Article

Placenta as a newly identified source of hematopoietic stem cells

Department of Obstetrics and Gynecology, University of California, Los Angeles, Los Angeles, California 90095, USA.
Current opinion in hematology (Impact Factor: 3.97). 07/2010; 17(4):313-8. DOI: 10.1097/MOH.0b013e328339f295
Source: PubMed

ABSTRACT

The lifelong stream of all blood cells originates from the pool of hematopoietic stem cells (HSCs) generated during embryogenesis. Given that the placenta has been recently unveiled as a major hematopoietic organ that supports HSC development, the purpose of this review is to present current advances in defining the origin and regulation of placental HSCs.
The mouse placenta has been shown to have the potential to generate multipotential myelo-lymphoid hematopoietic stem/progenitor cells de novo. The cellular origin of HSCs generated in the placenta and other sites has been tracked to the hemogenic endothelium by using novel genetic and imaging-based cell-tracing approaches. Transplantable, myelo-lymphoid hematopoietic stem/progenitor cells have also been recovered from the human placenta throughout gestation.
The discovery of the placenta as a major organ that generates HSCs and maintains them in an undifferentiated state provides a valuable model to further elucidate regulatory mechanisms governing HSC emergence and expansion during mouse and human development. Concurrent efforts to optimize protocols for placental banking and HSC harvesting may increase the therapeutic utility of the human placenta as a source of transplantable HSCs.

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    • "Primitive hematopoiesis is transient and does not involve transplantable hematopoietic stem cells (HSCs) (Cumano et al. 1996, 2001). Primitive hematopoiesis is replaced by ''definitive'' hematopoiesis, in which transplantable HSCs arise around E8.5 intraembryonically (Medvinsky and Dzierzak 1996; Sanchez et al. 1996; Cumano et al. 2001), as well as potentially within the yolk sac (Weissman et al. 1978; Yoder et al. 1997; Samokhvalov et al. 2007) and placenta (Gekas et al. 2005; Lee et al. 2010). These HSCs migrate into the fetal liver where they establish definitive hematopoiesis that endures throughout the rest of gestation. "
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    • "HSCs can be isolated from bone marrow, peripheral blood, umbilical cord blood [34], and a newly identified source, placenta [35]. HSCs are multipotent and capable of differentiating into multiple hematopoietic lineages, including erythroid (blood cells), myeloid (leukocyte), and lymphoid (lymphocyte) [36]. "
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