Triggered RNAi Therapy Using Metal Inorganic Nanovectors.

The administration of small interfering RNA (siRNA) is a very interesting therapeutic option to treat genetic diseases such as Alzheimer's or some types of cancer, but its effective delivery still remains a challenge. Herein, Au nanorod (GNR)-based platforms functionalized with polyelectrolyte layers were developed and analyzed as potential siRNA nanocarriers. The polymeric layers were successfully assembled on the particle surfaces by means of the layer-by-layer assembly technique through the alternating deposition of oppositely charged poly(styrene)sulfonate, PSS, poly(lysine), PLL, and siRNA biopolymers, with a final hyaluronic acid layer in order to provide the nanoconstructs with a potential targeting ability as well as colloidal stability in physiological medium. Once the hybrid nanocarriers were obtained, the cargo release, their colloidal stability in physiological-relevant media, cytotoxicity, cellular internalization and uptake, and knockdown activity were studied. The present hybrid particles release the genetic material inside cells by means of a protease-assisted and/or a light-triggered release mechanism in order to control the delivery of the oligonucleotides on demand. In addition, the hybrid nanovectors were observed to be nontoxic to cells and could efficiently deliver the genetic material in the cell cytoplasms. The GNR-based nanocarriers proposed here can provide a suitable environment to load and protect a sufficient amount of the genetic material to allow an efficient and sustained knockdown gene expression for long (up to 93% for 72 h), thanks to the slow degradation of PLL, without the observation of adverse side toxic effects. It was also found that the silencing activity was enhanced with the number of siRNA layers assembled in the nanoplatforms.

Micro/nanostructured inhalable formulation based on polysaccharides: Effect of a thermoprotectant on powder properties and protein integrity.

Combined micro- and nanosystems are appealing for pulmonary protein delivery, fulfilling the specific physiological requirements for efficient outcomes in-vivo. However, fabrication of protein formulations may impose stresses perturbing protein conformational stability and, hence, biological activity. Herein, a protein, insulin (INS), was nanoencapsulated inside chitosan nanoparticles (CS NPs) by ionic gelation. By spray drying, the resultant protein-loaded NPs were further encapsulated with a thermoprotectant into powders bearing adequate aerodynamic properties for lung delivery. Structural modifications and interactions of the protein/carrier system were investigated following processing, with special emphasis on protein integrity. Accordingly, physicochemical, elemental, structural and thermal experiments were performed. The analyses revealed the localization of a proportion of the protein on the NPs' surface following nanoencapsulation, and the involved molecular interactions between the NPs and thermoprotectant after microencapsulation. Protein integrity was conserved throughout the preparation processes. This highlights the non-invasiveness of the fabrication techniques, particularly spray drying, for preparing micro-nanosystems for effective administration of inhalable macromolecules.

The role of hyaluronic acid inclusion on the energetics of encapsulation and release of a protein molecule from chitosan-based nanoparticles.

The synergistic effects of the polysaccharides chitosan (CS) and hyaluronic acid (HA) formulated into hybrid nanoparticles are promising for drug delivery. In the present work, we performed a detailed analysis of the molecular interactions involved in the TPP-assisted ionotropic gelation of CS hybrid nanoparticles with the objective of investigating the impact of HA inclusion on the particle formulation and on the in vitro release of insulin (INS) as a protein cargo. To do that, an in-depth thermodynamic study was carried out by isothermal titration calorimetry (ITC), nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC) techniques. Such analysis allowed us to elucidate the type and extent of interactions established by INS within the hybrid nanoparticles and to get further knowledge on the nature of its release mechanism in vitro. Overall, INS release from the CS nanoparticles was thermodynamically driven, and when including HA a weaker INS binding to the nanoparticles, hence, a faster release rate in vitro were observed. As a negative polyelectrolyte, HA might have sterically blocked the activated sites of CS, such as the amino groups, through chain entanglement, thereby, attenuating the competitive binding interactions of INS. As a consequence, INS might have experienced a spatial exclusion onto the surface of the hybrid nanoparticles to a greater extent which, in turn, would explain its initial abrupt release.

An invertebrate model for CNS drug discovery: Transcriptomic and functional analysis of a mammalian P-glycoprotein ortholog.

BACKGROUND: ABC efflux transporters at the blood brain barrier (BBB), namely the P-glycoprotein (P-gp), restrain the development of central nervous system (CNS) drugs. Consequently, early screening of CNS drug candidates is pivotal to identify those affected by efflux activity. Therefore, simple, high-throughput and predictive screening models are required. The grasshopper (locust) has been developed as an invertebrate in situ model for BBB permeability assessment, as it has shown similarities to vertebrate models. METHODS: Transcriptome profiling of ABC efflux transporters in the locust brain was performed. Subsequently, identified transcripts were matched with their counterparts in human, rat, mouse and Drosophila melanogaster, based on amino acid sequence similarity, and phylogenetic trees were constructed to reveal the most likely evolutionary history of the proteins. Further, functional characterization of a P-gp ortholog was achieved through transport studies, using a selective P-gp substrate and locust brain in situ, followed by kinetic analyses. RESULTS: A protein with high sequence similarity to the ABCB1 gene of vertebrates was found in the locust brain, which encodes P-gp in human and is considered the most vital efflux pump. Functionally, this model showed transport kinetic behaviors comparable to those obtained from in vitro models. Particularly, substrate affinity of the putative P-gp was observed as in P-gp expressing cells lines, used for predicting drug penetration across biological barriers. CONCLUSION: Findings suggest a conserved mechanism of brain efflux activity between insects and vertebrates, confirming that this model holds promise for inexpensive and high-throughput screening relative to in vivo models, for CNS drug discovery.

Chitosan-hyaluronic acid nanoparticles for gene silencing: the role of hyaluronic acid on the nanoparticles' formation and activity.

Hyaluronic acid (HA) has been described as a biocompatibility enhancer for gene delivery systems; however, the mechanistic implications of its inclusion on the formation and activity of such systems and subsequent gene release are poorly understood. To better understand these issues, we describe herein the preparation and characterization of chitosan and chitosan-hyaluronic acid nanoparticles (CS and CS:HA NPs) for gene silencing. Different formulations were prepared by ionotropic gelation and evaluated for their physicochemical properties and biological activities in A549-Luc cells. Inclusion of HA to CS NPs resulted in a comparable silencing activity with Lipofectamine RNAiMAX (≈85% of luciferase knockdown) and significantly improved cell viability compared with CS NPs. As depicted by isothermal titration calorimetry, HA competed with siRNA for CS binding, lowering CS-siRNA binding strength by 25%. This suggests that besides improving cell biocompatibility of CS NPs, HA might also promote their gene release by loosening the CS-siRNA binding.