PROJECT SUMMARY Next-generation therapeutics based on extracellular vesicles (EVs) as biologically-derived drug carriers have emerged as a highly promising route to the treatment of a wide range of cardiovascular and respiratory diseases. Despite the broad interest in EV-based drug development, it is increasingly clear that existing methods for preparing therapeutic EVs suffer from a number of constraints that present a significant barrier to clinical translation. In addition to low throughput, long processing times, and labor-intensive operational steps, established separation methods suffer from poor separation efficiencies that result in vesicle loss, size bias, and co-elution of soluble proteins that contaminate the resulting nanovesicle drug. This latter challenge is of particular concern, as the presence of soluble proteins complicates interpretations of efficacy and safety. An additional issue is that while microRNAs (miRNAs) encapsulated within EVs represent a key component conferring therapeutic effect, the intrinsic concentration of miRNA in EVs is extremely low. As a result, effective EV therapies require that exogenous miRNA be loaded into the vesicles to increase potency. While a number of EV cargo loading techniques have been developed, many of these methods demand to introduction of external electrical or acoustic energy that can damage the vesicles and their cargo. Furthermore, existing EV separation and loading techniques require multiple processing steps that are not inherently scalable, increasing development cost and time, and presenting a practical challenge for moving EV therapeutics beyond the preclinical stage. In this R21 project, we propose a new scalable approach to EV separation and drug loading that is compatible with the needs for clinical translation, addressing a significant bottleneck in EV biomanufacturing and enabling a single-step streamlined workflow for the preparation of high potency EV therapeutics. The proposed technology consists of a single device integrating efficient size-based EV separation with drug loading into a scalable, automated, and self-contained process. The platform will leverage a miniature hydrocyclone technology previously developed by our team that has the potential to isolate EVs in the 30-150 nm range in a passive flow- through microfluidic chip. An array of hydrocyclones operating at high flow rates on the order of 1 mL/min will be combined with integrated microfluidic counterflow microdialysis elements to implement a proven pH-gradient- based loading method developed by our group to control EV cargo encapsulation. The scalable platform will enable in-line loading of purified EVs from any cell or biofluid source, using a simple workflow expected to significantly reduce therapeutic EV processing time and cost. The resulting system is further expected to improve vesicle purity and cargo loading efficiency, supporting the development and translation of a new class of EV therapeutics wit...