Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Fröhlich, J.
Oxygen modulates the response of first-trimester trophoblasts to hyperglycemia
[ Dissertation ] Medical University of Graz; 2011. pp. 86
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- Autor*innen der Med Uni Graz:
- Fröhlich Julia
- Betreuer*innen:
- Huppertz Berthold
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- Abstract:
- Pregestational diabetes retards embryonic growth in early pregnancy. Placental and fetal growth are tightly associated suggesting that also placental growth is impaired. At the end of the first trimester of gestation, oxygen tension rises steeply leading to excessive production of reactive oxygen species (ROS), which is exacerbated in diabetes and may affect placental development. Additionally, during the first half of pregnancy HLA-G negative proliferative trophoblasts form cell columns from which HLA-G positive extravillous trophoblasts invade maternal tissues. The hypotheses of the present study are that oxygen modifies hyperglycemic effects on ROS formation resulting in decreased first-trimester trophoblast growth and that cell survival of both trophoblast subpopulations can be differential influenced by the first trimester gradient ranges from placental low oxygen to decidual high oxygen under hyperglycemic conditions. To test this hypothesis the first trimester trophoblast-derived cell line ACH-3P was cultured up to 3 days under normoglycemia (5.5mmol/l D-glucose) and hyperglycemia (25mmol/l D-glucose) at different (2.5%, 8% and 21%) oxygen tensions. Intracellular and mitochondrial ROS levels were measured by fluorescence assays (H2DCFDA; MitoSOX Red). Proliferation and cell cycle were determined. Cell numbers of ACH-3P cells were measured with and without cytosolic and mitochondrial ROS formation inducers and inhibitors. Under normoglycemia oxygen did not alter trophoblast proliferation. Hyperglycemia reduced cell number by 65% and resulted in cell cycle (G1- and S-phase) changes but only at 21% oxygen. Proliferation reduction could be partially restored by an ERK1/2 but not Akt/PkB inhibitor. At 2.5% and 8% oxygen proliferation and cell cycle were unchanged. Intracellular ROS elevation under hyperglycemia was oxygen-independent, whereas mitochondrial superoxide levels were enhanced under hyperglycemia only at 21% oxygen. Intervention to modulate cytosolic and mitochondrial ROS did not alter cell growth under hyperglycemia at 21% oxygen. Furthermore, after separation, HLA-G positive and negative first trimester trophoblast-derived ACH-3P cells exhibit fewer viable cells under hyperglycemia at 2.5% and 8% oxygen, while at 21% oxygen no viable cells were detectable. A combination of hyperglycemia and high oxygen-levels (21%) reduce proliferation of human first-trimester trophoblasts in a ROS-independent manner involving MAPK. This may account for reduced placental growth and, therefore, also for embryonic growth during the first trimester of pregestational diabetic pregnancies when the oxygen tension increases. Furthermore, in conclusion separated cell types are sensitive to both oxygen and glucose independent from each other.