Tissue response and retention of micro- and nanosized liposomes in infarcted mice myocardium after ultrasound-guided transthoracic injection.

Different carrier systems have been investigated for myocardial delivery of biopharmaceuticals for heart disease. Here, we aimed to evaluate the heart retention and tissue response of liposomes intended for cardiac drug delivery. Liposomes were produced by the lipid thin film hydration method followed by sonication. Cytocompatibility tests were performed in murine L929 fibroblasts and H2c9 cardiomyocytes using the Alamar Blue assay. In vivo experiments were assessed in a model of myocardial infarction induced by isoproterenol in mice. Cardiac delivery of fluorescent liposomes (rhodamine B-labeled) with different mean sizes (165 nm, 468 nm, 1551 nm and 1954 nm) was performed by ultrasound-guided transthoracic injection. After three days, mice were euthanized for histological evaluation using optical and fluorescence microscopy. No cytotoxic lipid concentrations were determined in the range 9.3 - 120 µM for fibroblasts and cardiomyocytes exposed to liposomes. In vivo, large liposomes induced significant inflammation in myocardium compared with the control group (p < 0.0001). In contrast, heart mice injected with 468 nm-sized liposomes exhibited a lower number of inflammatory cells. Still, a greater tissue retention 72 h post-injection was found. Therefore, this study demonstrated the feasibility of the echocardiography-guided percutaneous injection to deliver liposomes successfully into the myocardium in a minimally invasive manner. In addition, these findings indicate the potential of liposomes as carriers of biopharmaceuticals for myocardial delivery, supporting the development of further research on these delivery systems for heart disease.

Oral immunotherapy using polymeric nanoparticles loaded with peanut proteins in a murine model of fatal anaphylaxis.

BACKGROUND: Peanut allergy is the most common cause of anaphylaxis and food-related death. However, there is currently no approved immunotherapy treatment. Hence, this warrants the need for relevant and convenient animal models to test for adequate immunotherapies. MATERIALS & METHODS: In this study, we compared three mouse strains: CD1, BALB/c and C57, to select a model of peanut allergy. After that, we conducted then a therapeutic study using an immunogenic peanut extract encapsulated in nanoparticles made with polymer Gantrez® following the solvent displacement method. RESULTS & CONCLUSION: After implementing a dosing schedule with oral commercial peanut butter, the antibody responses, cytokine profiles and, above all, the anaphylaxis induced after a challenge with peanut proteins, showed that the outbred CD1 strain was the most susceptible to peanut sensitization. CD1 sensitized mice were orally immunized with three doses of the nanoparticle formulation capable of protecting them against the severe anaphylactic symptoms induced by the peanut challenge.