Modeling Preeclampsia using human induced pluripotent stem cells [methylation]

Preeclampsia (PE) is a hypertensive disorder, which affects up to 10% of pregnancies worldwide. The primary etiology is considered to be abnormal development and function of placental cells called trophoblasts. We previously developed a two-step protocol for differentiation of human pluripotent stem cells, first into cytotrophoblast (CTB) progenitor-like cells, and then into both syncytiotrophoblast (STB)- and extravillous trophoblast (EVT)-like cells, and showed that this protocol can be used to model both normal and abnormal trophoblast differentiation. We have now applied this protocol to differentiate induced pluripotent stem cells (iPSC) derived from placentas of pregnancies with or without PE.  While we did not note any differences in CTB induction, PE-iPSC-derived CTB showed a defect in syncytialization, and had a >180-fold reduction in expression of PSG4, a mature STB marker (p<0.02). While EVT formation did not appear to be altered, the invasive capacity of PE-iPSC-derived EVT was non-responsive to a decrease in oxygen tension, while that of non-PE-iPSC-derived EVT was enhanced 3.8-fold. RNA sequencing analysis showed gene expression changes consistent with defects in STB formation and response to hypoxia in PE-iPSC derived trophoblast. However, differences in DNA methylation were minimal, with only documented differences consistent with part of the response to hypoxia. Overall, PE-associated iPSC recapitulated multiple defects associated with placental dysfunction, with their lack of response to decreased oxygen tension emphasizing the importance of the interface with the maternal microenvironment in normal placentation. 36 samples were run on the Illumina Epic methylation array. The 36 samples include three day 0 samples from each of the 6 patients, for a total of 18 samples. Each patient has one day +4 2% sample and day +4 21% sample from the same iPSC clone for a total of 12 samples. The remaining six samples are the MSC patient samples from which the iPSCs were derived.