Expression of tissue factor pathway inhibitor in human fetal and placentaltissues

The coagulation system differs markedly between fetuses, neonates, and adul ts, and fetal and neonatal thrombotic abnormalities are poorly understood. Tissue factor pathway inhibitor (TFPI) is an important inhibitor of the ext rinsic pathway of coagulation. To begin examining the role of TFPI in the m aternal-fetal relationship, TFPI expression in human fetal and placental ti ssues was studied by immunohistochemical staining. TFPI was widely expresse d in human fetal tissues from 8-24 weeks gestation, particularly in epithel ial and endothelial tissues. Fetal liver, lung, kidney, and intestine were notably positive for TFPI staining. Within the tissues, TFPI was expressed in pneumocytes, hepatocytes, renal tubular and glomerular cells, muscle fib ers, and enterocytes. In placental tissues, TFPI was expressed in syncytiot rophoblasts, cytotrophoblasts, vascular endothelium, and extravillus tropho blasts from 10 weeks through term. Advancing gestation had little effect on TFPI expression. Further studies are needed to determine the functional ro le of TFPI in fetal and placental tissues and to define perturbations in it s expression during fetal and neonatal disease states. (C) 2000 Elsevier Sc ience Ireland Ltd. All rights reserved.