Effect of Hypoxia on Telomerase Activity in Placental Tissue in Pregnancies with Fetal Growth Restriction

Jung, Young Nae; Kim, Sei Kwang; Chung, Hyun Cheol; Park, Kyu Hyun; Kim, Chang Han; Chang, Young Kwon; Kwon, Ja Young; Kim, Sung Hun; Roh, Sung Il; Cho, Dong Jae

Abstract

OBJECTIVE
To observe the difference in telomerase activity (TA) expression in the placenta between fetal growth restriction (FGR) with preeclampsia and those without and to evaluate the effect of oxygen concentration on the TA expression in the trophoblastic cells.
METHODS
Telomerase activity was measured in 48 (normal pregnancies, 16; preeclampsia with FGR, 15; normotensive FGR, 17) placentas which were obtained between 32 and 41 weeks' gestations. Trophoblastic cells were extracted from 8 chorionic villi samples obtained from 8-10 weeks' placenta and were cultured in either 2%, 8%, and 20% oxygen atmosphere. Then TA was examined by using telomeric repeat amplification protocol (TRAP) assay.
RESULTS
During 3rd trimester of pregnancy, exhibited TA expression in normal pregnancy, FGR complicated by preeclampsia, and normotensive FGR groups were 11 of 16 (68.8%), 4 of 15 (26.7%), and 4 of 17 (23.5%), respectively. Significantly lower level of TA was detected in the FGR group compared to the normal pregnancies (p=0.009), whereas within FGR pregnancies, presence of preeclampsia did not seem to have statistically significant effect on TA expression. TA expression levels were measured by optical density in trophoblasts cultured under various oxygen concentration which revealed that significantly higher TA was exhibited in the cells cultured in 2% oxygen compared to 8% and 20% (p<0.001). However no significant difference was noted in TA between cells cultured in 8% and 20% oxygen.
CONCLUSION
Decreased TA in the placenta from pregnancies with FGR was noted regardless of presence of preeclampsia indicating a probable correlation between FGR and placental senescence. Since increased TA was noted in trophoblastic cells that were cultured in hypoxic condition, we could speculate that the intervillous oxygen tension during early-stage placental development plays a certain role in the placental degeneration in pregnancies complicated by FGR and preeclampsia.