Frequent apoptosis in placental villi from pregnancies complicated with intrauterine growth restriction and without maternal symptoms.

The objective of this study was to examine the incidence of apoptosis in placentas of intrauterine growth restriction (IUGR) without maternal disease. We focused on cases of IUGR with both unknown causes and no maternal complications. In addition, apoptosis of IUGR placentas was correlated with the expression of proteins involved in apoptosis and cell turnover. The term placentas were obtained from 16 normal and 10 IUGR pregnancies without maternal symptoms. We analyzed the localization of apoptosis and counted >2000 nuclei by TUNEL assay and transmission electron microscopy in placentas from normal and IUGR cases. We found the incidence of apoptosis to be significantly higher in placentas with IUGR (2.98%) than in normal placentas (1.46%) by TUNEL assay (p=0.03). In addition, immunohistochemical analysis was performed to examine the expression of proteins related to apoptosis and general cell turnover, including the active form of caspase-3, Bax, p53, and Ki-67. Expression of the active form of caspase-3 was significantly higher in IUGR than in a normal pregnancy (p=0.03). These results suggest that enhanced execution of apoptosis through caspase-3 may play a role in IUGR without maternal symptoms.