The ex vivo expansion of feline marrow cells leads to increased numbers of BFU-E and CFU-GM but a loss of reconstituting ability.
Some studies in mice suggest that hematopoietic stem cells can be maintained and possibly expanded ex vivo. As there is a paucity of data from larger animals, we have studied hematologic reconstitution following autologous marrow transplantation in cats. Transplantation of very low density marrow cells (<1.050 g/ml), termed "1050 cells," at 2 x 10(5) cells/kg leads to rapid hematopoietic recovery (granulocytes >200/microl by day 20+/-2 and platelets >50 x 10(3)/microl by day 21+/-3). Recovery rates are comparable when 1-2 x 10(7) nucleated marrow cells/kg are infused, suggesting that reconstituting cells are enriched 50- to 100-fold in the 1050 cell preparation. To explore if the numbers of reconstituting cells could be expanded ex vivo, 1050 cells were cultured in the presence of 5 ng/ml recombinant human interleukin 1beta, 10 ng/ml recombinant canine (rc)G-CSF, 2 U/ml rHu erythropoietin, and 5 ng/ml rc stem cell factor. Maximum numbers of BFU-E and colony-forming units-granulocyte/macrophage (CFU-GM) were generated at day 6. However, when 10(6) 1050 cells/kg (5x that needed for hematologic recovery) were cultured for six days and all resulting cells infused into irradiated donor animals, two of nine (22%) engrafted. Even when flt3 ligand (100 ng/ml) was added to cultures, only two of five animals (40%) engrafted (p = NS versus studies without flt3 ligand). These data confirm that BFU-E and CFU-GM provide inaccurate estimates of reconstituting cells and demonstrate that the number or function of feline reconstituting cells is impaired by in vitro culture with cytokines.
Abkowitz
J L
JL
Department of Medicine, University of Washington, Seattle 98195-7710, USA.
Taboada
M R
MR
Sabo
K M
KM
Shelton
G H
GH
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology* / Q000187:drug effects; D002415:Cats; D002452:Cell Count; D002478:Cells, Cultured; D002498:Centrifugation; D003114:Colony-Forming Units Assay; D015672:Erythroid Precursor Cells / Q000166:cytology*; D006098:Granulocytes / Q000166:cytology*; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology; D006801:Humans; D008264:Macrophages / Q000166:cytology*; D008565:Membrane Proteins / Q000494:pharmacology
D008565:Membrane Proteins; C084881:flt3 ligand protein