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.

Antibody-Based Depletion of Hematopoietic Stem Cells Empties Niches for Efficient Transplantation.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. LB2-LB2
Author(s):  
Agnieszka Czechowicz ◽  
Daniel L. Kraft ◽  
Deepta Bhattacharya ◽  
Irving L. Weissman
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Conditioning Regimen ◽  
Myeloablative Conditioning ◽  
Hematopoietic Stem ◽  
Exact Function ◽  
Potential Applications ◽  
Conditioning Regimens

Abstract Hematopoietic stem cells (HSCs) are used therapeutically in bone marrow/hematopoietic stem cell transplantation (BMT/HSCT) to correct hematolymphoid abnormalities. Upon intravenous transplantation, HSCs can home to specialized bone marrow niches, self-renew and differentiate and thus generate a new, complete hematolymphoid system. Unfortunately BMT has had limited applications, due to the risks associated with the toxic conditioning regimens, such as irradiation and chemotherapy, that are deemed necessary for HSC engraftment. Elimination of these toxic conditioning regimens could expand the potential applications of BMT to include many non-malignant hematologic disorders, a wide variety of autoimmune disorders such as diabetes and multiple sclerosis, as well as in the facilitation of organ transplantation. The exact function of these traditional myeloablative conditioning regimens is not clear. To elucidate the barriers of HSC engraftment, we transplanted 50–1000 purified HSCs (Ckit+Lin−Sca1+CD34+CD150−) into immunodeficient, Rag2−/− or Rag2−/−gc−/− recipient mice and show that HSC engraftment levels rarely exceed 0.5% following transplantation without toxic conditioning, indicating that the immune system is not the only barrier to engraftment. Additionally, we did not observe a significant increase in HSC engraftment when HSC doses of >250 cells were transplanted. Even when up to 18000 HSC were transplanted, we did not see a linear increase in HSC engraftment, indicating that the increased doses of HSCs transplant inefficiently. We believe this is due to the naturally low frequency of available HSC niches, which we postulate may result from the physiologic migration of HSCs into circulation. Conversely, separation of the graft into small fractions and the subsequent time-delayed transplantation of these doses did result in increased engraftment due to the natural physiologic creation of new available HSC niches. When 1800 HSC were transplanted daily for seven days, the engraftment was 6.1-fold higher than transplantation of 12800 HSC in a single bolus. Here, we provide evidence that, aside from immune barriers, donor HSC engraftment is restricted by occupancy of appropriate niches by host HSCs. Through elimination of host HSCs we are able to increase available HSC niches for engraftment. We have developed a novel system where HSCs can be eliminated by targeting C-kit, a cell surface antigen that is highly expressed on the surface of HSCs. Cultivation of HSCs with ACK2, a depleting antibody specific for c-kit, prevented stem-cell factor (SCF) dependent HSC proliferation in vitro and resulted in cell death. Administration of ACK2 to mice led to the rapid and transient removal of >98% of endogenous HSCs in vivo thus resulting in equal numbers of available niches for engraftment. Following ACK2 clearance from serum, transplantation of these animals with donor HSCs led to chimerism levels of up to 90%, representing a 180-fold increase as compared to unconditioned animals. This non-myeloablative conditioning regimen had few side effects, other than temporary loss of coat color. The HSCs in even untransplanted animals rapidly recovered and animals remained healthy and fertile. This work redefines the way we approach BMT/HSCT, and places great emphasis on the necessity to create available HSC niches prior to transplantation. Extrapolation of these methods to humans may enable efficient yet mild conditioning regimens for transplantation, thus expanding the potential applications of BMT/HSCT.

Therapeutic Effect of HOXB4-Expanded Stem Cells in Mice with Beta Thalassemia Given a Non-Myeloablative Conditioning Regimen.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 341-341
Author(s):  
Silvia Bakovic ◽  
Patricia M. Rosten ◽  
Connie J. Eaves ◽  
R. Keith Humphries
Keyword(s):  
Stem Cells ◽  
Gene Therapy ◽  
Ex Vivo ◽  
Globin Gene ◽  
Conditioning Regimen ◽  
Beta Thalassemia ◽  
Mouse Bone Marrow ◽  
Myeloablative Conditioning ◽  
Hematopoietic Stem

Abstract The ultimate promise of gene therapy for patients with hemoglobinopathies depends on the development of safe strategies for achieving 2 goals. One is to obtain efficient and permanent correction of the gene defect in autologous hematopoietic stem cells (HSCs). The second is to develop methods for the pre-transplant amplification of transduced HSCs to high levels to ensure that they will outcompete the large residual endogenous HSC population remaining in non-myeloablated hosts (e.g. previous experiments have shown that a minimum of ~5 × 106 normal adult mouse bone marrow (BM) cells (~500 HSC) is required to achieve a level of chimerism of 20% in mice given 200 cGy). The ability of HOXB4 to promote HSC self-renewal divisions in short term culture prior to their use as transplants offers an attractive approach to achieve this latter goal. As a first test we transduced day-4 5FU BM cells from normal mice with a MSCV-HOXB4-IRES-GFP or control MSCV-IRES-GFP virus and then transplanted the cells either before or after 7 days maintenance in vitro into normal recipients given 250 cGy. Mice transplanted with an estimated 50 HSCs immediately after transduction with either virus reached equivalent low levels of chimerism (~10%) showing that HOXB4 does not impart an in vivo selective growth advantage under sublethal conditions. After ex vivo culture, the GFP transduced cells yielded an even lower level of chimerism (~5%), in contrast recipients of cultured HOXB4-transduced cells attained much higher stable levels of lympho-myeloid chimerism (~50%), indicative of a marked expansion of the HSCs pre-transplant and their retention of robust competitive repopulating potential. We then applied this approach to a gene therapy model of severe β-thalassemia in mice bearing a homozygous deletion of the β-major globin gene (β-MDD). To model a transplant of genetically corrected cells, BM cells were harvested from day-4 5FU pre-treated congenic wild-type donors and transduced with the HOXB4 virus. Cells were then cultured for 10 days and the progeny of 200K starting cells transplanted into 3 β-MDD and 4 normal recipients given 200 cGy. Transplantation of 500K freshly harvested day-4 5FU BM cells into 4 similarly conditioned control mice failed to produce significant chimerism (1–3% at 5 months). In contrast, all 4 control recipients of ex vivo expanded HOXB4-transduced cells exhibited significant stable chimerism (21±6% at 5 months). Similar levels of chimerism were also achieved in all 3 β-MDD recipients (18–76%), one of which was sustained at 34% at 5 months (52% in the RBCs). This was associated with substantial improvement in the Hct (36% vs 23% in untreated β-MDD), Hb (10.5 vs 5 g/dl) and RBC morphology. Southern blot analyses performed on 53 individual in vitro-expanded myeloid colonies generated from FACS-selected GFP+ marrow cells from this mouse 2 months post-transplant showed 19 distinct integration patterns indicating reconstitution from polyclonal expanded HSCs. This conclusion was further confirmed by proviral integration site analyses, which identified 13 separate integration sites from 9 colonies that had unique proviral patterns. These data demonstrate the curative potential of ex vivo expanded HSCs in a preclinical model of β-thalassemia treated with non-myeloablative conditioning. They also underscore the potential of HOXB4 as a potent tool to achieve the HSC expansions required.

Impact of Infusion Rate on the Early Engraftment Following Allogeneic Intra Bone Marrow Infusion of Hematopoietic Stem Cells in a Canine DLA-Identical Reduced Intensity Transplantation Model

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 5406-5406
Author(s):  
Stephanie Schaefer ◽  
Juliane Werner ◽  
Sandra Lange ◽  
Katja Neumann ◽  
Christoph Machka ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Infusion Rate ◽  
Conflicts Of Interest ◽  
Conditioning Regimen ◽  
Hematopoietic Stem ◽  
Time Points ◽  
The Impact ◽  
Reduced Intensity

Abstract Introduction: Direct intra bonemarrow (IBM) infusion of hematopoietic stem cells (HSC) is assumed to improve the homing efficiency and to accelerate the early engraftment in comparison to the conventional intravenous application of HSC. Especially for transplantation of low cell numbers i.e. "weak grafts" that is generally associated with delayed engraftment. The direct infusion of HSC in close proximity to the HSC niche by intra bone marrow transplantation (IBMT) might be a promising way. Whether the HSC infusion rate might influence the homing process and therefore the outcome after IBMT is so far unknown. Aims: Herein, we analyzed in a canine DLA-identical littermate model the impact of different graft infusion rates on the hematopoietic recovery as well as on the engraftment kinetics after IBMT following reduced intensity conditioning. Methods: Recipient dogs received IBMT following a 4.5 Gy total body irradiation (TBI). From day (d) -1 until d+35 Cyclosporin A (15mg/kg) was administered orally twice a day as immunosuppression. For IBM transfusion the graft volume was reduced by buffy coat centrifugation and dogs obtained 2x25 ml simultaneously into the humerus and femur. The infusion rate of the graft was 25ml/10 min in group 1 (IBM10, n = 8) and 25 ml/60 min in group 2 (IBM60, n = 7). A 28 day follow-up is currently available for twelve dogs (IBM10 n = 7; IBM60 n = 5). The development of the peripheral blood mononuclear cell (PBMC) and granulocyte chimerism was tested weekly. Blood count, kidney and liver enzymes were monitored routinely. Results: All animals engrafted. One dog of the IBM10 group died at d+15 (infection) and was therefore not included into analysis. The median number of infused total nucleated cells were in IBM10 4.1*108/kg (range 2.3-6.0*108/kg) and in IBM60 3.2*108/kg (range 1.8-4.4*108/kg; p=0.4). The infused CD34+ numbers were median 3.2*106/kg (range: 1.2-10.0*106/kg; IBM10) and 3.6*106/kg (range: 1.5-6.8*106/kg; IBM60; p=0.7). Time of leukocyte recovery was median d+11 after IBMT in both groups (range: d+4 to d+11, IBM10; d+8 to d+14, IBM60; p= 0.5). Median leukocytes nadirs amounted to 0.2*109/l for IBM10 and 0.3*109/l for IBM60 (p= 0.08). The median duration of leukopenia (<1*109/l) were similar (6d, range: 4-11d, IBM10; 3-9d, IBM60) (p= 0.6). Median platelet nadir was 0*109/l for both cohorts (range: 0.0-7.0*109/l, IBM10; 0.0-1.0*109/l, IBM60). The period of thrombocytopenia (≤20.0*109/l) was significantly prolonged in the IBM60 group (median 10d, range) compared to 5d (range: 3-12d) in the IBM10 group (p=0.05). Donor PBMC chimerisms at d+7, d+14 and d+28 were median 22% (range: 8-34%), 50% (range: 29-53%) and 67% (range: 47-73%) in IBM10. The results of PBMC chimerism for IBM60 were 11% (range: 5-34%), 42% (range: 20-42%) and 59% (range: 44-66%) at these time points (p = n.s.). Donor granulocyte chimerisms of median 33% (range: 11-83%), 100% (range: 58-100%) and 100% (range: 82-100%) were detected at d+7, d+14 and d+28 after HSCT in IBM10, respectively. The granulocyte chimerism in IBM60 amounted to 34% (range: 3-87%), 96% (range: 94-100%) and 98% (range: 96-100%) at the above mentioned time points p=n.s. for all time points). Conclusion: Our data suggest that early granulocyte and PBMC engraftment is not influenced by modification of the HSC infusion rate. However, the period of thrombocytopenia seems to be prolonged following a 60 minutes application. Therefore, longer infusion times in an IBMT setting seem not to be beneficial following toxicity reduced conditioning regimen. Disclosures No relevant conflicts of interest to declare.

scholarly journals Delayed activation of quiescent donor hematopoietic stem cells in the host marrow cavity by anti-host monoclonal antibody

Blood ◽  
1989 ◽  
Vol 74 (7) ◽  
pp. 2325-2329
Author(s):  
MW Sadelain ◽  
TG Wegmann
Keyword(s):  
Stem Cells ◽  
Monoclonal Antibody ◽  
Hematopoietic Stem Cells ◽  
Graft Failure ◽  
Cellular Proliferation ◽  
Conditioning Regimen ◽  
Host Cells ◽  
Hematopoietic Stem ◽  
F1 Hybrid ◽  
Marrow Cavity

To understand the mechanisms controlling hematopoietic engraftment in untreated, normal recipients, we investigated the fate of parental, donor hematopoietic stem cells after apparent graft failures in unconditioned F1 hybrid recipient mice. By administering an anti-host H- 2K monoclonal antibody, which targets host cells but spares the donor, we found that chimerism could be induced by delayed conditioning in animals with apparent graft failure. Engraftment kinetics in the host were followed by typing individual colony forming unit-- granulocyte/macrophage (CFU-GM) colonies for their origin and showed that parental cells, which were otherwise virtually absent, become promptly detectable within the marrow cavity after antibody administration. Marrow transfers to secondary hosts suggested that parental stem cells were present in the marrow of the untreated recipients. These findings establish that the elimination of all parental cells cannot account for the absence of peripheral blood chimerism in the unconditioned F1 hybrid recipient. Thus, viable and functional donor stem cells, which remain quiescent in the host marrow, can be activated by a selective conditioning regimen and can rescue an apparent graft failure. The selective activation in vivo of marked stem cells in an unirradiated microenvironment may be a useful system to study the regulation of cellular proliferation within the marrow cavity.

Full donor chimerism after allogeneic hematopoietic stem cells transplant for myelofibrosis: The role of the conditioning regimen

2020 ◽  
Author(s):  
Patrizia Chiusolo ◽  
Stefania Bregante ◽  
Sabrina Giammarco ◽  
Teresa Lamparelli ◽  
Lucia Casarino ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Conditioning Regimen ◽  
Hematopoietic Stem ◽  
Donor Chimerism

Low dose-rate irradiation specifically affects hematopoietic stem cells

2016 ◽  
Vol 44 (9) ◽  
pp. S101-S102
Author(s):  
Yoshihiro Takihara ◽  
Yoshinori Ohno ◽  
Kyoko Suzuki-Takedachi ◽  
Mimoko Santo ◽  
Shin’ichiro Yasunaga ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Dose Rate ◽  
Low Dose ◽  
Hematopoietic Stem ◽  
Low Dose Rate

Conditioning with fludarabine and targeted busulfan for transplantation of allogeneic hematopoietic stem cells

Blood ◽  
2003 ◽  
Vol 102 (3) ◽  
pp. 820-826 ◽  
Author(s):  
Martin Bornhäuser ◽  
Barry Storer ◽  
John T. Slattery ◽  
Frederick R. Appelbaum ◽  
H. Joachim Deeg ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Conditioning Regimen ◽  
Disease Free Survival ◽  
Myelogenous Leukemia ◽  
Hematopoietic Stem ◽  
Blood Stem Cells ◽  
Risk Patients ◽  
Unrelated Donors ◽  
Reduced Toxicity

Abstract A regimen of busulfan and cyclophosphamide is standard therapy before transplantation of allogeneic hematopoietic stem cells in patients with chronic myelogenous leukemia (CML) or myelodysplastic syndrome (MDS). The clinical trial reported here was undertaken to test the hypothesis that fludarabine can replace cyclophosphamide in this regimen and facilitate donor engraftment with reduced toxicity. The conditioning regimen consisted of 30 mg/m2 intravenous fludarabine daily from day -9 to day -6, and oral busulfan given at 1 mg/kg 4 times a day every 6 hours from day -5 to day -2, with doses adjusted to target plasma levels of 900 ± 100 ng/mL at steady state. Cyclosporine and methotrexate were used for prophylaxis for graft-versus-host disease. Enrolled were 42 patients with high-risk CML (n = 4) or MDS (n = 38). The median patient age was 52 years (range, 12-65 years). Mobilized blood stem cells were obtained from HLA-compatible siblings (n = 16) or unrelated donors (n = 26). Engraftment was achieved in all patients, and the day-100 regimen-related mortality was 7%. With a median follow-up of 18 months (range, 13-27 months), the probabilities of overall survival, disease-free survival, and nonrelapse mortality were 42.4%, 34.9%, and 24%, respectively. These data indicate that the combination of fludarabine and targeted busulfan is sufficiently immunosuppressive to facilitate engraftment of blood stem cells from HLA-matched siblings and unrelated donors. Based on these encouraging results, further studies of fludarabine and targeted busulfan are warranted in standard-risk patients.

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