Discussion
Fatty acids accumulate in trophoblast and fetal capillaries inversely according to their chain length. BODIPY-C5 accumulates in the fetal capillary in concentrations far greater than in the trophoblast, suggesting that medium-chain length BODIPY-labeled fatty acids are capable of being transported against a concentration gradient.
Methods
We employed BODIPY fluorophore conjugated fatty acid analogues of three chain lengths, medium (BODIPY-C5), long (BODIPY-C12), and very-long (BODIPY-C16), to study fatty acid uptake in isolated human trophoblast and explants using confocal microscopy. The three BODIPY-labeled fatty acids were added to freshly isolated explants and tracked for up to 30 min. Fatty acid uptake kinetics were quantified in trophoblast (cytotrophoblast and syncytiotrophoblast together) and the fetal capillary lumen.
Results
Long- (BODIPY-C12) and Very long-chain (BODIPY-C16) fatty acids accumulated more rapidly in the trophoblast layer than did medium-chain (BODIPY-C5) whereas BODIPY-C5 accumulated more rapidly in the fetal capillary than did the longer chain length fatty acids. The long-chain fatty acids, BODIPY-C12 and BODIPY-C16, are esterified and stored in lipid droplets in the cytotrophoblast layer, but medium-chain fatty acid, BODIPY-C5, is not.