Introduction to the Ultrasound Targeted Microbubble Destruction Technique

Abstract

In UTMD, bioactive molecules, such as negatively charged plasmid DNA vectors encoding a gene of interest, are added to the cationic shells of lipid microbubble contrast agents [7][8][9] . In mice these vector-carrying microbubbles can be administered intravenously or directly to the left ventricle of the heart. In larger animals they can also be infused through an intracoronary catheter. The subsequent delivery from the circulation to a target organ occurs by acoustic cavitation at a resonant frequency of the microbubbles. It seems likely that the mechanical energy generated by the microbubble destruction results in transient pore formation in or between the endothelial cells of the microvasculature of the targeted region 10 . As a result of this sonoporation effect, the transfection efficiency into and across the endothelial cells is enhanced, and transgene-encoding vectors are deposited into the surrounding tissue. Plasmid DNA remaining in the circulation is rapidly degraded by nucleases in the blood, which further reduces the likelihood of delivery to non-sonicated tissues and leads to highly specific target-organ transfection.

Long-term administration of angiotensin (1⿿7) prevents heart and lung dysfunction in a mouse model of type 2 diabetes ( db/db ) by reducing oxidative stress, inflammation and pathological remodeling

“…CO was calculated using a modified Simpson’s rule. To facilitate measurements, mice were injected with a microbubble contrast agent through the tail vein as described previously (20). …”

Ultrasound Directs a Transposase System for Durable Hepatic Gene Delivery in Mice

“…Lipid-stabilized microbubbles were prepared as previously described (Walton et al 2011). Briefly, a stock solution of 200 mg of DPCC (DL-α-Phosphtidlycholine, Dipalmitolyl) (Sigma-Aldrich), 50 mg DPPE (DL-α-Phosphtidylethanolamine, Dipalmitolyl (Sigma-Aldrich), and 1 gram glucose mixed with Phosphate Buffered Saline (PBS) to a final volume of 10 ml was heated and mixed in a boiling water-bath for 30 minutes and then stored at 4°C.…”

“…Under ultrasound guidance, 100ul of the DNA-loaded microbubble solution was injected into the left ventricle of the heart as previously described (Walton et al 2011). The microbubble bolus was visualized using a VisualSonics high frequency 30 MHz ultrasound transducer (VisualSonics 2100, transducer model RMV707B, Ontario, Canada) clamped above the thorax of the mouse in a long-axis view.…”

“…Briefly, in UTMD, a vector encoding a gene of interest is added to the shell of microbubbles; these are then injected intravenously and the construct is deposited at the target organ by acoustic cavitation at a resonant frequency of the bubbles (Walton et al 2011). In previous studies, UTMD has been used to deliver luciferase, green fluorescent protein (GFP) and beta-galactosidase reporter genes and potentially therapeutic genes, such as vascular endothelial growth factor (VEGF), Hexokinase I, and Factor IX (Chen et al 2003; Lindner 2004; Miao et al 2005; Kay 2011).…”

TGF-β1 and TIMP1 double directional rAAV targeted by UTMD in atherosclerotic vulnerable plaque

“…UTMD has been successfully applied in a variety of tissue and organ experimental research (12,13). In the present study, we combined the UTMD and recombinant adeno-associated virus (rAAV), to achieve a high safety and transfection, and gene expression (14).…”