Establishment and Characterization of an Immortalized Oviduct Epithelial Cell Line from Yak (Bos grunniens)

Oviduct epithelial cells (OECs) constitute a critical component of the oviductal mucosa, providing essential microenvironmental support for fertilization and early embryonic development. Their frequent application in embryo co-culture systems is constrained in yaks (Bos grunniens) by limited tissue availability and the short lifespan of primary yak oviduct epithelial cells (YOECs). To address this limitation, we established immortalized YOEC lines using a lentiviral vector system. Primary YOECs isolated from reproductive tract tissues of adult female yaks via enzymatic digestion were immortalized through individual and combined transfection with simian virus 40 large T antigen (SV40LT) and human telomerase reverse transcriptase (hTERT). The resulting immortalized lines (YOECs-S: SV40LT alone; YOECs-HS: dual SV40LT/hTERT) kept their typical cobblestone shape and still made cytokeratin 18. Both lines exhibited stable SV40LT and hTERT expression (p > 50), maintained diploid karyotypes, and demonstrated serum-dependent growth, contact inhibition, and hormone responsiveness. Notably, YOECs-HS displayed superior proliferative capacity and phenotypic stability during long-term culture. This study reports the first successful establishment and comprehensive characterization of immortalized YOEC lines. These validated models provide a valuable experimental platform for optimizing yak embryo–oviduct epithelial cell co-culture systems and advancing reproductive research in this high-altitude-adapted species.