Seminal plasma induces receptivity-associated genes and pathways in endometrial epithelial organoids

Research question: What is the effect of seminal plasma on the transcriptome of endometrial epithelial organoids (EEO) established from endometrial tissue of fertile (EEO-F) and subfertile (EEO-SF) women? Design: EEO-F (n = 5) and EEO-SF (n = 5) were treated with 1% seminal plasma (pooled from sperm donors; n = 5) for 6 h in the absence of progesterone, mimicking the proliferative phase. RNA sequencing was performed to identify differentially expressed genes (DEG), followed by pathway and Gene Ontology enrichment analysis. The observed seminal-plasma-induced transcriptomic response was validated using a second seminal plasma batch pooled from different donors (n = 6). Results: High heterogeneity was observed between all EEO, hampering conclusions based on fertility phenotype. Nevertheless, seminal plasma induced 105 DEG in all EEO, including genes associated with the (mid)secretory phase and receptivity genes. Enrichment analysis revealed pathways linked to immune response, hormone signalling and epithelial–mesenchymal transition – processes associated with endometrial receptivity. RNA sequencing data validation indicated that the seminal-plasma-induced response was male-factor independent, suggesting a key regulatory component in seminal plasma. Conclusions: Seminal plasma induces a complex and diverse molecular response in EEO. Despite this variability, a consistent expression pattern of 105 genes was observed among all EEO, including genes associated with endometrial receptivity and the (mid)secretory phase. This suggests that seminal plasma may stimulate a more receptive-like phenotype in EEO in the absence of progesterone or its derivatives. This study underscores the importance of understanding male‒female reproductive crosstalk and the need to identify regulatory components in seminal plasma to improve the outcomes of assisted reproduction technology.