Establishment and characterization of a telomerase immortalized porcine luteal cells

Luteal cells play a crucial role in pregnancy through secreting progesterone to maintain pregnancy and support of fetus. However, low cellular yields and inability to passage primary porcine luteal cells (PLCs) in vitro limit the luteal cell study. Therefore, developing an immortalized porcine luteal cell line is necessary for studying luteal cells activity and function in different diseases. In this study, primary PLCs were obtained from gilts at day 30 to day 50 of gestation and immortalized by human telomerase reverse transcriptase (hTERT). The porcine corpus luteal cell line (hTERT-PLCs) expressed hTERT gene steady, maintained high hTERT activity and normal karyotype. The phase contrast microscope and transmission electron microscope observation showed primary PLCs and hTERT-PLCs were polygonal and exhibited abundant mitochondria, smooth endoplasmic reticulum and lipid droplets. 3β hydroxysteroid dehydrogenase (3βHSD) and Oil-Red-O staining showed that hTERT-PLCs at passage 30 and 50 were similar to primary PLCs. The hTERT-PLCs expressed steroidogenesis-related proteins, enzymes and receptors, such as steroidogenic acute regulatory protein, P450 cholesterol side-chain cleavage, 3βHSD, 20αHSD, luteinizing hormone receptor, progesterone receptor, prolactin receptor, estrogen receptorα/β, as well as primary PLCs. Consequently, hTERT-PLCs could secret progesterone and exhibited similar responses to luteinizing hormone and prostaglandin F2α as primary PLCs. In addition, the hTERT-PLCs did not show neoplastic transformation or anchorage independent growth. In summary, we developed an immortalized porcine luteal cell line which maintained its originally morphological, biological and functional characteristics.