Continuous in vivo infusion of interferon-gamma (IFN-γ) enhances engraftment of syngeneic wild-type cells in Fanca–/– and Fancg–/– mice

Abstract

IntroductionFanconi anemia (FA) is a heterogeneous genetic disorder characterized by a progressive bone marrow aplasia, chromosomal instability, and the acquisition of malignancies. The progressive bone marrow failure in FA and the late developing myeloid malignancies account for 90% of the mortality in FA. 1 Currently, the only cure for the hematopoietic manifestations of FA is HLA-identical allogeneic bone marrow transplantation, a therapy available to only about 30% of patients. 2 Twelve FA complementation types (FANCA, FANCB, FANCC, FANCD1, FANCD2, FANCE, FANCF, FANCG, FANCI, FANCJ, FANCL, and FANCM) have been identified and the cDNAs of 11 FA genes have been sequenced. [3][4][5][6][7][8][9][10] The identification of these genes raises the potential of using gene transfer technology to express the functional cDNA into autologous stem cells. The bone marrow hypoplasia commonly observed in FA patients 1 and the reduced repopulating ability of stem cells in mice containing a disruption of the murine homologue of an FA gene 11,12 led to the hypothesis that autologous, genetically-corrected stem cells would have an engraftment and proliferation advantage. However, ex vivo culture is known to reduce stem cell engraftment in both normal murine and human cells, [13][14][15] and in an initial phase 1 clinical trial in FA patients where myelopreparation was not routinely performed 16 the detection of transduced cells was low in all patients. Furthermore, the most efficient engraftment of transduced cells in the clinical FA trial was observed in a single patient who received nonlethal ionizing radiation. Collectively, these data provide rationale for considering nonmyeloablative therapy prior to transplantation of autologous genetically-corrected stem cells.FA cells exhibit increased chromosomal breaks in response to DNA-damaging agents in vitro. 3,17 Thus there is a theoretical potential of FA patients having an increased incidence for secondary malignancies following myelopreparation with genotoxic agents. Due to the low frequency of FA in the general population 18 and the high incidence of malignant predisposition of FA patients, it is difficult to fully ascertain the risk associated with the genotoxic myelopreparation regimen in patients. However, several studies suggest an increased risk for hematopoietic and nonhematopoietic secondary malignancies [19][20][21][22] after hematopoietic stem cell transplantation in FA patients. For these reasons, a nongenotoxic myelopreparative regimen would be ideal in selecting geneticallycorrected stem cells in vivo.Interferon-gamma (IFN-␥) is a nongenotoxic immunoregulatory lymphokine with a high therapeutic index 23 that has been used to treat a number of malignancies. [24][25][26] Rathbun et al provided the first evidence that murine (Fancc Ϫ/Ϫ ) and human (FANCC) hematopoietic cells were hypersensitive to IFN-␥ via an increase in apoptosis. 27 These results were subsequently confirmed in an independent Fancc Ϫ/Ϫ murine model in vitro and in vivo. 28,29 Previous work indica...

AMD3100 synergizes with G-CSF to mobilize repopulating stem cells in Fanconi anemia knockout mice

“…As expected from previous studies [29,37,40], both Fanca −/− and Fancc −/− mice had a significant decrease in bone marrow repopulating ability as compared to the repopulating ability of WT mice. However, in response to GCSF alone, this decrease in repopulating ability was accompanied by an additional decrease in the proportion of repopulating units mobilized from the bone marrow to the peripheral blood.…”

“…Fanca −/− mice and Fancc −/− mice on a C57BL/6J background were used as detailed in previous studies [36,37]. Congenic wildtype C57BL/6J (WT) mice and wildtype B6.SJLPtrca Pep/BoyJ (BoyJ) mice were purchased from Jackson ImmunoResearch Laboratories.…”

From the Molecular Biology to the Gene Therapy of a DNA Repair Syndrome: Fanconi Anemia

“…This was demonstrated by the observation that BM cells from WT animals could repopulate in the long-term the hematopoietic tissues of FA-D1 unconditioned recipients [111]. This contrasts with studies conducted in other FA mouse models where only after the treatment with IFNγ [112,113] or DNA damaging drugs, wild-type BM cells could be engrafted in FA recipients (Table 2). In the field of gene therapy, it was shown for the first time in Fancc -/-mice that the retroviralmediated expression of Fancc corrects the defective repopulation ability of FA HSCs [114].…”

Mesenchymal stem/progenitor cells promote the reconstitution of exogenous hematopoietic stem cells in Fancg−/− mice in vivo

“…[29][30][31] The results show that the FA pathway is critical for the BM microenvironment to maintain normal hematopoiesis, and they provide the first quantitative and genetic evidence that transplantation of mesenchymal cells enhances the engraftment of wild-type (WT) HSPCs. For personal use only.…”