Effects of intermittent high glucose on BeWo choriocarcinoma cells in culture.

The aim of this study was to investigate the cellular effects of intermittent high glucose on the human BeWo placental choriocarcinoma cell line, used as a model of the effects of glucose fluctuation in diabetic pregnancies. BeWo cells were subjected to three different glucose conditions for 48 h: 7 mmol/L (control), 42 mmol/L (high glucose), or 7 and 42 mmol/L glucose (intermittent, alternated every 6 h). Cell viability was assessed using cell counts, a cell proliferation assay, and a cell viability assay. Apoptosis was also studied using a terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay and by immunocytochemistry of fractin, the N-terminal fragment of actin, which can distinguish apoptotic from necrotic cells. Furthermore, the expression of the well-known survival factors of trophoblast cells, heparin-binding epidermal growth factor-like growth factor and leptin, was evaluated by real-time polymerase chain reaction and Western blot analyses. Intermittent high-glucose conditions significantly decreased cell viability and enhanced apoptosis compared with control or continuous high-glucose conditions. Furthermore, the expression of heparin-binding epidermal growth factor-like growth factor, but not that of leptin, was significantly increased under intermittent high-glucose conditions compared to its expression under either control or continuous high-glucose conditions. These data indicate that intermittent high glucose is more deleterious to BeWo cells than continuous high-glucose conditions. Although further in vitro and in vivo study is necessary, excess fluctuation of glucose levels in the placental circulation might be involved in the impairment of placental development leading to the placental dysfunction.