PROJECT SUMMARY The delivery of biological therapeutics to cells or tissues is limited by a number of factors, including poor permeability, target specificity, and immunogenicity. Therefore, there is an urgent need to develop new technologies to deliver therapeutics more efficiently, safely, and specifically. We have recently discovered novel small vesicles known as ARMMs (ARRDC1- Mediated Microvesicles) that are naturally secreted by mammalian cells. We have found that ARMMs exhibit several important features that make them suitable for delivery of biological therapeutics: 1) ARMMs can be readily produced by overexpression of the ARRDC1 protein and are relatively uniform in size (average ~100 nm), 2) specific protein molecules are actively recruited into ARMMs and are protected by the lipid bilayer from degradation, and 3) ARMMs can deliver bioactive cargos into recipient cells. Specifically, I have shown that ARMMs can efficiently package and functionally deliver diverse payloads (tumor suppressor protein p53, GFP and p53 RNAs, and the CRISPR-Cas9/guide RNA complex) into cultured recipient cells. Additionally, ARMMs likely elicit little immunogenic response as they are produced by human cells endogenously and can be found in circulating blood. However, although ARMMs have shown great promise as ideal vehicles for the delivery of therapeutic cargos, our studies have been done primarily in cell culture. Thus, key questions remain: does ARMMs-mediated delivery work in vivo (and what is the tissue distribution of injected ARMMs)? Therefore, my overarching goal in the proposed study is to investigate the in vivo trafficking and tissue biodistribution of ARMMS. I plan to characterize ARMMs translocation in vivo using both C. elegans and mouse models by 1) Defining ARMMs trafficking potential in C. elegans and by 2) Elucidating ARMMs translocation and tissue bioavailability in mice. This proof-of-principle study will provide evidence to support further development of ARMMs into a potentially superior vehicle for delivery of a myriad of biological therapeutics.