Comparison of phospholipid molecular species between terminal and stem villi of human term placenta by imaging mass spectrometry.

Placental villi play pivotal roles in the feto-maternal transportation and phospholipids constitute major part of villous membrane. However, the functional contributions as well as pathological roles of placental phospholipids are yet to be fully clarified, because tissue distribution of phospholipids in the placental villi has not been identified. Recently, we have been developing and optimizing an imaging system based on a matrix-assisted laser desorption ionization (MALDI)-based mass spectrometer, which provides clear two-dimensional molecular identification with highly sensitive mass spectrometry from mixtures of ions generated on tissue surfaces. In the present study, we applied this technology to the molecular identification of phospholipids in the human term placenta and found that sphingomyelin (d18:1/16:0) and phosphatidylcholine (16:0/20:4) were distributed differently between stem and terminal villi. This methodology detected a distinct tissue distribution of phosphatidylcholine (16:0/20:4) of terminal villi, coupling with arachidonic acid (AA), which might be a clue leading to the future investigation of the possible involvement the synthetic cascade of eicosanoids in the physiology as well as pathological development of terminal villi, such as fetal growth restriction and/or fetal hypoxia, since terminal villi plays the central roles for nutrient and oxygen supply from maternal to fetal circulation.