Use of 5-fluorouracil to analyze the effect of macrophage inflammatory protein-1 alpha on long-term reconstituting stem cells in vivo

Abstract

A macrophage-derived inhibitor of early hematopoietic progenitors (colony-forming unit-spleen, CFU-A) called stem cell inhibitor was found to be identical to macrophage inflammatory protein-1 alpha (MIP-1 alpha). We investigated the effect of MIP-1 alpha on the earliest stem cells that sustain long-term hematopoiesis in vivo in a competitive bone marrow repopulation assay. Because long-term reconstituting (LTR) stem cells are normally quiescent, an in vivo model was first developed in which they are triggered to cycle. A first 5-fluorouracil (5-FU) injection was used to eliminate later progenitors, causing the LTR stem cells, which are normally resistant to 5-FU, to enter the cell cycle and become sensitive to a second 5-FU injection administered 5 days later. Human MIP-1 alpha administered from day 0 to 7 was unable to prevent the depletion of the LTR stem cells by the second 5-FU treatment, as observed on day 7 in this model, suggesting that the LTR stem cells were not prevented from being triggered into cycle despite the MIP-1 alpha treatment. However, the MIP-1 alpha protocol used here did substantially decrease the number of more mature hematopoietic progenitors (granulocyte-macrophage colony-forming cells [CFC], burst- forming unit-erythroid, CFCmulti, and preCFCmulti) recovered in the bone marrow shortly after a single 5-FU injection. In vitro, MIP-1 alpha had no inhibitory effect on the ability of these progenitors to form colonies. This study confirms the in vivo inhibitory effect of MIP- 1 alpha on subpopulations of hematopoietic progenitors that are activated in myelodepressed animals. However, MIP-1 alpha had no effect on the long-term reconstituting stem cells in vivo under conditions in which it effectively reduced all later progenitors.

The Tetrapeptide Acetyl-N-Ser-Asp-Lys-Pro (Goralatide) Protects From Doxorubicin-Induced Toxicity: Improvement in Mice Survival and Protection of Bone Marrow Stem Cells and Progenitors

“…37 Conversely, the chemokine MIP-1␣, a potent inhibitor of hematopoietic stem cell proliferation, which does not protect stem cells more primitive than CFU-S and MIP-1␣, given twice daily for 7 days, did not prevent the 10-fold LTRC depletion induced by 5FU in mice. 38 Thus, whereas the protection reported for MIP-1␣, 38,39 TGF-␤, 35 TNF-␣, 40 and pEEDCK 37,41 appears to be restricted to certain hematopoietic compartments, such a preservation of various hematopoietic cell compartments, including LTRCs, in correlation with a…”

Macrophage inflammatory protein 1 alpha, interleukin 3 and diffusible marrow stromal factors maintain human hematopoietic stem cells for at least eight weeks in vitro.

“…underlie the decreased recovery of LTBMC-IC from TGF-/5 plus IL-3-supplernented cultures, whereas this mechanism may not be operative in cultures supplemented with MIPlot + IL-3. Recent in vivo studies have demonstrated that M1P-1r may not maintain the mouse long-term repopulating stem cell, which is more primitive than the CFU-S and CFU-A progenitor, in a quiescent state when triggered into cycle by 5-fluorouracil treatment (24). These studies, together with data presented here indicating that addition of known proliferation inhibitory factors such as TGF-/3 results in significantly decreased recovery of LTBMC-IC from stroma-noncontact cultures, indicate that MIP-lo~ + IL-3 may not inhibit the proliferation of LTBMC-IC.…”

Chemokines

“…232,233 The non-ELR CXC chemokines, and GM-CSF), as well as CFU-GEMM and burst-forming including PF4, IP-10, and MIG are not only inactive chemounit erythroid (BFU-E) (colonies that require SCF and erythattractants and nonangiogenic themselves, but they inhibit ropoietin). 88,116,243,[246][247][248] This effect is a direct one on the the angiogenic effects of ELR chemokines and basic progenitor cells because the suppression is more complete FGF. 40,232,235 Although these data appear to assign angiogenic on CD34 / -selected cells.…”

“…236 These disparate reagents. 246,[249][250][251] Furthermore, analysis of these in vivo experisults may be related to differences in experimental systems.…”