title: The human placenta is a hematopoietic organ during the embryonic and fetal periods of development.
abstract: We studied the potential role of the human placenta as a hematopoietic organ during embryonic and fetal development. Placental samples contained two cell populations-CD34(++)CD45(low) and CD34(+)CD45(low)-that were found in chorionic villi and in the chorioamniotic membrane. CD34(++)CD45(low) cells express many cell surface antigens found on multipotent primitive hematopoietic progenitors and hematopoietic stem cells. CD34(++)CD45(low) cells contained colony-forming units culture (CFU-C) with myeloid and erythroid potential in clonogenic in vitro assays, and they generated CD56(+) natural killer cells and CD19(+)CD20(+)sIgM(+) B cells in polyclonal liquid cultures. CD34(+)CD45(low) cells mostly comprised erythroid- and myeloid-committed progenitors, while CD34(-) cells lacked CFU-C. The placenta-derived precursors were fetal in origin, as demonstrated by FISH using repeat-sequence chromosome-specific probes for X and Y. The number of CD34(++)CD45(low) cells increased with gestational age, but their density (cells per gram of tissue) peaked at 5-8 wk, decreasing more than sevenfold at the onset of the fetal phase (9 wk of gestation). In addition to multipotent progenitors, the placenta contained myeloid- and erythroid-committed progenitors indicative of active in situ hematopoiesis. These data suggest that the human placenta is an important hematopoietic organ, raising the possibility of banking placental hematopoietic stem cells along with cord blood for transplantation.
authors.affiliation: Institute for Regeneration Medicine, Human Embryonic Stem Cell Program, Department of Cell and Tissue Biology, University of California, San Francisco, 513 Parnassus Avenue, HSE-1619, San Francisco, California 94143-0512, USA. Alicia.Barcena@ucsf.edu
authors.forename: Alicia
authors.initials: A
authors.lastname: Bárcena
authors.forename: Mirhan
authors.initials: M
authors.lastname: Kapidzic
authors.forename: Marcus O
authors.initials: MO
authors.lastname: Muench
authors.forename: Matthew
authors.initials: M
authors.lastname: Gormley
authors.forename: Marvin A
authors.initials: MA
authors.lastname: Scott
authors.forename: Jingly F
authors.initials: JF
authors.lastname: Weier
authors.forename: Christy
authors.initials: C
authors.lastname: Ferlatte
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Fisher
mesh_terms: D001402:B-Lymphocytes; D001854:Bone Marrow Cells; D019070:Cell Lineage; D002478:Cells, Cultured; D047108:Embryonic Development; D015672:Erythroid Precursor Cells; D005260:Female; D005312:Fetal Blood / Q000166:cytology; D047109:Fetal Development; D053686:Fetal Stem Cells / Q000166:cytology; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology; D006801:Humans; D007694:Killer Cells, Natural; D023461:Myeloid Progenitor Cells; D010920:Placenta / Q000502:physiology*; D039904:Pluripotent Stem Cells / Q000166:cytology*