Abstract
Islet transplantation is a promising therapy for T1DM, but shows variable success. A long-standing goal is to develop an efficient system for the delivery of molecular cargos to islets in order to improve islet transplant outcomes. Common viral and non-viral systems can only deliver molecular cargos to the periphery cells of an islet. Most of these systems alternate islet function, pose potential oncogenic risks, and increase immunogenicity. Gold nanoparticles are macromolecular nanostructures with high biocompatibility containing void spaces in their interior regions and modifiable surface groups that allow conjugation of therapeutic drugs and proteins. Gold nanoparticles of 12 nm in size have demonstrated a high efficacy to enter cells without auxiliary agents and minimal cytotoxicity. We hypothesize that gold nanoparticles could be used as a unique vehicle to deliver functional molecular cargos for islets. Previous studies performed in the lab indicated the ability to use Cy5 labeled gold nanoparticles conjugated with a specific oligonucleotide sequence. A new spherical nanoparticle tagged with Cy5 was tested for penetration efficacy. Gold nanoparticles were conjugated with mRNA and tagged with green fluorescent protein (GFP) in order to further determine the stability and time required for the mRNA to be delivered and expressed. Gold nanoparticle transfection efficacy was tested in human islets using confocal microscopy and optimal concentration was determined. Islet function was evaluated by measuring the calcium influx and insulin secretion in response to glucose. (i) Confocal images showed high uptake of gold nanoparticles including islet cores. (ii) 12 nM of gold nanoparticles conjugated with Cy5, Cy5/Oligonucleotide and GFP/mRNA were tested for 24 hours, 48 hours and 72 hours of incubation in order to determine the optimal condition. (iii) The functionality of gold nanoparticle-treated islets was well preserved after 72 hours. There was no significant difference in the intracellular calcium concentration of the control group versus the islets treated with gold nanoparticles (p>0.05). Mitochondrial potential indices demonstrated similarity between the control group and islets treated with gold nanoparticles (p>0.05). With the ability to use gold nanoparticles as a delivery system to islets with high transfection efficacy will allow the possibility to conjugate a specific protein or siRNA.
Published Version
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