Improved hematopoietic stem cell engraftment following ex vivo expansion of murine marrow cells with SCF and Flt3L

• Published in: Cytotherapy (Oxford, England) England), 2007, Vol.9 (6), p.532-538
• Main Authors: Diehl, A, Stoelting, S, Nadrowitz, R, Wagner, T, Peters, S.O., MD
• Format: Article
• Language: English
• Subjects: Advanced Basic Science; Animals; Bone Marrow Cells - cytology; Bone Marrow Cells - drug effects; Bone Marrow Transplantation; Cell Count; Cell Proliferation - drug effects; Cells, Cultured; Colony-Forming Units Assay; cytokines; engraftment; Hematopoietic Stem Cell Transplantation - methods; Interleukins - pharmacology; Male; Membrane Proteins - pharmacology; Mice; Mice, Inbred C57BL; Models, Biological; Other; stem cell expansion; Stem Cell Factor - pharmacology; Time Factors; Whole-Body Irradiation
• ISSN: 1465-3249; 1477-2566
• DOI: 10.1080/14653240701452073

Background In vitro incubation of murine BM cells with IL-3, IL-6, IL-11 and SCF induces expansion of HPC but fails to preserve ‘engraftability’ in comparison with normal untreated marrow cells. We studied how culturing marrow cells for 48 and 72 h with a combination of the cytokines SCF and Flt3L influences cell expansion and engraftability. Methods Competitive repopulation of lethally irradiated C57BL/6 mice was used to examine engraftability of ex vivo cytokine-expanded Ptprc chimeric BM. A methylcellulose in vitro assay was used to determine the expansion of substitute progenitors. Results Both cytokine combinations successfully expanded progenitor populations when assayed in methylcellulose culture in vitro . After 72 h, the colony numbers of the expansion cultures increased 61% with IL-3, IL-6, IL-11 and SCF stimulation and 96% with SCF and Flt3L stimulation. Engraftment of competitively transplanted cells, cultured with IL-3, IL-6, IL-11 and SCF, consistently dropped to levels below 16%. However, 48 h culture with SCF and Flt3L resulted in 53.5 ± 1.6% engraftment at 17 days and 64 ± 3.7% engraftment at 19 weeks post-transplantation. Extending the cytokine exposure to 72 h resulted in 70 ± 4.4% short-term engraftment at 17 days, and 64 ± 2.4% engraftment at 19 weeks post-transplantation. Discussion The data demonstrate the ability of SCF and Flt3L cytokine-stimulated BM cells to maintain short- and long-term engraftability. We conclude that these cytokines play a crucial role in maintaining engraftment of hematopoietic progenitors.