Granulocyte colony-stimulating factor mobilized peripheral blood stem cells enter into G(1) of the cell cycle and express higher levels of amphotropic retrovirus receptor mRNA

We compared the cell cycle status and expression of mRNA for the amphotropi c retroviral receptor in hematopoietic stem cells isolated from bone marrow and cytokine mobilized peripheral blood, CD34(+) cells from six normal vol unteers were enriched by immune selection from steady-state bone marrow and granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood ( 10 mu g/kg/day for 5 days), Cell cycle status of the phenotypically primiti ve CD34(+)CD38(-) hematopoietic stem cell population was analyzed using a f our-color flow cytometry technique that distinguished the G(0), G(1), and S /G(2)/M phases of the cell cycle, Semiquantitative reverse transcriptase-po lymerase chain reaction was performed to measure mRNA expression of the amp hotropic retroviral receptor. Peripheral blood hematopoietic stem cells had 2.6-fold more cells in the G(1) phase of the cell cycle compared to steady -state bone marrow. Furthermore, lineage(-)CD34(+)CD38(-) cells from G-CSF mobilized peripheral blood had a fourfold higher level of amphotropic retro virus receptor mRNA. In conclusion, we found that CD34(+)CD38(-) hematopoie tic stem cells isolated from G-CSF mobilized peripheral blood differ from t hose isolated from steady-state bone marrow in that a significant proportio n have entered the G(1) phase of the cell cycle and express higher levels o f amphotropic receptor mRNA. These biologic properties are consistent with the reported rapid recovery of hematopoietic function following transplanta tion with peripheral blood hematopoietic stem cells and make these cells a preferred target for retroviral-based gene transfer. (C) 1999 International Society for Experimental Hematology. Published by Elsevier Science Inc.