Chemotherapy prior to autologous bone marrow transplantation impairs long-term engraftment in mice

Objective. Autologous bone marrow transplantation in cancer patients is often preceded by multiple cycles of chemotherapy. In this study, we assessed in a mouse model whether stem cells were affected by prior chemotherapy. Methods. Donor mice were treated with three consecutive injections of 150 mg/kg 5-fluorouracil (5-FU). Peripheral blood counts were allowed to recover before the subsequent dose of 5-FU was given. Mice recovered from three doses of 5-FU and showed normal steady-state hematopoiesis. Bone marrow cells from these mice were mixed with congenic competitor cells and transplanted into lethally irradiated recipients. Results. Although in vivo homing of cells from these mice was not impaired, donor leukocyte contribution steadily decreased posttransplantation. In contrast to in vivo homing, both in vitro migration toward stromal-derived factor (SDF)-1 and the average CXC chemokine receptor-4 (CXCR4) expression were lower in 5-FU-treated cells. Moderate reductions in L-selectin and CD11a expression were observed on stem cells of 5-FU-treated mice. CD43, CD44, CD49d, and CD49e were normally expressed and could thus not explain the reduced engraftment of these cells. Conclusion. We therefore conclude that 5-FU either directly damages stem cells or that the replicative stress induced by 5-FU causes a decline in stem cell reconstitution potential resulting in lower chimerism levels posttransplantation, that declines in time. (C) 2003 International Society for Experimental Hematology. Published by Elsevier Inc

Correction:Quantitative distribution of patient-derived leukemia clones in murine xenografts revealed by cellular barcodes

An amendment to this paper has been published and can be accessed via a link at the top of the paper.</p

Expression quantitative trait loci are highly sensitive to cellular differentiation state

Blood cell development from multipotent hematopoietic stem cells to specialized blood cells is accompanied by drastic changes in gene expression for which the triggers remain mostly unknown. Genetical genomics is an approach linking natural genetic variation to gene expression variation, thereby allowing the identification of genomic loci containing gene expression modulators (eQTLs). In this paper, we used a genetical genomics approach to analyze gene expression across four developmentally close blood cell types collected from a large number of genetically different but related mouse strains. We found that, while a significant number of eQTLs (365) had a consistent “static” regulatory effect on gene expression, an even larger number were found to be very sensitive to cell stage. As many as 1,283 eQTLs exhibited a “dynamic” behavior across cell types. By looking more closely at these dynamic eQTLs, we show that the sensitivity of eQTLs to cell stage is largely associated with gene expression changes in target genes. These results stress the importance of studying gene expression variation in well-defined cell populations. Only such studies will be able to reveal the important differences in gene regulation between different ce

Hepatocyte-specific glucose-6-phosphatase deficiency disturbs platelet aggregation and decreases blood monocytes upon fasting-induced hypoglycemia

International audienceObjective: Glycogen storage disease type 1a (GSD Ia) is a rare inherited metabolic disorder caused by mutations in the glucose-6-phosphatase (G6PC1) gene. When untreated, GSD Ia leads to severe fasting-induced hypoglycemia. Although current intensive dietary management aims to prevent hypoglycemia, patients still experience hypoglycemic events. Poor glycemic control in GSD Ia is associated with hypertriglyceridemia, hepatocellular adenoma and carcinoma, and also with an increased bleeding tendency of unknown origin.Methods: To evaluate the effect of glycemic control on leukocyte levels and coagulation in GSD Ia, we employed hepatocyte-specific G6pc1 deficient (L-G6pc-/-) mice under fed or fasted conditions, to match good or poor glycemic control in GSD Ia, respectively.Results: We found that fasting-induced hypoglycemia in L-G6pc-/- mice decreased blood leukocytes, specifically pro-inflammatory Ly6Chi monocytes, compared to controls. Refeeding reversed this decrease. The decrease in Ly6Chi monocytes was accompanied by an increase in plasma corticosterone levels and was prevented by the glucocorticoid receptor antagonist mifepristone. Further, fasting-induced hypoglycemia in L-G6pc-/- mice prolonged bleeding time in the tail vein bleeding assay, with reversal by refeeding. This could not be explained by changes in coagulation factors V, VII, or VIII, or von Willebrand factor. While the prothrombin and activated partial thromboplastin time, as well as total platelet counts were not affected by fasting-induced hypoglycemia in L-G6pc-/- mice, ADP-induced platelet aggregation was disturbed.Conclusions: These studies reveal a relationship between fasting-induced hypoglycemia, decreased blood monocytes, and disturbed platelet aggregation in L-G6pc-/- mice. While disturbed platelet aggregation likely accounts for the bleeding phenotype in GSD Ia, elevated plasma corticosterone decreases levels of pro-inflammatory monocytes. These studies highlight the necessity of maintaining good glycemic control in GSD Ia

Efficient mobilization of haematopoietic progenitors after a single injection of pegylated recombinant human granulocyte colony-stimulating factor in mouse strains with distinct marrow-cell pool sizes

We have compared the efficacy of a single injection of SD/01, a newly engineered, pegylated form of recombinant human granulocyte colony stimulating factor (rhG-CSF), with a single injection of glycosylated rhG-CSF (Filgrastim). SD/01 was administered to regular and recombinant inbred strains of mice (AKR, C557L/J, DBA/2, C57BL/6, AKXL) known to have widely distinct marrow-cell pool sizes and proliferation kinetics. A single injection of G-CSF was unable to mobilize granulocyte-macrophage colony-forming units (CFU-GM). In sharp contrast, a single dose of SD/01 resulted in massive mobilization of progenitors and stem cells. Although all mice strains showed qualitatively similar mobilization responses, large interstrain differences remained. C57L and C57BL/6 mice mobilized relatively poorly, whereas AKR and DBA/2, mice showed threefold to tenfold superior responses, In order to explain these different phenotypes, we studied the effects of SD/01 in nine AKXL recombinant inbred strains, derived from well-responding AKR and poorly responding C57L parental strains. The best predictor for SD/01 responsiveness in these strains was marrow cellularity prior to mobilization. Comparison of the AKXL strain distribution pattern for marrow cellularity with loci previously mapped in these strains showed complete concordance with Ant, a serine protease inhibitor mapping to chromosome 12

HEMATOPOIETIC STEM CELLS FROM TRANSLESION SYNTHESIS DEFICIENT MICE ARE REDUCED IN NUMBER AND HAVE DIMINISHED REPOPULATING ABILITY

Toxicogenetic

Mobilized peripheral blood stem cells provide rapid reconstitution but impaired long-term engraftment in a mouse model

In this study, we use competitive repopulation to compare the quality and frequency of stem cells isolated from mobilized blood with stem cells isolated from bone marrow (BM) in a mouse model. Lin(-)Sca-1(+)c-Kit(+) (LSK) cells were harvested from control BM and peripheral blood of mice following granulocyte colony-stimulating factor (GCSF) administration. LSK cells were used because of their resemblance to human CD34(+) cells. We confirmed that transplantation of phenotypically defined mobilized peripheral blood (MPB) stem cells results in rapid recovery of blood counts. However, in vitro results indicated that LSK cells purified from MPB had lower cobblestone area-forming cell day 35 activity compared to BM. Additionally, evaluation of chimerism after co-transplantation of LSK cells purified from blood and BM revealed that MPB stem cells contained 25-fold less repopulation potential compared to BM stem cells. Competitive repopulating unit frequency analysis showed that freshly isolated MPB LSK cells have 8.8-fold fewer cells with long-term repopulating ability compared to BM LSK cells. Secondary transplantation showed no further decline in contribution of hematopoiesis relative to BM. We conclude that the reduced frequency of stem cells within the LSK population of MPB, rather than poorer quality, causes the reduced repopulation potential