title: Angiopoietin-1 supports induction of hematopoietic activity in human CD34- bone marrow cells.
abstract: OBJECTIVE
  Hematopoietic stem cells (HSCs) consist of heterogenous subpopulations, one of which is CD34(-) HSCs. Recent development of successful engraftment by intra-bone marrow transplantation revealed severe combined immunodeficiency (scid) mouse-repopulating cell (SRC) activity in human CD34(-) cord blood (CB) cells. On the other hand, CD34(-) cells from bone marrow (BM) cells remain relatively undefined. Here, we investigated pre-SRC populations in human BM CD34(-) cells and the effect of the niche-related factor, angiopoietin-1, on them.
  
  
  METHODS
  Two populations in BM CD34(-) cells (namely M cells and S cells) were purified by flow cytometry. Then, they were cocultured with six growth factors on the hematopoietic-supportive mouse BM stromal cell line, HESS-5 or AHESS-5 that were engineered to produce human angiopoietin-1, because we detected Tie2 expression on M cells and S cells. Cultured cells were assessed for their in vitro and in vivo hematopietic activities.
  
  
  RESULTS
  After 7 days in coculture, AHESS-5 was stronger more effective than HESS-5 in converting M and S cells to CD34(+) cells (M cells: 67.4% vs 17.5%, n =6, p < 0.001) (S cells: 42.3% vs 2.3%, n = 6, p < 0.001). Furthermore, both M and S cells were able to engraft in immunodeficient mice after they were cocultured on AHESS-5.
  
  
  CONCLUSIONS
  Results suggest that angiopoietin-1 supports SRC activities in human CD34(-) BM cells, as murine studies demonstrated. Furthermore, identification of previously undetected subpopulations of BM CD34(-) HSCs unveils heterogenous components in the stem cell pool.
authors.affiliation: Division of Hematopoiesis, Research Center for Regenerative Medicine, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Takashi
authors.initials: T
authors.lastname: Yahata
authors.forename: Yukari
authors.initials: Y
authors.lastname: Muguruma
authors.forename: Tomoko
authors.initials: T
authors.lastname: Uno
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Sato
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Matsuzawa
authors.forename: Shunichi
authors.initials: S
authors.lastname: Kato
authors.forename: Yukari
authors.initials: Y
authors.lastname: Shirasugi
authors.forename: Tomomitsu
authors.initials: T
authors.lastname: Hotta
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ando
mesh_terms: D042683:Angiopoietin-1 / Q000502:physiology*; D018952:Antigens, CD34 / Q000276:immunology*; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000166:cytology* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006410:Hematopoiesis; D006801:Humans; D007150:Immunohistochemistry
chemical_list: D042683:Angiopoietin-1; D018952:Antigens, CD34