Depletion of murine fetal hematopoietic stem cells with c-Kit receptor and CD47 blockade improves neonatal engraftment.
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ABSTRACT:
SUBMITTER: Witt RG
PROVIDER: S-EPMC6306881 | biostudies-literature | 2018 Dec
REPOSITORIES: biostudies-literature
Publications
Depletion of murine fetal hematopoietic stem cells with c-Kit receptor and CD47 blockade improves neonatal engraftment.
Witt Russell G RG Wang Bowen B Nguyen Quoc-Hung QH Eikani Carlo C Mattis Aras N AN MacKenzie Tippi C TC
Blood advances 20181201 24
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Project description:Thrombospondin-1 (TSP-1)/CD47 signaling induces cell death and inhibits angiogenesis. Here, we investigated the possibility of improving donor engraftment by blocking the TSP-1/CD47 pathway in mouse models of total body irradiation (TBI)-conditioned syngeneic hematopoietic stem cell transplantation (HSCT). Our findings revealed that HSCT engraftment was improved in mice deficient in CD47 (Cd47 -/- ) or TSP-1 (Thbs1 -/- ) compared to wild-type (WT) mice. The lack of TSP-1 or CD47 enhanced the production of CXCL12 by megakaryocytes and platelets, promoting the seeding of donor hematopoietic stem cells (HSCs) in sinusoidal endothelial cell (SEC)/megakaryocyte niches. Both Cd47 -/- and Thbs1 -/- mice showed reduced platelet adhesion to sinusoidal vascular cells, attenuated endothelial injury, and enhanced BM vascular regeneration, preserving SEC niches. Antibody neutralization of TSP-1 significantly increased CXCL12 production, donor HSC engraftment, and vascular niche regeneration in WT mice. In summary, the TSP-1/CD47 pathway is a promising therapeutic target to enhance HSCT efficacy and reduce endothelial injury syndrome.
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Project description:Mixed chimerism approaches for induction of tolerance of solid organ transplants have been applied successfully in animal models and in the clinic. However, in xenogeneic models (pig-to-primate), host macrophages participate in the rapid clearance of porcine hematopoietic progenitor cells, hindering the ability to achieve mixed chimerism. CD47 is a cell-surface molecule that interacts in a species-specific manner with SIRP? receptors on macrophages to inhibit phagocytosis and expression of human CD47 (hCD47) on porcine cells has been shown to inhibit phagocytosis by primate macrophages. We report here the generation of hCD47 transgenic GalT-KO miniature swine that express hCD47 in all blood cell lineages. The effect of hCD47 expression on xenogeneic hematopoietic engraftment was tested in an in vivo mouse model of human hematopoietic cell engraftment. High-level porcine chimerism was observed in the bone marrow of hCD47 progenitor cell recipients and smaller but readily measurable chimerism levels were observed in the peripheral blood of these recipients. In contrast, transplantation of WT progenitor cells resulted in little or no bone marrow engraftment and no detectable peripheral chimerism. These results demonstrate a substantial protective effect of hCD47 expression on engraftment and persistence of porcine cells in this model, presumably by modulation of macrophage phagocytosis.
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Project description:BackgroundHematopoietic stem cell transplantation (HSCT) is a curative treatment for many diverse blood and immune diseases. However, HSCT regimens currently commonly utilize genotoxic chemotherapy and/or total body irradiation (TBI) conditioning which causes significant morbidity and mortality through inducing broad tissue damage triggering infections, graft vs. host disease, infertility, and secondary cancers. We previously demonstrated that targeted monoclonal antibody (mAb)-based HSC depletion with anti(α)-CD117 mAbs could be an effective alternative conditioning approach for HSCT without toxicity in severe combined immunodeficiency (SCID) mouse models, which has prompted parallel clinical αCD117 mAbs to be developed and tested as conditioning agents in clinical trials starting with treatment of patients with SCID. Subsequent efforts have built upon this work to develop various combination approaches, though none are optimal and how any of these mAbs fully function is unknown.MethodsTo improve efficacy of mAb-based conditioning as a stand-alone conditioning approach for all HSCT settings, it is critical to understand the mechanistic action of αCD117 mAbs on HSCs. Here, we compare the antagonistic properties of αCD117 mAb clones including ACK2, 2B8, and 3C11 as well as ACK2 fragments in vitro and in vivo in both SCID and wildtype (WT) mouse models. Further, to augment efficacy, combination regimens were also explored.ResultsWe confirm that only ACK2 inhibits SCF binding fully and prevents HSC proliferation in vitro. Further, we verify that this corresponds to HSC depletion in vivo and donor engraftment post HSCT in SCID mice. We also show that SCF-blocking αCD117 mAb fragment derivatives retain similar HSC depletion capacity with enhanced engraftment post HSCT in SCID settings, but only full αCD117 mAb ACK2 in combination with αCD47 mAb enables enhanced donor HSC engraftment in WT settings, highlighting that the Fc region is not required for single-agent efficacy in SCID settings but is required in immunocompetent settings. This combination was the only non-genotoxic conditioning approach that enabled robust donor engraftment post HSCT in WT mice.ConclusionThese findings shed new insights into the mechanism of αCD117 mAb-mediated HSC depletion. Further, they highlight multiple approaches for efficacy in SCID settings and optimal combinations for WT settings. This work is likely to aid in the development of clinical non-genotoxic HSCT conditioning approaches that could benefit millions of people world-wide.
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2022-06-29 | GSE165501 | GEO