Preparation and Characterization of Biocompatible Chitosan Nanoparticles for Targeted Brain Delivery of Peptides

Here, we describe a nanocarrier system that can transfer chitosan nanoparticles loaded with either small peptides such as the caspase inhibitor Z-DEVD-FMK or a large peptide like basic fibroblast growth factor across the blood-brain barrier. The nanoparticles are selectively directed to the brain and are not measurably taken up by the liver and spleen. Intravital fluorescent microscopy provides an opportunity to study the penetration kinetics of nanoparticles loaded with fluorescent agents such as Nile red. Nanoparticles functionalized with anti-transferrin antibody and loaded with peptides efficiently provided neuroprotection when systemically administered either as a formulation bearing a single peptide or a mixture of them. Failure of brain permeation of the nanoparticles after inhibition of vesicular transcytosis by imatinib as well as when nanoparticles were not functionalized with anti-transferrin antibody indicates that this nanomedicine formulation is rapidly transported across the blood-brain barrier by receptor-mediated transcytosis.

Systemically administered brain-targeted nanoparticles transport peptides across the blood-brain barrier and provide neuroprotection

Although growth factors and anti-apoptotic peptides have been shown to be neuroprotective in stroke models, translation of these experimental findings to clinic is hampered by limited penetration of peptides to the brain. Here, we show that a large peptide like the basic fibroblast growth factor (bFGF) and a small peptide inhibitor of caspase-3 (z-DEVD-FMK) can effectively be transported to the brain after systemic administration by incorporating these peptides to brain-targeted nanoparticles (NPs). Chitosan NPs were loaded with peptides and then functionalized by conjugating with antibodies directed against the transferrin receptor-1 on brain endothelia to induce receptor-mediated transcytosis across the blood-brain barrier (BBB). Pre-ischemic systemic administration of bFGF- or z-DEVD-FMK-loaded NPs significantly decreased the infarct volume after 2-hour middle cerebral artery occlusion and 22-hour reperfusion in mice. Co-administration of bFGF- or z-DEVD-FMK-loaded NPs reduced the infarct volume further and provided a 3-hour therapeutic window. bFGF-loaded NPs were histologically detected in the brain parenchyma and also restored ischemia-induced Akt dephosphorylation. The neuroprotection was not observed when receptor-mediated transcytosis was inhibited with imatinib or when bFGF-loaded NPs were not conjugated with the targeting antibody, which enables them to cross the BBB. Nanoparticles targeted to brain are promising drug carriers to transport large as well as small BBB-impermeable therapeutics for neuroprotection against stroke.

An aquaporin 4 antisense oligonucleotide loaded, brain targeted nanoparticulate system design

Aquaporins (AQPs), members of the water-channel protein family, are highly expressed in brain tissue especially in astrocytic end-feet. They are important players for water hemostasis during development of cytotoxic as well as vasogenic edema. Increased expression of AQPs is important in pathophysiology of neurological diseases such as neuroinflammation and ischemia. Unfortunately, there are a few pharmacological inhibitors of AQP4 with several side effects limiting their translation as a drug for use in clinical conditions. Another therapeutic approach is using antisense oligonucleotides (ASOs) to block AQP4 activity. These are short, synthetic, modified nucleic acids that bind RNA to modulate its function. However, they cannot pass the blood brain barrier (BBB). To overcome this obstacle we designed a nanoparticulate system made up of chitosan nanoparticles surface modified with PEG and conjugated with monoclonal anti transferrin receptor-1 antibody via streptavidin-biotin binding. The nanocarrier system could be targeted to the transferrin receptor-1 at the brain endothelial capillaries through monoclonal antibodies. It is hypothesized that the nanoparticles could pass the BBB via receptor mediated transcytosis and reach brain parenchyma. Particle size, zeta potential, loading capacity and release profiles of nanoparticles were investigated. It was observed that all types of chitosau (CS) nanoparticles had positive zeta potential values and nanoparticle particle size distribution varied between 100 and 800 nm. The association efficiency of ASOs into the nanoparticles was between 80-97% and the release profiles of the nanoparticles exhibited an initial burst effect followed by a controlled release. The results showed that the designed chitosan based nanocarriers could be a promising carrier system to transport nucleic acid based drugs to brain parenchyma.

Preparation and characterization of biocompatible chitosan nanoparticles for targeted brain delivery of peptides

Here, we describe a nanocarrier system that can transfer chitosan nanoparticles loaded with either small peptides such as the caspase inhibitor Z-DEVD-FMK or a large peptide like basic fibroblast growth factor across the blood-brain barrier. The nanoparticles are selectively directed to the brain and are not measurably taken up by liver and spleen. Intravital fluorescent microscopy provides an opportunity to study the penetration kinetics of nanoparticles loaded with fluorescent agents such as Nile red, and has demonstrated that this nanomedicine formulation is rapidly transported across the blood-brain barrier.

The influence of technological parameters on the physicochemical properties of blank PLGA nanoparticles

In this work, PLGA nanoparticles were prepared by an emulsification-diffusion technique. The main objective was to optimize the preparation of formulations by evaluating the influence of the technological parameters on the physicochemical properties of PLGA nanoparticles. The effects of variations in polymer and emulsifier concentrations, and homogenization duration, rate and type on the particle size distribution, surface charge and morphology of nanoparticles were assessed. The smallest nanoparticles (177.53 +/- 2.78 nm) were obtained with a 2% PLGA (w/v) concentration in the organic phase and 3% PVA (w/v) in the aqueous phase and were prepared by an emulsification-diffusion method via ultrasonic homogenization at a power of 80 W applied for 30 s. It was observed that nanoparticles prepared by Ultra Turrax were more spherical but larger. In addition, increasing the PVA concentration in the aqueous phase, increasing the PLGA concentration in the organic phase and increasing the homogenization rate decreased the zeta potential values of PLGA nanoparticles.

Current research on rapid cycling bipolar disorder and its treatment

Rapid cycling is a pattern of presentation of bipolar disorder that specifies the course of the illness and is associated with a greater morbidity. The validity of rapid cycling as a distinct course modifier for bipolar disorder has been demonstrated and the term has been incorporated into the DSM-IV. The phenomenon of rapid cycling tends to appear late in the course of the disorder, occurs more frequently among females, and is more frequently seen in patients with bipolar type II disorder. Stimulants such as cocaine may also play some role in rapid-cycling. It is generally accepted that a recent history of rapid cycling predicts non-response to monotherapy with lithium and probably carbamazepine as well; however it is also possible that concurrent use of antidepressants may play a role in destabilizing the illness course under these agents. Thus, clinical considerations suggest that discontinuing antidepressants may facilitate the recovery process. Among clinically available monotherapies, valproate and lamotrigine appear to be the most useful clinically. However, other treatments such as lithium, carbamazepine, the atypical antipsychotic agents, thyroid hormone, and bupropion are frequently needed augmentation strategies. Electroconvulsive therapy may also prove efficacious in selected cases. The present paper provides a critical review of the evidence for the foregoing clinical issues in rapid cycling.