Detection of functional haematopoietic stem cell niche using real-time imaging.
Haematopoietic stem cell (HSC) niches, although proposed decades ago, have only recently been identified as separate osteoblastic and vascular microenvironments. Their interrelationships and interactions with HSCs in vivo remain largely unknown. Here we report the use of a newly developed ex vivo real-time imaging technology and immunoassaying to trace the homing of purified green-fluorescent-protein-expressing (GFP(+)) HSCs. We found that transplanted HSCs tended to home to the endosteum (an inner bone surface) in irradiated mice, but were randomly distributed and unstable in non-irradiated mice. Moreover, GFP(+) HSCs were more frequently detected in the trabecular bone area compared with compact bone area, and this was validated by live imaging bioluminescence driven by the stem-cell-leukaemia (Scl) promoter-enhancer. HSCs home to bone marrow through the vascular system. We found that the endosteum is well vascularized and that vasculature is frequently localized near N-cadherin(+) pre-osteoblastic cells, a known niche component. By monitoring individual HSC behaviour using real-time imaging, we found that a portion of the homed HSCs underwent active division in the irradiated mice, coinciding with their expansion as measured by flow assay. Thus, in contrast to central marrow, the endosteum formed a special zone, which normally maintains HSCs but promotes their expansion in response to bone marrow damage.
Xie
Yucai
Y
Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, Missouri 64110, USA.
Yin
Tong
T
Wiegraebe
Winfried
W
He
Xi C
XC
Miller
Diana
D
Stark
Danny
D
Perko
Katherine
K
Alexander
Richard
R
Schwartz
Joel
J
Grindley
Justin C
JC
Park
Jungeun
J
Haug
Jeff S
JS
Wunderlich
Joshua P
JP
Li
Hua
H
Zhang
Simon
S
Johnson
Teri
T
Feldman
Ricardo A
RA
Li
Linheng
L
D000818:Animals; D001808:Blood Vessels / Q000166:cytology; D001853:Bone Marrow / Q000473:pathology; D015820:Cadherins / Q000032:analysis; D002455:Cell Division; D002465:Cell Movement; D002469:Cell Separation; D005269:Femur / Q000166:cytology; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D007118:Immunoassay / Q000379:methods*; D007150:Immunohistochemistry; D051379:Mice; D023421:Models, Animal; D010006:Osteoblasts / Q000166:cytology; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D055153:Stem Cell Niche / Q000166:cytology*; D013977:Tibia / Q000166:cytology
D015820:Cadherins; D019408:Platelet Endothelial Cell Adhesion Molecule-1