Background: We propose using an innovative technology that utilizes gold nanoparticles (AuNPs) as a non-viral method of delivery. Our laboratory was one of the first to describe the use of AuNPs in human islets and observe AuNP penetration into the islet core for gene delivery, without damaging the cell. AuNPs proved to be a biocompatible delivery system both in vitro and in vivo.

With advances in nanotechnology, and better understanding of the translation process, methods have been developed that allow for expression of specific proteins by intracellular delivery of protein-encoding mRNA.

Methods: Human islets were treated with 12 nm, 7 nm and 2 nm mCherry AuNPs for 24 hours. The expression of mCherry protein in human islets was analyzed by 3D image reconstruction of z-stack images acquired by confocal microscopy. A minimal amount of mCherry protein was expressed in human islets when treated with mCherry mRNA coupled to the 12 nm size AuNP. Decreasing the size of the AuNPs to 7 nm or 2 nm resulted in substantial increase in mCherry protein expression throughout human pancreatic islets when treated at concentrations of 20 nM and 50 nM with mCherry mRNA AuNPs for 24 hours.

We used measurements of calcium influx, KCL and mitochondrial potential to determine the effect of AuNP-mCherry mRNA treatment on islet cell function. The area under the curve was computed for intracellular calcium influx of three different islet preparations. There was no statistically significance difference between (2 nm) 20 nM versus (7 nm) 20 nM, (2 nm) 20 nM versus (7 nm) 50 nM, (2 nm) 50 nM versus (7 nm) 20 nM, (2 nm) 50 nM versus (7 nm) 50 nM. For the area under the curve for the KCL there was no significant statistical difference between the groups. In addition, mitochondrial potential indices demonstrated similarity between the control group and mCherry mRNA AuNPs treated human pancreatic islets, there was no statistical difference between the three different sizes and concentrations when compared to the non-treated group. Taken together, AuNP did not impair islet function when concentration was increased.

Conclusion: During the study of AuNPs conjugated to mCherry mRNA we were able to conclude there was protein expression in intact human pancreatic islets and islet function was not impaired when treated with mCherry mRNA AuNPs.

CITATION INFORMATION: Oberholzer J, Gutierrez D, Marchese E, Nourmohammadzadeh M, Wang Y. A Novel, Non-Viral mRNA Delivery System for Targeted Protein Translation in Human Islets. Am J Transplant. 2016;16 (suppl 3).

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