Equine Endometrial Explants Undergo Significant Degenerative Changes in Culture

The current study evaluated equine endometrial explants following 12, 24, and 48 hours in culture. Measurement of an indicator of cell death in explant supernatant, light microscopy, and gene expression of biomarkers of endometrial function and cellular stress, were used to compare the effect of six different media on explant viability and morphology. Viability of explants was assessed indirectly through measuring LDH activity in the culture supernatant. Regardless of culture medium composition, a significant increase in LDH activity was observed within 12 hours of culture, indicating occurrence of cell damage. Morphological analysis through light microscopy revealed degenerative changes occurring within 12 hours and after 48 hours there is nearly complete loss of luminal and superficial glandular epithelium and diffuse detachment of deep glandular epithelium. Transcript abundance of prostaglandin-endoperoxide synthase 2 (PTGS2), estrogen receptor 1 (ESR1), and vascular endothelial growth factor (VEGF) was assessed as biomarkers of endometrial function. A marked increase in PTGS2 and VEGF expression occurred, ESR1 displayed more or less steady expression levels. Above described changes were seen irrespective of cell culture medium used. The marked increase in expression in PTGS2 expression presents a limitation to using endometrial explants in the current culture system to study aspects of endometrial function such as the inflammatory response to insemination.