1771-P: Comprehensive Characterization of Individual Extracellular Vesicles from Beta-Cell Model Systems

In the United States, type II diabetes is prevalent in approximately 34-36 million Americans. To improve patient outcomes, extracellular vesicles (EVs) have emerged as an exciting potential modality. EVs are nano-scale particles released from all types of cells; they contain metabolites, nucleic acids, proteins, and lipids. EVs are an exciting source of biomarkers, a promising avenue for therapeutics, and important in understanding intercellular communication. Due to the heterogeneity of EVs from complex biofluids and the low abundance of EVs from specific organs (e.g., beta cells) it is technically challenging to isolate and characterize EVs from specific cell types. Towards this, we developed a new tool to molecularly characterize individual, low-abundant EVs. We used our Single Extracellular Vesicle Nanoscopy (SEVEN) approach, which combines affinity isolation and super-resolution microscopy, to characterize EVs from beta cell model systems. In particular, we characterized EVs from INS-1 832/13 beta cells, EndoC-beta H1 cells, and nondiabetic cadaveric human islets cultured ex vivo from two donors; EVs from L6.GLUT4myc myotube cells served as controls. The average diameter of beta cell EV ranged from 84 nm (islets) to 95 nm (INS-1 cells), while the average detected number of tetraspanins CD9, CD63, and CD81 ranged from 12 (INS-1 cells) to 17 (islets); as expected, all EVs displayed large heterogeneities in size, content, and circularity. In summary, we molecularly characterized individual EVs from cultured beta cell model systems and deciphered unique multiparametric information about their properties. This work paves the road to understanding the unique properties of EVs from beta cells. Ultimately, we hope to exploit these tools to better understand the role of EVs in normal and diabetogenic conditions.