Establishment of a canine endometrial organoid biobank and transcriptomic analysis of age-dependent gene expression.

Unlike humans, dogs do not exhibit menopause; instead, they experience a continuous, age-associated decline in reproductive function, making uterine aging a cumulative and lifelong process. Consequently, age-associated molecular changes in the canine endometrium result from prolonged and repeated physiological exposures. Despite the physiological importance of uterine aging in dogs, representative in vitro models that capture age-dependent molecular features remain limited. Herein, we established a canine endometrial organoid (CEO) biobank comprising samples from 21 donors across diverse age groups and clinical backgrounds. We conducted transcriptomic analyses and compared organoids derived from young and aged donors (n = 4 per group) to identify age-associated differentially expressed genes and enriched biological pathways. We found that CEOs retain transcriptional profiles specific to individual donor dogs under standardized culture conditions, exhibiting clear segregation by chronological age. Organoids from aged donors exhibited enrichment of pathways associated with extracellular matrix remodeling and cell-cell adhesion, accompanied by altered expression of genes associated with epithelial barrier integrity and oxidative stress responses. These results indicate that CEOs reflect age-associated molecular differences in the canine endometrium in vitro. This biobank provides a physiologically relevant platform for assessing endometrial aging in dogs and supports future research for identifying molecular indicators of age-associated uterine changes under controlled experimental conditions.