Effects of cell cycle activation on the short-term engraftment properties of ex vivo expanded murine hematopoietic cells.
Loss of long-term hematopoietic stem cell function in vitro is associated with cell cycle progression. To determine whether cytokine-induced proliferation also limits the rate of short-term engraftment and potential clinical utility of ex vivo expanded hematopoietic cells, murine Sca-1(+)c-kit(+)Lin(-) cells were cultured in interleukin-6 (IL-6), IL-11, granulocyte colony-stimulating factor (G-CSF), stem cell factor, flk-2 ligand, and thrombopoietin for 7 days. Cells amplified 2000-fold were then stained with Hoechst 33342, separated into G(0)/G(1) (72% +/- 3%) or S/G(2)/M (27% +/- 3%) fractions by flow sorting, and injected into lethally irradiated mice. Although long-term (more than 6 months) engraftment of lymphoid and myeloid lineages was greater in primary and secondary recipients of expanded cells residing in G(0)/G(1) at the time of transplantation, there were no noted differences in the short-term (less than 6 weeks) recovery kinetics of circulating blood cells. When hematopoietic cells were expanded in cultures containing the tetrapeptide stem cell inhibitor N-Acetyl-Ser-Asp-Lys-Pro (AcSDKP) to reduce progenitor cycling prior to transplantation, again there were no differences observed in short-term reconstitution by inhibited or uninhibited cells. Interestingly, AcSDKP significantly accelerated engraftment by expanded hematopoietic cells when administered in vivo at the time of transplantation. Leukocytes recovered to 20% of normal levels approximately 1 week faster, and thrombocytopenia was largely abrogated in AcSDKP-treated versus untreated mice. Therefore, while AcSDKP can accelerate the engraftment of ex vivo expanded hematopoietic progenitors, which suggests a relatively simple approach to improve their clinical utility, its effects appear unrelated to cell cycle arrest. (Blood. 2000;95:2829-2837)
Szilvassy
S J
SJ
Blood and Marrow Transplant Program, the Division of Hematology/Oncology, Lucille P. Markey Cancer Center, University of Kentucky, Lexington, KY 40536-0093, USA. szilvas@pop.uky.edu
Meyerrose
T E
TE
Grimes
B
B
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D018929:Cell Culture Techniques / Q000379:methods; D002453:Cell Cycle / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D006133:Growth Substances / Q000494:pharmacology; D019650:Hematopoietic Stem Cell Mobilization; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000145:classification / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains
D006133:Growth Substances