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Hematopoietic cells (HCs) promote blood vessel formation by producing various proangiogenic cytokines and chemokines and matrix metalloproteinases. We injected mouse colon26 colon cancer cells or human PC3 prostate adenocarcinoma cells into mice and studied the localization of HCs during tumor development. HCs were distributed in the inner tumor mass in all of the tumor tissues examined; however,the localization of HCs in the tumor tissue differed depending on the tumor cell type. In the case of colon26 tumors,as the tumor grew,many mature HCs migrated into the tumor mass before fine capillary formation was observed. On the other hand,although very few HCs migrated into PC3 tumor tissue,c-Kit+ hematopoietic stem/progenitor cells accumulated around the edge of the tumor. Bone marrow suppression induced by injection of anti-c-Kit neutralizing antibody suppressed tumor angiogenesis by different mechanisms according to the tumor cell type: bone marrow suppression inhibited the initiation of sprouting angiogenesis in colon26 tumors,while it suppressed an increase in the caliber of newly developed blood vessels at the tumor edge in PC3 tumors. Our findings suggest that HCs are involved in tumor angiogenesis and regulate the angiogenic switch during tumorigenesis. View Publication

Bone marrow-derived endothelial precursor cells incorporate into neovasculature and have been successfully used as vehicles for gene delivery to brain tumors. To determine whether systemically administered Sca1+ bone marrow cells labeled with superparamagnetic iron oxide nanoparticles can be detected by in vivo magnetic resonance imaging in a mouse brain tumor model,mouse Sca1+ cells were labeled in vitro with ferumoxides-poly-L-lysine complexes. Labeled or control cells were administered intravenously to glioma-bearing severe combined immunodeficient (SCID) mice. Magnetic resonance imaging (MRI) was performed during tumor growth. Mice that received labeled cells demonstrated hypointense regions within the tumor that evolved over time and developed a continuous dark hypointense ring at a consistent time point. This effect was not cleared by administration of a gadolinium contrast agent. Histology showed iron-labeled cells around the tumor rim in labeled mice,which expressed CD31 and von Willebrand factor,indicating the transplanted cells detected in the tumor have differentiated into endothelial-like cells. These results demonstrate that MRI can detect the incorporation of magnetically labeled bone marrow-derived precursor cells into tumor vasculature as part of ongoing angiogenesis and neovascularization. This technique can be used to directly identify neovasculature in vivo and to facilitate gene therapy by noninvasively monitoring these cells as gene delivery vectors. View Publication

PURPOSE: Allogeneic T lymphocytes can induce regression of metastatic breast cancer through an immune-mediated graft-versus-tumor (GVT) effect in murine models. To determine if a clinical GVT effect exists against metastatic breast cancer,allogeneic lymphocytes were used as adoptive cellular therapy after a reduced-intensity chemotherapy conditioning regimen and allogeneic hematopoietic stem-cell transplantation (HSCT) from human leukocyte antigen-matched siblings. PATIENTS AND METHODS: Sixteen patients with metastatic breast cancer that had progressed after treatment with anthracyclines,taxanes,hormonal agents,and trastuzumab,received allogeneic HSCT. The reduced-intensity transplant conditioning regimen consisted of cyclophosphamide and fludarabine. To distinguish an immunological GVT effect from any antitumor effect of cytotoxic chemotherapy in the transplant-conditioning regimen,allogeneic T lymphocytes were removed from the stem-cell graft and were subsequently administered late postallogeneic HSCT. Allogeneic lymphocytes containing 1 x 10(6),5 x 10(6),and 10 x 10(6) CD3(+) cells/kg were infused on days +42,+70,and +98 post-allogeneic HSCT,respectively. RESULTS: Objective tumor regressions occurred after day +28 post-allogeneic HSCT in six patients and were attributed to allogeneic lymphocyte infusions. Two of these responding patients had disease progression post-allogeneic HSCT before subsequent tumor regression. Tumor regressions occurred concomitantly with the establishment of complete donor T-lymphoid engraftment,were associated with the development of graft-versus-host disease (GVHD),and were abrogated by subsequent systemic immunosuppression for GVHD. CONCLUSION: Allogeneic lymphocytes can induce regression of advanced metastatic breast cancer. These results indicate that an immunological GVT effect from allogeneic lymphocytes exists against metastatic breast cancer and provide rationale for further development of allogeneic cellular therapy for this largely incurable disease. View Publication

The AML1/CBFbeta transcriptional complex is essential for the formation of definitive hematopoietic stem cells (HSCs). Moreover,development of the hematopoietic system is exquisitely sensitive to the level of this complex. To investigate the effect of AML1 dosage on adult hematopoiesis,we compared the hematopoietic systems of AML1+/- and AML1+/+ mice. Surprisingly,loss of a single AML1 allele resulted in a 50% reduction in long-term repopulating hematopoietic stem cells (LTR-HSCs). This decrease did not,however,extend to the next level of hematopoietic differentiation. Instead,AML1+/- mice had an increase in multilineage progenitors,an expansion that resulted in enhanced engraftment following transplantation. The expanded pool of AML1+/- progenitors remained responsive to homeostatic mechanisms and thus the number of mature cells in most lineages remained within normal limits. Two notable exceptions were a decrease in CD4(+) T cells,leading to an inversion of the CD4(+) to CD8(+) T-cell ratio and a decrease in circulating platelets. These data demonstrate a dosage-dependent role for AML1/CBFbeta in regulating the quantity of HSCs and their downstream committed progenitors,as well as a more restricted role in T cells and platelets. The latter defect mimics one of the key abnormalities in human patients with the familial platelet disorder resulting from AML1 haploinsufficiency. View Publication

Granulomas are innate sequestration responses that can be modified by superimposed acquired immune mechanisms. The present study examined the innate stage of pulmonary granuloma responses to bead-immobilized Th1- and Th2-inducing pathogen antigens (Ags),Mycobacteria bovis purified protein derivative (PPD) and Schistosoma mansoni soluble egg Ags (SEA). Compared to a nonpathogen Ag,PPD and SEA bead elicited larger lesions with the former showing accelerated inflammation. Temporal analyses of cytokine and chemokine transcripts showed all Ag beads induced tumor necrosis factor-alpha mRNA but indicated biased interleukin (IL)-1,IL-6,and IL-12 expression with PPD challenge. All beads elicited comparable levels of CXCL9,CXL10,CCL2,CCL17,and CCL22 mRNA,but PPD beads caused biased CXCL2 CXCL5,CCL3,and CCL4 expression whereas both pathogen Ags induced CCL7. Immunohistochemical,electron microscopic,and flow cytometric analyses showed that Ag beads mobilized CD11c+ dendritic cells (DCs) of comparable maturation. Transfer of DCs from PPD Ag-challenged lungs conferred a Th1 anamnestic cytokine response in recipients. Surprisingly,transfer of DCs from the helminth SEA-challenged lungs did not confer the expected Th2 response,but instead rendered recipients incapable of Ag-elicited IL-4 production. These results provide in vivo evidence that lung DCs recruited under inflammatory conditions favor Th1 responses and alternative mechanisms are required for Th2 commitment. View Publication

The functional characteristics were compared for acute myelogenous leukemia (AML) cells (native blasts and AML cell lines) cultured in three serum-free media (X-vivo 10,X-vivo 15,[Bio-Whitacker,Walkersville,MD] and StemSpan [Stem Cell Technologies,Vancouver,BC,Canada]) and in medium containing 10% inactivated fetal calf serum (FCS). For native AML blasts the following functions were compared: (1) autonomous and cytokine-dependent proliferation; (2) frequency of clonogenic cell; and (3) constitutive cytokine secretion. AML blast proliferation differed between patients independent of the culture medium used,and clonogenic cells were maintained after in vitro culture in all media. In contrast,constitutive cytokine secretion was higher for cells cultured in StemSpan and FCS-containing medium than for cells cultured in the X-vivo media. Native AML blasts incubated in StemSpan also showed a low frequency of apoptotic cells. The three serum-free media could also be used for long-term expansion of well-characterized AML cell lines,but the optimal medium for cell expansion and cytokine secretion differed between cell lines. We conclude that standardized serum-free culture conditions can be used for in vitro studies of native AML blasts and AML cell lines. View Publication