Spheroplexes: Hybrid PLGA-cationic lipid nanoparticles, for in vitro and oral delivery of siRNA.

Vectorized small interfering RNAs (siRNAs) are widely used to induce gene silencing. Among the delivery systems used, lipid-based particles are the most effective. Our objective was the development of novel lipid-polymer hybrid nanoparticles, from lipoplexes (complexes of cationic lipid and siRNAs), and poly (lactic-co-glycolic acid) (PLGA), using a simple modified nanoprecipitation method. Due to their morphology, we called these hybrid nanoparticles Spheroplexes. We elucidated their structure using several physico-chemical techniques and showed that they are composed of a hydrophobic PLGA matrix, surrounded by a lipid envelope adopting a lamellar structure, in which the siRNA is complexed, and they retain surface characteristics identical to the starting nanoparticles, i.e. lipoplexes siRNA. We analyzed the composition of the particle population and determined the final percentage of spheroplexes within this population, 80 to 85% depending on the preparation conditions, using fluorescent markers and the ability of flow cytometry to detect nanometric particles (approximately 200 nm). Finally, we showed that spheroplexes are very stable particles and more efficient than siRNA lipoplexes for the delivery of siRNA to cultured cells. We administered spheroplexes contain siRNAs targeting TNF-α to mice with ulcerative colitis induced by dextran sulfate and our results indicate a disease regression effect with a response probably mediated by their uptake by macrophages / monocytes at the level of lamina propria of the colon. The efficacy of decreased level of TNF-α in vivo seemed to be an association of spheroplexes polymer-lipid composition and the specific siRNA. These results demonstrate that spheroplexes are a promising hybrid nanoparticle for the oral delivery of siRNA to the colon.

Boron nitride nanotubes radiolabeled with 153Sm and 159Gd: Potential application in nanomedicine.

Boron nitride nanotubes (BNNTs) have been growing in notoriety in the development of systems aiming bioapplications. In this work we conducted an investigation about the mechanisms involved in the incorporation of samarium and gadolinium in BNNTs. The process was performed by the reduction of samarium and gadolinium oxides (Sm2O3 and Gd2O3, respectively) in the presence of NH3 gas (witch decomposes into N2 and H2) at high temperatures. Various characterization techniques were conducted to elucidate how Sm and Gd are introduced into the BNNT structure. Biological in vitro assays were performed with human fibroblasts and a human osteosarcoma cell line (SAOS-2). Our results show that the studied systems have high potential for biomedical application and can be used as non-invasive imaging agents, such as scintigraphy radiotracers or as magnetic resonance imaging (MRI) contrast medium, being able to promote the treatment of many types of tumors simultaneously to their diagnosis.

Modifying internal organization and surface morphology of siRNA lipoplexes by sodium alginate addition for efficient siRNA delivery.

Vectorized small interfering RNAs (siRNAs) are widely used to induce specific mRNA degradation in the intracellular compartment of eukaryotic cells. Recently, we developed efficient cationic lipid-based siRNA vectors (siRNA lipoplexes or siLex) containing sodium alginate (Nalg-siLex) with superior efficiency and stability properties than siLex. In this study, we assessed the physicochemical and some biological properties of Nalg-siLex compared to siLex. While no significant differences in size, ζ potential and siRNA compaction were detected, the addition of sodium alginate modified the particle morphology, producing smoother and heterogeneous particles characterized by transmission electron microscopy. We also noted that Nalg-siLex have surface differences observed by X-ray photoelectron spectroscopy. These differences could arise from an internal reorganization of components induced by the addition of sodium alginate, that is indicated by Small-Angle X-ray Scattering results. Moreover, Nalg-siLex did not trigger significant hepatotoxicity nor inflammatory cytokine secretion compared to siLex. Taken together these results suggest that sodium alginate played a key role by structuring and reinforcing siRNA lipoplexes, leading to more stable and efficient delivery vector.

Protection of normal cells from irradiation bystander effects by silica-flufenamic acid nanoparticles.

The development of a myriad of nanoparticles types has opened new possibilities for the diagnostics and treatment of many diseases, especially for cancer. However, most of the researches done so far do not focus on the protection of normal cells surrounding a tumor from irradiation bystander effects that might lead to cancer recurrence. Gap-junctions are known to be involved in this process, which leads to genomic instability of neighboring normal cells, and flufenamic acid (FFA) is included in a new group of gap-junction blockers recently discovered. The present work explores the use of mesoporous silica nanoparticles MCM-41 functionalized with 3-Aminopropyltriethoxysilane (APTES) for anchoring the flufenamic acid for its prolonged and controlled release and protection from radiation bystander effects. MCM-41 and functionalized samples were structurally and chemically characterized with multiple techniques. The biocompatibility of all samples was tested in a live/dead assay performed in cultured MRC-5 and HeLa cells. HeLa cells cultured were exposed to 50 Gy of gamma-rays and the media transferred to fibroblast cells cultured separately. Our results show that MCM-41 and functionalized samples have high biocompatibility with MCR-5 and HeLa cells, and most importantly, the FFA delivered by these NPs was able to halt apoptosis, one of main bystander effects.