Antigenic identification of cells in spiral artery trophoblastic invasion: validation of histologic studies by triple-antibody immunocytochemistry.

Abstract

Trophoblastic invasion of spiral arteries in the placental bed is essential for normal human placentation. Because the absence of these physiologic changes is associated with abnormal pregnancies, we developed a simple immunocytochemical approach that allows simultaneous study of three cell types involved in spiral artery changes (i.e., trophoblastic, endothelial, and smooth muscle cells). Spiral and uteroplacental arteries in the basal plate of 70 term placentas were studied simultaneously with antibodies to keratin to identify cytotrophoblasts, alpha-smooth muscle actin to identify vascular smooth muscle cells, and von Willebrand factor to identify endothelial cells in 15 normal placentas and 55 placentas from abnormal pregnancies. Normal term placentas showed keratin-positive, alpha-smooth muscle actin-negative and von Willebrand factor-negative uteroplacental arteries. Most (37/55) placentas from abnormal pregnancies had keratin-negative, alpha-smooth muscle actin and von Willebrand factor-positive spiral arteries. Spiral artery atherosclerosis was keratin negative, alpha-smooth muscle actin positive, and von Willebrand factor positive and was identified in 22 abnormal and 0 normal placentas. Simultaneous identification of three principal cell types involved in human placentation allowed qualitative and quantitative studies of placentas from normal and abnormal pregnancies that validated previous histologic investigations and provided a new approach to detect spiral arterial changes.