Increase in circulating stem cells following chemotherapy in man

The number of circulating granulocytic stem cells (CFU-C) was determined by the in vitro methylcellulose technique in cancer patients receiving intermittent chemotherapy. In 17 patients studied prior to therapy, the median CFU-C concentration per 2 X 10(5) mononuclear cells plated was six, compared to a posttreatment median of 23 in 21 patients (p less than 0.001). Large numbers of stem cells were obtained by leukopheresis and cryopreserved with a 99.5% median CFU-C recovery. Cyclical changes in the concentration of stem cells with maximum values of 20 times baseline were demonstrated in a patient studied at weekly intervals during multiple courses of treatment. It was estimated that, at peak CFU-C concentrations, a quantity of stem cells equivalent to that present in a bulk bone marrow harvest could be obtained from the peripheral blood by a 17-liter pheresis. These results suggest that it may be practical to obtain an adequate number of stem cells from the peripheral blood to study autologous stem cell infusion as a means of averting myelosuppression in patients receiving intensive chemotherapy.

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Increase in circulating stem cells following chemotherapy in man

Blood ◽

10.1182/blood.v47.6.1031.1031 ◽

1976 ◽

Vol 47 (6) ◽

pp. 1031-1039 ◽

Cited By ~ 291

Author(s):

CM Richman ◽

RS Weiner ◽

RA Yankee

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Stem Cell ◽

Cancer Patients ◽

Peripheral Blood ◽

Mononuclear Cells ◽

Intensive Chemotherapy ◽

Large Numbers ◽

Intermittent Chemotherapy

Abstract The number of circulating granulocytic stem cells (CFU-C) was determined by the in vitro methylcellulose technique in cancer patients receiving intermittent chemotherapy. In 17 patients studied prior to therapy, the median CFU-C concentration per 2 X 10(5) mononuclear cells plated was six, compared to a posttreatment median of 23 in 21 patients (p less than 0.001). Large numbers of stem cells were obtained by leukopheresis and cryopreserved with a 99.5% median CFU-C recovery. Cyclical changes in the concentration of stem cells with maximum values of 20 times baseline were demonstrated in a patient studied at weekly intervals during multiple courses of treatment. It was estimated that, at peak CFU-C concentrations, a quantity of stem cells equivalent to that present in a bulk bone marrow harvest could be obtained from the peripheral blood by a 17-liter pheresis. These results suggest that it may be practical to obtain an adequate number of stem cells from the peripheral blood to study autologous stem cell infusion as a means of averting myelosuppression in patients receiving intensive chemotherapy.

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Abstract 239: Stem Cell Therapy Improves Critical Limb Ischemia

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.32.suppl_1.a239 ◽

2012 ◽

Vol 32 (suppl_1) ◽

Author(s):

Alaa Marzouk

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Stem Cell ◽

Peripheral Blood ◽

Mononuclear Cells ◽

Embryonic Stem ◽

Limb Ischemia ◽

Control Group ◽

Chronic Limb Ischemia

Introduction: The journey from single cell to complex being is attributable to stem cells role. Adult stem cells originate during ontogeny & persist in specialized niches within organs. Asymmetric division of each stem cell during differentiation produces : one daughter stem cell & one daughter transit amplifying/intermediate cell having migratory properties. Forced migration of hematopoietic stem/progenitor cells (HSPC) from bone marrow into peripheral blood is called mobilization. Accumulating evidence suggests that attenuation of the chemokine stromal derived factor-1(SDF-1)-CXCR4 axis that plays a pivotal role in retention of HSPC in bone marrow (BM) results in the release of these cells from the BM into peripheral blood. Recently, adult cells have been genetically reprogrammed to an embryonic stem cell like state. Induced pluripotent stem cells (IPSCs) were similar to human embryonic stem cells in morphology, proliferative capacity, expression of cell surface antigens, & gene expression. Treatment of ischemic vascular disease of lower limbs remains a significant challenge. Unfortunately, if medical & surgical salvage procedures fail, amputation is an unavoidable result for those patients. Aim of Work: (Hypothesis) To assess the application of implantation of autologous stem/progenitor cell in the treatment of chronic limb ischemia & to evaluate the safety, efficacy & feasibility of this novel therapeutic approach. Methods: A total of 24 patients with chronic limb ischemia not eligible for arterial reconstruction or endovascular procedures were enrolled & randomized (1:1) to either the implanted group or the control group. Control group: Conventional medical therapy in the form of anti platelet therapy & vasodilators. Implanted group: Subcutaneous injection of 300μ g/day of recombinant human granulocyte colony stimulating factor (G-CSF) for 5 days to mobilize stem/progenitor cells from BM. Total leucocytic count is measured daily to follow up successful mobilization of bone marrow mononuclear cells (BMMNCs). Stem cell Harvesting After 5 days peripheral blood mononuclear cells (PBMNCs) were harvested using a cell separator. Samples from apheresis products are subjected to TLC measurement & immunophenotypic characterization of CD34+ cells by flow cytometry. The collected PBMNCs were implanted by multiple intramuscular injections into ischemic limbs. Results: There was significant increase in pain free walking distance & ankle/brachial index (ABI) & significant decreased rest pain. Effectiveness was documented by : reduced number of amputation, increase ABI & improvement of the quality of life in therapeutic group compared to control group. Conclusion: The novel therapeutic approach of PBMNCs implantation in patients with chronic limb ischemia is safe, feasible & effective in decreasing co-morbidity & rate of amputation. Safety was manifested by absence of complications during G-CSF therapy or during harvesting & injection of the stem cells. Recommendations: 1- Future studies on larger number of patients & longer follow up. 2- Controlled studies using different methods & different cell population (PBMNCs, BMMNCs or MSCs) to compare the outcome of each. 3-Studing the role of endothelial progenitor cell dysfunction in different ischemic diseases to develop successful gene therapy.

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Abstract 697: Mobilization of Oct-4 + Bone Marrow-Derived Very Small Embryonic-Like Stem Cells in Patients with Acute Myocardial Infarction

Circulation ◽

10.1161/circ.116.suppl_16.ii_130-a ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Wojciech Wojakowski ◽

Magda Kucia ◽

Boguslaw Machalinski ◽

Edyta Paczkowska ◽

Joanna Ciosek ◽

...

Keyword(s):

Myocardial Infarction ◽

Acute Myocardial Infarction ◽

Stem Cells ◽

Bone Marrow ◽

Pluripotent Stem Cells ◽

Peripheral Blood ◽

Mononuclear Cells ◽

Small Cells ◽

Acute Mi

Bone marrow-derived CD34 + CXCR4 + progenitor cells are mobilized into peripheral blood early in acute myocardial infarction (MI). Adult murine bone marrow contains population of small CD34 + lin − CD45 − CXCR4 + cells expressing markers of pluripotent stem cells (PSC) SSEA, Oct-4 and Nanog. This population of very small embryonic-like cells (VSEL) has unique morphology (small size 2– 4 μm, large nucleus, euchromatin) and capability to form embrioid bodies (EB). Murine EB-derived cells can in vitro differentiate into cells from all three germ layers including cardiomyocytes. We hypothesized that in patients with acute MI small cells expressing the VSEL immunophenotype and PSC markers are present in bone marrow and mobilized into peripheral blood. Blood samples (20 mL) from 18 patients with acute MI were obtained after 12 hours, 2 and 5 days after symptoms onset. Bone marrow samples (20 mL) were obtained from 2 patients with acute MI and 3 healthy volunteers. Mononuclear cells were isolated using hypotonic lysis and samples were analyzed by FACS. Mobilization of following cell populations was confirmed: hematopoietic lin − CD45 + CXCR4 + , lin − CD45 + CD133 + , lin − CD45 + CD34 + and non-hematopoietic (VSEL) lin − CD45 − CXCR4 + , lin − CD45 − CD133 + , lin − CD45 − CD34 + . Analysis of the cell number using lymphocyte gate showed more significant increase of CD45 + (hematopoietic) populations of lin − CD34 + , lin − CD133 + and lin − CXCR4 + cells. After gating for small events (VSEL size range) we found more significant mobilization of small, non-hematopoietic populations of lin − CD34 + , lin − CD133 + and lin − CXCR4 + cells (Table ). The expression of PSC markers (Oct-4, Nanog, SSEA-1) in VSEL was confirmed using real-time RT-PCR. Conclusion: We report for the first time that acute MI is associated with mobilization of non-hematopoietic VSELs expressing pluripotent stem cells markers.

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Donor Origin of Multipotent Adult Progenitor Cells in Radiation Chimeras.

Blood ◽

10.1182/blood.v106.11.1395.1395 ◽

2005 ◽

Vol 106 (11) ◽

pp. 1395-1395

Author(s):

Morayma Reyes ◽

Jeffrey S. Chamberlain

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Stem Cell ◽

Progenitor Cells ◽

Y Chromosome ◽

Stromal Cells ◽

Mononuclear Cells ◽

Multipotent Adult Progenitor Cells

Abstract Multipotent Adult Progenitor Cells (MAPC) are bone marrow derived stem cells that can be extensively expanded in vitro and can differentiate in vivo and in vitro into cells of all three germinal layers: ectoderm, mesoderm, endoderm. The origin of MAPC within bone marrow (BM) is unknown. MAPC are believed to be derived from the BM stroma compartment as they are isolated within the adherent cell component. Numerous studies of bone marrow chimeras in human and mouse point to a host origin of bone marrow stromal cells, including mesenchymal stem cells. We report here that following syngeneic bone marrow transplants into lethally irradiated C57Bl/6 mice, MAPC are of donor origin. When MAPC were isolated from BM chimeras (n=12, 4–12 weeks post-syngeneic BM transplant from a transgenic mouse ubiquitously expressing GFP), a mixture of large and small GFP-positive and GFP-negative cells were seen early in culture. While the large cells stained positive for stroma cell markers (smooth muscle actin), mesenchymal stem cell makers (CD73, CD105, CD44) or macrophages (CD45, CD14), the small cells were negative for all these markers and after 30 cell doublings, these cells displayed the classical phenotype of MAPC (CD45−,CD105−, CD44−, CD73−, FLK-1+(vascular endothelial growth factor receptor 2, VEGFR2), Sca-1+,CD13+). In a second experiment, BM obtained one month post BM transplant (n=3) was harvested and mononuclear cells were sorted as GFP-positive and GFP-negative cells and were cultured in MAPC expansion medium. MAPC grew from the GFP-positive fraction. These GFP positive cells displayed the typical MAPC-like immunophenotypes, displayed a normal diploid karyotype and were expanded for more than 50 cell doublings and differentiated into endothelial cells, hepatocytes and neurons. To rule out the possibility that MAPC are the product of cell fusion between a host and a donor cell either in vivo or in our in vitro culture conditions, we performed sex mismatched transplants of female GFP donor BM cells into a male host. BM from 5 chimeras were harvested 4 weeks after transplant and MAPC cultures were established. MAPC colonies were then sorted as GFP-positive and GFP- negative and analyzed for the presence of Y-chromosome by FISH analysis. As expected all GFP-negative (host cells) contained the Y-chromosome whereas all GFP-positive cells (donor cells) were negative for the Y-chromosome by FISH. This proves that MAPC are not derived from an in vitro or in vivo fusion event. In a third study, BM mononuclear cells from mice that had been previously BM-transplanted with syngeneic GFP-positive donors (n=3) were transplanted into a second set of syngeneic recipients (n=9). Two months after the second transplant, BM was harvested and mononuclear cells were cultured in MAPC medium. The secondary recipients also contained GFP-positive MAPC. This is the first demonstration that BM transplantation leads to the transfer of cells that upon isolation in vitro generate MAPCs and, whatever the identity of this cell may be, is eliminated by irradiation. We believe this is an important observation as MAPC hold great clinical potential for stem cell and/or gene therapy and, thus, BM transplant may serve as a way to deliver and reconstitute the MAPC population. In addition, this study provides insight into the nature of MAPC. The capacity to be transplantable within unfractionated BM transplant renders a functional and physiological distinction between MAPC and BM stromal cells. This study validates the use of unfractionated BM transplants to study the nature and possible in vivo role of MAPC in the BM.

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Differential Role for VLA-5 in Mobilization of Heamotopoieic Stem Cells Toward Peripheral Blood and Homing to Bone Marrow and Spleen.

Blood ◽

10.1182/blood.v106.11.2190.2190 ◽

2005 ◽

Vol 106 (11) ◽

pp. 2190-2190 ◽

Cited By ~ 1

Author(s):

Pieter K. Wierenga ◽

Ellen Weersing ◽

Bert Dontje ◽

Gerald de Haan ◽

Ronald P. van Os

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Stem Cell ◽

Progenitor Cells ◽

Peripheral Blood ◽

Hematopoietic Stem ◽

Late Antigen ◽

Cell Mobilization

Abstract Adhesion molecules have been implicated in the interactions of hematopoietic stem and progenitor cells with the bone marrow extracellular matrix and stromal cells. In this study we examined the role of very late antigen-5 (VLA-5) in the process of stem cell mobilization and homing after stem cell transplantation. In normal bone marrow (BM) from CBA/H mice 79±3 % of the cells in the lineage negative fraction express VLA-5. After mobilization with cyclophosphamide/G-CSF, the number of VLA-5 expressing cells in mobilized peripheral blood cells (MPB) decreases to 36±4%. The lineage negative fraction of MPB cells migrating in vitro towards SDF-1α (M-MPB) demonstrated a further decrease to 3±1% of VLA-5 expressing cells. These data are suggestive for a downregulation of VLA-5 on hematopoietic cells during mobilization. Next, MPB cells were labelled with PKH67-GL and transplanted in lethally irradiated recipients. Three hours after transplantation an increase in VLA-5 expressing cells was observed which remained stable until 24 hours post-transplant. When MPB cells were used the percentage PKH-67GL+ Lin− VLA-5+ cells increased from 36% to 88±4%. In the case of M-MPB cells the number increased from 3% to 33±5%. Although the increase might implicate an upregulation of VLA-5, we could not exclude selective homing of VLA-5+ cells as a possible explanation. Moreover, we determined the percentage of VLA-5 expressing cells immediately after transplantation in the peripheral blood of the recipients and were not able to observe any increase in VLA-5+ cells in the first three hours post-tranpslant. Finally, we separated the MPB cells in VLA-5+ and VLA-5− cells and plated these cells out in clonogenic assays for progenitor (CFU-GM) and stem cells (CAFC-day35). It could be demonstared that 98.8±0.5% of the progenitor cells and 99.4±0.7% of the stem cells were present in the VLA-5+ fraction. Hence, VLA-5 is not downregulated during the process of mobilization and the observed increase in VLA-5 expressing cells after transplantation is indeed caused by selective homing of VLA-5+ cells. To shed more light on the role of VLA-5 in the process of homing, BM and MPB cells were treated with an antibody to VLA-5. After VLA-5 blocking of MPB cells an inhibition of 59±7% in the homing of progenitor cells in bone marrow could be found, whereas homing of these subsets in the spleen of the recipients was only inhibited by 11±4%. For BM cells an inhibition of 60±12% in the bone marrow was observed. Homing of BM cells in the spleen was not affected at all after VLA-5 blocking. Based on these data we conclude that mobilization of hematopoietic progenitor/stem cells does not coincide with a downregulation of VLA-5. The observed increase in VLA-5 expressing cells after transplantation is caused by preferential homing of VLA-5+ cells. Homing of progenitor/stem cells to the bone marrow after transplantation apparantly requires adhesion interactions that can be inhibited by blocking VLA-5 expression. Homing to the spleen seems to be independent of VLA-5 expression. These data are indicative for different adhesive pathways in the process of homing to bone marrow or spleen.

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Novel In Vivo Evidence That Not Only Androgens But Also Pituitary Gonadotropins and Prolactin Directly Stimulate Murine Bone Marrow Stem Cells – Implications For Potential Treatment Strategies In Aplastic Anemias

Blood ◽

10.1182/blood.v122.21.2476.2476 ◽

2013 ◽

Vol 122 (21) ◽

pp. 2476-2476

Author(s):

Kasia Mierzejewska ◽

Ewa Suszynska ◽

Sylwia Borkowska ◽

Malwina Suszynska ◽

Maja Maj ◽

...

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Stem Cell ◽

Progenitor Cells ◽

Sex Hormones ◽

Peripheral Blood ◽

Hematopoietic Stem ◽

Clonogenic Potential

Abstract Background Hematopoietic stem/progenitor cells (HSPCs) are exposed in vivo to several growth factors, cytokines, chemokines, and bioactive lipids in bone marrow (BM) in addition to various sex hormones circulating in peripheral blood (PB). It is known that androgen hormones (e.g., danazol) is employed in the clinic to treat aplastic anemia patients. However, the exact mechanism of action of sex hormones secreted by the pituitary gland or gonads is not well understood. Therefore, we performed a complex series of experiments to address the influence of pregnant mare serum gonadotropin (PMSG), luteinizing hormone (LH), follicle-stimulating hormone (FSH), androgen (danazol) and prolactin (PRL) on murine hematopoiesis. In particular, from a mechanistic view we were interested in whether this effect depends on stimulation of BM-residing stem cells or is mediated through the BM microenvironment. Materials and Methods To address this issue, normal 2-month-old C57Bl6 mice were exposed or not to daily injections of PMSG (10 IU/mice/10 days), LH (5 IU/mice/10 days), FSH (5 IU/mice/10 days), danazol (4 mg/kg/10 days) and PRL (1 mg/day/5days). Subsequently, we evaluated changes in the BM number of Sca-1+Lin–CD45– that are precursors of long term repopulating hematopoietic stem cells (LT-HSCs) (Leukemia 2011;25:1278–1285) and bone forming mesenchymal stem cells (Stem Cell & Dev. 2013;22:622-30) and Sca-1+Lin–CD45+ hematopoietic stem/progenitor cells (HSPC) cells by FACS, the number of clonogenic progenitors from all hematopoietic lineages, and changes in peripheral blood (PB) counts. In some of the experiments, mice were exposed to bromodeoxyuridine (BrdU) to evaluate whether sex hormones affect stem cell cycling. By employing RT-PCR, we also evaluated the expression of cell-surface and intracellular receptors for hormones in purified populations of murine BM stem cells. In parallel, we studied whether stimulation by sex hormones activates major signaling pathways (MAPKp42/44 and AKT) in HSPCs and evaluated the effect of sex hormones on the clonogenic potential of murine CFU-Mix, BFU-E, CFU-GM, and CFU-Meg in vitro. We also sublethally irradiated mice and studied whether administration of sex hormones accelerates recovery of peripheral blood parameters. Finally, we determined the influence of sex hormones on the motility of stem cells in direct chemotaxis assays as well as in direct in vivo stem cell mobilization studies. Results We found that 10-day administration of each of the sex hormones evaluated in this study directly stimulated expansion of HSPCs in BM, as measured by an increase in the number of these cells in BM (∼2–3x), and enhanced BrdU incorporation (the percentage of quiescent BrdU+Sca-1+Lin–CD45– cells increased from ∼2% to ∼15–35% and the percentage of BrdU+Sca-1+Lin–CD45+ cells increased from 24% to 43–58%, Figure 1). These increases paralleled an increase in the number of clonogenic progenitors in BM (∼2–3x). We also observed that murine Sca-1+Lin–CD45– and Sca-1+Lin–CD45+ cells express sex hormone receptors and respond by phosphorylation of MAPKp42/44 and AKT in response to exposure to PSMG, LH, FSH, danazol and PRL. We also observed that administration of sex hormones accelerated the recovery of PB cell counts in sublethally irradiated mice and slightly mobilized HSPCs into PB. Finally, in direct in vitro clonogenic experiments on purified murine SKL cells, we observed a stimulatory effect of sex hormones on clonogenic potential in the order: CFU-Mix > BFU-E > CFU-Meg > CFU-GM. Conclusions Our data indicate for the first time that not only danazol but also several pituitary-secreted sex hormones directly stimulate the expansion of stem cells in BM. This effect seems to be direct, as precursors of LT-HSCs and HSPCs express all the receptors for these hormones and respond to stimulation by phosphorylation of intracellular pathways involved in cell proliferation. These hormones also directly stimulated in vitro proliferation of purified HSPCs. In conclusion, our studies support the possibility that not only danazol but also several other upstream pituitary sex hormones could be employed to treat aplastic disorders and irradiation syndromes. Further dose- and time-optimizing mouse studies and studies with human cells are in progress in our laboratories. Disclosures: No relevant conflicts of interest to declare.

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Semicontinuous flow centrifugation for the pheresis of immunocompetent cells and stem cells

Blood ◽

10.1182/blood.v49.3.391.bloodjournal493391 ◽

1977 ◽

Vol 49 (3) ◽

pp. 391-397 ◽

Cited By ~ 1

Author(s):

RS Weiner ◽

CM Richman ◽

RA Yankee

Keyword(s):

Bone Marrow ◽

Peripheral Blood ◽

Mononuclear Cells ◽

Human Peripheral Blood ◽

Buffy Coat ◽

Immunocompetent Cells ◽

Antitumor Therapy ◽

Volume Analysis ◽

Large Numbers

Mononuclear cells from human peripheral blood were purified by semicontinuous flow centrifugation (SCFC) using the Haemonetics model 30 blood cell separator; 64% +/- 7% of the mononuclear cells in 600 ml of peripheral blood were collected in a 30-ml volume. Analysis of sequential 5-ml aliquots of the mononuclear cell concentrate revealed that both immunocompetent cells and granulocytic progenitor cells (CFU- C) were proportional to the cell count throughout the buffy coat. In vitro pheresis of large volumes of human bone marrow resulted in recovery of 63% of the cells, 12% of the hemoglobin, and 84% of the CFU- C in 20% of the original volume. Further centrifugation eliminated 80% of the platelets without loss of cells or CFU-C. SCFC of peripheral blood or bone marrow selectively concentrated mononuclear cells and reduced the contamination by granulocytes and erythrocytes. Large numbers of mononuclear cells can thus be collected for studies in vitro or for cryopreservation and the autologous reconstitution of immunosuppressed or myelosuppressed patients undergoing intensive antitumor therapy.

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The Sooner the Better: Rapid Transduction Enhances the Engraftment/Selection of Gene Corrected Fanconi Anemia HSC.

Blood ◽

10.1182/blood.v110.11.194.194 ◽

2007 ◽

Vol 110 (11) ◽

pp. 194-194 ◽

Cited By ~ 1

Author(s):

Lars U.W. Muller ◽

Michael Milsom ◽

Chad E. Harris ◽

Jeff Bailey ◽

David A. Williams

Keyword(s):

Stem Cells ◽

Gene Therapy ◽

Bone Marrow ◽

Stem Cell ◽

Reporter Gene ◽

Fanconi Anemia ◽

Peripheral Blood ◽

Bone Marrow Cells

Abstract Fanconi anemia (FA) is amenable to genetic correction of hematopoietic stem cells (HSCs). However, as demonstrated in previous clinical gene therapy trials, successful extension of murine studies into human therapies is limited by low numbers of target HSC and poor engraftment of transduced FA HSC (Kelly et al., Mol Ther, 2007). To examine the potential biological consequences/benefits of shortened transduction we used a FA mouse model in which HSC are deficient and prone to excessive loss during in vitro manipulation. We applied a rapid transduction protocol (Mostoslavsky et al., Mol Ther, 2005) utilizing lentiviral vectors and demonstrate that this shortened transduction preserves engraftment of FA HSC to the level of C57BL/6 wt cells. Lin− Sca-1+ c-Kit+ bone marrow cells were isolated from Fanca−/− CD45.2 mice and underwent 4-hr rapid (RT) vs. 96-hr conventional (CT) transduction. An equivalent number of transduced cells were transplanted into lethally irradiated CD45.1 BoyJ mice. Analysis of engraftment chimerism three months post transplantation revealed a significantly higher level of engraftment in animals receiving RT vs. CT cells (90% +/− 14% vs. 26% +/− 31%, respectively, p=<0.01). Rapid transduction also resulted in a significant reduction of engraftment failure (0/36 animals RT vs. 20/36 animals CT). Importantly--emphasizing the FA disease-specific stem cell phenotype, RT vs. CT of C57BL/6 wt cells was associated with no significant difference in engraftment of these cells (93% +/− 1.2% RT vs. 84 +/− 19% CT, p=0.33). Analysis of peripheral blood cells expressing the proviral enhanced green fluorescent protein (eGFP) reporter gene revealed a normal distribution of B-lymphocytes (B220), T-lymphocytes (CD3 epsilon), and granulocytes (MAC-1), indicating multi-lineage engraftment of gene modified cells. In spite of this engraftment advantage, transduction efficiency was low (<30%) using RT. The 6-benzylguanine (6-BG) resistant P140K mutant of O6-methylguanine DNA methyltransferase (MGMTP140K) confers a selective advantage to tranduced HSC treated with alkylating drugs. Following RT with a MGMTP140K/ eGFP expressing lentivirus, 5/6 mice treated with 6-BG and the alkylating drug temozolomide showed a significant rise in the percentage of GFP reporter gene expression in peripheral blood. We extended this approach to the FA model by generating a tri-cistronic lentiviral vector expressing the FANCA cDNA, MGMTP140K, and eGFP. Despite modest in vivo gene marking with this vector, up to 37-fold selection (85% GFP-positive cells) was achieved following exposure of bone marrow of transplant recipients to 6-BG and the alkylating drug temozolomide in vitro. Concurrently, phenotypic correction of mitomycin C hypersensitivity of transduced Fanca−/− bone marrow cells was observed. These data suggest that RT improves stem cell engrafting capacity of FA stem cells in a relevant animal model of stem cell gene therapy. The combination of RT and in vivo selection may allow more successful reconstitution of the lympho-hematopoietic system in gene therapy applications.

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Homing and Engraftment of Mobilized Hematopoietic Stem Cells: Involvement of VLA-5.

Blood ◽

10.1182/blood.v104.11.4943.4943 ◽

2004 ◽

Vol 104 (11) ◽

pp. 4943-4943

Author(s):

Pieter K. Wierenga ◽

Gerald de Haan ◽

Bert Dontje ◽

Ellen Weersing ◽

Ronald van Os

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Stem Cell ◽

Progenitor Cells ◽

Peripheral Blood ◽

Hematopoietic Stem ◽

Post Transplant ◽

Hematopoietic Reconstitution

Abstract VLA-5 has been implicated in the adhesive interactions of stem and progenitor cells with the bone marrow extracellular matrix and stromal cells and is therefore considered to play an important role in the hematopoietic reconstitution after stem cell transplantation. In normal bone marrow (BM) from CBA/H mice 79±3% of the cells in the lineage negative fraction express VLA-5. After mobilization with cyclophosphamide/G-GSF, the number of VLA-5 expressing cells in mobilized peripheral blood cells (MPB) decreases to 38±3%. Despite this low frequency of VLA-5+ cells, however, even when equal numbers of progenitor cells are transplanted MPB cells provide a much faster hematopoietic recovery compared to BM cells. To shed more light on the role of VLA-5 in the process of homing and engraftment, we investigated whether differences in homing potential of the stem cell subsets might be responsible for this enhanced reconstitution. At 3 hours post-transplant, however, no differences in homing efficiency of progenitor and stem cells from MPB and BM grafts in both bone marrow and spleen could be detected. It should be realized that MPB and BM grafts demonstrate different ratios of stem/progenitor cells which might be another explanation for the observed differences in repopulation potential. Furthermore, MPB cells migrating in vitro towards SDF-1α showed potent reconstitution while VLA-5 expression was reduced on these cells. In fact, in vitro treatment with SDF-1α showed further decrease in VLA-5 expressing cells (from 38% to 4%) in the lin- fraction. When equal numbers of MPB were transplanted with and without SDF-1α pretreatment, no difference in hematopoietic reconstitution was observed suggesting a minor role of VLA-5 in homing and engraftment. On the other hand, after VLA-5 blocking an inhibition of 59±7% in the homing of MPB progenitor cells in the bone marrow could be found, whereas homing in the spleen of the the recipients is only inhibited by 11±4%. To elucidate whether the observed enhanced reconstitution could be explained by a selective homing of VLA-5+ cells or a rapid upregulation of VLA-5 expression, cells were labelled with PKH67-GL and transplanted in lethally irradiated recipients. It could be demonstrated that at 3 hours post-transplant cells from MPB grafts showed a rapid increase from 38±3% up to 66±9% of VLA-5+ cells in the bone marrow of the recipient. In the spleen no significant increase in VLA-5+ cells was observed. When MPB cells were transplanted after pretreatment with SDF-1α an increase from 2±1% up to 33±5% of VLA-5+ cells in the bone marrow was detected. When calculating the number of cells recovered from bone marrow, a selective homing of VLA-5+ cells cannot be excluded. Therefore, we also assessed the number of VLA-5+ cells in the PKH+ fraction in peripheral blood from the recipient immediately (½-1 hour) after transplantation but found no increase during that time period. So far it can be concluded that MPB cells show low number of VLA-5+ cells but these cells possess an enhanced hematopoietic reconstitution potential. Homing of progenitor cells to the spleen seems to be less dependent on VLA-5 expression than homing to the bone marrow. A rapid upregulation of VLA-5 expression on engrafting MPB cells early after transplantation does not occur and hence our data are suggestive for the preferential homing of VLA-5+ cells in the bone marrow after transplantation.

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Semicontinuous flow centrifugation for the pheresis of immunocompetent cells and stem cells

Blood ◽

10.1182/blood.v49.3.391.391 ◽

1977 ◽

Vol 49 (3) ◽

pp. 391-397 ◽

Cited By ~ 48

Author(s):

RS Weiner ◽

CM Richman ◽

RA Yankee

Keyword(s):

Bone Marrow ◽

Peripheral Blood ◽

Mononuclear Cells ◽

Human Peripheral Blood ◽

Buffy Coat ◽

Immunocompetent Cells ◽

Antitumor Therapy ◽

Volume Analysis ◽

Large Numbers

Abstract Mononuclear cells from human peripheral blood were purified by semicontinuous flow centrifugation (SCFC) using the Haemonetics model 30 blood cell separator; 64% +/- 7% of the mononuclear cells in 600 ml of peripheral blood were collected in a 30-ml volume. Analysis of sequential 5-ml aliquots of the mononuclear cell concentrate revealed that both immunocompetent cells and granulocytic progenitor cells (CFU- C) were proportional to the cell count throughout the buffy coat. In vitro pheresis of large volumes of human bone marrow resulted in recovery of 63% of the cells, 12% of the hemoglobin, and 84% of the CFU- C in 20% of the original volume. Further centrifugation eliminated 80% of the platelets without loss of cells or CFU-C. SCFC of peripheral blood or bone marrow selectively concentrated mononuclear cells and reduced the contamination by granulocytes and erythrocytes. Large numbers of mononuclear cells can thus be collected for studies in vitro or for cryopreservation and the autologous reconstitution of immunosuppressed or myelosuppressed patients undergoing intensive antitumor therapy.

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