title: A new role for the human placenta as a hematopoietic site throughout gestation.
abstract: We investigated whether the human placenta contributes to embryonic and fetal hematopoietic development. Two cell populations--CD34(++)CD45(low) and CD34( +)CD45(low)--were found in chorionic villi. CD34(++) CD45(low) cells display many markers that are characteristic of multipotent primitive hematopoietic progenitors and hematopoietic stem cells. Clonogenic in vitro assays showed that CD34(++)CD45( low) cells contained colony-forming units-culture with myeloid and erythroid potential and differentiated into CD56(+) natural killer cells and CD19(+) B cells in culture. CD34(+)CD45(low) cells were mostly enriched in erythroid- and myeloid-committed progenitors. While the number of CD34(++)CD45(low) cells increased throughout gestation in parallel with placental mass. However, their density (cells per gram of tissue) reached its peak at 5 to 8 weeks, decreasing more than 7-fold from the ninth week onward. In addition to multipotent progenitors, the placenta contained intermediate progenitors, indicative of active hematopoiesis. Together, these data suggest that the human placenta is potentially an important hematopoietic organ, opening 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 at San Francisco, California 94143, USA. Alicia.Barcena@ucsf.edu
authors.forename: Alicia
authors.initials: A
authors.lastname: Bárcena
authors.forename: Marcus O
authors.initials: MO
authors.lastname: Muench
authors.forename: Mirhan
authors.initials: M
authors.lastname: Kapidzic
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Fisher
mesh_terms: D018941:Antigens, CD19 / Q000032:analysis; D018952:Antigens, CD34 / Q000032:analysis; D001853:Bone Marrow / Q000196:embryology; D019002:CD56 Antigen / Q000032:analysis; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D002824:Chorionic Villi / Q000502:physiology; D053595:Embryonic Stem Cells / Q000276:immunology / Q000502:physiology*; D015672:Erythroid Precursor Cells / Q000502:physiology; D005260:Female; D005312:Fetal Blood / Q000166:cytology; D053686:Fetal Stem Cells / Q000276:immunology / Q000502:physiology*; D005865:Gestational Age; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000502:physiology*; D006801:Humans; D017493:Leukocyte Common Antigens / Q000032:analysis; D039902:Multipotent Stem Cells / Q000276:immunology / Q000502:physiology*; D023461:Myeloid Progenitor Cells / Q000502:physiology; D010920:Placenta / Q000166:cytology / Q000276:immunology / Q000502:physiology*; D011247:Pregnancy
chemical_list: D018941:Antigens, CD19; D018952:Antigens, CD34; D019002:CD56 Antigen; D017493:Leukocyte Common Antigens; C516769:PTPRC protein, human