Establishment of Immortalized Yak Ruminal Epithelial Cell Lines by Lentivirus-Mediated SV40T and hTERT Gene Transduction

Yak is a unique species of cattle that is adapted to the harsh natural environment of the Qinghai-Tibet Plateau. Research on the function of the yak rumen is limited to animal experiments, and the cell molecular mechanism is very limited. The high cost of isolation and culture of adult yak rumen epithelial cells (YRECs), low success rate, and limited cell life limit the scope of long-term physiological functions and nutrient absorption mechanisms of yak rumen epithelium in vitro studies. This study aimed to explore the isolation and immortal culture methods of primary YRECs and establish a new cell line model for studying cell molecular mechanisms. The human telomerase reverse transcriptase gene (hTERT) and simian virus 40 large T antigen (SV40T) were transferred into primary YDECs using mammalian gene expression lentiviral vectors. The immortalized cell line (SV40T-YREC-hTERT) retains the morphological and functional characteristics of primary cells. The epithelial cell marker protein cytokeratin 18 of the immortalized cell lines was positive, and the cell proliferation and karyotype were normal. The SV40T and hTERT genes were successfully transferred into immortalized cell lines and maintained high expression. Simultaneously, the immortalized cell lines had normal function of short-chain fatty acid (SCFA) transport and absorption, and the immortalized yak rumen epithelial cell lines were successfully established. In addition, the transepithelial electrical resistance value gradually increased with culture time, and the permeability of epithelial cells decreased by culturing epithelial cells in Transwell culture chambers. Transmission electron microscopy demonstrated the submicroscopic structure of cells in the integrity barrier model and established the YREC barrier model in vitro.