title: Human CD34- hematopoietic stem cells: basic features and clinical relevance.
abstract: CD34 has been widely used as a stem and progenitor cell marker, and clinical CD34+ stem cell transplantation (CD34+ SCT) has been performed for tumor purging and for prevention of graft-versus-host disease. Recently, CD34-negative hematopoietic stem cells (CD34 HSCs) were identified in mice and humans. Xenogeneic chimera engraftment assays with immunodeficient mice or preimmune fetal sheep resulted in identification of human CD34- HSCs in cord blood, bone marrow, and granulocyte colony-stimulating factor-mobilized peripheral blood, although no significant clonogenic activity was detected in vitro. These characteristics of CD34- HSCs make the assessment of clinical samples difficult. The generation of CD34+ HSCs from CD34 cells in vitro may be a surrogate assay for detecting CD34- HSC activity. This approach was used in recipients of CD34+ SCT and revealed the absence of a CD34 precursor population. The identification of a positive marker in CD34- HSCs and the development of a simpler and more efficient in vivo assay for CD34- HSCs may allow the diagnostic evaluation of human CD34- HSCs in various clinical procedures and diseases.
authors.affiliation: Department of Hematology and Rheumatology and Research Center for Cell Transplantation, Tokai University, School of Medicine, Kanagawa, Japan. andok@keyaki.cc.u-tokai.ac.jp
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ando
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D002454:Cell Differentiation; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology*; D006801:Humans; D016130:Immunophenotyping; D033581:Stem Cell Transplantation
chemical_list: D018952:Antigens, CD34