EVT cells, or extravillous trophoblasts, are a specialized type of cell crucial for the development of the placenta. They are derived from trophoblast cells, which are the cells forming the outer layer of a blastocyst, the early embryo. These cells play a vital role in establishing and maintaining a healthy pregnancy.
Key Functions of EVT Cells:
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Invasion and Remodeling: EVT cells migrate from the anchoring villi of the placenta and invade the uterine wall (decidua basalis). This invasion is not destructive; instead, it's a carefully regulated process that remodels the maternal spiral arteries. This remodeling is essential for ensuring adequate blood flow to the developing fetus. Interstitial EVTs destroy the muscular coat of these arteries, while endovascular EVTs replace the endothelial cells, ultimately adapting the arteries to accommodate the increased blood flow needed during pregnancy.
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Placental-Uterine Interface Establishment: EVTs create a crucial connection between the developing placenta and the mother's uterus. This interface facilitates nutrient and waste exchange between the mother and the fetus.
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Immune Regulation: Unlike most cells, EVT cells lack HLA-G, a major histocompatibility complex (MHC) class I molecule. This lack of HLA-G helps to prevent the mother's immune system from rejecting the fetus, which is essentially foreign tissue. Their interaction with decidual natural killer (dNK) cells is a key component of immune regulation at the maternal-fetal interface.
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Pathological Significance: Dysregulation of EVT cells has been linked to pregnancy complications like miscarriage. Studies show altered biomarkers in EVT cells during early placentation in pathological pregnancies.
In Vitro Studies of EVT Cells:
EVT cells can be studied in vitro (in a laboratory setting). For instance, tissue explants of anchoring villi cultured on extracellular matrix (like Matrigel) can be used to generate EVT cells for research. These in vitro models allow researchers to investigate EVT cell differentiation, invasion, and their response to various stimuli.
Further Research:
Ongoing research explores the detailed mechanisms of EVT cell differentiation, their communication with other cells in the decidua (like dNK cells), and the role of specific signaling pathways in EVT function. Genome-wide expression profiling of EVT cells offers a deeper understanding of their unique molecular signature.
