Olsalazine inhibits cell proliferation and DNA methylation in canine lymphoid tumor cell lines.

Abnormal DNA methylation is involved in the initiation and progression of lymphoid tumors. Hence, DNA demethylating agents are promising candidate drugs for chemotherapy against these tumors. The salicylic acid derived anti-inflammatory agent, olsalazine, reportedly suppresses DNA methyltransferase in human cells and has the potential to be clinically applied as a DNA demethylating agent. In this study, we investigated the effects of olsalazine on cell proliferation and DNA methylation using canine lymphoid tumor cell lines (CLBL-1, GL-1, and UL-1). Treatment with olsalazine led to significant cell growth inhibition and increased the apoptotic rate in all three cell lines. Treatment with olsalazine reduced the total amount of 5-methylcytosine in genomic DNA, as assessed by enzyme-linked immunosorbent assay. Genome-wide analysis of DNA methylation revealed that 1,801 to 5,626 CpG sites showed decreased DNA methylation levels in three cell lines, including the promoter regions of ADAM23, FES, and CREB3L1 genes. The outcomes of the present study demonstrate that a DNA demethylating agent olsalazine, inhibits cell proliferation and DNA methylation in canine lymphoid tumor cells, suggesting that it can be a candidate drug for the treatment of lymphoid tumors in dogs.

Dynamic changes in DNA methylation patterns in canine lymphoma cell lines demonstrated by genome-wide quantitative DNA methylation analysis.

DNA methylation is the conversion of cytosine to 5-methylcytosine, leading to changes in the interactions between DNA and proteins. Methylation of cytosine-guanine (CpG) islands (CGIs) is associated with gene expression silencing of the involved promoter. Although studies focussing on global changes or a few single loci in DNA methylation have been performed in dogs with certain diseases, genome-wide analysis of DNA methylation is required to prospectively identify specific regions with DNA methylation change. The hypothesis of this study was that next-generation sequencing with methylation-specific signatures created by sequential digestion of genomic DNA with SmaI and XmaI enzymes can provide quantitative information on methylation levels. Using blood from healthy dogs and cells obtained from canine lymphoma cell lines, approximately 100,000CpG sites across the dog genome were analysed with the novel method established in this study. CpG sites in CGIs broadly were shown to be either methylated or unmethylated in normal blood, while CpG sites not within CpG islands (NCGIs) were largely methylated. Thousands of CpG sites in lymphoma cell lines were found to gain methylation at normally unmethylated CGI sites and lose methylation at normally methylated NCGI sites. These hypermethylated CpG sites are located at promoter regions of hundreds of genes, such as TWIST2 and TLX3. In addition, genes annotated with 'Homeobox' and 'DNA-binding' characteristics have hypermethylated CpG sites in their promoter CGIs. Genome-wide quantitative DNA methylation analysis is a sensitive method that is likely to be suitable for studies of DNA methylation changes in cancer, as well as other common diseases in dogs.

Decreased immunoglobulin A concentrations in feces, duodenum, and peripheral blood mononuclear cells of dogs with inflammatory bowel disease.

BACKGROUND: Although immunoglobulin A (IgA) plays a key role in regulating gut homeostasis, its role in canine inflammatory bowel disease (IBD) is unknown. HYPOTHESIS: IgA expression may be altered in dogs with IBD, unlike that observed in healthy dogs and dogs with other gastrointestinal diseases. ANIMALS: Thirty-seven dogs with IBD, 10 dogs with intestinal lymphoma, and 20 healthy dogs. METHODS: Prospective study. IgA and IgG concentrations in serum, feces, and duodenal samples were measured by ELISA. IgA(+) cells in duodenal lamina propria and IgA(+) CD21(+) peripheral blood mononuclear cells (PBMCs) were examined by immunohistochemistry and flow cytometry, respectively. Duodenal expression of the IgA-inducing cytokine transforming growth factor ß (TGF-ß), B cell activating factor (BAFF), and a proliferation-inducing ligand (APRIL) was quantified by real-time RT-PCR. RESULTS: Compared to healthy dogs, dogs with IBD had significantly decreased concentrations of IgA in fecal and duodenal samples. The number of IgA(+) CD21(+) PBMCs and IgA(+) cells in duodenal lamina propria was significantly lower in dogs with IBD than in healthy dogs or dogs with intestinal lymphoma. Duodenal BAFF and APRIL mRNA expression was significantly higher in IBD dogs than in the healthy controls. Duodenal TGF-ß mRNA expression was significantly lower in dogs with IBD than in healthy dogs and dogs with intestinal lymphoma. CONCLUSIONS AND CLINICAL IMPORTANCE: IBD dogs have decreased IgA concentrations in feces and duodenum and fewer IgA(+) PBMCs, which might contribute to development of chronic enteritis in dogs with IBD.

Ultrasonographic evaluation of vincristine-induced gastric hypomotility and the prokinetic effect of mosapride in dogs.

BACKGROUND: Vincristine induces gastrointestinal motility disorders in humans. Adverse gastrointestinal events are commonly observed in dogs receiving vincristine. OBJECTIVES: To evaluate gastric motility after vincristine administration in dogs and the prophylactic effect of a prokinetic agent, mosapride. ANIMALS: Five healthy Beagle dogs. METHODS: Five dogs received vincristine i.v. at a dosage of 0.75 mg/m(2). The motility index (MI) of the antral contraction was ultrasonographically evaluated 30 minutes postfeeding before administration of vincristine and for 6 days after vincristine treatment. After a 6-week washout period, the dogs received vincristine with mosapride (2 mg/kg p.o., q24h for 6 days), and the MI was re-evaluated. Adverse gastrointestinal events were evaluated according to the Veterinary Co-operative Group Common Terminology Criteria for Adverse Events (VCOG-CTCAE). RESULTS: After vincristine administration, a significant decrease (P < .05) in MI was observed on days 3 (6.64 ± 0.30) and 4 (8.02 ± 0.94), compared with pretreatment levels (10.00 ± 0.62). Gastrointestinal adverse events were observed in 4 dogs (grade 2 decreased appetite: 3 dogs; grade 1 vomiting: 2 dogs; and grade 1 diarrhea and grade 2 hematochezia: 1 dog). When mosapride citrate was administered with vincristine and for the next 5 days, no decrease in MI was observed. Furthermore, adverse gastrointestinal events occurred less frequently (grade 1 vomiting and grade 2 hematochezia in 1 dog each). CONCLUSIONS AND CLINICAL IMPORTANCE: Vincristine (0.75 mg/m(2)) induces gastric hypomotility in dogs. Preventive administration of mosapride citrate (2.0 mg/kg p.o., q24h) improves hypomotility and may decrease the adverse gastrointestinal effects of vincristine.

Treatment of post-transplanted, relapsed patients with hematological malignancies by infusion of HLA-matched, allogeneic-dendritic cells (DCs) pulsed with irradiated tumor cells and primed T cells.

Patients with hematological malignancies who relapse after bone marrow transplantation (BMT) are often treated with donor lymphocyte infusion. However, this procedure often results in graft-versus-host disease (GVHD). While, Dendritic cells (DCs), which present antigens to naive T cells, have been used in the immunotherapy of cancer, this approach has been logistically difficult due to limiting numbers of DCs. We have now developed a method for obtaining a large number of DCs by treating the granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood stem cells (PBSCs) from healthy donors with granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-4 (IL-4), and tumor necrosis factor-alpha (TNF-alpha). The resulting cells possess the morphologic, phenotypic, and functional characteristics of mature DCs. In in vitro studies, culture of these HLA-matched donor derived-DCs with irradiated each patient's tumor cells as an antigen source, followed by incubation with T cells from the patient, induced the production of highly cytotoxic T lymphocytes (CTLs) specific for the respective tumor cells in the semi-allogeneic setting. A transient, but objective clinical response was obtained in the absence of GVHD when we injected the DCs which had been pulsed with irradiated tumor cells as well as primed T cells from the same original donor of related- allogeneic stem cell transplantation into the relapsed patients. Our findings suggest that treatment of relapsed patients with such donor-derived DCs, and primed T cells may be effective as an adjunctive immunotherapy.

Transplantation of a fetus with paternal Thy-1(+)CD34(+)cells for chronic granulomatous disease.

A fetus diagnosed with X-linked chronic granulomatous disease was transplanted with Thy-1(+)CD34(+) cells of paternal origin. The transplant was performed at 14 weeks gestation by ultrasound guided injection into the peritoneal cavity. The fetus was delivered at 38 weeks gestation after an otherwise uneventful pregnancy. Umbilical cord blood was collected and used to determine the level of peripheral blood chimerism as well as levels of functional engrafted cells. Flow cytometry was used to detect donor leukocytes identified as HLA-A2(-)B7(+) cells, whereas recipient cells were identified as HLA-A2(+)B7(-) cells. No evidence of donor cell engraftment above a level of 0.01% was found. PCR was used to detect HLA-DRB1*15(+) donor cells among the recipient's HLA-DRB1*15(-) cells, but no engraftment was seen with a sensitivity of 1:1000. The presence of functional, donor-derived neutrophils was assessed by flow cytometry using two different fluorescent dyes that measure reactive oxygen species generated by the phagocyte NADPH oxidase. No evidence of paternal-derived functional neutrophils above a level of 0.15% was observed. Peripheral blood and bone marrow samples were collected at 6 months of age. Neither sample showed engraftment by HLA typing using both flow cytometry and PCR. Functional phagocytes were also not observed. Furthermore, no indication of immunological tolerance specific for the donor cells was indicated by a mixed lymphocyte reaction assay performed at 6 months of age. While there appears to be no engraftment of the donor stem cells, the transplant caused no harm to the fetus and the child was healthy at 6 months of age. Analyses of fetal tissues, obtained from elective abortions, revealed that CD3(+) T cells and CD56(+)CD3(-) NK cells are present in the liver at 8 weeks gestation and in the blood by 9 weeks gestation. The presence of these lymphocytes may contribute to the lack of donor cell engraftment in the human fetus.

Direct isolation of human central nervous system stem cells.

Stem cells, which are clonogenic cells with self-renewal and multilineage differentiation properties, have the potential to replace or repair damaged tissue. We have directly isolated clonogenic human central nervous system stem cells (hCNS-SC) from fresh human fetal brain tissue, using antibodies to cell surface markers and fluorescence-activated cell sorting. These hCNS-SC are phenotypically 5F3 (CD133)(+), 5E12(+), CD34(-), CD45(-), and CD24(-/lo). Single CD133(+) CD34(-) CD45(-) sorted cells initiated neurosphere cultures, and the progeny of clonogenic cells could differentiate into both neurons and glial cells. Single cells from neurosphere cultures initiated from CD133(+) CD34(-) CD45(-) cells were again replated as single cells and were able to reestablish neurosphere cultures, demonstrating the self-renewal potential of this highly enriched population. Upon transplantation into brains of immunodeficient neonatal mice, the sorted/expanded hCNS-SC showed potent engraftment, proliferation, migration, and neural differentiation.

Regulation of angiogenesis in human hepatomas: possible involvement of p53-inducible inhibitor of vascular endothelial cell proliferation.

Mechanisms regulating angiogenesis in human hepatomas were analyzed. Huh7 hepatoma cells transplanted into athymic mice formed highly vascularized reddish tumors with abundant microvessels, while angiogenesis by PLC/PRF/5 hepatoma cells was less remarkable. However, the production of angiogenesis stimulators such as VEGF and IL6 by Huh7 cells was much less than by PLC/PRF/5 cells. In addition, the production of angiogenesis inhibitor TSP-1 by Huh7 cells was greater than by PLC/PRF/5 cells. Therefore, the difference in angiogenesis between these two hepatomas was not explained by the production of these known angiogenesis regulators. On the other hand, PLC/PRF/5 cells but not Huh7 cells secreted an inhibitor of the proliferation of vascular endothelial cells, which was enhanced by p53-gene transfer. These results suggest that the production of this p53-inducible angiogenesis inhibitor is responsible, at least partly, for the regulation of angiogenesis in human hepatomas.

[Adult T-cell leukemia with elevated serum hyaluronic acid levels paralleling disease activity].

We report on two adult T-cell leukemia (ATL) patients whose levels of serum hyaluronic acid (HA) moved in parallel with the clinical activity of their disease. A 66-year-old man was admitted to our hospital because of unconsciousness and hypotension. Acute type ATL complicated by hypercalcemia and myelofibrosis was diagnosed. Before therapy, the level of patient's serum HA was 2,045 to 4,010 ng/ml (normal range: 50 >). After he achieved complete remission (CR) through chemotherapy, his serum HA was 36 ng/ml. Several months later, however, his ATL relapsed, and his serum HA increased to 393 ng/ml. The other patient was an 80-year-old man who had been admitted on the suspected diagnosis of ATL. Before chemotherapy, his serum HA was high (3,420 ng/ml). After CHOP therapy, he entered CR and his HA decreased to 122 ng/ml. He remains in CR with slightly elevated levels of HA (127 to 212 ng/ml), and is being followed up on an out-patient basis.

[Allogeneic peripheral blood stem cell transplantation in 30 patients with hematologic disorders].

Thirty patients (median age of 32 years; range, 6-61) with hematologic disorders received unmanipulated peripheral blood stem cell transplants from HLA-matched or one-antigen-mismatched related donors following myeloablative therapy for acute lymphoblastic leukemia (7), acute myelogenous leukemia (6), chronic myelogenous leukemia (8), myelodysplastic syndrome (3), or other disorders (6). Granulocyte colony stimulating factor (G-CSF) mobilized peripheral blood stem cells were collected from donors in 1 to 3 aphereses. The apheresis products contained mean counts of 11.3 x 10(8) (range, 3.8-17.2) nucleated cells/kg and 6.7 x 10(6) (range, 1.3-16.7) CD34+ cells/kg. Graft-versus-host-disease (GVHD) prophylaxis consisted of cyclosporin A plus methotrexate, or FK506 plus methotrexate. All patients received G-CSF following their transplant. Although 1 patient died of pneumonia 6 days after transplantation, the others demonstrated rapid engraftment. Median days to recovery to 500/microliter neutrophils and 20,000/microliter platelets were 13 (range, 8-21) and 14 (range, 1-23) days, respectively. The incidence of acute GVHD grade II-IV was 33%; chronic GVHD developed in 57% of the assessable patients. There were no episodes of graft failure or rejection. Nineteen patients (63%) were alive and in complete remission from 147 to 839 days following their transplant (median follow-up of 560 days). Further follow-up study will be required to assess the incidence of chronic GVHD and graft-versus-leukemia (GVL) effects.

Suppression of hepatoma growth and angiogenesis by a fumagillin derivative TNP470: possible involvement of nitric oxide synthase.

TNP470, a derivative of fumagillin, suppressed in vivo growth of human PLC/PRF/5 hepatoma and ameliorated cachexia of hepatoma-bearing mice. These in vivo effects were associated with reductions in microvessel and macrophage counts. In in vitro experiments, TNP470 inhibited the growth and migration of human hepatoma and bovine vascular endothelial (VE) cells. TNP470 did not inhibit the production of VE growth factor by the hepatoma, which suggests that this compound acts directly on VE cells in vivo. In contrast, TNP470 inhibited the production of leukemia inhibitory factor, which may be related to the amelioration of cancer cachexia. TNP470 induced apoptosis and enhanced the expression of beta-galactosidase, a biomarker of senescence, which was partly mimicked by a nitric oxide (NO) donor S-nitroso-N-acetyl penicillamin. TNP470 inhibited myristoylation and membrane translocation of NO synthase and increased the cellular content of NO synthase and production of NO. Therefore, it is suggested that the actions of TNP470 are mediated, at least in part, through the inhibition of membrane translocation of biologically active proteins.

2-Methoxyestradiol, an endogenous metabolite of estrogen, enhances apoptosis and beta-galactosidase expression in vascular endothelial cells.

2-Methoxyestradiol (2ME) is an endogenous metabolite of estradiol (E2) and is known to inhibit tumor angiogenesis. In the present study, the direct effects of 2ME on the vascular endothelial cells were examined. 2ME enhanced apoptosis and beta-galactosidase expression in bovine vascular endothelial cells. A nitric oxide (NO) donor S-nitroso-N-acetyl penicillamin (SNAP) also enhanced beta-galactosidase expression, suggesting a possible role of NO in mediating the action of 2ME. 2ME increased the cellular content of nitric oxide synthase (NOS) and the production of NO. In addition, 2ME altered the membrane localization pattern of NOS. These suggest that the effects of 2ME on apoptosis and senescence of vascular endothelial cells were mediated, at least partly, by NOS and NO.

Collection, tumor contamination, and engraftment kinetics of highly purified hematopoietic progenitor cells to support high dose therapy in multiple myeloma.

Unfractionated peripheral blood stem cell (PBSC) grafts contain measurable quantities of myeloma cells and are therefore a potential source of relapse posttransplantation. In contrast, fluorescence-activated cell sorting (FACS)-sorted CD34+ Thy1+ Lin- peripheral blood cells are substantially enriched for stem cell activity, yet contain virtually no clonal myeloma cells. A study was performed in patients with symptomatic myeloma, who had received 12 months or less of preceding standard chemotherapy, to evaluate the feasibility of large scale purification of primitive hematopoietic stem cells in order to study engraftment kinetics posttransplantation and the degree of tumor cell contamination of this cell population, based on polymerase chain reaction (PCR) analysis for the patient-specific complementarity-determining region III (CDR III). PBSC were mobilized with high dose cyclophosphamide and granulocyte-macrophage colony-stimulating factor (GM-CSF). A combination of elutriation and chemical lysis was used to deplete PBSC collections of monocytes, granulocytes, erythrocytes, and platelets. Subsequently, CD34+ Thy1+ Lin- progenitor cells were purified with high speed cell sorting. Of the 10 evaluable patients, nine met the required minimum criteria of >/=7.2 x 10(5) cells/kg to support tandem transplants. After high dose melphalan (200 mg/m2) eight engrafted successfully, although granulocyte (absolute neutrophil count [ANC] >0.5 x 10(9)/L, 16 days) and platelet recovery (platelets > 50 x 10(9)/L, 39 days) was substantially delayed when compared with unmanipulated PBSC grafts; one patient required infusion of a reserve graft because of lack of evidence of engraftment by day +28. Three patients proceeded to a second graft with high dose melphalan and total body irradiation; two required infusion of a reserve graft and both died of infectious complications; one showed delayed, but complete, engraftment after this myeloablative regimen. Two of the nine evaluable patients attained a clinical complete remission (CR). The grafts from three patients were tested for tumor contamination and contained no detectable clonal myeloma cells. Larger quantities of purified cells may be required to resolve the problem of delayed engraftment.

Cystothiazoles A and B, new bithiazole-type antibiotics from the myxobacterium Cystobacter fuscus.

New bithiazole-type antibiotics, cystothiazoles A (C20H26N2O4S2) and B (C20H26N2O5S2), have been isolated from a culture broth of the myxobacterium, Cystobacter fuscus. The gross structures of these compounds were elucidated by spectroscopic analysis, and their absolute stereochemistry was determined by chemical degradation of cystothiazole A. Cystothiazole A inhibits fungi and human tumor cells, whereas it is inactive against bacteria. The antifungal activity appears to result from the inhibition of submitochondrial NADH oxidation. Although these compounds are structurally related to the known antibiotic myxothiazol, cystothiazole A was more active against fungi and less cytotoxic than myxothiazol.

High doses of purified stem cells cause early hematopoietic recovery in syngeneic and allogeneic hosts.

In humans, autologous transplants derived from bone marrow (BM) usually engraft more slowly than transplants derived from mobilized peripheral blood. Allogeneic BM transplants show a further delay in engraftment and have an apparent requirement for donor T cells to facilitate engraftment. In mice, Thy-1.1(lo)Lin-/loSca-1+ hematopoietic stem cells (HSCs) are the principal population in BM which is responsible for engraftment in syngeneic hosts at radioprotective doses, and higher doses of HSCs can radioprotect an allogeneic host in the absence of donor T cells. Using the mouse as a preclinical model, we wished to test to what extent engraftment kinetics was a function of HSC content, and whether at high doses of c-Kit+Thy-1.1(lo)Lin-/loSca-1+ (KTLS) cells rapid allogeneic engraftment could also be achieved. Here we demonstrate that engraftment kinetics varied greatly over the range of KTLS doses tested (100-10,000 cells), with the most rapid engraftment being obtained with a dose of 5,000 or more syngeneic cells. Mobilized splenic KTLS cells and the rhodamine 123(lo) subset of KTLS cells were also able to engraft rapidly. Higher doses of allogeneic cells were needed to produce equivalent engraftment kinetics. This suggests that in mice even fully allogeneic barriers can be traversed with high doses of HSCs, and that in humans it may be possible to obtain rapid engraftment in an allogeneic context with clinically achievable doses of purified HSCs.

Hydroxyurea can be used to increase mouse c-kit+Thy-1. 1(lo)Lin-/loSca-1(+) hematopoietic cell number and frequency in cell cycle in vivo.

The DNA synthesis inhibitor hydroxyurea (HU) was administered to determine whether it induces changes in the cell-cycle status of primitive hematopoietic stem cells (HSCs)/progenitors. Administration of HU to mice leads to bone marrow accumulation of c-kit+Thy-1.1(lo)Lin-/loSca-1(+) (KTLS) cells in S/G2/M phases of the cell cycle. HU is a relatively nontoxic, reversible cell-cycle agent that can lead to approximately a threefold expansion of KTLS cells in vivo and approximately an eightfold increase in the number of KTLS cells in S/G2/M. HSCs in HU-treated mice have undiminished multilineage long-term and short-term clonal reconstitution activity.

The characterization, molecular cloning, and expression of a novel hematopoietic cell antigen from CD34+ human bone marrow cells.

The adhesion molecule BEN/SC1/DM-GRASP (BEN) is a marker in the developing chicken nervous system that is also expressed on the surface of embryonic and adult hematopoietic cells such as immature thymocytes, myeloid progenitors, and erythroid progenitors. F84.1 and KG-CAM, two monoclonal antibodies to rat neuronal glycoproteins with similarity to BEN, cross-react with an antigen on rat hematopoietic progenitors, but F84.1 only also recognizes human blood cell progenitors. We have defined the antigen recognized by F84.1 as the hematopoietic cell antigen (HCA). HCA expression was detected on 40% to 70% of CD34+ fetal and adult bone marrow cells and mobilized peripheral blood cells. Precursor cell activity for long-term in vitro bone marrow cell culture was confined to the subset of CD34+ cells that coexpress HCA. HCA is expressed by the most primitive subsets of CD34+ cells, including all rhodamine 123(lo), Thy-1+, and CD38(-/lo) CD34+ adult bone marrow cells. HCA was also detected on myeloid progenitors but not on early B-cell progenitors. We also describe here the cloning and characterization of cDNAs encoding two variants of the human HCA antigen (huHCA-1 and huHCA-2) and of a cDNA clone encoding rat HCA (raHCA). The deduced amino acid sequences of huHCA and raHCA are homologous to that of chicken BEN. Recombinant proteins produced from either human or rat HCA cDNAs were recognized by F84.1, whereas rat HCA but not human HCA was recognized by antirat KG-CAM. Expression of either form of huHCA in CHO cells conferred homophilic adhesion that could be competed with soluble recombinant huHCA-Fc. The molecular cloning of HCA and the availability of recombinant HCA should permit further evaluation of its role in human and rodent hematopoiesis.

The unexpected G0/G1 cell cycle status of mobilized hematopoietic stem cells from peripheral blood.

Treatment with a combination of cytokines and chemotherapy can effectively stimulate the release of hematopoietic stem cells (HSC) into the peripheral blood (PB), which can then be harvested for transplantation. The cell cycle status of the harvested HSC from mobilized PB (MPB) is of interest because of the impact that cell cycling may have on optimizing the conditions for ex vivo expansion, retrovirus-mediated gene transfer, and the engraftment of transplanted tissues. Therefore, we characterized the cell cycling status of mobilized HSC from mice and humans. The murine HSC, which express the phenotype c-kit+ Thy-1.1lo Lin-/lo Sca-1+, were purified from PB, bone marrow (BM), and spleen after the mice were treated with the mobilizing regimen of granulocyte colony-stimulating factor (G-CSF) or a combination of cyclophosphamide (CTX) and G-CSF. Human HSC (CD34+ Thy-1+ Lin-) and progenitor cells (CD34+ Thy-1-Lin-) were isolated from the BM of untreated healthy volunteers and from MPB of healthy volunteers and patients treated with G-CSF or a combination of CTX and GM-CSF. Cell cycle status was determined by quantitating the amount of DNA in the purified cells after staining with the dye Hoechst 33342. Fluorescence-activated cell sorting analysis of the progenitor cells from the murine and human samples showed an unexpected finding, ie, virtually none of the cells from the MPB was cycling. The G0/G1 status of HSC from MPB was surprising, because a significant proportion of HSC from BM are actively proliferating and, after mobilization, the HSC in the spleen and BM were also actively cycling.