Increased expression of apoptotic markers in human full-term placenta after exposure to elevated environmental cadmium levels during pregnancy

Cadmium (Cd), a toxic heavy metal, produces various forms of environmental contaminations and health problems in human. In this study, we aimed to examine the localization of several apoptotic markers in human placentas from pregnant women who were environmentally exposed to Cd. Twelve pregnant women participated in this analysis and they were divided into 2 groups according to their living areas: high-Cd (H-Cd) and low-Cd (L-Cd) groups. After delivery, the placentas were immediately harvested, and the placental width, length, and weight were measured. The placental Cd concentration was determined by using ICP-MS. The expression of three apoptotic markers, cleaved caspase-3, cleaved lamin A/C, and TUNEL, was examined in immunohistochemistry. In results, the placental Cd concentration in the H-Cd group was higher than that in the L-Cd group. In contrast, a significant decrease in the BW (birth weight):PW (placenta weight) ratio representing the placental nutrient transport function was found in the H-Cd group, and an inverse correlation between placental Cd concentration and BW:PW ratio was demonstrated. Additionally, significant elevations in the expression of cleaved caspase-3, cleaved lamin A/C proteins, and TUNEL were shown in the H-Cd placenta. Moreover, positive correlations were found between the placental Cd concentration and the expression of cleaved caspase-3 and TUNEL. Collectively, our findings suggest that the exposure of pregnant women to environmental Cd might induce Cd to be transferred to the body and then accumulated in the placenta, resulting in disturbance of the placental function and eventual apoptosis.