Spatial Transcriptomic Characteristics of the Aging Human Ovary

Ovarian aging is a complex process that compromises fertility and elevates the risk of reproductive disorders. To elucidate its spatiotemporal dynamics, we integrated single-nucleus RNA sequencing and spatial transcriptomics to construct a comprehensive aging atlas of 12 human ovarian tissues spanning ages 12-54 (prepubertal, age 12, n = 1; young, ages 23-29, n = 4; middle-aged, ages 32-34, n = 2; and older-aged, ages 42-54, n = 5). Our analysis revealed aging-related transcriptomic shifts, including impaired mitochondrial oxidative phosphorylation and reproductive structure development in aged human ovaries. We identified a novel endothelial cell (EDC) subtype, CLDN5⁺ blood EDCs, which exhibited unique functional specialization as semiprofessional antigen-presenting cells. In contrast to other cell types that lost cell identity during aging, CLDN5⁺ blood EDCs displayed transcriptomic sensitivity to aging, characterized by enhanced antigen-presenting capabilities, and heightened inflammatory activity. Spatial mapping further uncovered immunoglobulin-expressing (IGHG1⁺/IGKC⁺) cell accumulation in the ovarian periphery, correlating with advancing age. Critically, aging disrupted global cellular connectivity while amplifying the DLK1:NOTCH3 axis between theca cells and CLDN5⁺ blood EDCs, which may contribute to the dysregulation of ovarian functions. We also detected the upregulation of DLK1 in granulosa cells from patients with primary ovarian insufficiency. This study significantly enhances our comprehension of the underlying mechanisms of human ovarian aging and concurrently pinpoints potential therapeutic avenues for addressing related disorders.