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Research Program


 

Overall Question of Interest

The Winn Laboratory research program revolves around understanding the process of normal and abnormal human placentation. Acquiring knowledge about human placentation will provide important insights about pregnancy complications such as preeclampsia, intrauterine growth restriction (IUGR), placenta accreta and gestational trophoblastic disease. As a physician scientist, my ultimate goal is to see this knowledge translate into improved clinical care resulting in healthier mothers and infants. Current projects include:

Prostaglandin Regulation During Human Cytotrophoblast Differentiation

The goal of this research is to determine the role of prostaglandins/prostanoids (PGs) during differentiation of the invasive population of human cytotrophoblasts (CTBs). CTB progenitor cells differentiate along one of two pathways: either they fuse to form multinucleated syncytiotrophoblasts or they proliferate to form cell columns providing a pool of CTBs that invade the uterus to anchor the placenta (interstitial invasion) and remodel the maternal vasculature (endovascular invasion). This latter aspect of differentiation has been termed CTB pseudovasculogenesis. The cyclooxygenase isoforms (COX-1 and COX-2) are key regulatory enzymes in the production of PGs. COX-2 has been demonstrated to play an important role in angiogenesis, cell migration and metastasis. These biological processes are utilized by human CTBs during differentiation along the invasive pathway. Our previous work has characterized the expression of COX-1 and –2 at the RNA and protein levels clearly showing a link between the up-regulation of COX-2 and invasive differentiation. Our current hypothesis is that COX-1 and COX-2 generated PGs differentially affect CTBs differentiation along the invasive pathway. This hypothesis is being tested by utilizing both a villous explant model and an in vitro culture system that recapitulate in vivo CTB differentiation. Explants or purified CTBs are cultured in the absence or presence of specific and non-specific COX inhibitors. Stage-specific markers of differentiation are evaluated (e.g. E-cadherin, HLA-G, integin alpha 1, and VE-cadherin) by immunoblot analysis or immunocytochemisty. The effects on invasive capacity are also assessed using a Matrigel invasion assay. Using a global unbiased approach (microarrays), alteration of gene expression over differentiation in the absence and presence of COX-specific inhibitors is being performed to identify differentially expressed genes among the different drug conditions.

Gene Profiling of The Normal and Abnormal Maternal-Fetal Interface

Image courtesy of S.J. Fisher lab

The ultimate goal of this project is to shed light on the pathophysiology of preeclampsia; a pregnancy complication characterized by maternal hypertension, proteinuria and edema with the hope of providing better diagnostic markers and improved therapeutic approaches. The underlying pathophysiology of preeclampsia still remains elusive although recent advances have been made with the identification of the role of sFlt-1 and sEndoglin. One clearly established principle is that the placenta plays a pivotal role. Preeclampsia only occurs in the presence of trophoblastic tissue and the clinical condition resolves with the delivery of the placenta. The placental basal plate is the site of known anatomical abnormalities in preeclampsia. Shallow CTB invasion and limited remodeling of the uterine spiral arteries is noted in the basal plate region of preeclamptic placentas. Hence, this region has been the focus of our studies. We have recently determined the gene expression profile of this region from normal second trimester and term samples utilizing microarray technology (Affymetrix GeneChips). This analysis has identified those genes that are expressed in this region and those which have altered expression over gestation. Additionally, we have determined the gene expression profile of the basal plate region from preterm preeclamptic placentas and preterm labor placentas serving as controls. Analysis of the resulting gene profiles has identified potential pathways and molecules altered within the basal plate of preeclampsia. Our hypothesis is that those differentially expressed genes in preeclampsia that are not also regulated over gestation may contribute to the abnormal CTB invasion seen in preeclampsia. Ongoing projects in the lab are confirming the expression pattern of the identified molecules and to determine which cell-type(s) is (are) expressing the molecules of interest (i.e. CTBs, decidua or immune cells) in the basal plate. This is being done by using immunohistochemistry where antibodies are available or alternatively by in situ hybridization on banked basal plate biopsies from normal, preterm labor and preeclamptic placentas. Then, the functional significance of molecules in regards to CTB invasion will be determined. Functional perturbation studies using our in vitro model systems (as discussed above). Perturbations will be performed by using either blocking/stimulating antibodies where appropriate or by transfection using adeno/lentiviral systems to either over-express or knockdown expression of the target gene. Ultimately the results of these studies should identify key molecules and molecular pathways that could potentially serve as therapeutic targets for the prevention and/or treatment of preeclampsia.