Efficient gene delivery to pancreatic islets with ultrasonic microbubble destruction technology

Abstract

This study describes a method of gene delivery to pancreatic islets of adult, living animals by ultrasound targeted microbubble destruction (UTMD). The technique involves incorporation of plasmids into the phospholipid shell of gas-filled microbubbles, which are then infused into rats and destroyed within the pancreatic microcirculation with ultrasound. Specific delivery of genes to islet beta cells by UTMD was achieved by using a plasmid containing a rat insulin 1 promoter (RIP), and reporter gene expression was regulated appropriately by glucose in animals that received a RIP-luciferase plasmid. To demonstrate biological efficacy, we used UTMD to deliver RIP-human insulin and RIP-hexokinase I plasmids to islets of adult rats. Delivery of the former plasmid resulted in clear increases in circulating human C-peptide and decreased blood glucose levels, whereas delivery of the latter plasmid resulted in a clear increase in hexokinase I protein expression in islets, increased insulin levels in blood, and decreased circulating glucose levels. We conclude that UTMD allows relatively noninvasive delivery of genes to pancreatic islets with an efficiency sufficient to modulate beta cell function in adult animals.diabetes ͉ gene therapy ͉ ultrasound

Ultrasound-assisted non-viral gene transfer to the salivary glands

“…27,28 Our approach is in the former category as the intraductal volume of the salivary gland is encased within the capsule of connective tissue that encompasses the gland, sequestering our gene delivery and microbubbles. This schema allows more precise control of plasmid/ microbubble concentration and localization than is possible with the intravascular delivery of plasmid/ microbubbles.…”

Acoustically-active microbubbles conjugated to liposomes: Characterization of a proposed drug delivery vehicle

“…The thin microbubble shell and gas core each have limited drug-carrying capacity, and therefore, do not yield an efficient therapeutic delivery vehicle. Recent pre-clinical studies of gene delivery with plasmids attached to the microbubble shell have utilized on the order of 10-100 times the typical human dose of microbubbles [18]. Liposomes are membrane-enclosed vesicles composed of a lipid bilayer shell (which can trap hydrophobic and amphipathic drugs) surrounding an aqueous core (which can encapsulate hydrophilic drugs) [19][20][21].…”

Transgene and islet cell delivery systems using nano-sized carriers for the treatment of diabetes mellitus

“…Improved glucose toleranceJean et al (2011)[28] ABPExendin-4 plasmid DNAWhole bodyIntravenous injectionDecreased blood glucose levelKim et al (2012)[29] Ultrasound-targeted microbubbleANGPTL8 plasmid DNAWhole bodyIntravenous injectionPromoted the proliferation of aged β cells and expandedthe β cell mass. Improved glucose tolerance andincreased the fasting blood insulin levelChen et al (2006)[30] Abbreviations : PDX-1: pancreas/duodenum homeobox protein 1; ISL-1: insulin gene enhancer protein-1; GLP-1: glucagon-like peptide-1; DNA: deoxyribonucleic acid; AAV: adeno-associated viral vector; HGF/NK1: N and K1 domains of hepatocyte growth factor; REG3: regenerating islet-derived protein 3; IL-2: interleukin-2; PEI: polyethylenimine; ATR3: activating transcription factor 3; ER: endoplasmic reticulum; IL-4: interleukin-4; IL-10: interleukin-10; ABP: arginine-grafted bioreducible polymer; ANGPTL8: angiopoietin-like protein 8.

10.1080/20022727.2017.1341758-F0001Figure 1.Viral and non-viral vectors for the treatment of renal fibrosis in vivo .

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“…Transgene delivery to the pancreas using an ultrasound device has been reported [30,58]. In that method, lipid-stabilized microbubbles containing plasmid DNA were injected into a catheter that was inserted into the internal jugular vein.…”

“…Ultrasound was directed at the pancreas to destroy the microbubbles within the pancreatic microcirculation. This transgene delivery system was reported to provide substantial transgene expression in the pancreas in vivo [30,58]. An electroporation method was also shown to be effective at transfecting transgenes into the pancreas.…”