Expression and characterization of vitamin C transporter in the human trophoblast cell line HTR-8/SVneo: effect of steroids, flavonoids and NSAIDs

Vitamin C plays an important role in embryogenesis and fetal growth as well as in the progression of pregnancy and delivery. Therefore, it is important to understand the mechanism that mediates its transport to the fetus as well as the possible influences by endogenous and exogenous substances on its placental uptake. The aim of this study was to investigate placental sodium-dependent vitamin C transporters (SVCT) 1 and 2. By means of RT-PCR, we found that SVCT2, but not SVCT1, mRNA is expressed in human trophoblast cell line HTR-8/SVneo. Our method was able to confirm SVCT2 mRNA expression in human first-trimester chorionic villi but not in term placental tissue. Cell line kinetic studies of [C-14] ascorbic acid (AA) uptake indicated a one-site model and a saturable process. Fetal bovine serum (FBS) and epidermal growth factor (EGF) do not influence the transport properties, although they significantly increase the expression of SVCT2. Steroid hormones (17 beta-estradiol, progesterone and cortisol), flavonoids (genistein and quercetin) and non-steroidal anti-inflammatory drugs (NSAIDs) (indomethacin and diclofenac) inhibit [C-14]AA uptake in a dose-dependent and non-competitive manner. On the contrary, the process is not influenced by aspirin. Our study suggests the use of HTR-8/SVneo cells as a suitable model for trophoblast vitamin C transport investigation.