Submission Number: YAN-4-99-122

Abstract Number: 523

IMMORTALIZATION OF NORMAL HUMAN PLACENTA-ORIGIN CYTOTROPHOBLAST CELL LINE (NPC) BY REGENERATION OF TELOMERASE ACTIVITY.

YL Wang* ¹, Y Liu* ², YS Piao ¹, LZ Zhuang* ¹ and SW Tsao* ²

State Key Laboratory of Reproductive Biology, Institute of Zoology, The Chinese Academy of Sciences, P. R. China ¹
Department of Anatomy, University of Hong Kong, Hong Kong, P. R. China ²

Abstract:
Telomerase is a ribonucleoprotein that is directly involved in synthesizing telomeric DNA into chromosome ends to maintain the special telomere length and thus enable cells to escape from replicative senescence. Recently, detectable telomerase activity was shown in human normal chorionic villi, especially at early gestational age, while the level decreased during gestation. This may suggest the relationship between trophoblast cell growth and telomerase activity. In the present study, through regenerating telomerase activity by transfecting cells with human telomerase catalytic subunit (hTERT) gene, we tried to immortalize the human normal placenta-origin cytotrophoblast cell line (NPC) which was previously established in this laboratory while showed senescent after passage 30. In summary, a total of three hTERT-expressing clones with strong telomerase activity were obtained, and one of them, named as B6TERT-1, was characterized. Flow cytometry DNA content analysis and growth rate assay indicated the increase in proliferation capability of the cells transfected with hTERT gene. The B6TERT-1 cells showed almost similar morphology, growth-dependency on EGF and the overall expression pattern of cytoskeletal filaments, MMPs and TIMPs with the early passages of the parental NPCB6 cells, while the hCG secretion of the parental cells was higher. Normal karyotype was observed in both NPCB6 and B6TERT-1 cells, and no tumor was detected in nude mice injected with either cells for more than three months. Moreover, B6TERT-1 cells showed no sign of senescence when passaged to more than 70 population doubling. Thus the immortalized human normal cytotrophoblast cell line was established.

Keywords: Implantation, cytotrophoblast cell

This abstract is being presented at: 8:00 AM in session:
Implantation and Early Development