Impaired bone marrow homing of cytokine-activated CD34+ cells in the NOD/SCID model

Abstract

The reduced engraftment potential of hematopoietic stem/progenitor cells (HSPCs) after exposure to cytokines may be related to the impaired homing ability of actively cycling cells. We tested this hypothesis by quantifying the short-term homing of human adult CD34 ؉ cells in nonobese diabetic/severe combined immunodeficient (NOD/SCID) animals. We show that the loss of engraftment ability of cytokine-activated CD34 ؉ cells is associated with a reduction in homing of colony-forming cells (CFCs) to bone marrow (BM) at 24 hours after transplantation (from median 2.8% [range, 1.9%-6.1%] to 0.3% [0.0%-0.7%]; n ‫؍‬ 3; P < .01), coincident with an increase in CFC accumulation in the lungs (P < .01). Impaired BM homing of cytokine-activated cells was not restored by using sorted cells in G 0 G 1 or by inducing cell cycle arrest at the G 1 /S border. Blocking Fas ligation in vivo did not increase the BM homing of cultured cells. Finally, we tested cytokine combinations or culture conditions previously reported to restore the engraftment of cultured cells but did not find that any of these was able to reverse the changes in homing behavior of cytokine-exposed cells. We suggest that these changes in homing and, as a consequence, engraftment result from the increased migratory capacity of infused activated cells, leading to the loss of selectivity of the homing process.

Measles virus envelope pseudotyped lentiviral vectors transduce quiescent human HSCs at an efficiency without precedent

“…63,64 Therefore, it might be crucial to not overexpose the hCD34 1 HSCs to cytokines, which are currently required for high-level transduction with VSV-G-LVs. 13,14 Indeed, recent clinical trials [1][2][3][4] still use strong cytokine cocktails, although this can affect the integrity of the HSC pool. [65][66][67] Importantly, compared with hCD34 1 cells in G 0 , cells in G 1 or SG 2 M phases of the cell cycle demonstrated diminished engraftment.…”

“…Thus, the less the cells are prestimulated, the more they keep their stem cell characteristics. 13,14,37,38,41 Therefore, we performed LV transductions of hCD34 1 cells by using different cytokine prestimulation conditions ( Figure 1B). Remarkably, stimulation with TPO or SCF was sufficient to transduce hCD34 1 cells up to 75% (TPO) and 90% (SCF) using H/F-LVs, whereas VSV-G-LVs reached maximum transduction levels of 10% at an MOI of 10.…”

“…12 However, intense exposure of HSCs to cytokines affects their homing and trafficking ability and might promote differentiation rather than expansion of the HSC pool. 13,14 It was also shown that exit from dormancy provokes DNA damage-induced attrition in HSCs. 15 High hCD34 1 -cell transduction was achieved only by combining high VSV-G-LV doses with strong cytokine stimulation that increased the risk for multicopy integration.…”

Animal models of acute myelogenous leukaemia – development, application and future perspectives

“…While these models have certainly been fundamental to our current understanding of leukemogenesis, they may not be sufficient for the further development necessary in the evolution of more optimal AML models. [449][450][451][452][453] Following the sequencing of the Brown Norwegian rat genome, it should be possible to exploit what we have learned from the mouse and relate it to this more physiologically, pharmacologically, toxicologically and pathologically significant animal. Recent breakthroughs in controlling egg activation 454 have in addition paved the way for the development of genetically manipulated rats.…”

A new xenograft model of myeloma bone disease demonstrating the efficacy of human mesenchymal stem cells expressing osteoprotegerin by lentiviral gene transfer

“…24 Briefly, MSCs were labelled with 8 mM PKH-26, injected at 2 Â 10 6 per animal by tail vein administration, and murine tissues analysed 24 h later for the presence of PKH-24-positive cells by FACS analysis of single-cell suspensions. At least 100 000 events were collected on the Epics-Elite flow cytometer (Beckman-Coulter, High Wycombe, UK).…”