Direct visualization of transplanted hematopoietic cell reconstitution in intact mouse organs indicates the presence of a niche.
OBJECTIVE
The temporal and spatial behavior of transplanted hematopoietic stem cells (HSCs) within bones remains to be clarified. Our goal is to examine in vivo reconstitution processes and candidate niches in all bones in the mouse body using a new visualization method.


METHODS
Using bone marrow cells from green fluorescent protein (GFP) transgenic mice, the reconstitution processes of transplanted hematopoietic cells (HCs) under myeloablative or nonmyeloablative conditions were observed sequentially from outside the bones with a fluorescent stereomicroscope.


RESULTS
In case of myeloablative transplantation, GFP(+) spots were first detected at the epiphysis of femurs, and in some ribs and vertebrae among all intact bones. Thereafter, engrafted cells proliferated and spread into other bones. In case of nonmyeloablative transplantation with lin(-)Sca-1(+)c-kit(+) cells into W/Wv neonates, characterized by vacant niches because of stem cell defects, GFP(+) cells localized at the epiphysis of femurs and in some vertebrae and ribs, but not in all bones even 4 months after transplantation.


CONCLUSIONS
Our findings show that transplanted HSCs or their immature progenies engraft preferentially at the epiphysis of the femurs or short and flat bones such as ribs and vertebrae. The transplanted cells remain quiescent for at least 4 months under nonmyloablative conditions, which implies the presence of stem cells in a niche. Our approach for the first time graphically demonstrates the kinetics of HCs in vivo and should facilitate analysis of HSC behavior in a three-dimensional mode.
Yoshimoto
Momoko
M
Department of Pediatrics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Shinohara
Takashi
T
Heike
Toshio
T
Shiota
Mitsutaka
M
Kanatsu-Shinohara
Mito
M
Nakahata
Tatsutoshi
T
D000818:Animals; D002465:Cell Movement; D003114:Colony-Forming Units Assay; D004838:Epiphyses / Q000166:cytology; D005269:Femur / Q000166:cytology; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008954:Models, Biological; D009928:Organ Specificity; D011828:Radiation Chimera; D012272:Ribs / Q000166:cytology; D013131:Spine / Q000166:cytology; D019172:Transplantation Conditioning
D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins