Nanosystems based on siRNA silencing HuR expression counteract diabetic retinopathy in rat

We evaluated whether specifically and directly targeting human antigen R (HuR), a member of embryonic lethal abnormal vision (ELAV) proteins family, may represent a new potential therapeutic strategy to manage diabetic retinopathy. Nanosystems loaded with siRNA silencing HuR expression (lipoplexes), consisting of solid lipid nanoparticles (SLN) and liposomes (SUV) were prepared. Photon correlation spectroscopy analysis, Zeta potential measurement and atomic force microscopy (AFM) studies were carried out to characterize the complexation of siRNA with the lipid nanocarriers. Nanosystems were evaluated by using AFM and scanning electron microscopy. The lipoplexes were injected into the eye of streptozotocin (STZ)-induced diabetic rats. Retinal HuR and VEGF levels were detected by Western blot and ELISA, respectively. Retinal histology was also carried out. The results demonstrated that retinal HuR and VEGF are significantly increased in STZ-rats and are blunted by HuR siRNA treatment. Lipoplexes with a weak positive surface charge and with a 4:1 N/P (cationic lipid nitrogen to siRNA phosphate) ratio exert a better transfection efficiency, significantly dumping retinal HuR and VEGF levels. In conclusion, we demonstrated that siRNA can be efficiently delivered into the rat retina using lipid-based nanocarriers, and some of the lipoplexes loaded with siRNA silencing HuR expression are potential candidates to manage retinal diseases.

A study on the encapsulation of an occludin lipophilic derivative in liposomal carriers

Many peptides and proteins, although potentially useful for the treatment of various diseases, are hindered in their clinical use by poor oral absorption and rapid enzymatic degradation. One of the available solutions to these problems is to increase the lipophilicity by conjugating the peptides to lipophilic moieties, making them more able to cross the biomembranes by passive transport. Occludin is a 65-kDa integral plasma-membrane protein located at the tight junctions. This protein and the peptide derived from it have potential clinical application for drug delivery. Peptide OP90-103 (1) is a fragment of occludin that shows a very poor oral bioavailability and is highly susceptible to enzymatic degradation. The conjugation of 1 with two lipoamino acid (LAA) moieties has been shown to enhance its lipophilicity and bioavailability, as well as its enzymatic stability. The purpose of this study was to evaluate the possibility of encapsulating fluorescein modified lipidated OP90-103 (2), in unilamellar- (LUV) and multilamellar liposomes (MLV), which have a different composition and surface charge and are produced by different methods. The cell internalization of the carrier systems was evaluated in vitro.

New amphiphilic derivatives of poly(ethylene glycol) (PEG) as surface modifiers of colloidal drug carriers. III. Lipoamino acid conjugates with carboxy- and amino-PEG(5000) polymers

Within a research directed to developing new polymeric materials, suitable for decorating the surface of colloidal drug carriers, PEG5000 polymers containing a free carboxyl or amine group at one end were conjugated to an α-lipoamino moiety (LAA). The conjugates were characterized by FT-IR, (1)H-NMR, and MALDI-TOF mass spectrometry. They showed the same profile of solubility as the parent PEGs in water and in some polar and apolar solvents of pharmaceutical use. Representative terms showed to be well tolerated when incubated with Caco-2 or L929 cell cultures. Dedicated differential scanning calorimetry (DSC) studies were performed to prove the interaction of increasing molar fractions of the PEG5000-LAA conjugates with dipalmitoylphosphatidylcholine (DPPC) bilayers, to gain information about their possible incorporation in drug nanocarriers. While the parent PEGs affected only the superficial structure of bilayers, the amphiphilic PEG-LAA conjugates induced a perturbing effect on the thermotropic behavior of DPPC liposomes, according to the structure of the linked LAA residue. A molar concentration of these PEG-LAA between 5 and 10% was individuated as the most suitable to produce stable vesicles.