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

OBJECTIVE: 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). STUDY
DESIGN: 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.
RESULTS: 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.
CONCLUSION: 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.