biofilm infections. Prepared IL-incorporated PLGA NPs using surfactants such as Tween-80 and poloxamer-188 showed a high antibacterial activity to the bacterial cells under the biofilm. Additionally, antibacterial mechanism of IL-incorporated PLGA NPs was revealed by annular dark field scanning transmission electron microscopy combined a simple sample pretreatment method. We established a drug delivery system using IL-incorporated PLGA NPs to enhance the potential of polymeric nanocarriers for treating biofilm infections.

Polymerization-Induced Phase Separation Formation of Structured Hydrogel Particles via Microfluidics for Scar Therapeutics

Excessive scar formation can form disabling contractures that result in a debilitating psychological outcome. Sustainable hydrophobic corticosteroid release in vivo is essential to regulate the wound healing process. Functional hydrogel particles are widely applied for sustainable release. However, due to the limited aqueous solubility of hydrophobic compounds, most of the corticosteroid is released from the hydrogels within seconds, causing undesirable scar formation and recurrence. In this study, a novel polymerization-induced phase separation is investigated to form well-defined polyethylene glycol diacrylate (PEGDA) core/alginate shell structured hydrogel particles using microfluidics without toxic organic solvents. Based on their wettability preference, hydrophobic corticosteroid-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles are compartmentalized in the PEGDA core during polymerization to control the corticosteroid release. The distribution of the PLGA nanoparticles is precisely regulated by the phase separation boundary and characterized using a fluorescent dye. The thickness of the shell and partition coefficients are determined using the UV intensity and irradiation period. Upon encapsulation of the PLGA nanoparticles within the poly(PEGDA) core, a long-term corticosteroid treatment is developed and effective scar therapeutic outcomes are evaluated using both in vitro and in vivo models.

Imaging of intracellular behavior of polymeric nanoparticles in Staphylococcus epidermidis biofilms by slit-scanning confocal Raman microscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy

In drug delivery systems employing polymeric nanoparticles, accurate delivery of drugs to target sites such as bacterial cells, cell tissues, and organelles is essential. In particular, when designing drug delivery systems for the treatment of the biofilm infections, evaluation of the interaction between polymeric nanoparticles and biofilm or bacterial cells using a simple technique is of significant importance. Here we develop two types of novel techniques for the biological imaging of the intracellular behavior of two types of polymeric nanoparticles, biodegradable chitosan-modified poly (dl-lactide-co-glycolide) (PLGA) nanoparticles and chitosan-modified polyvinyl caprolactam - polyvinyl acetate -polyethylene glycol graft copolymer (Soluplus®, Sol) nanoparticles, within a Staphylococcus epidermidis biofilm. As the first technique, Raman imaging of unstained biological materials using slit-scanning confocal Raman microscopy (unstained Raman imaging) was performed, and as the second, field-emission scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis of biological materials labeled with quantum dots (SEM-QD imaging) was demonstrated. These analyses revealed differing localization of the respective nanoparticles within the biofilm in accordance with the specific interactions of PLGA nanoparticles and Sol nanoparticles with the biofilm. These novel techniques open the door to biological imaging and analyses with high spatial resolution, which will help to understand the efficacy of drug delivery to target materials.

Visualization of silver-decorated poly (DL-lactide-co-glycolide) nanoparticles and their efficacy against Staphylococcus epidermidis

Understanding of self-protection activity of the bacteria and interaction with drug substances has significant importance for designing of effective drug delivery system for treatment of biofilm infections. Recently silver nanoparticle has attracted attention as antibacterial substance for drug delivery system because of its high antibacterial activity. Here, efflux of silver nanoparticles obtained from within the prepared silver-decorated poly (DL-lactide-co-glycolide) (Ag PLGA) nanoparticles derived from Staphylococcus epidermidis bacterial cell was successfully visualized using scanning transmission electron microscopy (STEM). We also revealed the interaction between prepared Ag PLGA nanoparticles and the bacterial cells at the nanoscale level using field emission scanning electron microscopy and STEM, after a pretreatment process by an ionic liquid. This finding is significant to understand a fundamental function of S. epidermidis bacterial cells, which is not explored previously. The results suggest that Ag PLGA nanoparticles could demonstrate high efficacy against biofilm infections.

Respirable controlled release polymeric colloid (RCRPC) of bosentan for the management of pulmonary hypertension: in vitro aerosolization, histological examination and in vivo pulmonary absorption

Bosentan is an endothelin receptor antagonist (ERA) prescribed for patients with pulmonary arterial hypertension (PAH). The oral delivery of bosentan possesses several drawbacks such as low bioavailability (about 50%), short duration of action, frequent administration, hepatotoxicity and systemic hypotension. The pulmonary administration would circumvent the pre-systemic metabolism thus improving the bioavailability and avoids the systemic adverse effects of oral bosentan. However, the short duration of action and the frequent administration are the major drawbacks of inhalation therapy. Thus, the aim of this work is to explore the potential of respirable controlled release polymeric colloid (RCRPC) for effective, safe and sustained pulmonary delivery of bosentan. Central composite design was adopted to study the influence of formulation and process variables on nanoparticles properties. The particle size, polydispersity index (PDI), entrapment efficiency (EE) and in vitro bosentan released were selected as dependent variables. The optimized RCRPC showed particle size of 420 nm, PDI of 0.39, EE of 60.5% and sustained release pattern where only 31.0% was released after 16 h. The in vitro nebulization of RCRPC indicated that PLGA nanoparticles could be incorporated into respirable nebulized droplets better than drug solution. Pharmacokinetics and histopathological examination were determined after intratracheal administration of the developed RCRPC to male albino rats compared to the oral bosentan suspension. Results revealed the great improvement of bioavailability (12.71 folds) and sustained vasodilation effect on the pulmonary blood vessels (more than 12 h). Bosentan-loaded RCRPC administered via the pulmonary route may therefore constitute an advance in the management of PAH.

Nanoparticle-Mediated Delivery of Irbesartan Induces Cardioprotection from Myocardial Ischemia-Reperfusion Injury by Antagonizing Monocyte-Mediated Inflammation

Myocardial ischemia-reperfusion (IR) injury limits the therapeutic effect of early reperfusion therapy for acute myocardial infarction (AMI), in which the recruitment of inflammatory monocytes plays a causative role. Here we develop bioabsorbable poly-lactic/glycolic acid (PLGA) nanoparticles incorporating irbesartan, an angiotensin II type 1 receptor blocker with a peroxisome proliferator-activated receptor (PPAR)γ agonistic effect (irbesartan-NP). In a mouse model of IR injury, intravenous PLGA nanoparticles distribute to the IR myocardium and monocytes in the blood and in the IR heart. Single intravenous treatment at the time of reperfusion with irbesartan-NP (3.0 mg kg(-1) irbesartan), but not with control nanoparticles or irbesartan solution (3.0 mg kg(-1)), inhibits the recruitment of inflammatory monocytes to the IR heart, and reduces the infarct size via PPARγ-dependent anti-inflammatory mechanisms, and ameliorates left ventricular remodeling 21 days after IR. Irbesartan-NP is a novel approach to treat myocardial IR injury in patients with AMI.

Intratracheal instillation of ethyl pyruvate nanoparticles prevents the development of shunt-flow-induced pulmonary arterial hypertension in a rat model

Purpose

To investigate whether inhalation of ethyl pyruvate (EP) encapsulated with poly(ethylene glycol)-block-lactide/glycolide copolymer nanoparticles (EP-NPs) can prevent the development of shunt-flow-induced hyperkinetic pulmonary arterial hypertension (PAH) in a rat model.

Materials and methods

Rats were separated into five groups: blank (ie, no treatment after shunt flow), normal control (ie, no shunt flow or treatment), EP-NP instillation, EP-only instillation, and vehicle. The animals received intratracheal instillation of EP-NPs or other treatments immediately after a shunt flow, and treatment continued weekly until the end of the experiment. Hemodynamic data were recorded, pulmonary arterial remodeling was assessed, and levels of inflammatory mediators and ET1 expression in the lung and serum were analyzed. In addition, retention of EP in the lungs of rats in the EP-NP and EP-only groups was measured using high-performance liquid chromatography.

Results

After 12 weeks, hemodynamic abnormalities and pulmonary arterial remodeling were improved in the EP-NP instillation group, compared with the blank, EP-only, and vehicle groups (P<0.05). In addition, the EP-NP group showed significantly decreased levels of HMGB1, IL-6, TNFα, reactive oxygen species, and ET1 in the lung during PAH development (P<0.05). Furthermore, EP-NP instillation was associated with reduced serum levels of inflammatory factors and ET1. High-performance liquid-chromatography measurement indicated that EP retention was greater in the lungs of the EP-NP group than in the EP-only group.

Conclusion

EP-NP instillation attenuated inflammation and prevented pulmonary arterial remodeling during the development of PAH induced by shunt flow. In the future, EP-NP delivery into the lung might provide a novel approach for preventing PAH.

Morphological study of efficacy of clarithromycin-loaded nanocarriers for treatment of biofilm infection disease

In this study, we developed a drug delivery system (DDS) using polymeric nanocarriers for the treatment of biofilm infection disease. Clarithromycin (CAM)-encapsulated and chitosan (CS) modified polymeric nanoparticles (NPs) were prepared using a polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus^®) (Sol) and poly-(DL-lactide-co-glycolide), respectively. To understand the availability of the prepared NPs, we made morphological observations of the antibacterial activity derived from the NPs toward the bacterial cells within the biofilm using scanning electron microscopy and transmission electron microscopy measurements. These results revealed different antibacterial activities for the two types of drug carriers. In the case of CAM-encapsulated + CS-modified Sol micelles treatment, NPs can exert their antibacterial activity not only by the surfactant, CAM and CS effects but also by intrusion into the bacterial cells. Thereby, CAM-encapsulated + CS-modified Sol micelles had a higher antibacterial activity. The morphological information is useful to design suitable NPs for the treatment against biofilm infections.

Anti-inflammatory Nanoparticle for Prevention of Atherosclerotic Vascular Diseases

Recent technical innovation has enabled chemical modifications of small materials and various kinds of nanoparticles have been created. In clinical settings, nanoparticle-mediated drug delivery systems have been used in the field of cancer care to deliver therapeutic agents specifically to cancer tissues and to enhance the efficacy of drugs by gradually releasing their contents. In addition, nanotechnology has enabled the visualization of various molecular processes by targeting proteinases or inflammation. Nanoparticles that consist of poly (lactic-co-glycolic) acid (PLGA) deliver therapeutic agents to monocytes/macrophages and function as anti-inflammatory nanoparticles in combination with statins, angiotensin receptor antagonists, or agonists of peroxisome proliferator-activated receptor-γ (PPARγ). PLGA nanoparticle-mediated delivery of pitavastatin has been shown to prevent inflammation and ameliorated features associated with plaque ruptures in hyperlipidemic mice. PLGA nanoparticles were also delivered to tissues with increased vascular permeability and nanoparticles incorporating pitavastatin, injected intramuscularly, were retained in ischemic tissues and induced therapeutic arteriogenesis. This resulted in attenuation of hind limb ischemia. Ex vivo treatment of vein grafts with imatinib nanoparticles before graft implantation has been demonstrated to inhibit lesion development. These results suggest that nanoparticle-mediated drug delivery system can be a promising strategy as a next generation therapy for atherosclerotic vascular diseases.

Recent advances in the engineering of nanosized active pharmaceutical ingredients: Promises and challenges

The advances in the field of nanotechnology have revolutionized the field of delivery of poorly soluble active pharmaceutical ingredients (APIs). Nanosized formulations have been extensively investigated to achieve a rapid dissolution and therefore pharmacokinetic properties similar to those observed in solutions. The present review outlines the recent advances, promises and challenges of the engineering nanosized APIs. The principles, merits, demerits and applications of the current 'bottom-up' and 'top-down' technologies by which the state of the art nanosized APIs can be produced were described. Although the number of research reports on the nanoparticle engineering topic has been growing in the last decade, the challenge is to take numerous research outcomes and convert them into strategies for the development of marketable products.

Antibacterial activities of polymeric poly(dl-lactide-co-glycolide) nanoparticles and Soluplus® micelles against Staphylococcus epidermidis biofilm and their characterization

We have successfully prepared polymeric micelles based on polyvinyl caprolactam–polyvinyl acetate–polyethylene glycol graft copolymer (Soluplus®) for a drug delivery system on a biofilm.

Poly(lactic-co-glycolic) acid microspheres encapsulated in Pluronic F-127 prolong hirudin delivery and improve functional recovery from a demyelination lesion

Components of the blood have been proposed as potential therapeutic targets for improving cellular regeneration after injury and neurodegenerative disease. In this work, thrombin is shown to increase endogenous neural progenitor proliferation in the intact murine spinal cord. A local injection of heparin before a spinal cord injury reduces cell proliferation and astrogliogenesis associated with scarring. We sought to create depot-formulations of PLGA microsphere and Pluronic F-127 for sustained local delivery of two thrombin inhibitors, heparin and hirudin. Each hydrogel depot-formulation showed delayed drug release compared to microspheres or hydrogel alone. Animals with a lateral demyelination lesion showed a reduction in CD68+ macrophages when treated with hirudin-loaded PLGA/F-127 gels compared to control and heparin-treated animals. Moreover, hirudin-loaded materials showed an accelerated recovery in coordinated stepping and increased oligodendrocyte densities. Together, these data demonstrate that controlled delivery of hirudin accelerates functional recovery from a demyelination lesion in the spinal cord.

Nanoparticle-mediated drug delivery system for cardiovascular disease

Administration of drugs and other therapeutic agents has been the central strategy of contemporary medicine for cardiovascular disease. The use of a drug delivery system (DDS) is always demanded to enhance the efficacy and safety of therapeutic agents, and improve the signal-to-noise ratio of imaging agents. Nano-scale materials modify in vivo drug kinetics, depending on (patho)physiological mechanisms such as vascular permeability and incorporation by the mononuclear phagocyte system, which constitute 'passive-targeting' properties of nano-DDS. By contrast, an 'active-targeting' strategy employs a specific targeting structure on nano-DDS, which binds to the target molecule that is specific for a certain disease process, such as tumor specific antigens and the induction of adhesion molecules. In this review, we summarize recent studies that applied nano-DDS for the diagnosis and treatment of cardiovascular disease, especially focusing on atherosclerosis and myocardial ischemia-reperfusion (IR) injury. Pathophysiological changes in atherosclerosis and myocardial IR injury are successfully targeted by nano-DDS and preclinical studies in animals showed positive effects of nano-DDS enhancing efficacy and reducing adverse effects. The development of nano-DDS in clinical medicine is keenly being awaited.

Drug carriers in osteoporosis: preparation, drug encapsulation and applications

Carriers are largely used to enhance therapy efficiency via the encapsulation of active molecules. The encapsulation enhances the stability of drug molecules, improves the targeting properties and prolongs pharmacological activity via continuous local release of active molecules. The aim of this review is to report the carrier systems used in osteoporosis therapy. This state of the art research has mainly focused on describing all types of carriers used in this area, their elaboration and properties, the drug characteristics used in such specific application, and drug release and efficiency. In this field, various processes have been used in order to obtain well-defined capsules, spheres and more complex carriers. In this exhaustive review, each process is described, illustrated and discussed.

Nanoparticle-Mediated Delivery of Pioglitazone Enhances Therapeutic Neovascularization in a Murine Model of Hindlimb Ischemia

Objective—

Critical limb ischemia is a severe form of peripheral artery disease (PAD) for which neither surgical revascularization nor endovascular therapy nor current medicinal therapy has sufficient therapeutic effects. Peroxisome proliferator activated receptor-γ agonists present angiogenic activity in vitro; however, systemic administration of peroxisome proliferator−activated receptor-γ agonists is hampered by its side effects, including heart failure. Here, we demonstrate that the nanoparticle (NP)-mediated delivery of the peroxisome proliferator activated receptor-γ agonist pioglitazone enhances its therapeutic efficacy on ischemia-induced neovascularization in a murine model.

Methods and Results—

In a nondiabetic murine model of hindlimb ischemia, a single intramuscular injection of pioglitazone-incorporated NP (1 µg/kg) into ischemic muscles significantly improved the blood flow recovery in the ischemic limbs, significantly increasing the number of CD31-positive capillaries and α-smooth muscle actin–positive arterioles. The therapeutic effects of pioglitazone-incorporated NP were diminished by the peroxisome proliferator activated receptor-γ antagonist GW9662 and were not observed in endothelial NO synthase–deficient mice. Pioglitazone-incorporated NP induced endothelial NO synthase phosphorylation, as demonstrated by Western blot analysis, as well as expression of multiple angiogenic growth factors in vivo, including vascular endothelial growth factor-A, vascular endothelial growth factor-B, and fibroblast growth factor-1, as demonstrated by real-time polymerase chain reaction. Intramuscular injection of pioglitazone (1 µg/kg) was ineffective, and oral administration necessitated a >500 μg/kg per day dose to produce therapeutic effects equivalent to those of pioglitazone-incorporated NP.

Conclusion—

NP-mediated drug delivery is a novel modality that may enhance the effectiveness of therapeutic neovascularization, surpassing the effectiveness of current treatments for peripheral artery disease with critical limb ischemia.

Ultrastructural and Immunohistochemical Studies on Uptake and Distribution of FITC-Conjugated PLGA Nanoparticles Administered Intratracheally in Rats

Polylactide-glycolide (PLGA) nanoparticles have been developed as pulmonary drug delivery carriers. To investigate their behavior, small- (d50 = 74 nm) and large-sized (d50 = 250 nm) FITC-conjugated PLGA nanoparticles were intratracheally administered to rats and were traced for 5, 30 and 60 minutes and 24 hours after administration (HAT). Immunohistochemically, a, FITC-positive reaction was observed in type-I alveolar epithelial cells (type-I AEC), endothelial cells and alveolar macrophages in the lungs from 5 minutes after treatment (MAT) to 24 HAT in both nanoparticle groups. In the kidneys, a positive reaction was observed in proximal tubular epithelial cells at 30 MAT; the reaction peaked at 60 MAT and was reduced at 24 HAT, while no positive reaction was seen in other sites. Ultrascructurally, the number of membrane-bound vesicles, which were approximately 70 nm in size and hard to distinguish from pinocytic vesicles, apparently increased in type-I AEC and endothelial cells at 5 MAT in the small-sized group, in comparison with the control group receiving physiological saline. The number of vesicles in the large-sized group was almost same as that in the control group. On the other hand, in both nanoparticle groups, lysosomes filled with nanoparticles appeared in alveolar macrophages from 30 MAT to 24 HAT. These results indicate that PLGA nanoparticles might be quickly transferred from the alveolar space to the blood vessel via type-I alveolar epithelial cells and excreted into urine, and that there is a threshold for particle size, less than approximately 70 nm in diameter, with regard to absorption through the alveolar wall.

Preparation of sustained release rifampicin microparticles for inhalation

Objectives

The aim of this research was to develop a novel carrier-free dry powder formulation of rifampicin for inhalation with controlled-release properties.

Methods

Rifampicin dihydrate (RFDH) microcrystals were prepared by a polymorphic transformation of rifampicin. The prepared RFDH microcrystals were coated with poly (dl-lactide-co-glycolide) or poly (dl-lactide), using a spray-dryer equipped with two different types of three-fluid (3F) spray nozzles. The physicochemical and aerodynamic properties of the coated RFDH microcrystals were compared with those of conventional matrix microparticles.

Key findings

The coated RFDH powder, encapsulating 50% of rifampicin, was successfully prepared by simple in-situ coating methods using two different types of 3F nozzles and had mass median aerodynamic diameter values of 3.5–4.5 µm. The thin flaky morphology of RFDH powders, providing good aerosolization properties, was maintained after coating. The coated RFDH formulations showed relatively low initial rifampicin release, compared with the uncoated RFDH crystals, followed by slow rifampicin release (about 70%) over 8 h in phosphate-buffered saline media (pH 7.4). Significant chemical degradations were not observed from the crystalline-structured RFDH formulations, while the amorphous-structured matrix formulations showed chemical degradation in six months.

Conclusions

These polymer coated RFDH formulations may be a valuable alternative in the treatment of tuberculosis since the carrier-free formulation offers the benefit of delivering a maximum-potency formulation of the antibiotic directly to the site of infection, and long drug residence times may be achieved by the controlled release of the drug.

Inhalable sustained-release formulation of long-acting vasoactive intestinal peptide derivative alleviates acute airway inflammation

The present study was undertaken to develop a respirable sustained-release powder (RP) formulation of long-acting VIP derivative, [Arg(15, 20, 21), Leu(17)]-VIP-GRR (IK312532), using PLGA nanospheres (NS) with the aim of improving the duration of action. NS formulation of IK312532 (IK312532/NS) was prepared by an emulsion solvent diffusion method in oil, and a mixture of the IK312532/NS and erythritol was jet-milled and mixed with lactose carrier to obtain the IK312532/NS-RP. Physicochemical properties were characterized focusing on appearance, particle size, and drug release, and in vivo pharmacological effects were assessed in antigen-sensitized rats. The IK312532/NS with a diameter of 140 nm showed a biphasic release pattern in distilled water with ca. 20% initial burst for 30 min and a sustained slow release up to ca. 55% for 24h. Laser diffraction analysis demonstrated that IK312532/NS-RP had fine dispersibility and suitable particle size for inhalation. In antigen-sensitized rats, insufflated IK312532/NS-RP (10 μg of IK312532/rat) could suppress increases of granulocyte recruitment and myeloperoxidase in pulmonary tissue for up to 24h after antigen challenge, although IK312532-RP at the same dose was less effective with limited duration of action. From these findings, newly prepared IK312532/NS-RP might be of clinical importance in improving duration of action and medication compliance for treatment of airway inflammatory diseases.

Nanomedical system for nucleic acid drugs created with the biodegradable nanoparticle platform

Nanomedical applications of biodegradable poly(DL-lactide-co-glycolide) (PLGA) nanoparticles (NPs) developed are discussed in this review. A surface-functionalized PLGA NP platform for drug delivery was established to encapsulate a number of macromolecular drugs such as peptides and nucleic acids as well as low-molecular-weight drugs by the emulsion solvent diffusion method. The interaction of PLGA NPs with cells and tissues could be controlled by changing the surface properties of NPs, suggesting their potential utility for the intracellular drug delivery of nucleic acid-based drugs. Furthermore, orally administered NF-κB decoy oligonucleotide-loaded CS-PLGA NPs are also useful in treating experimental colitis. These approaches using surface-modified PLGA NPs could be able to open new possibilities for nucleic acid-based drug delivery via noninvasive administration method.

Improvements in transfection efficiency with chitosan modified poly(DL-lactide-co-glycolide) nanospheres prepared by the emulsion solvent diffusion method, for gene delivery

This study sought to evaluate the in vitro transfection efficiency of plasmid DNA (pDNA)-loaded chitosan-modified poly(DL-lactide-co-glycolide) nanospheres (CS-PLGA NS) in a gene-delivery system. Using the emulsion solvent diffusion (ESD) method, pDNA-loaded PLGA NS was prepared and the surface of the PLGA NS was modified by binding to CS. Gene transfection ability of CS-PLGA NS was examined in A549 cells. The luciferase gene was used as a reporter gene. The pattern of luciferase activity by pDNA-loaded CS-PLGA NS was initially weak, but gradually grew stronger before decreasing activity. These phenomena should be in accordance with the sustained-release profile of pDNA from PLGA NS in the cytosol and the pDNA protection against DNase. Positively charged CS-PLGA NS was found, by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay, not to exhibit cytotoxicity on A549 cells. These results suggest that CS-PLGA NS are potential contributors to efficient pDNA delivery due to their increased interactions with cells and lack of cytotoxic effects.

Nanoparticle-Mediated Delivery of Pitavastatin Into Lungs Ameliorates the Development and Induces Regression of Monocrotaline-Induced Pulmonary Artery Hypertension

Pulmonary artery hypertension (PAH) is an intractable disease of the small PAs in which multiple pathogenic factors are involved. Statins are known to mitigate endothelial injury and inhibit vascular remodeling and inflammation, all of which play crucial roles in the pathogenesis of PAH. We tested the hypothesis that nanoparticle (NP)-mediated delivery of pitavastatin into the lungs can be a novel therapeutic approach for the treatment of PAH. Among the marketed statins, pitavastatin was found to have the most potent effects on proliferation of PA smooth muscle cells in vitro. We formulated pitavastatin-NP and found that pitavastatin-NP was more effective than pitavastatin alone in inhibiting cellular proliferation and inflammation in vitro. In a rat model of monocrotaline-induced PAH, a single intratracheal instillation of NP resulted in the delivery of NP into alveolar macrophages and small PAs for up to 14 days after instillation. Intratracheal treatment with pitavastatin-NP, but not with pitavastatin, attenuated the development of PAH and was associated with a reduction of inflammation and PA remodeling. NP-mediated pitavastatin delivery was more effective than systemic administration of pitavastatin in attenuating the development of PAH. Importantly, treatment with pitavastatin-NP 3 weeks after monocrotaline injection induced regression of PAH and improved survival rate. This mode of NP-mediated pitavastatin delivery into the lungs is effective in attenuating the development of PAH and inducing regression of established PAH, suggesting potential clinical significance for developing a new treatment for PAH.