scholarly journals A Large-Scale Bank of Organ Donor Bone Marrow and Matched Mesenchymal Stem Cells for Promoting Immunomodulation and Transplant Tolerance

2021 ◽  
Vol 12 ◽  
Author(s):  
Brian H. Johnstone ◽  
Franka Messner ◽  
Gerald Brandacher ◽  
Erik J. Woods
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Living Donor ◽  
Progenitor Cell ◽  
Large Scale ◽  
Organ Donor ◽  
Mixed Chimerism ◽  
Solid Organ ◽  
Transplant Tolerance ◽  
Hematopoietic Stem

Induction of immune tolerance for solid organ and vascular composite allografts is the Holy Grail for transplantation medicine. This would obviate the need for life-long immunosuppression which is associated with serious adverse outcomes, such as infections, cancers, and renal failure. Currently the most promising means of tolerance induction is through establishing a mixed chimeric state by transplantation of donor hematopoietic stem cells; however, with the exception of living donor renal transplantation, the mixed chimerism approach has not achieved durable immune tolerance on a large scale in preclinical or clinical trials with other solid organs or vascular composite allotransplants (VCA). Ossium Health has established a bank of cryopreserved bone marrow (BM), termed “hematopoietic progenitor cell (HPC), Marrow,” recovered from deceased organ donor vertebral bodies. This new source for hematopoietic cell transplant will be a valuable resource for treating hematological malignancies as well as for inducing transplant tolerance. In addition, we have discovered and developed a large source of mesenchymal stem (stromal) cells (MSC) tightly associated with the vertebral body bone fragment byproduct of the HPC, Marrow recovery process. Thus, these vertebral bone adherent MSC (vBA-MSC) are matched to the banked BM obtained from each donor, as opposed to third-party MSC, which enhances safety and potentially efficacy. Isolation and characterization of vBA-MSC from over 30 donors has demonstrated that the cells are no different than traditional BM-MSC; however, their abundance is >1,000-fold higher than obtainable from living donor BM aspirates. Based on our own unpublished data as well as reports published by others, MSC facilitate chimerism, especially at limiting hematopoietic stem and progenitor cell (HSPC) numbers and increase safety by controlling and/or preventing graft-vs.-host-disease (GvHD). Thus, vBA-MSC have the potential to facilitate mixed chimerism, promote complementary peripheral immunomodulatory functions and increase safety of BM infusions. Both HPC, Marrow and vBA-MSC have potential use in current VCA and solid organ transplant (SOT) tolerance clinical protocols that are amenable to “delayed tolerance.” Current trials with HPC, Marrow are planned with subsequent phases to include vBA-MSC for tolerance of both VCA and SOT.

scholarly journals Myelosuppressive conditioning is required to achieve engraftment of pluripotent stem cells contained in moderate doses of syngeneic bone marrow

Blood ◽  
1994 ◽  
Vol 83 (4) ◽  
pp. 939-948 ◽  
Author(s):  
Y Tomita ◽  
DH Sachs ◽  
M Sykes
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Whole Body ◽  
Mixed Chimerism ◽  
Hematopoietic Stem ◽  
Donor Cells ◽  
Donor Type ◽  
Low Levels

Abstract We have investigated the requirement for whole body irradiation (WBI) to achieve engraftment of syngeneic pluripotent hematopoietic stem cells (HSCs). Recipient B6 (H-2b; Ly-5.2) mice received various doses of WBI (0 to 3.0 Gy) and were reconstituted with 1.5 x 10(7) T-cell-depleted (TCD) bone marrow cells (BMCs) from congenic Ly-5.1 donors. Using anti-Ly-5.1 and anti-Ly-5.2 monoclonal antibodies and flow cytometry, the origins of lymphoid and myeloid cells reconstituting the animals were observed over time. Chimerism was at least initially detectable in all groups. However, between 1.5 and 3 Gy WBI was the minimum irradiation dose required to permit induction of long-term (at least 30 weeks), multilineage mixed chimerism in 100% of recipient mice. In these mice, stable reconstitution with approximately 70% to 90% donor-type lymphocytes, granulocytes, and monocytes was observed, suggesting that pluripotent HSC engraftment was achieved. About 50% of animals conditioned with 1.5 Gy WBI showed evidence for donor pluripotent HSC engraftment. Although low levels of chimerism were detected in untreated and 0.5-Gy-irradiated recipients in the early post-BM transplantation (BMT) period, donor cells disappeared completely by 12 to 20 weeks post-BMT. BM colony assays and adoptive transfers into secondary lethally irradiated recipients confirmed the absence of donor progenitors and HSCs, respectively, in the marrow of animals originally conditioned with only 0.5 Gy WBI. These results suggest that syngeneic pluripotent HSCs cannot readily engraft unless host HSCs sustain a significant level of injury, as is induced by 1.5 to 3.0 Gy WBI. We also attempted to determine the duration of the permissive period for syngeneic marrow engraftment in animals conditioned with 3 Gy WBI. Stable multilineage chimerism was uniformly established in 3-Gy-irradiated Ly-5.2 mice only when Ly-5.1 BMC were injected within 7 days of irradiation, suggesting that repair of damaged host stem cells or loss of factors stimulating engraftment may prevent syngeneic marrow engraftment after day 7.

Durable Engraftment of Purified Allogeneic Hematopoietic Stem Cells Following Non-Myeloablative Conditioning.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2204-2204
Author(s):  
Mary-Elizabeth A. Muchmore ◽  
Matthew J. Burge ◽  
Judith A. Shizuru
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Low Dose ◽  
Conditioning Regimen ◽  
Mixed Chimerism ◽  
Host Immune System ◽  
Solid Organ ◽  
Myeloablative Conditioning ◽  
Hematopoietic Stem ◽  
Hsc Transplantation

Abstract Transplantation of purified allogeneic hematopoietic stem cells (HSC) has the potential to be a curative treatment for autoimmune diseases. Before it becomes a viable therapy, however, the treatment-related mortality and difficulty of achieving engraftment must be addressed. Our research has focused on developing non-myeloablative regimens that lead to donor-derived engraftment of purified HSC in a murine model. Total lymphoid irradiation (TLI) consists of low-dose fractionated irradiation targeted to the thymus, abdomen, and peripheral nodes, while the skull, lungs, and long bones remain shielded. The non-myeloablative conditioning regimen of TLI and anti-thymocyte globulin (ATG) was followed by HSC transplantation. HSCs were isolated by the composite phenotype of Thy1.1+, c-kit+, Sca-1+, and lineage- (KTLS) or, in strains lacking the Thy1.1 marker, c-kit+, Sca-1+, and lineage- (KSL). We tested HSC transplantations across three major histocompatiblity complex (MHC)-matched strain combinations known through previous studies in our group to have significantly different barriers to engraftment. In all three strain combinations we observed stable mixed chimerism (approximately 50% donor-derived cells) when high doses of HSC (10,000/mouse) were administered. Chimerism was measured at thirty-day intervals, and initially sharply increased and then stabilized around day ninety post-transplantation. In prior studies from our laboratory in a spontaneously arising autoimmune diabetes model, we demonstrated that mixed allogeneic chimerism alone following low dose total body irradiation (TBI) and HSC transplantation was sufficient to block the autoimmune pathogenesis. In order to establish a second clinically relevant conditioning regimen, we attempted here to lower the dose of TBI by using cyclophosphamide and ATG in addition to low dose TBI. However, less robust engraftment was observed as compared to the TLI/ATG approach. To study how TLI/ATG allows engraftment, we have examined the marrow of TLI/ATG conditioned, untransplanted animals. Though TUNEL and Caspase-3 assays did not show a significant increase in apoptosis compared to controls, a 71% decrease in the quantitative number of HSCs isolated from these animals was observed. This depletion of HSCs in the marrow could provide a niche for donor HSCs to inhabit. Further histologic studies on lymphoid organs exposed to radiation through TLI, including the thymus and spleen, are ongoing and may further elucidate the mechanisms by which TLI reconditions the host immune system. The durable mixed chimerism observed following TLI/ATG conditioning and HCT will be applied to mice affected with the rodent form of multiple sclerosis (experimental autoimmune encephalomyelitis) and to tolerance induction of solid-organ grafts. SUMMARY: The combination of TLI/ATG non-myeloablative conditioning and transplantation of allogeneic HSC leads to a durable mixed chimeric state between donor and host and will next be applied to the induction of tolerance to autoantigens and alloantigens.

Non-Random Lentiviral Vector Insertions in Bone Marrow Progenitors from Fanconi Anemia Patients

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2358-2358
Author(s):  
Ali Nowrouzi ◽  
Africa Gonzales-Murillo ◽  
Anna Paruzynski ◽  
Ariana Jacome ◽  
Paula Rio ◽  
...  
Keyword(s):  
Stem Cells ◽  
Gene Therapy ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Fanconi Anemia ◽  
Large Scale ◽  
Random Distribution ◽  
Ex Vivo ◽  
Hematopoietic Stem ◽  
In Cis

Abstract Improved protocols using lentiviral vectors have been established with minimal cytokine exposure and short transduction times proving more suitable for overcoming the disease-specific challenge in correcting functionally defective hematopoietic stem cells (HSCs) of Fanconi Anemia (FA) patients. Bone marrow (BM) cells from FA patients were transduced ex vivo with lentiviral vectors (LVs) expressing FANCA and/or EGFP using optimized conditions to preserve the repopulating properties of the primitive hematopoietic stem cells (manuscript submitted). In a forward preclinical screening of possible LV-induced side effects we analyzed the insertional inventory in colonies generated by FA BM cells previously transduced with the LVs. We have established and optimized DNA and RNA isolation procedures for minimal cell numbers, suitable for large scale screening of colony forming cell (CFC) derived colonies by linear amplification-mediated PCR (LAM-PCR) and massive parallel pyrosequencing (454 GS Flx system; Roche). This approach is applicable for detecting early indicators of clonal selection, and is based on the analysis of common integration sites (CIS) and non-random distribution of vector insertions in particular genomic loci. From a total of 180 CFC-derived colonies expressing the EGFP LV marker gene, 298 vector insertions could be sequenced and mapped to the human genome. The analysis of vector targeted gene coding regions showed a non-random genomic distribution of LV insertions, with a significant overrepresentation of RefSeq genes that are part of distinct functional categories. Accordingly vector associated genes are predominantly involved in cellular signal cascades regulated by the MAP Kinase family known to be involved in a wide variety of cellular processes such as proliferation, differentiation, transcription regulation and development. Apart from the observed high integration frequency in genes (>80%), partial loss of vector LTR nucleotides was detected in >10% of the integrants (3–25bp). Notably, >20% of the lentiviral insertions were found to be located in CIS of predominantly 2nd order. Further screening assays of LV transduced CFC-derived colonies will allow a deeper investigation in the functional consequences of such CIS targeting in gene therapy protocols of FA. However our results suggest that the LV transduction of FA BM progenitors leads to a relatively high frequency of insertions in CIS which may be indicative of an insertion based (specific) selection mechanism. We herby show that the ex vivo large scale integration site analyses of CFC-derived colonies from patients considered to undergo gene therapeutic treatments constitutes a robust approach, which combined with mouse preclinical biosafety studies will help to improve the safety of clinical gene therapy protocols. The non-random distribution of LV integrations in CIS associated genes and in genes involved in particular cellular pathways may be indicative for the altered biochemical pathways characteristic of FA stem cells, with reported defects in DNA repair and self-renewal.

scholarly journals The human CD34 hematopoietic stem cell antigen promoter and a 3' enhancer direct hematopoietic expression in tissue culture

Blood ◽  
1992 ◽  
Vol 80 (12) ◽  
pp. 3051-3059 ◽  
Author(s):  
TC Burn ◽  
AB Satterthwaite ◽  
DG Tenen
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Tissue Culture ◽  
Stem Cell ◽  
Transcription Factors ◽  
Progenitor Cell ◽  
Hematopoietic Stem ◽  
Culture Cells ◽  
Human Cd34 ◽  
Tissue Culture Cells

Abstract The human CD34 hematopoietic stem cell antigen is a highly glycosylated type 1 membrane protein of unknown function. CD34 is expressed on 1% to 4% of bone marrow cells, including pluripotent stem cells and committed progenitors of each hematopoietic lineage. CD34 has also been shown to be expressed on the small vessel endothelium of a variety of tissues and on a subset of bone marrow stromal cells. We have chosen to use the human CD34 gene as model to examine the transcription factors and cis-elements required for stem cell/progenitor cell-specific gene regulation. We show here that the CD34 gene is transcriptionally regulated in tissue culture cells. Using a luciferase reporter gene, we have isolated and characterized an active CD34 promoter. A CD34- luciferase construct, containing 4.5 kb of 5′ flanking DNA from a CD34 genomic clone, was 30-fold more active in CD34+ tissue culture cells than in HeLa cells. Sequences from the 3′ end of the CD34 gene were shown to have enhancing activity in CD34+ T-lymphoblastic RPMI-8402 cells and not in CD34- U937 cells or in nonhematopoietic HeLa cells. We also show that a cytidine-guanosine island in the 5′ end of the CD34 gene is heavily methylated in two CD34- hematopoietic cell lines and demethylated in two CD34+ cell lines. Analysis of the CD34 promoter should result in the identification of stem cell/progenitor cell- specific transcription factors and should provide a means to direct the expression of heterologous genes in hematopoietic stem cells and progenitors.

Characterization of Hematopoietic and Non-Hematopoietic Stem/Progenitor Cells in Freshly Isolated Adult Human Bone Marrow Using an 8-Color Flow Cytometric Assay.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4045-4045
Author(s):  
Ferda Tekinturhan ◽  
Ludovic Zimmerlin ◽  
Vera S. Donnenberg ◽  
Melanie E. Pfeifer ◽  
Darlene A. Monlish ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Mesenchymal Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Progenitor Cells ◽  
Endothelial Progenitor Cells ◽  
Progenitor Cell ◽  
P Value ◽  
Hematopoietic Stem ◽  
Adult Human

Abstract Bone marrow (BM) contains hematopoietic stem cells (HSCs), which can give rise to all mature blood cells and marrow stromal cells as well. Recently, it has been shown that non-hematopoietic stem/progenitor cells which can differentiate into non-hematopoietic tissues also reside in the BM. Although culture expanded cells have been studied in great detail, little is known about the phenotype and quantity of these cells in freshly harvested adult human BM. The aim of this study is to isolate and characterize hematopoietic and non-hematopoietic stem/progenitor cells in adult human BM by comparing two different isolation techniques and their effects on the yield of hematopoietic, mesenchymal and endothelial stem/progenitor cell populations. BM samples were collected mechanically from isolated rib specimens obtained during lung resection (n=10), or from BM aspirates harvested from the humerus of orthopedic patients (n=17). BM mononuclear cells were purified on a Ficoll/Hypaque density gradient and stained simultaneously using CD105 FITC, CD73 PE, CD34 ECD, CD90 PE.Cy5, CD117 PE.Cy7, CD133 APC, CD45 APC.Cy7 and DAPI as a marker of nucleated cells. 2–15 million cells per sample were acquired on a Dako CyAn cytometer and the data were analyzed offline using prototype analytical software (Venturi, Applied Cytometry Systems). The significant difference in the percentage of the CD45 − singlets (non-hematopoietic cells) between BM aspirates and rib-derived samples indicates hemodilution in the bone marrow aspirates. Although we have observed a slight difference in the mean of hematopoietic stem cell content between samples, it was not statistically significant. According to our results, the quantity of mesenchymal stem cells was higher in rib-derived BM than BM aspirates (p value=0.028). The expression of some stem/progenitor cell markers, such as CD90 (Thy-1), CD117 (c-Kit) and CD133 remained similar for all cell types. Our results are shown in the table below. Surface Antigens RibBM (n=10)¥ BMA (n=17)¥ p Value % % Total Cells CD45- of nucleated cells 15.3 ± 7.9 5.7 ± 5.2 0.004 CD34+ Hematopoietic Stem Cells (HSCs)* CD34 of CD45+ 1.7 ± 1.48 2.6 ± 2.0 0.883 CD117 74.6 ± 31.3 53.3 ± 18.8 0.073 CD90 60.3 ± 44.5 35.9 ± 36.5 0.134 CD133 70.3 ± 31.8 62.3 ± 21.4 0.443 Endothelial Progenitor Cells (EPCs)* EPCs of nucleated cells 0.05 ± 0.03 0.12 ± 0.2 0.323 CD117 81.3 ± 29.8 78.1 ± 20.2 0.746 CD90 66.7 ± 39.7 53.7 ± 31.4 0.356 CD133 45.9 ± 32.7 33.9 ± 22.0 0.265 Mesenchymal Stem Cells (MSCs)* MSCs of nucleated cells 0.086 ± 0.14 0.008 ± 0.01 0.028 CD117 60.2 ± 36.8 49.8 ± 34.3 0.471 CD90 66.0 ± 27.7 65.7 ± 29.1 0.981 CD133 37.8 ± 27.4 39.9 ± 28.9 0.857 RibBM: Rib-derived BM, BMA: Bone Marrow Aspirate ¥Data are given as mean ± SD. *CD90, CD117 and CD133 expressions are shown for each stem/progenitor fraction: Hematopoietic stem cells (CD34 + CD45 + and light scatter properties according to the ISHAGE protocol), endothelial progenitor cells (CD34bright CD45 − CD105 +) and mesenchymal stem cells (CD34 − CD45 − CD73 + CD105 +).

The Role of Akt-Forkhead Signaling in the Hematopoietic Stem-Progenitor Cell Differentiation: Expansion of Hematopoietic and Endothelial Progenitors from Akt-1 Null Marrows and Peripheral Blood Involving FKHRL1-Activation.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1704-1704
Author(s):  
Masaki Mogi ◽  
Kenneth Walsh ◽  
Tetsuro Miki
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Cell Differentiation ◽  
Cell Survival ◽  
Progenitor Cell ◽  
Akt Signaling ◽  
Hematopoietic Stem ◽  
Colony Forming Units ◽  
Macrophage Colony

Abstract Akt is an important regulator of cell survival, growth and glucose metabolism in many cell types. In the previous annual meeting, we first reported the role of Akt in the hematopoietic stem cells with Akt-gene knockout mouse models. We described that Akt-signaling modulates the side population (SP) cell by directly regulating the molecular site of Bcrp1, one of the ATP-binding cassette transporters. Akt regulates many downstream targets through phosphorylation of a number of cellular substrates. FKHRL1, one of the FOXO subclass members of the forkhead box transcription factors, has a role in not only regulation of cell-cycle progression and cell survival phosphorylated but also control of cell-differentiation and transformation. FKHRL1 transcription-activities are inhibited by Akt, following induction of a prompt and sustained nuclear exclusion through phosphorylation. In this meeting, we will exhibit how Akt and its downstream signaling, FKHRL1 act during hematopoietic stem-progenitor cell differentiation with Akt1-null mouse studies and endothelial progenitor cell (EPC) assays. In bone marrow cells, a significant increase in formation of macrophage colony-forming units (CFU-M) and granulocyte-macrophage colony-forming units (CFU-GM) was seen in Akt1-null mice. Multiple growth factor responsive progenitor cultures were also more from Akt1-deficient marrows. Moreover, flow cytometry analysis showed the higher ratio of the lineage-negative progenitor cell-population in these marrows. Previously, we reported that bone marrow cellularity and the number of hematopoietic stem cells is normal in Akt1-null mice. These results indicate that lacking of Akt1-signaling leads to the proliferation potential of progenitor cells. Next, we analyzed the number of EPCs in Akt1-deficit mice from peripheral blood mononuclear cells (PBMCs) cultured on mouse fibronectin (FN)-coated dishes. DiI-Ac-LDL/lectin stained EPCs were detected after 10 days. Interestingly, Akt1-defecit mouse-EPCs were quite an increase in number, whereas few EPCs are usually detected from wild-type PBMCs. To address why EPCs were expanded, we used human EPC assay for analyzing signal transduction at detail. After attached on FN, circulating stem cells in PBMCs differentiated into EPCs with four different steps; foci-formation, sprout from the foci, migration for cord-like structure and maturation. Western blot analysis clearly showed that Akt was gradually activated during EPC-differentiation following the inactivation at the first step of differentiation. On the contrary, Akt-downstream targets, FKHRL1 and GSK3-β were inactivated through phosphorylation during differentiation. Immunofluorescent staining showed FKHRL1 was located in nucleus at the foci-formation and translocated into cytosol at the time of sprout from foci formation. Finally, lentivirus-mediated overexpression of Akt and FKHRL1 gene into mouse PBMCs showed FKHRL1-triple mutant, which is not phosphorylatable because of replacing three phosphorylation sites by alanine residues, significantly increased the number of EPCs, while constitutive active-Akt and dominant negative-FKHRL1 failed to. These data suggest that Akt-signaling has an important modulator of the hematopoietic stem-progenitor cell differentiation. FKHRL1 is involved in this mechanism.

MTG16, a Target of the T(16;21) in Acute Myeloid Leukemia, Is Required for Hematopoietic Stem and Progenitor Cell Functions

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 609-609
Author(s):  
Melissa Ann Steapleton ◽  
Isabel Moreno ◽  
Brenda Chyla ◽  
Scott Hiebert
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Progenitor Cells ◽  
Progenitor Cell ◽  
Rapid Expansion ◽  
Erythroid Progenitor ◽  
Hematopoietic Stem ◽  
Cell Fate Decisions ◽  
Cell Functions ◽  
Erythroid Progenitor Cells

Abstract The t(8;21) and t(16;21) disrupt two closely related Myeloid Translocation Gene family members respectively, MTG8 and MTG16. Whereas the expression of MTG8 is highly regulated, MTG16 is more widely expressed and is the family member most highly expressed in hematopoietic stem cells. Therefore, to address the contribution of MTG16 to HSC functions and hematopoiesis, we created mice lacking this gene. We show that this transcriptional co-repressor is required for hematopoietic stem and progenitor cell functions such as cell fate decisions and early progenitor cell proliferation. Inactivation of Mtg16 skewed early myeloid progenitor cells towards the granulocytic/macrophage lineage, while reducing the numbers of megakaryocyte-erythroid progenitor cells, which was shown using both flow cytometry and methylcellulose colony formation assays. In addition, inactivation of Mtg16 impaired the rapid expansion of long and short-term stem cells, multi-potent progenitor cells and megakaryocyte-erythroid progenitor cells that are required under hematopoietic stress/emergency. Due to this, the Mtg16-null mice could not respond to phenylhydrazine or 5-fluorouracil treatment and were completely defective in the colony forming unit-spleen (CFU-S) assays. Additionally, Mtg16-null bone marrow failed to repopulate the hematopoietic system when it was transplanted into an irradiated recipient mouse and also failed to compete with wild-type bone marrow in a competitive bone marrow transplant. This impairment appeared to be due to a failure to proliferate rather than an induction of cell death, as expression of c-Myc, but not Bcl2, complemented the Mtg16(−/−) defect. Thus, like other key transcriptional co-repressors (e.g., the retinoblastoma protein, pRB, and the nuclear hormone co-repressor, N-CoR) Mtg16 is a key regulator of stem cell functions and lineage commitment in hematopoiesis.

Contribution of α6 integrins to hematopoietic stem and progenitor cell homing to bone marrow and collaboration with α4 integrins

Blood ◽  
2006 ◽  
Vol 107 (9) ◽  
pp. 3503-3510 ◽  
Author(s):  
Hong Qian ◽  
Karl Tryggvason ◽  
Sten Eirik Jacobsen ◽  
Marja Ekblom
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Progenitor Cells ◽  
Progenitor Cell ◽  
Laminin Receptor ◽  
Short Term ◽  
Hematopoietic Stem ◽  
Cell Homing ◽  
Stem And Progenitor Cells

The laminin receptor integrin α6 chain is ubiquitously expressed in human and mouse hematopoietic stem and progenitor cells. We have studied its role for homing of stem and progenitor cells to mouse hematopoietic tissues in vivo. A function-blocking anti–integrin α6 antibody significantly reduced progenitor cell homing to bone marrow (BM) of lethally irradiated mice, with a corresponding retention of progenitors in blood. Remarkably, the anti–integrin α6 antibody profoundly inhibited BM homing of long-term multilineage engrafting stem cells, studied by competitive repopulation assay and analysis of donor-derived lymphocytes and myeloid cells in blood 16 weeks after transplantation. A similar profound inhibition of long-term stem cell homing was obtained by using a function-blocking antibody against α4 integrin, studied in parallel. Furthermore, the anti–integrin α6 and α4 antibodies synergistically inhibited homing of short-term repopulating stem cells. Intravenous injection of anti–integrin α6 antibodies, in contrast to antibodies against α4 integrin, did not mobilize progenitors or enhance cytokine-induced mobilization by G-CSF. Our results provide the first evidence for a distinct functional role of integrin α6 receptor during hematopoietic stem and progenitor cell homing and collaboration of α6 integrin with α4 integrin receptors during homing of short-term stem cells.

scholarly journals Myelosuppressive conditioning is required to achieve engraftment of pluripotent stem cells contained in moderate doses of syngeneic bone marrow

Blood ◽  
1994 ◽  
Vol 83 (4) ◽  
pp. 939-948 ◽  
Author(s):  
Y Tomita ◽  
DH Sachs ◽  
M Sykes
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Whole Body ◽  
Mixed Chimerism ◽  
Hematopoietic Stem ◽  
Donor Cells ◽  
Donor Type ◽  
Low Levels

We have investigated the requirement for whole body irradiation (WBI) to achieve engraftment of syngeneic pluripotent hematopoietic stem cells (HSCs). Recipient B6 (H-2b; Ly-5.2) mice received various doses of WBI (0 to 3.0 Gy) and were reconstituted with 1.5 x 10(7) T-cell-depleted (TCD) bone marrow cells (BMCs) from congenic Ly-5.1 donors. Using anti-Ly-5.1 and anti-Ly-5.2 monoclonal antibodies and flow cytometry, the origins of lymphoid and myeloid cells reconstituting the animals were observed over time. Chimerism was at least initially detectable in all groups. However, between 1.5 and 3 Gy WBI was the minimum irradiation dose required to permit induction of long-term (at least 30 weeks), multilineage mixed chimerism in 100% of recipient mice. In these mice, stable reconstitution with approximately 70% to 90% donor-type lymphocytes, granulocytes, and monocytes was observed, suggesting that pluripotent HSC engraftment was achieved. About 50% of animals conditioned with 1.5 Gy WBI showed evidence for donor pluripotent HSC engraftment. Although low levels of chimerism were detected in untreated and 0.5-Gy-irradiated recipients in the early post-BM transplantation (BMT) period, donor cells disappeared completely by 12 to 20 weeks post-BMT. BM colony assays and adoptive transfers into secondary lethally irradiated recipients confirmed the absence of donor progenitors and HSCs, respectively, in the marrow of animals originally conditioned with only 0.5 Gy WBI. These results suggest that syngeneic pluripotent HSCs cannot readily engraft unless host HSCs sustain a significant level of injury, as is induced by 1.5 to 3.0 Gy WBI. We also attempted to determine the duration of the permissive period for syngeneic marrow engraftment in animals conditioned with 3 Gy WBI. Stable multilineage chimerism was uniformly established in 3-Gy-irradiated Ly-5.2 mice only when Ly-5.1 BMC were injected within 7 days of irradiation, suggesting that repair of damaged host stem cells or loss of factors stimulating engraftment may prevent syngeneic marrow engraftment after day 7.

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