Development of functional human immune system with the transplantations of human fetal liver/thymus tissues and expanded hematopoietic stem cells in RAG2-/-gamma(c)-/- MICE.
BACKGROUND
There is an increasing need for suitable animal models for the study of the human immune system and disease. The purpose of this study was to develop a practical in vivo model of human immune cell repopulation using ex vivo expanded human fetal liver-derived CD34(+) hematopoietic stem cells and subrenally coimplanted fetal liver/thymus tissues.


METHODS
Freshly isolated fetal liver-derived CD34(+) hematopoietic stem cells were frozen until injected and ex vivo expanded with various cytokines for 7 days. After fetal liver/thymus tissues were subrenally coimplanted into preirradiated Rag2(-/-)gamma(c)(-/-) mice, frozen and ex vivo expanded CD34(+) cells were injected intravenously. The peripheral blood of the mice was monitored for the detection of human cell engraftment using flow cytometry. Then we confirmed human T-cell function by in vitro function assays.


RESULTS
After fetal liver/thymus tissues were coimplanted into the irradiated Rag2(-/-)gamma(c)(-/-) mice, with frozen and ex vivo expanded CD34(+) hematopoietic stem cells, human cell engraftments were determined using hCD45 and multilineage markers. The cultured cells with the cytokine combination of stem cell factor, thrombopoietin, Flk2/Flk3 ligand (FL), and interleukin-3 showed stable and long-term engraftment compared to other combinations. The ex vivo expanded human fetal liver-derived CD34(+) hematopoietic stem cells, under our culture conditions, accomplished a large volume of expanded cells that were sustained, demonstrating self-renewal of the evaluated markers, which may have indicated long- term repopulation activity.


CONCLUSIONS
The results of this study demonstrated a practical mouse model of expanded human immune cells especially T cells in Rag2(-/-)gamma(c)(-/-) mice.
Joo
S-Y
SY
Transplantation Research Center, Samsung Biomedical Research Institute, Seoul, Korea.
Choi
B-K
BK
Kang
M J
MJ
Jung
D Y
DY
Park
K S
KS
Park
J B
JB
Choi
G S
GS
Joh
J
J
Kwon
C H
CH
Jung
G O
GO
Lee
S K
SK
Kim
S-J
SJ
D000818:Animals; D018952:Antigens, CD34 / Q000502:physiology; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D016332:Fetal Tissue Transplantation; D005434:Flow Cytometry; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods; D006801:Humans; D008099:Liver / Q000196:embryology; D016031:Liver Transplantation / Q000276:immunology*; D017710:Lymphocyte Transfusion; D051379:Mice; D018345:Mice, Knockout; D016513:Mice, SCID; D013370:Subrenal Capsule Assay; D013950:Thymus Gland / Q000196:embryology / Q000637:transplantation*; D014183:Transplantation, Heterologous
D018952:Antigens, CD34; D004268:DNA-Binding Proteins; C499308:Rag2 protein, mouse