Small Extracellular Vesicles Orchestrate Cisplatin‐Induced Ototoxicity: Potential Biomarker and Targets Discovery

Abstract Cisplatin‐induced ototoxicity remains a clinical dilemma with limited mechanistic understanding and no food and drug administration (FDA)‐approved therapies. Despite emerging roles of small extracellular vesicles (sEV) in drug ototoxicity, their molecular cargo profiles and causal roles to cisplatin‐induced ototoxicity are unexplored. This study systematically investigates sEV derived from cochlear explants treated with cisplatin (Cis‐sEV) and controls (Ctrl‐sEV) using multi‐omics profiling. Through small RNA sequencing, 83 differentially expressed microRNAs (miRNAs) are identified in Cis‐sEV compared to Ctrl‐sEV. Notably, mmu‐miR‐34a‐5p, mmu‐miR‐140‐5p, mmu‐miR‐15b‐5p, mmu‐miR‐25‐3p, and mmu‐miR‐339‐5p are significantly upregulation in Cis‐sEVs. Predicted target pathways of these differentially expressed miRNAs are enriched in apoptosis, inflammation, and cellular damage, indicating their potential involvement in cisplatin‐induced cochlear damage. LC‐MS/MS analysis reveals 90 upregulated and 150 downregulated proteins in Cis‐sEV, with many involved in damage response. Specifically, CLTC, CCT2, ANXA6, and HSPA8 are uniquely upregulated proteins in Cis‐sEV, and CLTC and ANXA6 are exclusively co‐localized in hair cells (HCs) post‐cisplatin exposure, suggesting that Cis‐sEV originate primarily from damaged HCs. Moreover, CLTC in sEV may serve as a potential biomarker for cisplatin‐induced ototoxicity as verified in both in vitro and in vivo models. This study provides novel insights into the molecular mechanisms of cisplatin‐induced ototoxicity and identifies potential biomarker and therapeutic targets.