EP9

EP9 is a peptide targeting CD63. EP9 binds specifically to the extracellular region of CD63, including a groove in the large extracellular loop (EC2) or the extracellular end of CD63’s central cavity, triggering endocytosis of decorated nanoemulsions/liposomes into cells. EP9 promotes cellular uptake of decorated nanoemulsions/liposomes into activated cardiac fibroblasts and epicardial stromal cells via caveolae and/or clathrin-coated pits. EP9 can be used for the research of myocardial infarction, cardiac fibrosis ^[1].

In Vivo, EP9 (25 µg per 100 µL EP9-PFC-NE; 150 µL total; i.v.; single dose) mediates selective accumulation of conjugated PFC-NE in infarcted myocardial tissue, with preferential uptake by cardiac fibroblasts and epicardial stromal cells^[1].

In Vitro, EP9 (5 µg; 30 min) binds specifically to mouse cardiac fibroblasts and EpiSC, human primary cardiac fibroblasts, and normal human dermal fibroblasts, with the highest binding affinity for mouse EpiSC and human primary cardiac fibroblasts^[1]. EP9 (1 mM; 1 h) specifically binds to the tetraspanin CD63, a transmembrane protein on the surface of normal human dermal fibroblasts, as confirmed by significant enrichment in EP9 probe samples relative to control MUT probe samples^[1].

References:
[1]. Euan Martínez AA, et al. CD63 as novel target for nanoemulsion-based 19 F MRI imaging and drug delivery to activated cardiac fibroblasts. Theranostics. 2025;15(1):1-18. Published 2025 Jan 1.