Follicular Fluid Exosomes From Diminished Ovarian Reserve Patients Impair Granulosa Cell Function via miR-135a-5p-Mediated Suppression of BIRC5

Diminished ovarian reserve (DOR) is associated with poor reproductive outcomes; however, the underlying molecular mechanisms-particularly those involving the regulation of granulosa cell (GC) function by exosomal microRNAs (miRNAs) derived from follicular fluid-remain unclear. This study integrated clinical analysis with molecular profiling to investigate the regulatory effects of DOR patient-derived follicular fluid exosomes on GC function. Clinical data confirmed significantly poorer embryological and clinical outcomes in DOR patients. Follicular fluid was collected from patients with normal ovarian reserve (NOR) and those with DOR. Exosomes and GCs were subsequently isolated from the respective follicular fluid samples. Molecular profiling of follicular fluid exosomes and GCs from both groups identified differentially expressed miRNAs and mRNAs via next-generation sequencing. Integrated bioinformatics analysis and dual‑luciferase reporter assays confirmed that exosomal hsa‑miR‑135a‑5p directly targets and suppresses BIRC5 expression in GCs. Functional experiments demonstrated that incubating NOR GCs with DOR exosomes not only significantly downregulated BIRC5 but also induced marked cellular autophagy and mitochondrial dysfunction. These findings reveal a novel exosome‑mediated regulatory pathway in which DOR follicular fluid exosomes deliver miR‑135a‑5p to recipient GCs, repress the anti‑apoptotic gene BIRC5, and disrupt cellular homeostasis, thereby providing a potential mechanistic explanation for the compromised follicular microenvironment and adverse clinical outcomes in DOR.