Fibroblasts retrovirally transfected with the human IL-3 gene initiate and sustain multilineage human hematopoiesis in SCID mice: comparison of CD34-enriched vs CD34-enriched and in vitro expanded grafts.
Peripheral blood progenitor cells (PBPCs) obtained from cytapheresis products (CPs) of tumor patients undergoing mobilizing chemotherapy for PBPC support and dose-intensified anticancer chemotherapy initiate multilineage human hematopoiesis after intraperitoneal (i.p.) transplantation into young severe combined immunodeficient (SCID) mice. The engraftment process was significantly accelerated by subcutaneous cotransplants of a rat fibroblast cell line stably transfected with a retroviral vector carrying the human interleukin-3 (hIL-3) gene and producing sustained in vivo levels of circulating human IL-3 over a prolonged period of time. These cotransplants were found to provide a suitable microenvironment for i.p. transplanted CD34-positive cells separated from PBPC preparations using immunomagnetic beads. Flow cytometry analysis and immunocytology revealed that selected PB CD34- cells, more than 90% pure, were capable of initiating and sustaining a productive multilineage hematopoiesis preferentially within the hIL-3-secreting cotransplants followed by release of mature human cells into the circulation, spleen and thymus. The percentages of human cells found in hIL-3 cotransplants 8 weeks post-transplantation (p.t.) were generally higher than those measured after transplantation of complete CP mononuclear cells containing comparable doses of CD34-positive cells. When selected PB CD34+ cells that were expanded ex vivo with combinations of human hematopoietic growth factors including the c-kit ligand (KL), interleukin (IL)-1 beta, IL-3, IL-6, erythropoietin (EPO) and granulocyte-macrophage colony-stimulating factor (GM-CSF) for 14 days were grafted to cotransplant-carrying SCID mice, a considerable loss of their proliferative potential was observed regardless of the HGF combination used. When experiments with grafts of selected PBPC were compared to those performed with selected/expanded PBPC on a per CD34+ cell basis the results revealed that over a dose range of 0.3 to 1.0 x 10(6) cells/graft the in vivo proliferative capacity of expanded cells was reduced by a factor of 2 to 3.
Goan
S R
SR
Department of Internal Medicine III, University of Ulm, Germany.
Schwarz
K
K
von Harsdorf
S
S
von Schilling
C
C
Fichtner
I
I
Junghahn
I
I
Just
U
U
Herrmann
F
F
D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis*; D002455:Cell Division; D002460:Cell Line; D005347:Fibroblasts / Q000378:metabolism; D006410:Hematopoiesis; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D007377:Interleukin-3 / Q000235:genetics*; D051379:Mice; D016513:Mice, SCID; D051381:Rats; D014162:Transfection; D014183:Transplantation, Heterologous
D018952:Antigens, CD34; D007377:Interleukin-3