Project Summary/Abstract Exosomes are nanoscale vesicles with a diameter of 50-200 nm, actively secreted by various types of cells in our body. As they carry biomolecules (e.g., proteins, RNAs, or metabolites) specific to their parental cells and are easily found in biofluids (e.g., blood or urine), exosomes have emerged as a promising biomarker for the detection and treatment monitoring of various diseases. Also, exosomes have the strong potential as a therapeutic agent for regeneration and immune regulation; for example, exosomes from mesenchymal stem cells (MSCs) have been tested in clinical trials for the treatment of brain injury. However, the fundamental mechanisms of what makes cells secrete exosomes and how the molecular contents in exosomes are determined remain unclear; for example, we have limited information about how to regulate MSCs to maximize the production of their exosomes carrying therapeutic molecules. My Lab aims to address these questions by investigating the role of metabolism in exosome biogenesis, because multiple steps of exosome biogenesis, including vesicle formation inside a cell and fusing into the plasma membrane, are directly associated with metabolic processes. In this Project, we will investigate how the exosome generation rate and molecular contents are determined under different metabolic conditions, specifically with the modulation of nutrients and NAD levels. We will also develop a single exosome sorting technology based on intravesicular proteins and investigate the biogenesis of exosomes with mitochondrial molecules under mitochondrial stress conditions. The research accomplishments from this Project will deepen our understanding of exosomes and help us develop exosome-based diagnostic and therapeutic strategies more effectively. Our long-term research goal is to identify the mechanisms of the interplay between metabolism and biogenesis of extracellular vesicles (EVs). This MIRA research focuses on exosomes, a subpopulation of EVs. Based on our research progresses, we will expand our research scope to other EVs, including microvesicles, in the future.