Partial restoration of left ventricular systolic function by asPLB gene transfer using ultrasound-mediated microbubble destruction

Facile Synthesis of Lipid-Perfluorocarbon Nanoemulsion Coated with Silica Shell as an Ultrasound Imaging Agent

A novel organic/inorganic hybrid nanovesicle as an ultrasound imaging agent is synthesized via facile emulsion and silica deposition methods. This nanovesicle, hyaluronate (HA)-docetaxel (DTX)/perfluoro-n-pentane (PFP)@SNC, consists of an encapsulated liquid PFP core, loaded DTX, and an HA-decorated silica shell. The HA-DTX/PFP@SNC has a narrow size distribution of 274.5 ± 3.25 nm, a negative zeta potential of -11.6 ± 0.47 mV, and an entrapment efficiency of 86.70% ± 1.42%. HA-DTX/PFP@SNC possesses an ultrasound (US)-triggered drug release and a temperature-dependent size change behavior. Compared with DTX/PFP@soybean phosphatidylcholine (SPC), which has no silica shell, the HA-DTX/PFP@SNC is more stable under various conditions. The MTT assay indicates that the blank HA-PFP@SNC vehicle has no cytotoxicity to A549 cells. Furthermore, due to the HA-mediated tumor-targeting ability, the HA-DTX/PFP@SNC shows obvious cytotoxicity to A549 cells. In vitro and in vivo US imaging results indicate that HA-DTX/PFP@SNC has a stronger and more durable echo signal than DTX/PFP@SPC. Moreover, the in vivo echo signal of HA-DTX/PFP@SNC is stronger than that of DTX/PFP@SNC due to the HA-mediated tumor targeting. Therefore, this novel organic/inorganic hybrid vesicle is a US contrast agent candidate.

Electric pulses augment reporter gene expression in the beating heart

BACKGROUND

Gene therapy of the heart has been attempted in a number of clinical trials with the injection of naked DNA, although quantitative information on myocellular transfection rates is not available. The present study aimed to quantify the efficacy of electropulsing protocols that differ in pulse duration and number to stimulate transfection of cardiomyocytes and to determine the impact on myocardial integrity.

METHODS

Reporter plasmid for constitutive expression of green fluorescent protein (GFP) was injected into the left ventricle of beating hearts of adult, male Lewis rats. Four electrotransfer protocols consisting of repeated long pulses (8 × 20 ms), trains of short pulses (eight trains of either 60 or 80 × 100 µs) or their combination were compared with control procedures concerning the degree of GFP expression and the effect on infiltration, fibrosis and apoptosis.

RESULTS

All tested protocols produced GFP expression at the site of plasmid injection. Continuous pulses were most effective and increased the number of GFP-positive cardiomyocytes by more than 300-fold compared to plasmid injection alone (p < 0.05). Concomitantly, the incidence of macrophage infiltration, fibrosis and cell death was increased. Trains of short pulses reduced macrophage infiltration and fibrosis by four- and two-fold, respectively, although they were 20-fold less efficient in stimulating cardiomyocyte transfection. GFP expression co-related to delivered electric energy, infiltration and fibrosis, although not apoptosis.

CONCLUSIONS

The data imply that electropulsing of the myocardium promotes the overexpression of exogenous protein in mature cardiomyocytes in relation to an injury component. Fractionation of pulses is indicated as a option for sophisticated gene therapeutic approaches to the heart.