Angiopoietin-1 supports induction of hematopoietic activity in human CD34- bone marrow cells.
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.
Nakamura
Yoshihiko
Y
Division of Hematopoiesis, Research Center for Regenerative Medicine, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
Yahata
Takashi
T
Muguruma
Yukari
Y
Uno
Tomoko
T
Sato
Tadayuki
T
Matsuzawa
Hideyuki
H
Kato
Shunichi
S
Shirasugi
Yukari
Y
Hotta
Tomomitsu
T
Ando
Kiyoshi
K
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
D042683:Angiopoietin-1; D018952:Antigens, CD34