Abstract

Adeno-associated viruses (AAVs) are one of the most extensively used tools for gene delivery into mammalian cells due to their low toxicity and long-term transgene expression. Several serotypes of AAV have thus far been identified, which differ in their tropism, or the types of cells they optimally infect, making AAV a very useful system for preferentially transducing specific cell types. Modification of gene expression in pancreatic islets can be a powerful strategy for understanding the pathology of diabetes and developing novel therapeutic strategies against it. We previously established a method for highly-efficient and homogeneous viral transduction of human islet microtissues (a standardized islet model), produced by optimized dissociation and controlled scaffold-free reaggregation of primary human islet cells. This process allowed for an ideal experimental window for accessing and manipulating the pancreatic endocrine cells at their single cell state, while enabling production of uniform islet microtissues displaying long-term (>28 days) and robust function. In this study we compared the tropism for pancreatic islets of 8 high-efficiency adeno-associated virus (AAV) serotypes previously identified. We quantified transduction efficiency via 3D confocal microscopy followed by assessment of insulin secretory function, insulin content, and cell viability of transduced islet microtissues. The serotype AAV2.7m8 exhibited superior transduction efficiency in two different human islet donors, maintaining islet microtissue functionality and ATP levels. Here we present a novel diabetes research tool for the optimization of AAV serotype tropism for pancreatic islets and a scalable system that may be used for efficient modification of gene expression in functional reaggregated islets by AAV transduction.