Prevalence of infarct and villous clumps, and the expression of ?-smooth muscle actin in the placental basal plate in severe preeclampsia

Abstract

The present study was conducted to investigate the prevalence of multifocal infarcts and multifocal villous clumps, as well as the expression of ?-smooth muscle actin (?-SMA) in the basal plate of the placenta. Multifocal infarcts and/or multifocal villous clumps were more frequently observed in early onset severe preeclampsia (EOSPE; n=20) compared with the early control (n=18), late onset severe preeclampsia (LOSPE; n=20) and late control (n=20) groups. Infarct in transitional and late stages was significantly more frequent compared with that in the early stage in EOSPE. In LOSPE, the infarct in the early stage was significantly increased compared with transitional and late stages. The expression of ?-SMA mRNA and protein was determined by RT-PCR and western blotting, respectively, and increased progressively in late, transitional and early infarct, and positively correlated with the number of smooth muscle cells of villous vessels and myofibroblasts of villous stroma studied by immunohistochemistry. These results indicated that multifocal infarct and multifocal villous clumps may affect the blood flow through the basal plate, not only by directly blocking vessels, but also by indirectly making the vessels extruded by contraction of cells stained by ?-SMA. In addition, foci in the early stage may be more important in affecting the contractility of the placental basal plate.