Fluorescently Labeled PLGA Nanoparticles for Visualization In Vitro and In Vivo: The Importance of Dye Properties.

Fluorescently labeled nanoparticles are widely used for evaluating their distribution in the biological environment. However, dye leakage can lead to misinterpretations of the nanoparticles' biodistribution. To better understand the interactions of dyes and nanoparticles and their biological environment, we explored PLGA nanoparticles labeled with four widely used dyes encapsulated (coumarin 6, rhodamine 123, DiI) or bound covalently to the polymer (Cy5.

Exploring the systemic delivery of a poorly water-soluble model drug to the retina using PLGA nanoparticles.

During the drug development process, many pharmacologically active compounds are discarded because of poor water solubility, but nanoparticle-based formulations are increasingly proposed as a solution for this problem. We therefore studied the distribution of nanoparticulate carriers and the delivery of their poorly water-soluble cargo to a structure of the central nervous system, the retina, under naive and pathological conditions. The lipophilic fluorescent dye coumarin 6 (Cou6) was encapsulated into poly(lactic-co-glycolic acid) PLGA nanoparticles (NPs).

Live Neuroimaging Reveals the Transport of Lipophilic Cargo Through the Blood-Retina Barrier with Modified Amphiphilic Poly-N-Vinylpyrrolidone Nanoparticles.

The blood-retina barrier (BRB), analogous to the blood-brain barrier, is a major hurdle for the passage of drugs from the blood to the central nervous system. Here, we designed polymeric nanoparticles from amphiphilic poly-/V-vinylpyrrolidone (Amph-PVP NPs) as a new carrier-system and investigated their ability to pass the BRB using a live neuroimaging system for the retina in rats and wholemounted retinae preparation. Amph-PVP NPs were loaded with hydrophobic fluorescent markers as a surrogate for hydrophobic drugs.

Gene therapy with caspase-3 small interfering RNA-nanoparticles is neuroprotective after optic nerve damage.

Apoptosis, a key mechanism of programmed cell death, is triggered by caspase-3 protein and lowering its levels with gene therapy may rescue cell death after central nervous system damage. We developed a novel, non-viral gene therapy to block caspase-3 gene expression using small interfering RNA (siRNA) delivered by polybutylcyanoacrylate nanoparticles (CaspNPs). In vitro CaspNPs significantly blocked caspase-3 protein expression in C6 cells, and when injected intraocularly in vivo, CaspNPs lowered retinal capsase-3 immunofluorescence by 57.

Assessment of Amphiphilic Poly--vinylpyrrolidone Nanoparticles' Biocompatibility with Endothelial Cells and Delivery of an Anti-Inflammatory Drug.

Nanoparticles (NPs) produced from amphiphilic derivatives of poly--vinylpyrrolidone (Amph-PVP), composed of various molecular weight polymeric hydrophilic fragments linked into hydrophobic -alkyl chains of varying lengths, were previously shown to exert excellent biocompatibility. Although routes of administration can be different, finally, most nanosystems enter the blood circulation or lymphatic vessels, and by this, they establish direct contact with endothelial cells. In this study, Amph-PVP NPs and fluorescently labeled Amph-PVP-based NPs, namely "PVP" NPs (Amph-PVP-NPs (6000 Da) unloaded) and "F"-NPs (Amph-PVP-NPs (6000 Da) loaded with fluorescent FITC), were synthesized to study Amph-PVP NPs interactions with HMEC-1 endothelial cells.

Release kinetics of fluorescent dyes from PLGA nanoparticles in retinal blood vessels: In vivo monitoring and ex vivo localization.

PLGA (poly(lactic-co-glycolic acid))-based nanoparticles (NPs) are promising drug carrier systems because of their excellent biocompatibility and ability for sustained drug release. However, it is not well understood how the kinetics of such drug delivery system perform in the retinal blood circulation as imaged in vivo and in real time. To answer this question, PLGA NPs were loaded either with lipophilic carbocyanine perchlorate (DiI) or hydrophilic Rhodamine 123 (Rho123) and coated with poloxamer 188 (P188): PLGA-DiI/P188 and PLGA-Rho123/P188.

Vision modulation, plasticity and restoration using non-invasive brain stimulation - An IFCN-sponsored review.

The visual system has one of the most complex structures of all sensory systems and is perhaps the most important sense for everyday life. Its functional organization was extensively studied for decades in animal and humans, for example by correlating circumscribed anatomical lesions in patients with the resulting visual dysfunction. During the past two decades, significant achievements were accomplished in characterizing and modulating visual information processing using non-invasive stimulation techniques of the normal and damaged human eye and brain.

How Nanoparticle Physicochemical Parameters Affect Drug Delivery to Cells in the Retina via Systemic Interactions.

Minor changes in the composition of poloxamer 188-modified, DEAE-dextran-stabilized (PDD) polybutylcyanoacrylate (PBCA) nanoparticles (NPs), by altering the physicochemical parameters (such as size or surface charge), can substantially influence their delivery kinetics across the blood-retina barrier (BRB) in vivo. We now investigated the physicochemical mechanisms underlying these different behaviors of NP variations at biological barriers and their influence on the cellular and body distribution. Retinal whole mounts from rats injected in vivo with fluorescent PBCA NPs were processed for retina imaging ex vivo to obtain a detailed distribution of NPs with cellular resolution in retinal tissue.

The blood-brain barrier and beyond: Nano-based neuropharmacology and the role of extracellular matrix.

Restrained drug delivery due to the blood-brain barrier (BBB) considerably limits options for the treatment of brain pathologies. The utilization of nanoparticulate (NP) carriers has been proposed as a solution. The development strategies need to address the important hurdle of NP passage across the BBB as well as the altered cellular up-take due to the pathophysiological changes of the damaged or diseased tissue as well as immunological and toxicological aspects of nanomedicine penetration.

Major effects on blood-retina barrier passage by minor alterations in design of polybutylcyanoacrylate nanoparticles.

Because the blood-brain barrier (BBB) is an obstacle for drug-delivery, carrier systems such as polybutylcyanoacrylate (PBCA) nanoparticles (NPs) have been studied. Yet, little is known of how physiochemical features such as size, surfactants and surface charge influence BBB passage in vivo. We now used a rat model of in vivo imaging of the retina - which is brain tissue and can reflect the situation at the BBB - to study how size and surface charge determine NPs' ability to cross the blood-retina barrier (BRB).

Evaluation of Toxicity and Neural Uptake In Vitro and In Vivo of Superparamagnetic Iron Oxide Nanoparticles.

Superparamagnetic iron oxide nanoparticles (SPIO-NPs) have great potential to be used in different pharmaceutical applications, due to their unique and versatile physical and chemical properties. The aim of this study was to quantify in vitro cytotoxicity of dextran 70,000-coated SPIO-NPs labelled/unlabelled with rhodamine 123, in C6 glioma cells and primary hippocampal neural cells. In addition, we analyzed the in vitro and in vivo cellular uptake of labelled SPIO-NPs.

Brain Targeting Delivery Facilitated by Ligand-Functionalized Layered Double Hydroxide Nanoparticles.

A delivery platform with highly selective permeability through the blood-brain barrier (BBB) is essential for brain disease treatment. In this research, we designed and prepared a novel target nanoplatform, that is, layered double hydroxide (LDH) nanoparticle conjugated with targeting peptide-ligand Angiopep-2 (Ang2) or rabies virus glycoprotein (RVG) via intermatrix bovine serum albumin for brain targeting. In vitro studies show that functionalization with the target ligand significantly increases the delivery efficiency of LDH nanoparticles to the brain endothelial (bEnd.

Co-expression of β Subunits with the Voltage-Gated Sodium Channel Na1.7: the Importance of Subunit Association and Phosphorylation and Their Effects on Channel Pharmacology and Biophysics.

The voltage-gated sodium ion channel Na1.7 is crucial in pain signaling. We examined how auxiliary β2 and β3 subunits and the phosphorylation state of the channel influence its biophysical properties and pharmacology.

Non-invasive electrical brain stimulation: from acute to late-stage treatment of central nervous system damage.

Non-invasive brain current stimulation (NIBS) is a promising and versatile tool for inducing neuroplasticity, protection and functional rehabilitation of damaged neuronal systems. It is technically simple, requires no surgery, and has significant beneficial effects. However, there are various technical approaches for NIBS which influence neuronal networks in significantly different ways.

Cholinergic Potentiation of Restoration of Visual Function after Optic Nerve Damage in Rats.

Enhancing cortical plasticity and brain connectivity may improve residual vision following a visual impairment. Since acetylcholine plays an important role in attention and neuronal plasticity, we explored whether potentiation of the cholinergic transmission has an effect on the visual function restoration. To this end, we evaluated for 4 weeks the effect of the acetylcholinesterase inhibitor donepezil on brightness discrimination, visually evoked potentials, and visual cortex reactivity after a bilateral and partial optic nerve crush in adult rats.

Mechanistic understanding of nanoparticles' interactions with extracellular matrix: the cell and immune system.

Extracellular matrix (ECM) is an extraordinarily complex and unique meshwork composed of structural proteins and glycosaminoglycans. The ECM provides essential physical scaffolding for the cellular constituents, as well as contributes to crucial biochemical signaling. Importantly, ECM is an indispensable part of all biological barriers and substantially modulates the interchange of the nanotechnology products through these barriers.

Electrical brain stimulation induces dendritic stripping but improves survival of silent neurons after optic nerve damage.

Repetitive transorbital alternating current stimulation (rtACS) improves vision in patients with chronic visual impairments and an acute treatment increased survival of retinal neurons after optic nerve crush (ONC) in rodent models of visual system injury. However, despite this protection no functional recovery could be detected in rats, which was interpreted as evidence of "silent survivor" cells. We now analysed the mechanisms underlying this "silent survival" effect.

Oral application of carbon nanofibers in rats increases blood concentration of IL6 and IL10 and decreases locomotor activity.

Carbon nanofibers (CNF) are versatile nanomaterials that are widely used in various fields of science and technology. As a consequence, animals as well as humans may be exposed to such compounds via different routes. We hypothesized that oral intake of CNF will lead to an inflammatory reaction and consequently induce behavioral impairments.

Cytotoxicity and apoptotic gene expression in an in vitro model of the blood-brain barrier following exposure to poly(butylcyanoacrylate) nanoparticles.

Background Poly(butylcyanoacrylate) (PBCA) nanoparticles (NPs) loaded with doxorubicin (DOX) and coated with polysorbate 80 (PS80) have shown efficacy in the treatment of rat glioblastoma. However, cytotoxicity of this treatment remains unclear. Purpose The purpose of this study was to investigate cytotoxicity and apoptotic gene expression using a proven in vitro co-culture model of the blood-brain barrier.

Repetitive Transcorneal Alternating Current Stimulation Reduces Brain Idling State After Long-term Vision Loss.

Background: Deafferentation of visual system structures following brain or optic nerve injury leaves cortical areas deprived of visual input. Deprived cortical areas have a reduced sensory information processing and are characterized with localized enhanced or synchronized rhythms believed to represent an "idling state".

Objective/hypothesis: We hypothesized that cortical idling can be modified with transcorneal alternating current stimulation (tACS) known to modulate cortical oscillations and thus change the functional state of the deafferented areas.

Preclinical model of transcorneal alternating current stimulation in freely moving rats.

Purpose: Transcorneal alternating current stimulation (tACS) has become a promising tool to modulate brain functions and treat visual diseases. To understand the mechanisms of action a suitable animal model is required. However, because existing animal models employ narcosis, which interferes with brain oscillations and stimulation effects, we developed an experimental setup where current stimulation via the eye and flicker light stimulation can be applied while simultaneously recording local field potentials in awake rats.

Functional protection of learning and memory abilities in rats with vascular dementia.

Purpose: The present study clarified the effects of repetitive transcranial magnetic stimulation (rTMS) in rats with vascular dementia (VaD) and explored the underlying mechanisms.

Methods: Two-vessel occlusion was used as a VaD model. Two weeks after carotid artery occlusion, high (5 Hz) or low (1 Hz) frequency rTMS were applied for 10 days.

Toxicity of polymeric nanoparticles in vivo and in vitro.

Polybutylcyanoacrylate nanoparticles (PBCA NPs) are candidates for a drug delivery system, which can cross the blood-brain barrier (BBB). Because little is known about their toxicity, we exposed cells to PBCA NPs in vitro and in vivo and monitored their life and death assays. PBCA NPs were fabricated with different surfactants according to the mini-emulsion technique.