Apotracker™ Peptides Facilitate Calcium-Independent Phosphatidylserine Targeting for Extracellular Vesicle Isolation and Analysis 2267168

Abstract Introduction Extracellular vesicles (EVs) are membrane-bound nanostructures secreted by diverse cell types, mediating intercellular signaling, immunomodulation, and pathological processes. A defining molecular feature of EVs is the externalization of phosphatidylserine (PS) on their lipid bilayer surface. Apotracker™ is a proprietary suite of synthetic peptides engineered by BioLegend (Revvity Inc.) to selectively bind PS in a calcium-independent manner, overcoming limitations of conventional annexin-based probes. These reagents have demonstrated robust performance in the detection and quantification of apoptotic and necrotic cells via flow cytometry, fluorescence microscopy, and have been integrated into MojoSort workflows for dead cell depletion. In this study, we extend the utility of Apotracker™ peptides to the enrichment and detection of PS-positive EVs derived from cultured human and murine primary cells, as well as hematological and solid tumor cell lines. Using optimized binding protocols, Apotracker™ enables efficient capture and downstream analysis of EV populations, facilitating high-resolution characterization of vesicle heterogeneity and biomarker expression. Our findings establish Apotracker™ as a versatile tool for PS positive EV research, supporting both preparative isolation and analytical detection in translational and basic science applications. Methods Using Phosphatidylserine (PS) binding reagent to enrich PS-positive Apoptotic body in calcium independent manner Results Phosphatidylserine (PS) binding reagent can detect and enrich PS-positive apoptotic bodies. Conclusion Our findings establish Apotracker™ as a versatile tool for PS positive EV research, supporting both preparative isolation and analytical detection in translational and basic science applications Funding Source n/a Topic Categories Technological Innovations in Immunology (TECH)