Rapid On-Demand Extracellular Vesicle Augmentation with Versatile Oligonucleotide Tethers.

Abstract

Exosomes show potential as ideal vehicles for drug delivery because of their natural role in transferring biological cargo between cells. However, current methods to engineer exosomes without negatively impacting their function remain challenging. Manipulating exosome-secreting cells is complex and time-consuming, while direct functionalization of exosome surface proteins suffers from low specificity and low efficiency. We demonstrate a rapid, versatile, and scalable method with oligonucleotide tethers to enable diverse surface functionalization on both human and murine exosomes. These exosome surface modifiers, which range from reactive functional groups and small molecules to aptamers and large proteins, can readily and efficiently enhance native exosome properties. We show that cellular uptake of exosomes can be specifically altered with a tethered AS1411 aptamer, and targeting specificity can be altered with a tethered protein. We functionalize exosomes with an immunomodulatory protein, FasL, and demonstrate their biological activity both <i>in vitro</i> and <i>in vivo</i>. FasL-functionalized exosomes, when bioprinted on a collagen matrix, allows spatial induction of apoptosis in tumor cells and, when injected in mice, suppresses proliferation of alloreactive T cells. This oligonucleotide tethering strategy is independent of the exosome source and further circumvents the need to genetically modify exosome-secreting cells.