Telomerase activity in human trophoblast

Abstract

Summary Recent reports have suggested that many proliferating normal cells express telomerase activity, although telomerase activity was previously considered to be specific for cancer cells. This fact draws attention to the investigation of telomerase activity in trophoblast cells which have characteristics of proliferation, differentiation and invasion. Sub-populations of trophoblast cells were separated by a modification of Kliman's method and magnetic cell sorting with antibodies of integrins. Telomerase activity was assayed semi-quantitatively using fluorescence-based TRAP. Cytological detection of telomerase activity was also examined by the newly developed in situ TRAP procedure and the expression of human TERT was detected by RT-PCR. Telomerase activity was detected in 42% of normal placental tissues, and demonstrated decreased activity with gestational age. Telomerase activities was closely correlated with expression of TERT. In sub-populations of CT separated from placenta from early and term gestation, telomerase activity was predominantly detected in columnar CT from early placenta. Fluorescence signals after in situ TRAP were observed in the trophoblastic cell layers in early placenta as well as isolated CT, but not in term placenta. These results suggest that telomerase activity correlates with the regulation of trophoblastic cell proliferation and in situ TRAP is useful for the detection of telomerase positive cells.