1. ¹UPMC Univ Paris 6, Laboratoire de Physiopathologie du Développement, EA 4053, Paris, France
2. ²INSERM UMR_S893, Saint-Antoine Research Center, Paris, France

Correspondence: Dr K Khosrotehrani, MD, PhD, Faculté de médecine Pierre et Marie Curie: Saint-Antoine, Laboratoire de Physiopathologie du développement, UPRES EA4053, UPMC Univ Paris 6, 27 rue de Chaligny, Paris 75012, France. E-mail: kiarash.khosrotehrani@tnn.aphp.fr

Received 30 December 2008; Revised 8 April 2009; Accepted 13 April 2009; Published online 1 June 2009.

Abstract

Fetal CD34+ cells enter the maternal circulation during pregnancy and may persist for decades. These cells are usually depicted as hematopoietic stem/progenitor cells. Our objective was to further determine the phenotype of fetal chimeric CD34+ cells in placental maternal blood from the intervillous space (IVS). Human healthy term placentas were analyzed (n=9). All fetuses were male. CD34+ cells were identified in the IVS and further characterized as fetal or maternal using X and Y chromosome fluorescence in situ hybridization. The phenotype of fetal cells was further analyzed using anti-CD117 (c-kit), anti-CD133, anti-CD31, anti-von Willebrand factor (vWF), anti-vimentin, anti-CD45 and anti-cytokeratin (CK) antibodies. We used preeclamptic placentas of male (n=3) and healthy placentas of female fetuses (n=3) as controls. As expected fetal cells were easily identified in the IVS and significantly increased in cases of preeclampsia. Most CD34+ cells in the IVS were of fetal origin (90%) and were not surrounded by CK staining further showing that they were not in fetal trophoblastic villi. Similarly, about 40% of CD31+ and 6% of vimentin+ cells in the IVS were fetal in origin. No CD117+ or CD133+ fetal cells were found in the IVS of examined placentas. Besides, all the CD34+ cells identified in the IVS were co-labeled with vWF or CD31, suggesting their endothelial origin. These results suggest that most CD34+ cells in maternal placental blood at term are fetal in origin from endothelial and not hematopoietic lineages.