Ex vivo expansion of human adult stem cells capable of primary and secondary hemopoietic reconstitution.
OBJECTIVE
Ex vivo expansion of human hemopoietic stem cells (HSC) is an important issue in transplantation and gene therapy. Encouraging results have been obtained with cord blood, where extensive amplification of primitive progenitors was observed. So far, this goal has been elusive with adult cells, in which amplification of committed and mature cells, but not of long-term repopulating cells, has been described.


METHODS
Adult normal bone marrow (BM) and mobilized peripheral blood (MPB) CD34(+) cells were cultured in a stroma-free liquid culture in the presence of Flt-3 ligand (FL), thrombopoietin (TPO), stem cell factor (SCF), interleukin-6 (IL-6), or interleukin-3 (IL-3). Suitable aliquots of cells were used to monitor cell production, clonogenic activity, LTC-IC output, and in vivo repopulating capacity.


RESULTS
Here we report that BM and MPB HSC can be cultured in the presence of FL, TPO, SCF, and IL-6 for up to 10 weeks, during which time they proliferate and produce large numbers of committed progenitors (up to 3000-fold). Primitive NOD/SCID mouse repopulating stem cells (SRC) are expanded sixfold after 3 weeks (by limiting dilution studies) and retain the ability to repopulate secondary NOD/SCID mice after serial transplants. Substitution of IL-6 with IL-3 leads to a similarly high production of committed and differentiated cells but only to a transient (1 week) expansion of SRC(s), which do not possess secondary repopulation capacity.


CONCLUSIONS
We report evidence to show that under appropriate culture conditions, adult human SRC can also be induced to expand with limited differentiation.
Gammaitoni
Loretta
L
Department of Oncological Sciences, Institute for Cancer Research and Treatment, Candiolo, Torino, Italy.
Bruno
Stefania
S
Sanavio
Fiorella
F
Gunetti
Monica
M
Kollet
Orit
O
Cavalloni
Giuliana
G
Falda
Michele
M
Fagioli
Franca
F
Lapidot
Tsvee
T
Aglietta
Massimo
M
Piacibello
Wanda
W
D000818:Animals; D001773:Blood Cells; D001854:Bone Marrow Cells; D018929:Cell Culture Techniques / Q000379:methods; D002455:Cell Division / Q000187:drug effects; D016207:Cytokines / Q000494:pharmacology; D006085:Graft Survival; D006410:Hematopoiesis; D019650:Hematopoietic Stem Cell Mobilization; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D014183:Transplantation, Heterologous
D016207:Cytokines