Assessing Cholesterol Efflux on Primary Human Trophoblast Cells

Cholesterol transport across the placenta must be tightly regulated to avoid a deficiency or an oversupply of cholesterol which is transferred from the mother to the fetus. In trophoblasts, the transport of cholesterol across the cell membrane is mainly mediated by the ATP-binding transporters, ABCA1 and ABCG1. The localization of the transporters at the apical and basal sides of syncytiotrophoblasts has been described. A frequently used method to quantify the amount of cholesterol that cells are capable of exporting is the cholesterol efflux assay. The principle of this assay is that when exogenous [3H]-labeled cholesterol is provided to cultured cells, the efflux of the radioactive cholesterol toward different acceptors in the culture medium is evaluated. Then, the percentage of cholesterol efflux from the cells to the acceptors is calculated. The present work gives an overview on the principle of this assay and a detailed protocol of this technique performed in primary trophoblasts isolated from human term placentas.