Engineered Red Blood Cell‐Derived Extracellular Vesicles With Klotho Peptide Protect the Kidney From Fibrosis

Chronic kidney disease is characterized by progressive tubular injury and fibrosis, ultimately leading to irreversible loss of renal function. Extracellular vesicles (EVs) have emerged as promising therapeutic platforms due to their biocompatibility and engineering potential. In this study, we engineered red blood cell–derived EVs to deliver an active peptide (RBC-EVKP1) from the anti-aging hormone klotho, as a targeted antifibrotic strategy. EVs were isolated from healthy donors and surface-functionalized with the peptide. Fibrosis was evaluated in proximal tubular epithelial cells exposed to TGFβ and in a 3D proximal tubule-on-chip model. RBC-EVKP1 treatment significantly attenuated TGFβ-induced fibrotic and mesenchymal gene expression, reduced extracellular matrix accumulation, and suppressed SMAD signaling. In addition, RBC-EVKP1 reduced cell migration and preserved epithelial organization. In the tubule-on-chip system, engineered EVs maintained cytoskeletal integrity and reduced injury-associated marker expression under fibrotic conditions. Collectively, these findings demonstrate that klotho-engineered EVs effectively inhibit TGFβ-driven fibrosis and preserve tubular integrity, highlighting a promising therapeutic strategy for targeting kidney fibrosis.